5. interaction of ionizing radiation with matter2fe607d0-fe61-47e8-b55d-839480… · interaction of...
TRANSCRIPT
CHE-711-Teil2-FS17-1
5 Interaction of Ionizing Radiation with Matter
Type of radiationcharged particles
photonenneutronen Uncharged bdquoparticlesldquo
Charged particleselectrons (b-) neg
He2+ (a) H+(p) D+ (d)Recoil nuclidesFission fragments
Wir koumlnnen die Wechselwirkung dieser Strahlen als Elementarprozesse betrachten (Einzelprozesse)
oder als makroskopische Effekte (Abschwaumlchung Absorption Streuung etc)
260417
CHE-711-Teil2-FS17-2
Interaction of Ionizing Radiation with MatterPraktische Auswirkungen der Strahlung
Strahlung Bremsung Energieabnahme
Materie Physikalische chemische biologische Wirkung
Parameter welche bei der Wechselwirkung eine Rolle spielen
TeilchenMasse LadungGeschwindigkeit kinetische EnergieSpin
Materie
Atommasse M IKernladungszahl ZAnzahl e- pro VolumenDichteIonisationspotentiale
260417
CHE-711-Teil2-FS17-3
Synopsis of interactions with the electronshell
Ungeladene Teilchen PhotonenPhotoeffektComptoneffekt(Paar Erzeugung)
geladene Teilchen Kernreaktionen
PhotonenBremsstrahlungPaarbildungKernreaktionen
Neutronen Kernreaktionen
Mit den Atomkernen
Interaction of Ionizing Radiation with Matter
260417
CHE-711-Teil2-FS17-4
Wir unterscheiden zwischen direkt ionisierend a b- b+ hellip
Energie reicht aus durch Stoss Ionen zu erzeugen
und indirekt ionisierend n + g setzen erst im Material Ionen frei
In the context of radiation absorption two definitions are important
linear stopping power
and linear energy transfer
If no Bremsstrahlung (see later) SI and LI are equal otherwise there will be a substantial difference
also important
Ionizing Radiation
260417
CHE-711-Teil2-FS17-5
Uumlbersicht der Wechselwirkung (von Materie) mit Elektronen
Geladene Teilchen - Bremsung durch unelastische Streuung
- Ionisation und Anregung
Interaction of Ionizing Radiation with Matter
260417
CHE-711-Teil2-FS17-6
by collision with electrons the incident particle ionizes matter
the mean energy to remove an electron is called the W-factor
W-factor for air is 3385eVIP
When the charged particle travels through matter it makes
an energy dependent number of ionization length
this is the specific ionization SI
we can determine the mean energy loss per path length
LET = SI∙WLinear Energy Transfer
Ionizing Radiation
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CHE-711-Teil2-FS17-7
The lower the energy the higher the SI
since probability of interaction with shell electron increases
Bragg Peak
Ionizing Radiation
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CHE-711-Teil2-FS17-8
Letlsquos make an example
241 Am was in smoke detectors Ea=548 MeV
specific ionization (SI) = 34104 IPcm
LET = 34middot104middot338 = 12 MeVcm
Range = = = 48 cm
This is the maximum range since the SI increases dramatically at the end of the path
Ionizing Radiation
260417
CHE-711-Teil2-FS17-9
Interaction with other materials SI will change since e--density changesone measure is the relative stopping power (see before)
RSP = RairRabs (R = Range)
RSP values for some materials and particles
Ionizing Radiation
260417
CHE-711-Teil2-FS17-10
Ranges in air for different particles and energies
Ionizing Radiation
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CHE-711-Teil2-FS17-11
Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms
Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber
-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells
thereby ions are generated
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-12
mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials
please note since e- are light particles relativistic effects have to be considered
E = 100 keVE = 1000 keV
v = 055 cv = 094 c
m = 12 ∙ mo
m = 3 ∙ mo
for lower energies the relativistic effects can be neglected
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-13
both formulas predict a minimum value
depending only on the mass of the particle
thus the slower the particle the more ionization per length will appear
dEdx at a certain energy
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-14
absorption of electrons (b- radiation)
Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons
Y(x) = Y(0) ∙ e-micro∙x
with micro = konst
or N(x) = N0 ∙ e-micro∙x
with micro = linear absorption coefficient (see x-ray crystallography)
inspecting the Bethe-Bloch formula it is obviously an exponential formula
empiricallyit translates into
Ionizing Radiation Electrons
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CHE-711-Teil2-FS17-15
thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x
then
with microd = mass absorption coefficient
note that micro is a function of the electron energy and the material
it allows to calculate the maximum range of electrons in a material
it allows to calculate the thickness of materials for shielding
absorption of electrons (b- radiation)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-16
Example equivalent range of e- in Al
one can easily calculate the path for reducing the e--flux to 50
x12 can be determined experimentally and micro be calculated for a particular material
andx12 = ln2micro
d12 = (ln2)(micro8)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-17
There exists also a semiempirical relationship between micro d and Emax
and there are semiempirical relationships for connecting range with electron energy
(015 lt Eβ lt 08 MeV)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-18
Calculate the maximum range of different β-emitters
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-19
How much energy can be lost in a single collision
of particular interest collision with a shell electron
maximum energy transfer
incoming particle mass Mi speed Vi1
electron mass me speed 0
after collision Mi v2 me ve
Energy frac12 Mimiddotv12 = frac12 Mimiddotv2
2 + frac12 memiddot ve2
momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)
Ionizing Radiation Electrons
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CHE-711-Teil2-FS17-20
maximum energy transfer
speed of reflected particle
MET Qmax = nicht relativistisch
If Mi = me (electron on electron)
then Qmax = E
explains why light particles have a zigzag pass in matter
take an a-particle colliding with an e-
me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u
QmaxE = = 000054 = 005
Thatlsquos why heavy particles travel straight
Ionizing Radiation Electrons
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CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
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CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
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CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
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CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
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CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
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CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
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CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
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CHE-711-Teil2-FS17-28
Bremsstrahlung
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CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
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CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
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CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
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CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
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CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
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CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
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CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
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CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
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CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
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CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
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CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
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CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
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CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
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CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
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CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
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CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
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CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-2
Interaction of Ionizing Radiation with MatterPraktische Auswirkungen der Strahlung
Strahlung Bremsung Energieabnahme
Materie Physikalische chemische biologische Wirkung
Parameter welche bei der Wechselwirkung eine Rolle spielen
TeilchenMasse LadungGeschwindigkeit kinetische EnergieSpin
Materie
Atommasse M IKernladungszahl ZAnzahl e- pro VolumenDichteIonisationspotentiale
260417
CHE-711-Teil2-FS17-3
