CÁC HỆ THỐNG THIẾT BỊ & KỸ THUẬT GHI ĐO

TRONG Y HỌC HẠT NHÂN

Nguyễn Văn Hoà

Clinical problem

Radiopharmaceutical Instrumentation

Diagnosis and therapy withunsealed sources

NUCLEAR MEDICINE

99mTc

eluted

99mTc

eluted

99Mo

Column

99Mo

Column

SalineSaline

(99Mo 99mTc ) GENERATOR

(99Mo 99mTc ) GENERATOR

ShieldShield

AugersAlphasAugersAlphas

Range of -

of maximum

Energy (Emax)

in soft tissue

RADIONUCLIDE THERAPY IN CRH NUCLREAR MEDICINE

DÖÔÏC CHAÁT PHOÙNG XAÏ cho SPECT

TC99m Pertechnetate

Tc99m MIBI

Tc99m MIBITc99m Phytate

Tc99m DTPA

DMSATc99m MDP

Assay of Absolute Activity

• Two methods are used for the determination of absolute activity from the counting rate: calibration table and calibration (standard) source

• Long-lived radionuclides are used as calibration (“mock”) source: 137Cs for 131I, 129I for 125I and 57Co for 99mTc.

• Sample’s absolute activity X is given by X = κA(mock)[R(sample)/R(mock)], where A is mock activity and κ the ratio of emission frequencies

Dose Calibrators

• Dose calibrators are gas filled ionising chambers. The gas is air and sealed to avoid variations in temperature and atmospheric pressure.

• Dose calibrators are used to assay large quantities of activities where it is too large for NaI(Tl) detector (generator, patient preparation, shipment etc).

• The activity is determined by measuring the total amount of ionisations in the chamber with no inherent ability of energy discrimination.

Dose Calibrator

Introduction

Pulse height analyzer

UL

LL

Time

Pulse height (V)

The pulse height analyzer allows only pulses of a certain height(energy) to be counted.

counted not counted

Pulse-height distributionNaI(Tl)

Nuclear Medicine Counting

• Nuclear Medicine radionuclide decay counting follows Poisson distribution.

• Nuclear Medicine question is that how good is the result N from a single measurement?

• The assumption is that Nm so that there is 68.3% chance that m is within the range NN. N is uncertainty in N.

• Percentage uncertainty is defined as V= (N/N) x 100%.

Counting Systems

• Semiconductor systems • Liquid Scintillation Detectors• Gas-filled detectors• In vivo counting systems

Coincident Summing

• Occurs when a radionuclide emits two or more γ rays from single disintegration.

• Prominent in detector system with high geometric efficiency, such as well counter.

• Summing also occurs between x and γ rays as well as two 511 KeV annihilation photons

Scalers and Timers

• A device that only counts pulses is called a scaler

• An auxiliary device that controls the scaler counting time is called timer.

Counting Rates• If N counts are recorded during time t, then the

counting rate is R=N/t. The uncertainty in counting rate is then given by

tRNNttR

2)/1(

And the percentage uncertaintyVR=(R/R)100%=100%/Rt

Detector

PhotocathodecathoddDynodes

Anode

Amplifier

PHA

Scaler

Scintillation detector

Well Counter

Automatic Multiple-Sample Systems

• Automatic multiple sample systems are necessary for counting large number of samples or repeated tests

• The main problem of the multiple sample well counters is the background shielding on top of the wells

• SCA, MCA and computers are all being used for the interface with the detectors.

Multiple-Sample System

Multi-Sample Through-Hole System

Automatic Multiple Sample Liquid Scintillation Counters

• Automatic multiple sample liquid scintillation counters are designed to handle large amount samples or repeated counting.

Multi-Sample Liquid Counter

Analog Ratemeters

• A analog ratemeter is used to determine the average number of events occurring per unit time. The average is determined continuously rather than over discrete counting time

• Linear vs logarithmic ratemeters: V0=knQRp vs V0=klog(nQRp) - wider range of counting rate

• Ratemeter responds to the rate change has a time constant which can be adjusted (change the capacitor)

NaI(Tl) Probe System

THYROID UPTAKE MEASUREMENT

In Vivo Counting Systems

• In vivo refers to human or animals body• Probe system is designed to detect single

organ or localised parts of the body • A typical probe system employs 5x5cm

NaI(Tl) cylinder crystal plus cylindrical or conical shaped collimator (as well as PM tube etc).

Surgical Gamma Ray Probes

Gamma Ray Probe System

In Vivo Counting Systems

• Whole body counting system is designed to measure total radioactivity of whole body (not local activity).

• Most whole body counters employ large NaI(Tl) crystal (15-30cm diam x 5-10 cm thick) in order to detect high energy photons and small activities.

B. Cassen H.O. Anger

PIONEERS

Gamma cameraGamma camera

Used to measure the spatial and temporal distribution of a radiopharmaceutical

Gamma camera(principle of operation)

PM-tubesDetectorCollimator

Position XPosition YEnergy Z

C ounter

C lock

PulsesE nergy windowr

T ime

PHA

ADC

C omputer

Patient

z x y

GAMMA CAMERA

Static Dynamic ECG-gated Wholebody scanning Tomography ECG-gated tomography Wholebody tomography

Gamma cameraData acquisition

Camera based SPECT systems can be one of the configurations below:

Distances vs Positions

Step-and-Shot Acquisition

Rotational SPECT Camera

GAMMA CAMERA

SPECT cameras are used to determine the three-dimensional

distribution of the radiotracer

Acquisition Protocols

Various different acquisitions can be performed with a SPECT camera….

1. Planar Imaging2. Planar Dynamic Imaging3. SPECT Imaging4. Gated SPECT Imaging

Cinematic Display

• Dynamic sequence of images may be displayed as a continuous- loop movie known as cinematic display.

It is ideal to mark the background region in such a manner as to exclude the arteries and calycial region.

KIDNEY FUNCTION (Tc99m-DTPA)

Renogram

Ejection Fraction Calculation

Segmental Wall Motion Calculation

THYROID SCAN

Single probe Scanner Gammacamera

BONE SCAN

Whole Body Imaging -Different Intensity

normal pathologic

BONE SCAN

normalnormal Alzheimers diseaseAlzheimers disease

CEREBRAL BLOODFLOW

First Pass Cardiac Studies

• Data acquisition technique– List or Frame: 0.5 second per image

• Data reformat• Ventricular function evaluation

– EF, Ventricle size, wall motion similar to multiple gated studies

• Detection of Intra-cardiac shunts– Left to right shunt: Qs=Qp-Qsh; (Qp/Qs)>1.3– Right to left shunt: some activity goes directly into the left

ventricle without first passing through the lung.

Gated SPECT

Phase Image

SHUNT QUANTIFICATION

ECG-GATED BLOODPOOL SCANNING

coronal

transversal

sagittal

MYOCARDIAL PERFUSION TOMOGRAPHIC SLICES

Stress Rest

MYOCARDIAL PERFUSION

MYOCARDIAL PERFUSION

Cinematic Display

• The images to be displayed are formatted into an area memory known as buffer so that information can be retrieved quickly.

ECG-GATED MYOCARDIAL PERFUSION

SPECT/CT TECHNOLOGY & FACILITY

DESIGN

SPECT / CT

Scintillators

• Na(Tl) I works well at 140 keV, and is the most common scintillator used in SPECT cameras

Density (g/cc)

Z Decay time (ns)

Light yield (% NaI)

Atten. length (mm)

Na(Tl)I 3.67 51 230 100 30

BGO 7.13 75 300 15 11

LSO 7.4 66 47 75 12

GSO 6.7 59 43 22 15

SPECT / CT

SUMMARY OF SPET/CT• SPECT cameras are scintillation cameras, also called

gamma cameras, which image one gamma ray at a time, with optimum detection at 140 KeV, ideal for gamma rays emitted by Tc-99m

• SPECT cameras rotate about the patient in order to determine the three-dimensional distribution of radiotracer in the patient

• SPECT/CT scanners have a CT scanner immediately adjacent to the SPECT camera, enabling accurate registration of the SPECT scan with the CT scan, enabling attenuation correction of the SPECT scan by the CT scan and anatomical localization of areas of unusually high activity revealed by the SPECT scan

PETPositron Emission Tomography

Overall data flow during PET acquisition and processing

Acquisition

Calibration data

Correction data

Reconstruction

Sinogram

Counts/ray

Image

ANNIHILATIONANNIHILATION

++

++

--

511 keV511 keV

511 keV511 keV

positron

CYCLOTRONS IN HOSPITALSCYCLOTRONS IN HOSPITALS

FDG Module

Dees

Beam extractor

Magnetic coil

Target

Ion

Source

PET Radiopharmaceuticals

Nuclide Half-life Tracer Application

O-15 2 mins Water Cerebral blood flow

C-11 20 mins Methionine Tumour protein synthesis

N-13 10 mins Ammonia Myocardial blood flow

F-18 110 mins FDG Glucose metabolism

Ga-68 68 min DOTANOC Neuroendocrine imaging

Rb-82 72 secs Rb-82 Myocardial perfusion

F18-FDGF18-FDG

Manufacture of FDG

• End of bombardment of the target material with the ion source beam is only 18F, NOT FDG