Synopsis of interactions with the electronshell
Ungeladene Teilchen PhotonenPhotoeffektComptoneffekt(Paar Erzeugung)
geladene Teilchen Kernreaktionen
PhotonenBremsstrahlungPaarbildungKernreaktionen
Neutronen Kernreaktionen
Mit den Atomkernen
Interaction of Ionizing Radiation with Matter
260417
CHE-711-Teil2-FS17-4
Wir unterscheiden zwischen direkt ionisierend a b- b+ hellip
Energie reicht aus durch Stoss Ionen zu erzeugen
und indirekt ionisierend n + g setzen erst im Material Ionen frei
In the context of radiation absorption two definitions are important
linear stopping power
and linear energy transfer
If no Bremsstrahlung (see later) SI and LI are equal otherwise there will be a substantial difference
also important
Ionizing Radiation
260417
CHE-711-Teil2-FS17-5
Uumlbersicht der Wechselwirkung (von Materie) mit Elektronen
Geladene Teilchen - Bremsung durch unelastische Streuung
- Ionisation und Anregung
Interaction of Ionizing Radiation with Matter
260417
CHE-711-Teil2-FS17-6
by collision with electrons the incident particle ionizes matter
the mean energy to remove an electron is called the W-factor
W-factor for air is 3385eVIP
When the charged particle travels through matter it makes
an energy dependent number of ionization length
this is the specific ionization SI
we can determine the mean energy loss per path length
LET = SI∙WLinear Energy Transfer
Ionizing Radiation
260417
CHE-711-Teil2-FS17-7
The lower the energy the higher the SI
since probability of interaction with shell electron increases
Bragg Peak
Ionizing Radiation
260417
CHE-711-Teil2-FS17-8
Letlsquos make an example
241 Am was in smoke detectors Ea=548 MeV
specific ionization (SI) = 34104 IPcm
LET = 34middot104middot338 = 12 MeVcm
Range = = = 48 cm
This is the maximum range since the SI increases dramatically at the end of the path
Ionizing Radiation
260417
CHE-711-Teil2-FS17-9
Interaction with other materials SI will change since e--density changesone measure is the relative stopping power (see before)
RSP = RairRabs (R = Range)
RSP values for some materials and particles
Ionizing Radiation
260417
CHE-711-Teil2-FS17-10
Ranges in air for different particles and energies
Ionizing Radiation
260417
CHE-711-Teil2-FS17-11
Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms
Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber
-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells
thereby ions are generated
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-12
mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials
please note since e- are light particles relativistic effects have to be considered
E = 100 keVE = 1000 keV
v = 055 cv = 094 c
m = 12 ∙ mo
m = 3 ∙ mo
for lower energies the relativistic effects can be neglected
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-13
both formulas predict a minimum value
depending only on the mass of the particle
thus the slower the particle the more ionization per length will appear
dEdx at a certain energy
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-14
absorption of electrons (b- radiation)
Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons
Y(x) = Y(0) ∙ e-micro∙x
with micro = konst
or N(x) = N0 ∙ e-micro∙x
with micro = linear absorption coefficient (see x-ray crystallography)
inspecting the Bethe-Bloch formula it is obviously an exponential formula
empiricallyit translates into
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-15
thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x
then
with microd = mass absorption coefficient
note that micro is a function of the electron energy and the material
it allows to calculate the maximum range of electrons in a material
it allows to calculate the thickness of materials for shielding
absorption of electrons (b- radiation)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-16
Example equivalent range of e- in Al
one can easily calculate the path for reducing the e--flux to 50
x12 can be determined experimentally and micro be calculated for a particular material
andx12 = ln2micro
d12 = (ln2)(micro8)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-17
There exists also a semiempirical relationship between micro d and Emax
and there are semiempirical relationships for connecting range with electron energy
(015 lt Eβ lt 08 MeV)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-18
Calculate the maximum range of different β-emitters
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-19
How much energy can be lost in a single collision
of particular interest collision with a shell electron
maximum energy transfer
incoming particle mass Mi speed Vi1
electron mass me speed 0
after collision Mi v2 me ve
Energy frac12 Mimiddotv12 = frac12 Mimiddotv2
2 + frac12 memiddot ve2
momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-20
maximum energy transfer
speed of reflected particle
MET Qmax = nicht relativistisch
If Mi = me (electron on electron)
then Qmax = E
explains why light particles have a zigzag pass in matter
take an a-particle colliding with an e-
me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u
QmaxE = = 000054 = 005
Thatlsquos why heavy particles travel straight
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-3
Synopsis of interactions with the electronshell
Ungeladene Teilchen PhotonenPhotoeffektComptoneffekt(Paar Erzeugung)
geladene Teilchen Kernreaktionen
PhotonenBremsstrahlungPaarbildungKernreaktionen
Neutronen Kernreaktionen
Mit den Atomkernen
Interaction of Ionizing Radiation with Matter
260417
CHE-711-Teil2-FS17-4
Wir unterscheiden zwischen direkt ionisierend a b- b+ hellip
Energie reicht aus durch Stoss Ionen zu erzeugen
und indirekt ionisierend n + g setzen erst im Material Ionen frei
In the context of radiation absorption two definitions are important
linear stopping power
and linear energy transfer
If no Bremsstrahlung (see later) SI and LI are equal otherwise there will be a substantial difference
also important
Ionizing Radiation
260417
CHE-711-Teil2-FS17-5
Uumlbersicht der Wechselwirkung (von Materie) mit Elektronen
Geladene Teilchen - Bremsung durch unelastische Streuung
- Ionisation und Anregung
Interaction of Ionizing Radiation with Matter
260417
CHE-711-Teil2-FS17-6
by collision with electrons the incident particle ionizes matter
the mean energy to remove an electron is called the W-factor
W-factor for air is 3385eVIP
When the charged particle travels through matter it makes
an energy dependent number of ionization length
this is the specific ionization SI
we can determine the mean energy loss per path length
LET = SI∙WLinear Energy Transfer
Ionizing Radiation
260417
CHE-711-Teil2-FS17-7
The lower the energy the higher the SI
since probability of interaction with shell electron increases
Bragg Peak
Ionizing Radiation
260417
CHE-711-Teil2-FS17-8
Letlsquos make an example
241 Am was in smoke detectors Ea=548 MeV
specific ionization (SI) = 34104 IPcm
LET = 34middot104middot338 = 12 MeVcm
Range = = = 48 cm
This is the maximum range since the SI increases dramatically at the end of the path
Ionizing Radiation
260417
CHE-711-Teil2-FS17-9
Interaction with other materials SI will change since e--density changesone measure is the relative stopping power (see before)
RSP = RairRabs (R = Range)
RSP values for some materials and particles
Ionizing Radiation
260417
CHE-711-Teil2-FS17-10
Ranges in air for different particles and energies
Ionizing Radiation
260417
CHE-711-Teil2-FS17-11
Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms
Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber
-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells
thereby ions are generated
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-12
mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials
please note since e- are light particles relativistic effects have to be considered
E = 100 keVE = 1000 keV
v = 055 cv = 094 c
m = 12 ∙ mo
m = 3 ∙ mo
for lower energies the relativistic effects can be neglected
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-13
both formulas predict a minimum value
depending only on the mass of the particle
thus the slower the particle the more ionization per length will appear
dEdx at a certain energy
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-14
absorption of electrons (b- radiation)
Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons
Y(x) = Y(0) ∙ e-micro∙x
with micro = konst
or N(x) = N0 ∙ e-micro∙x
with micro = linear absorption coefficient (see x-ray crystallography)
inspecting the Bethe-Bloch formula it is obviously an exponential formula
empiricallyit translates into
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-15
thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x
then
with microd = mass absorption coefficient
note that micro is a function of the electron energy and the material
it allows to calculate the maximum range of electrons in a material
it allows to calculate the thickness of materials for shielding
absorption of electrons (b- radiation)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-16
Example equivalent range of e- in Al
one can easily calculate the path for reducing the e--flux to 50
x12 can be determined experimentally and micro be calculated for a particular material
andx12 = ln2micro
d12 = (ln2)(micro8)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-17
There exists also a semiempirical relationship between micro d and Emax
and there are semiempirical relationships for connecting range with electron energy
(015 lt Eβ lt 08 MeV)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-18