• Bombardment could typically be 2 hours (one half-life)• 18F then sent to a chemistry module (synthesis module)

to react with a number of reagents to produce fluorinated deoxyglucose

• Synthesis module performs a number of steps such as heating, cooling, filtering, purifying, etc.

• FDG synthesis typically adds another hour

Manufacture of 18F

• Proton is accelerated• Strikes 18O target• Merges with 18O• Neutron ejected

nFpO 11

189

11

188

FDG

CH2HO

HO

HO

O

OH18F

CH2HO

HO

HO

O

OH

OH

glucose

2-deoxy-2-(F-18) fluro-D-glucose

• Most widely used PET tracer

• Glucose utilization• Taken up avidly by

most tumours

• E = mc²• = 9.11 x10-31kg x (3x108)² m/sec• = 8.2 x10-14 J• = 8.2 x10-14 J ÷ (1.6x10-19 J/eV)• = 511 keV

01

188

189 OF

Coincidence Detection

Detector

Detector

PET• Positron Emission

Tomography• Functional information• Tracers produced in

cyclotron• Biological tracers• ‘Hot spot’ on image• Few anatomical

landmarks

CT

• Anatomical detail• Cannot differentiate

between active and benign disease

• Better resolution than PET

• Good dynamic range bone to lung

PET/CTPET/CT

CYCLOTRON

PET/CT

• Combines the functional information with the anatomical detail

• Accurate anatomical registration

• Higher diagnostic accuracy than PET or CT alone

MULTIMODALITY IMAGING

PET

CT

Scan Process

1)CT scout view performed first

2)Full CT performed second

3)Patient moved into scanner and PET scan acquired third

biograph LSO standard protocol

CT PET

Topogram

Upper limit

Lower limitCT acquisition

attenuation correctionscatter correction

FOREAWOSEM

Fused PET/CT

XAÏ TRÒ NGOAØI : MAÙY GIA TOÁC (LINAC )

pre-treatment post-treatment

Treatment plan

RT planning and responseCase: Female with bronchial CA for RTP.

Scan protocol:Standard whole-body PET/CT scan pre- and post-therapy. Pre- and post-therapy PET/CT can beregistered using manual syngo-fusion tool.Findings:

Evaluate extent of disease prior to RT. RT planningbased CT or PET/CT. Evaluate RT response.

Data Courtesy of University Essen (Dr s S Marnitz and S Mueller)

   

CT

PET

Catheter

Aorta

16

89

HeartSpleen

ABDOMINAL AORTA

CAÁP LIEÀU 188Re-HDD-Lipiodol Kieåm tra baèng

DSA Tieâm Re-188

Lieàu Re-188

thaùm saùt (5mCi) Lieàu Re-188

ñieàu trò (< MTD)

Catheter

Aorta

1689

HeartSplee

n

ABDOMINAL AORTA

Tieâm lieàu 188Re-HDD-Lipiodol thaùm saùt 5mCi duøng DSA höôùng daãn

Maùy DSA

Tieâm lieàu Re-188

thaùm saùt (5mCi)

Coâng thöùc tính lieàu cô baûn : Coâng thöùc tính lieàu cô baûn :

Giaû ñònh :Giaû ñònh :

Hình hoïc cô quan ngöôøi chuaån , tröø Hình hoïc cô quan ngöôøi chuaån , tröø khoái U.khoái U.

Cô quan nguoàn phaân boá hoaït ñoä ñoàng Cô quan nguoàn phaân boá hoaït ñoä ñoàng nhaát.nhaát.

Cô quan bia haáp thuï naêng löôïng ñoàng Cô quan bia haáp thuï naêng löôïng ñoàng nhaát. nhaát.