Calculate the maximum range of different β-emitters
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-19
How much energy can be lost in a single collision
of particular interest collision with a shell electron
maximum energy transfer
incoming particle mass Mi speed Vi1
electron mass me speed 0
after collision Mi v2 me ve
Energy frac12 Mimiddotv12 = frac12 Mimiddotv2
2 + frac12 memiddot ve2
momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-20
maximum energy transfer
speed of reflected particle
MET Qmax = nicht relativistisch
If Mi = me (electron on electron)
then Qmax = E
explains why light particles have a zigzag pass in matter
take an a-particle colliding with an e-
me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u
QmaxE = = 000054 = 005
Thatlsquos why heavy particles travel straight
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-4
Wir unterscheiden zwischen direkt ionisierend a b- b+ hellip
Energie reicht aus durch Stoss Ionen zu erzeugen
und indirekt ionisierend n + g setzen erst im Material Ionen frei
In the context of radiation absorption two definitions are important
linear stopping power
and linear energy transfer
If no Bremsstrahlung (see later) SI and LI are equal otherwise there will be a substantial difference
also important
Ionizing Radiation
260417
CHE-711-Teil2-FS17-5
Uumlbersicht der Wechselwirkung (von Materie) mit Elektronen
Geladene Teilchen - Bremsung durch unelastische Streuung
- Ionisation und Anregung
Interaction of Ionizing Radiation with Matter
260417
CHE-711-Teil2-FS17-6
by collision with electrons the incident particle ionizes matter
the mean energy to remove an electron is called the W-factor
W-factor for air is 3385eVIP
When the charged particle travels through matter it makes
an energy dependent number of ionization length
this is the specific ionization SI
we can determine the mean energy loss per path length
LET = SI∙WLinear Energy Transfer
Ionizing Radiation
260417
CHE-711-Teil2-FS17-7
The lower the energy the higher the SI
since probability of interaction with shell electron increases
Bragg Peak
Ionizing Radiation
260417
CHE-711-Teil2-FS17-8
Letlsquos make an example
241 Am was in smoke detectors Ea=548 MeV
specific ionization (SI) = 34104 IPcm
LET = 34middot104middot338 = 12 MeVcm
Range = = = 48 cm
This is the maximum range since the SI increases dramatically at the end of the path
Ionizing Radiation
260417
CHE-711-Teil2-FS17-9
Interaction with other materials SI will change since e--density changesone measure is the relative stopping power (see before)
RSP = RairRabs (R = Range)
RSP values for some materials and particles
Ionizing Radiation
260417
CHE-711-Teil2-FS17-10
Ranges in air for different particles and energies
Ionizing Radiation
260417
CHE-711-Teil2-FS17-11
Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms
Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber
-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells
thereby ions are generated
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-12
mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials
please note since e- are light particles relativistic effects have to be considered
E = 100 keVE = 1000 keV
v = 055 cv = 094 c
m = 12 ∙ mo
m = 3 ∙ mo
for lower energies the relativistic effects can be neglected
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-13
both formulas predict a minimum value
depending only on the mass of the particle
thus the slower the particle the more ionization per length will appear
dEdx at a certain energy
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-14
absorption of electrons (b- radiation)
Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons
Y(x) = Y(0) ∙ e-micro∙x
with micro = konst
or N(x) = N0 ∙ e-micro∙x
with micro = linear absorption coefficient (see x-ray crystallography)
inspecting the Bethe-Bloch formula it is obviously an exponential formula
empiricallyit translates into
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-15
thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x
then
with microd = mass absorption coefficient
note that micro is a function of the electron energy and the material
it allows to calculate the maximum range of electrons in a material
it allows to calculate the thickness of materials for shielding
absorption of electrons (b- radiation)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-16
Example equivalent range of e- in Al
one can easily calculate the path for reducing the e--flux to 50
x12 can be determined experimentally and micro be calculated for a particular material
andx12 = ln2micro
d12 = (ln2)(micro8)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-17
There exists also a semiempirical relationship between micro d and Emax
and there are semiempirical relationships for connecting range with electron energy
(015 lt Eβ lt 08 MeV)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-18
Calculate the maximum range of different β-emitters
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-19
How much energy can be lost in a single collision
of particular interest collision with a shell electron
maximum energy transfer
incoming particle mass Mi speed Vi1
electron mass me speed 0
after collision Mi v2 me ve
Energy frac12 Mimiddotv12 = frac12 Mimiddotv2
2 + frac12 memiddot ve2
momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-20
maximum energy transfer
speed of reflected particle
MET Qmax = nicht relativistisch
If Mi = me (electron on electron)
then Qmax = E
explains why light particles have a zigzag pass in matter
take an a-particle colliding with an e-
me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u
QmaxE = = 000054 = 005
Thatlsquos why heavy particles travel straight
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-5
Uumlbersicht der Wechselwirkung (von Materie) mit Elektronen
Geladene Teilchen - Bremsung durch unelastische Streuung
- Ionisation und Anregung
Interaction of Ionizing Radiation with Matter
260417
CHE-711-Teil2-FS17-6
by collision with electrons the incident particle ionizes matter
the mean energy to remove an electron is called the W-factor
W-factor for air is 3385eVIP
When the charged particle travels through matter it makes
an energy dependent number of ionization length
this is the specific ionization SI
we can determine the mean energy loss per path length
LET = SI∙WLinear Energy Transfer
Ionizing Radiation
260417
CHE-711-Teil2-FS17-7
The lower the energy the higher the SI
since probability of interaction with shell electron increases
Bragg Peak
Ionizing Radiation
260417
CHE-711-Teil2-FS17-8
Letlsquos make an example
241 Am was in smoke detectors Ea=548 MeV
specific ionization (SI) = 34104 IPcm
LET = 34middot104middot338 = 12 MeVcm
Range = = = 48 cm
This is the maximum range since the SI increases dramatically at the end of the path
Ionizing Radiation
260417
CHE-711-Teil2-FS17-9
Interaction with other materials SI will change since e--density changesone measure is the relative stopping power (see before)
RSP = RairRabs (R = Range)
RSP values for some materials and particles
Ionizing Radiation
260417
CHE-711-Teil2-FS17-10
Ranges in air for different particles and energies
Ionizing Radiation
260417
CHE-711-Teil2-FS17-11
Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms
Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber
-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells
thereby ions are generated
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-12
mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials
please note since e- are light particles relativistic effects have to be considered
E = 100 keVE = 1000 keV
v = 055 cv = 094 c
m = 12 ∙ mo
m = 3 ∙ mo
for lower energies the relativistic effects can be neglected
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-13
both formulas predict a minimum value
depending only on the mass of the particle
thus the slower the particle the more ionization per length will appear
dEdx at a certain energy
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-14
absorption of electrons (b- radiation)
Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons
Y(x) = Y(0) ∙ e-micro∙x
with micro = konst
or N(x) = N0 ∙ e-micro∙x
with micro = linear absorption coefficient (see x-ray crystallography)
inspecting the Bethe-Bloch formula it is obviously an exponential formula
empiricallyit translates into
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-15
thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x
then
with microd = mass absorption coefficient
note that micro is a function of the electron energy and the material
it allows to calculate the maximum range of electrons in a material
it allows to calculate the thickness of materials for shielding
absorption of electrons (b- radiation)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-16
Example equivalent range of e- in Al
one can easily calculate the path for reducing the e--flux to 50
x12 can be determined experimentally and micro be calculated for a particular material
andx12 = ln2micro
d12 = (ln2)(micro8)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-17
There exists also a semiempirical relationship between micro d and Emax
and there are semiempirical relationships for connecting range with electron energy
(015 lt Eβ lt 08 MeV)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-18
Calculate the maximum range of different β-emitters
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-19
How much energy can be lost in a single collision
of particular interest collision with a shell electron
maximum energy transfer
incoming particle mass Mi speed Vi1
electron mass me speed 0
after collision Mi v2 me ve
Energy frac12 Mimiddotv12 = frac12 Mimiddotv2
2 + frac12 memiddot ve2
momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-20
maximum energy transfer
speed of reflected particle
MET Qmax = nicht relativistisch
If Mi = me (electron on electron)
then Qmax = E
explains why light particles have a zigzag pass in matter
take an a-particle colliding with an e-
me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u
QmaxE = = 000054 = 005
Thatlsquos why heavy particles travel straight
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-6
by collision with electrons the incident particle ionizes matter
the mean energy to remove an electron is called the W-factor
W-factor for air is 3385eVIP
When the charged particle travels through matter it makes
an energy dependent number of ionization length
this is the specific ionization SI
we can determine the mean energy loss per path length
LET = SI∙WLinear Energy Transfer
Ionizing Radiation
260417
CHE-711-Teil2-FS17-7
The lower the energy the higher the SI
since probability of interaction with shell electron increases
Bragg Peak
Ionizing Radiation
260417
CHE-711-Teil2-FS17-8
Letlsquos make an example
241 Am was in smoke detectors Ea=548 MeV
specific ionization (SI) = 34104 IPcm
LET = 34middot104middot338 = 12 MeVcm
Range = = = 48 cm
This is the maximum range since the SI increases dramatically at the end of the path
Ionizing Radiation
260417
CHE-711-Teil2-FS17-9
Interaction with other materials SI will change since e--density changesone measure is the relative stopping power (see before)
RSP = RairRabs (R = Range)
RSP values for some materials and particles
Ionizing Radiation
260417
CHE-711-Teil2-FS17-10
Ranges in air for different particles and energies
Ionizing Radiation
260417
CHE-711-Teil2-FS17-11
Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms
Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber
-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells
thereby ions are generated
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-12
mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials
please note since e- are light particles relativistic effects have to be considered
E = 100 keVE = 1000 keV
v = 055 cv = 094 c
m = 12 ∙ mo
m = 3 ∙ mo
for lower energies the relativistic effects can be neglected
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-13
both formulas predict a minimum value
depending only on the mass of the particle
thus the slower the particle the more ionization per length will appear
dEdx at a certain energy
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-14
absorption of electrons (b- radiation)
Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons
Y(x) = Y(0) ∙ e-micro∙x
with micro = konst
or N(x) = N0 ∙ e-micro∙x
with micro = linear absorption coefficient (see x-ray crystallography)
inspecting the Bethe-Bloch formula it is obviously an exponential formula
empiricallyit translates into
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-15
thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x
then
with microd = mass absorption coefficient
note that micro is a function of the electron energy and the material
it allows to calculate the maximum range of electrons in a material
it allows to calculate the thickness of materials for shielding
absorption of electrons (b- radiation)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-16
Example equivalent range of e- in Al
one can easily calculate the path for reducing the e--flux to 50
x12 can be determined experimentally and micro be calculated for a particular material
andx12 = ln2micro
d12 = (ln2)(micro8)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-17
There exists also a semiempirical relationship between micro d and Emax
and there are semiempirical relationships for connecting range with electron energy
(015 lt Eβ lt 08 MeV)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-18
Calculate the maximum range of different β-emitters
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-19
How much energy can be lost in a single collision
of particular interest collision with a shell electron
maximum energy transfer
incoming particle mass Mi speed Vi1
electron mass me speed 0
after collision Mi v2 me ve
Energy frac12 Mimiddotv12 = frac12 Mimiddotv2
2 + frac12 memiddot ve2
momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-20
maximum energy transfer
speed of reflected particle
MET Qmax = nicht relativistisch
If Mi = me (electron on electron)
then Qmax = E
explains why light particles have a zigzag pass in matter
take an a-particle colliding with an e-
me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u
QmaxE = = 000054 = 005
Thatlsquos why heavy particles travel straight
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-7
The lower the energy the higher the SI
since probability of interaction with shell electron increases
Bragg Peak
Ionizing Radiation
260417
CHE-711-Teil2-FS17-8
Letlsquos make an example
241 Am was in smoke detectors Ea=548 MeV
specific ionization (SI) = 34104 IPcm
LET = 34middot104middot338 = 12 MeVcm
Range = = = 48 cm
This is the maximum range since the SI increases dramatically at the end of the path
Ionizing Radiation
260417
CHE-711-Teil2-FS17-9
Interaction with other materials SI will change since e--density changesone measure is the relative stopping power (see before)
RSP = RairRabs (R = Range)
RSP values for some materials and particles
Ionizing Radiation
260417
CHE-711-Teil2-FS17-10
Ranges in air for different particles and energies
Ionizing Radiation
260417
CHE-711-Teil2-FS17-11
Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms
Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber
-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells
thereby ions are generated
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-12
mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials
please note since e- are light particles relativistic effects have to be considered
E = 100 keVE = 1000 keV
v = 055 cv = 094 c
m = 12 ∙ mo
m = 3 ∙ mo
for lower energies the relativistic effects can be neglected
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-13
both formulas predict a minimum value
depending only on the mass of the particle
thus the slower the particle the more ionization per length will appear
dEdx at a certain energy
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-14
absorption of electrons (b- radiation)
Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons
Y(x) = Y(0) ∙ e-micro∙x
with micro = konst
or N(x) = N0 ∙ e-micro∙x
with micro = linear absorption coefficient (see x-ray crystallography)
inspecting the Bethe-Bloch formula it is obviously an exponential formula
empiricallyit translates into
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-15
thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x
then
with microd = mass absorption coefficient
note that micro is a function of the electron energy and the material
it allows to calculate the maximum range of electrons in a material
it allows to calculate the thickness of materials for shielding
absorption of electrons (b- radiation)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-16
Example equivalent range of e- in Al
one can easily calculate the path for reducing the e--flux to 50
x12 can be determined experimentally and micro be calculated for a particular material
andx12 = ln2micro
d12 = (ln2)(micro8)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-17
There exists also a semiempirical relationship between micro d and Emax
and there are semiempirical relationships for connecting range with electron energy
(015 lt Eβ lt 08 MeV)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-18
Calculate the maximum range of different β-emitters
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-19
How much energy can be lost in a single collision
of particular interest collision with a shell electron
maximum energy transfer
incoming particle mass Mi speed Vi1
electron mass me speed 0
after collision Mi v2 me ve
Energy frac12 Mimiddotv12 = frac12 Mimiddotv2
2 + frac12 memiddot ve2
momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-20
maximum energy transfer
speed of reflected particle
MET Qmax = nicht relativistisch
If Mi = me (electron on electron)
then Qmax = E
explains why light particles have a zigzag pass in matter
take an a-particle colliding with an e-
me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u
QmaxE = = 000054 = 005
Thatlsquos why heavy particles travel straight
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-8
Letlsquos make an example
241 Am was in smoke detectors Ea=548 MeV
specific ionization (SI) = 34104 IPcm
LET = 34middot104middot338 = 12 MeVcm
Range = = = 48 cm
This is the maximum range since the SI increases dramatically at the end of the path
Ionizing Radiation
260417
CHE-711-Teil2-FS17-9
Interaction with other materials SI will change since e--density changesone measure is the relative stopping power (see before)
RSP = RairRabs (R = Range)
RSP values for some materials and particles
Ionizing Radiation
260417
CHE-711-Teil2-FS17-10
Ranges in air for different particles and energies
Ionizing Radiation
260417
CHE-711-Teil2-FS17-11
Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms
Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber
-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells
thereby ions are generated
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-12
mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials
please note since e- are light particles relativistic effects have to be considered
E = 100 keVE = 1000 keV
v = 055 cv = 094 c
m = 12 ∙ mo
m = 3 ∙ mo
for lower energies the relativistic effects can be neglected
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-13
both formulas predict a minimum value
depending only on the mass of the particle
thus the slower the particle the more ionization per length will appear
dEdx at a certain energy
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-14
absorption of electrons (b- radiation)
Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons
Y(x) = Y(0) ∙ e-micro∙x
with micro = konst
or N(x) = N0 ∙ e-micro∙x
with micro = linear absorption coefficient (see x-ray crystallography)
inspecting the Bethe-Bloch formula it is obviously an exponential formula
empiricallyit translates into
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-15
thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x
then
with microd = mass absorption coefficient
note that micro is a function of the electron energy and the material
it allows to calculate the maximum range of electrons in a material
it allows to calculate the thickness of materials for shielding
absorption of electrons (b- radiation)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-16
Example equivalent range of e- in Al
one can easily calculate the path for reducing the e--flux to 50
x12 can be determined experimentally and micro be calculated for a particular material
andx12 = ln2micro
d12 = (ln2)(micro8)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-17
There exists also a semiempirical relationship between micro d and Emax
and there are semiempirical relationships for connecting range with electron energy
(015 lt Eβ lt 08 MeV)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-18
Calculate the maximum range of different β-emitters
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-19
How much energy can be lost in a single collision
of particular interest collision with a shell electron
maximum energy transfer
incoming particle mass Mi speed Vi1
electron mass me speed 0
after collision Mi v2 me ve
Energy frac12 Mimiddotv12 = frac12 Mimiddotv2
2 + frac12 memiddot ve2
momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-20
maximum energy transfer
speed of reflected particle
MET Qmax = nicht relativistisch
If Mi = me (electron on electron)
then Qmax = E
explains why light particles have a zigzag pass in matter
take an a-particle colliding with an e-
me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u
QmaxE = = 000054 = 005
Thatlsquos why heavy particles travel straight
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-9
Interaction with other materials SI will change since e--density changesone measure is the relative stopping power (see before)
RSP = RairRabs (R = Range)
RSP values for some materials and particles
Ionizing Radiation
260417
CHE-711-Teil2-FS17-10
Ranges in air for different particles and energies
Ionizing Radiation
260417
CHE-711-Teil2-FS17-11
Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms
Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber
-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells
thereby ions are generated
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-12
mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials
please note since e- are light particles relativistic effects have to be considered
E = 100 keVE = 1000 keV
v = 055 cv = 094 c
m = 12 ∙ mo
m = 3 ∙ mo
for lower energies the relativistic effects can be neglected
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-13
both formulas predict a minimum value
depending only on the mass of the particle
thus the slower the particle the more ionization per length will appear
dEdx at a certain energy
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-14
absorption of electrons (b- radiation)
Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons
Y(x) = Y(0) ∙ e-micro∙x
with micro = konst
or N(x) = N0 ∙ e-micro∙x
with micro = linear absorption coefficient (see x-ray crystallography)
inspecting the Bethe-Bloch formula it is obviously an exponential formula
empiricallyit translates into
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-15
thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x
then
with microd = mass absorption coefficient
note that micro is a function of the electron energy and the material
it allows to calculate the maximum range of electrons in a material
it allows to calculate the thickness of materials for shielding
absorption of electrons (b- radiation)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-16
Example equivalent range of e- in Al
one can easily calculate the path for reducing the e--flux to 50
x12 can be determined experimentally and micro be calculated for a particular material
andx12 = ln2micro
d12 = (ln2)(micro8)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-17
There exists also a semiempirical relationship between micro d and Emax
and there are semiempirical relationships for connecting range with electron energy
(015 lt Eβ lt 08 MeV)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-18
Calculate the maximum range of different β-emitters
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-19
How much energy can be lost in a single collision
of particular interest collision with a shell electron
maximum energy transfer
incoming particle mass Mi speed Vi1
electron mass me speed 0
after collision Mi v2 me ve
Energy frac12 Mimiddotv12 = frac12 Mimiddotv2
2 + frac12 memiddot ve2
momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-20
maximum energy transfer
speed of reflected particle
MET Qmax = nicht relativistisch
If Mi = me (electron on electron)
then Qmax = E
explains why light particles have a zigzag pass in matter
take an a-particle colliding with an e-
me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u
QmaxE = = 000054 = 005
Thatlsquos why heavy particles travel straight
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-10
Ranges in air for different particles and energies
Ionizing Radiation
260417
CHE-711-Teil2-FS17-11
Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms
Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber
-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells
thereby ions are generated
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-12
mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials
please note since e- are light particles relativistic effects have to be considered
E = 100 keVE = 1000 keV
v = 055 cv = 094 c
m = 12 ∙ mo
m = 3 ∙ mo
for lower energies the relativistic effects can be neglected
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-13
both formulas predict a minimum value
depending only on the mass of the particle
thus the slower the particle the more ionization per length will appear
dEdx at a certain energy
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-14
absorption of electrons (b- radiation)
Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons
Y(x) = Y(0) ∙ e-micro∙x
with micro = konst
or N(x) = N0 ∙ e-micro∙x
with micro = linear absorption coefficient (see x-ray crystallography)
inspecting the Bethe-Bloch formula it is obviously an exponential formula
empiricallyit translates into
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-15
thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x
then
with microd = mass absorption coefficient
note that micro is a function of the electron energy and the material
it allows to calculate the maximum range of electrons in a material
it allows to calculate the thickness of materials for shielding
absorption of electrons (b- radiation)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-16
Example equivalent range of e- in Al
one can easily calculate the path for reducing the e--flux to 50
x12 can be determined experimentally and micro be calculated for a particular material
andx12 = ln2micro
d12 = (ln2)(micro8)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-17
There exists also a semiempirical relationship between micro d and Emax
and there are semiempirical relationships for connecting range with electron energy
(015 lt Eβ lt 08 MeV)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-18
Calculate the maximum range of different β-emitters
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-19
How much energy can be lost in a single collision
of particular interest collision with a shell electron
maximum energy transfer
incoming particle mass Mi speed Vi1
electron mass me speed 0
after collision Mi v2 me ve
Energy frac12 Mimiddotv12 = frac12 Mimiddotv2
2 + frac12 memiddot ve2
momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-20
maximum energy transfer
speed of reflected particle
MET Qmax = nicht relativistisch
If Mi = me (electron on electron)
then Qmax = E
explains why light particles have a zigzag pass in matter
take an a-particle colliding with an e-
me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u
QmaxE = = 000054 = 005
Thatlsquos why heavy particles travel straight
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-11
Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms
Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber
-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells
thereby ions are generated
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-12
mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials
please note since e- are light particles relativistic effects have to be considered
E = 100 keVE = 1000 keV
v = 055 cv = 094 c
m = 12 ∙ mo
m = 3 ∙ mo
for lower energies the relativistic effects can be neglected
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-13
both formulas predict a minimum value
depending only on the mass of the particle
thus the slower the particle the more ionization per length will appear
dEdx at a certain energy
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-14
absorption of electrons (b- radiation)
Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons
Y(x) = Y(0) ∙ e-micro∙x
with micro = konst
or N(x) = N0 ∙ e-micro∙x
with micro = linear absorption coefficient (see x-ray crystallography)
inspecting the Bethe-Bloch formula it is obviously an exponential formula
empiricallyit translates into
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-15
thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x
then
with microd = mass absorption coefficient
note that micro is a function of the electron energy and the material
it allows to calculate the maximum range of electrons in a material
it allows to calculate the thickness of materials for shielding
absorption of electrons (b- radiation)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-16
Example equivalent range of e- in Al
one can easily calculate the path for reducing the e--flux to 50
x12 can be determined experimentally and micro be calculated for a particular material
andx12 = ln2micro
d12 = (ln2)(micro8)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-17
There exists also a semiempirical relationship between micro d and Emax
and there are semiempirical relationships for connecting range with electron energy
(015 lt Eβ lt 08 MeV)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-18
Calculate the maximum range of different β-emitters
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-19
How much energy can be lost in a single collision
of particular interest collision with a shell electron
maximum energy transfer
incoming particle mass Mi speed Vi1
electron mass me speed 0
after collision Mi v2 me ve
Energy frac12 Mimiddotv12 = frac12 Mimiddotv2
2 + frac12 memiddot ve2
momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-20
maximum energy transfer
speed of reflected particle
MET Qmax = nicht relativistisch
If Mi = me (electron on electron)
then Qmax = E
explains why light particles have a zigzag pass in matter
take an a-particle colliding with an e-
me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u
QmaxE = = 000054 = 005
Thatlsquos why heavy particles travel straight
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-12
mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials
please note since e- are light particles relativistic effects have to be considered
E = 100 keVE = 1000 keV
v = 055 cv = 094 c
m = 12 ∙ mo
m = 3 ∙ mo
for lower energies the relativistic effects can be neglected
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-13
both formulas predict a minimum value
depending only on the mass of the particle
thus the slower the particle the more ionization per length will appear
dEdx at a certain energy
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-14
absorption of electrons (b- radiation)
Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons
Y(x) = Y(0) ∙ e-micro∙x
with micro = konst
or N(x) = N0 ∙ e-micro∙x
with micro = linear absorption coefficient (see x-ray crystallography)
inspecting the Bethe-Bloch formula it is obviously an exponential formula
empiricallyit translates into
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-15
thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x
then
with microd = mass absorption coefficient
note that micro is a function of the electron energy and the material
it allows to calculate the maximum range of electrons in a material
it allows to calculate the thickness of materials for shielding
absorption of electrons (b- radiation)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-16
Example equivalent range of e- in Al
one can easily calculate the path for reducing the e--flux to 50
x12 can be determined experimentally and micro be calculated for a particular material
andx12 = ln2micro
d12 = (ln2)(micro8)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-17
There exists also a semiempirical relationship between micro d and Emax
and there are semiempirical relationships for connecting range with electron energy
(015 lt Eβ lt 08 MeV)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-18
Calculate the maximum range of different β-emitters
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-19
How much energy can be lost in a single collision
of particular interest collision with a shell electron
maximum energy transfer
incoming particle mass Mi speed Vi1
electron mass me speed 0
after collision Mi v2 me ve
Energy frac12 Mimiddotv12 = frac12 Mimiddotv2
2 + frac12 memiddot ve2
momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-20
maximum energy transfer
speed of reflected particle
MET Qmax = nicht relativistisch
If Mi = me (electron on electron)
then Qmax = E
explains why light particles have a zigzag pass in matter
take an a-particle colliding with an e-
me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u
QmaxE = = 000054 = 005
Thatlsquos why heavy particles travel straight
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-13
both formulas predict a minimum value
depending only on the mass of the particle
thus the slower the particle the more ionization per length will appear
dEdx at a certain energy
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-14
absorption of electrons (b- radiation)
Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons
Y(x) = Y(0) ∙ e-micro∙x
with micro = konst
or N(x) = N0 ∙ e-micro∙x
with micro = linear absorption coefficient (see x-ray crystallography)
inspecting the Bethe-Bloch formula it is obviously an exponential formula
empiricallyit translates into
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-15
thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x
then
with microd = mass absorption coefficient
note that micro is a function of the electron energy and the material
it allows to calculate the maximum range of electrons in a material
it allows to calculate the thickness of materials for shielding
absorption of electrons (b- radiation)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-16
Example equivalent range of e- in Al
one can easily calculate the path for reducing the e--flux to 50
x12 can be determined experimentally and micro be calculated for a particular material
andx12 = ln2micro
d12 = (ln2)(micro8)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-17
There exists also a semiempirical relationship between micro d and Emax
and there are semiempirical relationships for connecting range with electron energy
(015 lt Eβ lt 08 MeV)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-18
Calculate the maximum range of different β-emitters
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-19
How much energy can be lost in a single collision
of particular interest collision with a shell electron
maximum energy transfer
incoming particle mass Mi speed Vi1
electron mass me speed 0
after collision Mi v2 me ve
Energy frac12 Mimiddotv12 = frac12 Mimiddotv2
2 + frac12 memiddot ve2
momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-20
maximum energy transfer
speed of reflected particle
MET Qmax = nicht relativistisch
If Mi = me (electron on electron)
then Qmax = E
explains why light particles have a zigzag pass in matter
take an a-particle colliding with an e-
me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u
QmaxE = = 000054 = 005
Thatlsquos why heavy particles travel straight
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-14
absorption of electrons (b- radiation)
Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons
Y(x) = Y(0) ∙ e-micro∙x
with micro = konst
or N(x) = N0 ∙ e-micro∙x
with micro = linear absorption coefficient (see x-ray crystallography)
inspecting the Bethe-Bloch formula it is obviously an exponential formula
empiricallyit translates into
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-15
thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x
then
with microd = mass absorption coefficient
note that micro is a function of the electron energy and the material
it allows to calculate the maximum range of electrons in a material
it allows to calculate the thickness of materials for shielding
absorption of electrons (b- radiation)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-16
Example equivalent range of e- in Al
one can easily calculate the path for reducing the e--flux to 50
x12 can be determined experimentally and micro be calculated for a particular material
andx12 = ln2micro
d12 = (ln2)(micro8)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-17
There exists also a semiempirical relationship between micro d and Emax
and there are semiempirical relationships for connecting range with electron energy
(015 lt Eβ lt 08 MeV)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-18
Calculate the maximum range of different β-emitters
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-19
How much energy can be lost in a single collision
of particular interest collision with a shell electron
maximum energy transfer
incoming particle mass Mi speed Vi1
electron mass me speed 0
after collision Mi v2 me ve
Energy frac12 Mimiddotv12 = frac12 Mimiddotv2
2 + frac12 memiddot ve2
momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-20
maximum energy transfer
speed of reflected particle
MET Qmax = nicht relativistisch
If Mi = me (electron on electron)
then Qmax = E
explains why light particles have a zigzag pass in matter
take an a-particle colliding with an e-
me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u
QmaxE = = 000054 = 005
Thatlsquos why heavy particles travel straight
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-15
thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x
then
with microd = mass absorption coefficient
note that micro is a function of the electron energy and the material
it allows to calculate the maximum range of electrons in a material
it allows to calculate the thickness of materials for shielding
absorption of electrons (b- radiation)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-16
Example equivalent range of e- in Al
one can easily calculate the path for reducing the e--flux to 50
x12 can be determined experimentally and micro be calculated for a particular material
andx12 = ln2micro
d12 = (ln2)(micro8)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-17
There exists also a semiempirical relationship between micro d and Emax
and there are semiempirical relationships for connecting range with electron energy
(015 lt Eβ lt 08 MeV)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-18
Calculate the maximum range of different β-emitters
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-19
How much energy can be lost in a single collision
of particular interest collision with a shell electron
maximum energy transfer
incoming particle mass Mi speed Vi1
electron mass me speed 0
after collision Mi v2 me ve
Energy frac12 Mimiddotv12 = frac12 Mimiddotv2
2 + frac12 memiddot ve2
momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-20
maximum energy transfer
speed of reflected particle
MET Qmax = nicht relativistisch
If Mi = me (electron on electron)
then Qmax = E
explains why light particles have a zigzag pass in matter
take an a-particle colliding with an e-
me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u
QmaxE = = 000054 = 005
Thatlsquos why heavy particles travel straight
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-16
Example equivalent range of e- in Al
one can easily calculate the path for reducing the e--flux to 50
x12 can be determined experimentally and micro be calculated for a particular material
andx12 = ln2micro
d12 = (ln2)(micro8)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-17
There exists also a semiempirical relationship between micro d and Emax
and there are semiempirical relationships for connecting range with electron energy
(015 lt Eβ lt 08 MeV)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-18
Calculate the maximum range of different β-emitters
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-19
How much energy can be lost in a single collision
of particular interest collision with a shell electron
maximum energy transfer
incoming particle mass Mi speed Vi1
electron mass me speed 0
after collision Mi v2 me ve
Energy frac12 Mimiddotv12 = frac12 Mimiddotv2
2 + frac12 memiddot ve2
momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-20
maximum energy transfer
speed of reflected particle
MET Qmax = nicht relativistisch
If Mi = me (electron on electron)
then Qmax = E
explains why light particles have a zigzag pass in matter
take an a-particle colliding with an e-
me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u
QmaxE = = 000054 = 005
Thatlsquos why heavy particles travel straight
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-17
There exists also a semiempirical relationship between micro d and Emax
and there are semiempirical relationships for connecting range with electron energy
(015 lt Eβ lt 08 MeV)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-18
Calculate the maximum range of different β-emitters
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-19
How much energy can be lost in a single collision
of particular interest collision with a shell electron
maximum energy transfer
incoming particle mass Mi speed Vi1
electron mass me speed 0
after collision Mi v2 me ve
Energy frac12 Mimiddotv12 = frac12 Mimiddotv2
2 + frac12 memiddot ve2
momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-20
maximum energy transfer
speed of reflected particle
MET Qmax = nicht relativistisch
If Mi = me (electron on electron)
then Qmax = E
explains why light particles have a zigzag pass in matter
take an a-particle colliding with an e-
me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u
QmaxE = = 000054 = 005
Thatlsquos why heavy particles travel straight
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-18
Calculate the maximum range of different β-emitters
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-19
How much energy can be lost in a single collision
of particular interest collision with a shell electron
maximum energy transfer
incoming particle mass Mi speed Vi1
electron mass me speed 0
after collision Mi v2 me ve
Energy frac12 Mimiddotv12 = frac12 Mimiddotv2
2 + frac12 memiddot ve2
momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-20
maximum energy transfer
speed of reflected particle
MET Qmax = nicht relativistisch
If Mi = me (electron on electron)
then Qmax = E
explains why light particles have a zigzag pass in matter
take an a-particle colliding with an e-
me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u
QmaxE = = 000054 = 005
Thatlsquos why heavy particles travel straight
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-19
How much energy can be lost in a single collision
of particular interest collision with a shell electron
maximum energy transfer
incoming particle mass Mi speed Vi1
electron mass me speed 0
after collision Mi v2 me ve
Energy frac12 Mimiddotv12 = frac12 Mimiddotv2
2 + frac12 memiddot ve2
momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-20
maximum energy transfer
speed of reflected particle
MET Qmax = nicht relativistisch
If Mi = me (electron on electron)
then Qmax = E
explains why light particles have a zigzag pass in matter
take an a-particle colliding with an e-
me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u
QmaxE = = 000054 = 005
Thatlsquos why heavy particles travel straight
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-20
maximum energy transfer
speed of reflected particle
MET Qmax = nicht relativistisch
If Mi = me (electron on electron)
then Qmax = E
explains why light particles have a zigzag pass in matter
take an a-particle colliding with an e-
me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u
QmaxE = = 000054 = 005
Thatlsquos why heavy particles travel straight
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-21
before going further what is the speed of a particle of a given energy E and rest mass m0
easy E = frac12 mo∙v2 true for energies with speed away from c
relativistic equation
aufgeloumlst for an electron with E = 100keV
1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec
E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-22
of speed of light c
this can be calculated for all particles back to maximum energy transfer
Qmax =
reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually
with
Ionizing Radiation Electrons
260417
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-23
Examples for protons H
Proton KineticEnergy E(MeV)
011
10100
103
104
105
106
107
Qmax(MeV)
00002200022002190229333136106 x 104
538 x 105
921 x 106
Maximum percentageenergy transfer
100QmaxE
02202202202303314
106538921
Ionizing Radiation Protons
260417
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-24
Specific ionizations for eg elecrons in air can be calculated if their velocity is known
SI =
(keep in mind that v changes upon absorption)
example 32P (Emax (b) = 1709 MeV)
calculate v = 26∙108 ms b = 087
SI = 6000 IPm
LET = 02 MeVcm
keep in mind that not only ionization takes place but also scattering of electrons at the nucleus
Ionizing Radiation
260417
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-25
Ionizing Radiation Bremsstrahlung
The most important interaction is inelastic scattering
Which results in the emission of Bremsstrahlung
260417
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-26
The stopping power of atoms or materials does notonly depend on ionization but also on
direct electron-target nucleus interactions
This energy loss generates photons so called bdquoBremsstrahlungldquo
thus total stopping power
From Bethe-Formula the ratio between collision and radiation is
thus the higher the energy the more Bremsstrahlung
and the higher the atomic number the more Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-27
since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z
the formation of Bremsstrahlung increases with E
The following formula gives this ratio
example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung
Bremsstrahlung
260417
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-28
Bremsstrahlung
260417
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-29
The Bremsstrahlung is used to produce Synchrotronradiation
Bremsstrahlung
260417
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-30
this means donlsquot shield b-emitters with lead
letlsquos make an example
How much energy does a 22 MeV electron loose by passing
through 5mm Lucite (Acrylglas) r = 119
1 We calculate the maximum range of 22 MeV using the formula for low Z materials
R = 0412∙E(127-0095middotlnE)
= 106 gcm2
Bremsstrahlung
260417
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-31
The same result can be received from the range vs energy graph
Bremsstrahlung
260417
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-32
2 now we relate the stopping power and the energy by the formula for low Z materials
InEafter = 663-324(329-lnEbefore)frac12 = 0105
Eafter = 111 MeV and 109 MeV is absorbed
with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)
Bremsstrahlung
260417
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-33
Interaction of g-radiation and x-rays with matter
Photo Effect Compton Effect Pair Formation
Three principle modes of interaction
- Photons do not steadily lose energy as they penetrate matter
- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34
- interaction between g - quanta andelectrons of the inner shells
- emission of a photoelectron(ionization)
- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant
Photo electron
Photon
radiation
Electron of the shell
L- shell
K- shell
g-quant
Higherenergylevell
Lowerenergylevell
The Photo Effect
- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-35
The Photo Effect
The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom
Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)
g ndash spectroscopy
jn -=hT
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-36
The Photo Effect
The photo effect depends strongly on the atomic number Z and theenergy hn of the photons
3)(4nhZyprobabilit =
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-37
- interaction between g -quanta and e- of the outer electron shells (Compton electrons)
- emission of a Compton electron (ionization)
- g -quant loses energy (shift to longer wavelengths Compton shift)
- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon
- resulting quant can undergo more Compton reaction or finally photo reactions
incoming g-quant
scatteredg-quant
Compton electron
The Compton effect
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-38
- The emitted Compton electrons have no defined energy (Compton continuum)
The Compton effect
Compton continuum
httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-39
In coming g-quant
The bdquomysticalldquo Pair Formation
Never forget 2cmE times=
THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus
22 cemh sup3n
- Excess energy is kinetic energy of the products
- The distribution of the excess energy is continuous
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-40
The bdquomysticalldquo Pair Formation
- Pair production becomes more likely with increasing photon energy
- The probability also increases with the atomic number
2Zyprobabilit raquo
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-41
The Annihilation of Positrons
The produced positron immediately reacts with an electron
nhee =-++
Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum
The produced photons going off in opposite directions
nhcem =22Due to the photon energy is 511 keV (1022 MeV2)
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-42
- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard
Advantages and Disadvantages of the Pair Formation
Disadvantage
Advantages
- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)
THORN easier to shield
Question How would you shield a g-emitter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-43
Ato
mic
num
ber o
f abs
orbe
rOccurrence of the three mechanisms of interaction
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-44
Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron
(no direct ionization)
- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)
Classification of Neutrons
Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV
(most probable energy in the distribution at 20degC)
Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV
Fast Neutrons Energy le 20 MeV
Relativistic Neurtons Energy gt 20 MeV
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-45
Elastic and inelastic impacts
slow neutronW2
W3
Fast neutronW1
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
W1 gt W2 + W3
Energy range 1 - 10 MeV- emission of excess energy as g -quants
- main mechanisms elastic and inelastic impacts neutron capturing
Interaction of Neutrons with Matter
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-46
Energy range 10 keV - 1 MeV
Back-scattered nucleusW3
slow neutronW2
W1 = W2 + W3
Fast neutronW1
Interaction of Neutrons with Matter
Elastic Scattering
2)(4
max mMnmMEQ
+=
M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron
Maximum Fraction of Energy Lost Qmax En
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-47
Interaction of Neutrons with Matter
If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus
Slowing-down neutrons is called neutron moderation
Nuclear reaction (np) (n 2n) (n a) (n g)
Neutron Activation Analysis
Ionizing Radiation High Energy Photons
260417
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-48
6 Biological action of ionizing radiation
260417
Interaction of radiation with a biological system leads to an energy transfer
The biological impact depends on
type of radiation
type of irradiated biological material
How to quantify the biological impact
How to quantify the amount of transferred energy
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-49
6 Biological action of ionizing radiation
Dose and Dose Rate
air irradiated of masscharges producedI =
mQIDD
=
SI Unitair kg
pairs Ion10625kg
C(As)I 18times==
- Measurement of the ionisation in an ionisation chamber
- gasfilled container with a window of thin material
- electric current is produced by ionswhich are produced by the influenceof radiation
Ionisation chamber
Radiationsource
R10388air kg
C1airkg
C102581R 34
times=times
=-
Old unit R (Roentgen)
Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare
260417
Ion Dose (Exposure)
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-50
Old unit rd (rad) 1rd = 10-2 Gy
ΔmΔW D
massenergy radiationabsorbedD ==
with this information we have a direct information about the transfered energy
From Ion Dose to Energy Dose
the formation of 1 ion pair requires 34 eV
SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-51
old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)
Equivalent dose H = D middot W
W = weighting factor of the radiation
From Energy Dose to Equivalent Dose
Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)
The bigger the absorption is the bigger is the impact
Energy dose exclusively reflects the pure energy value (not the impact)
Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)
SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg
260417
6 Biological action of ionizing radiation
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-52
Equivalent dose H = D middot W
W = weighting factor of the radiation
Radiation types W X-rays g- and szlig-radiation 1
Neutron radiation about 10
a - radiation 20
Normal cell
Damaged cell
Biological sample after irradiation with Beta-Particles
relative destruction 1Energy dose 1 Gy
Biological sample after irradiation with Alpha-Particles
relative destruction 1Energy dose 005 Gy
Equivalent Dose
Dose rate dTdH (Sv h)
260417
6 Biological action of ionizing radiation
Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-53260417
6 Biological action of ionizing radiation
Radiobiological Functional Chain
Physical Processenergy transfer
molecular amp biochemical changes
cellular changessomatic cell gamete cell
acute direkt damage
non-malignant later damage
neoplasms(cancer leukemia)
genetic damage
instantaneous
minutes
hours
days
weeksmonth
years
nextgeneration
deterministic stochastic
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-54260417
6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-55260417
6 Biological action of ionizing radiationDNA Damages
Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides
Chemical modificationof a nucleotide (mutation) losing of one nucleobase
Chemical linkage of two strands
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-56260417
6 Biological action of ionizing radiationDNA Damages
spontaneous radiation-induced
Event per second per hour per year per mGy
Single-strand break 14 ca 5 x 103 ca 44 x 107 10
Double-strand break 004
Depurination ca 15 x 103 ca 14 x 107 001
Base damage 08 ca 125 x 103 ca 11 x 107 095
Total 22 ca 8 x 103 ca7 x 107 ca 20
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-57260417
6 Biological action of ionizing radiationRadiation Damages
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-58
Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen
httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417
6 Biological action of ionizing radiationStochastic vs Deterministic Effects
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-59260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-60260417
6 Biological action of ionizing radiationDeterministic Radiation Damage
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-61260417
6 Biological action of ionizing radiation
Strahlenverbrennung der Haut
Deterministic Radiation Damage
Strahlendermatitis und Epilation
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits
CHE-711-Teil2-FS17-62
Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)
20 mSv (people working with activity)max 50 mSv (exceptional with permission)
Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv
Biological action Dose and dose rate
260417
Dose Limits