D(rD(rkk) =) =ii ii (r(rkkrrhh)) AAhh

~~

MMkk

ii

AAhh~~ SS (r(rkkrrhh)) ==

MIRD phantom

THUAÄT TOAÙN TÍNH LIEÀU MIRD

Lieàu haáp thuï taïi cô quan bia : Lieàu haáp thuï taïi cô quan bia :

Giaû ñònh Giaû ñònh

Hình hoïc cô quan Hình hoïc cô quan ngöôøi chuaån , tröø ngöôøi chuaån , tröø

khoái U.khoái U.Cô quan nguoàn Cô quan nguoàn

phaân boá hoaït ñoä phaân boá hoaït ñoä ñoàng nhaátñoàng nhaát

Cô quan bi a haáp Cô quan bi a haáp thuï naêng löôïng thuï naêng löôïng

ñoàng nhaát. ñoàng nhaát.

MIRD phanto

m D(rD(rkk) =) =ii ii (r(rkkrrhh)) AAhh

~~

MMkk

ii

AAhh~~ SS (r(rkkrrhh)) ==

B.2. THUAÄT TOAÙN TÍNH LIEÀU MIRD

Beänh nhaânBeänh nhaânS S (r(rkkrrhh))

Ngöôøi chuaån Ngöôøi chuaån S S (r(rkkrrhh) )

A.3. NGUOÀN XAÏ Re-188

Naêng löôïng : β-(max) : 2.12

MeV

γ : 155 KeV(15%)

Khoaûng chaïy trung bình cuûa β : 3.8 - 11 mm

Kieåu phaân raõ : β- to 188Osmium Thôøi gian baùn huûy : 17.005 giôø

Nhaân meï : 188Tungsten

1. CT / MRI chaån ñoaùn, tính theå tích Gan, U gan.

2. LABO pha cheá Re-188 -HDD-Lipiodol vaø ño chuaån lieàu.

3. SPECT chuïp aûnh tính heä soá chuaån, suy giaûm,taùn xaï.

4. DSA höôùng daãn caáp lieàu Re-188 thaùm saùt .

5. SPECT chuïp aûnh phaân boá Re-188 thaùm saùt .

6. MIRD tính phaân boá lieàu haáp thuï trong cô theå.

7. Excel spreadsheet tính lieàu xaï trò dung naïp cöïc ñaïi ñeå lieàu

Gan laønh < 30Gy , phoåi < 12 Gy, tuûy xöông <1.5Gy.

8. DSA höôùng daãn caáp lieàu Re-188 xaï trò .

9. CT/ MRI ….ñaùnh giaù keát quûa.

B.6. QUI TRÌNH LAÄP KEÁ HOAÏCH & TÍNH LIEÀU DUNG NAÏP CÖÏC ÑAÏI Re-188

B.5. LAÄP KEÁ HOAÏCH & TÍNH LIEÀU DUNG NAÏP CÖÏC ÑAÏI Re-188

THEO THUAÄT TOAÙN MIRD

DOSIMETRY

TREATMENT

SCOUT

FLOOD

STANDARD

PHARMACEUTICAL

WEIGHT

MASSES

ANATOMY

PATIENT DATA

FOLLOW UP

VOLUME

DIAGNOSIS

CT / MRI

FPLLOW UP

TREATMENT

SCOUT

DSA

FOLLOW UP

SCOUT

FLOOD

STANDARD

SPECT

TREATMENT DOSEOUTPUT

DATA INPUT

EXCELSPREAD SHEET

ALGORITHM( MIRD )

DOSE CALCULATION

EXCEL SPREAD SHEET

TREATMENT DOSE

TÍNH LIEÀU Re - 188 XAÏ TRÒ K GAN HCC

D(D(Gan laønh Gan laønh )) = = D(D(Gan laønh Gan laønh Gan laønh Gan laønh vôùi U vôùi U )) ++D(D(Gan Gan Phoåi Phoåi ) *) * ++D(Gan D(Gan Tuûy xöông )Tuûy xöông ) * *

++D(Gan D(Gan Phaàn coøn laïi cuûa cô theå Phaàn coøn laïi cuûa cô theå ) *) *

D(Lung)D(Lung) = = D(D(Phoåi Phoåi Gan laønh vôùi Gan laønh vôùi U U ) *) * ++D(D(Phoåi Phoåi Phoåi Phoåi ) *) *

++D(D(PhoåiPhoåi Tuûy xöông Tuûy xöông ) *) *

++D(D(PhoåiPhoåi Phaàn coøn laïi cuûa cô theå Phaàn coøn laïi cuûa cô theå ) ) * *

D(Red Marrow)D(Red Marrow) = = D(D(Tuûy xöông Tuûy xöông Gan laønh Gan laønh vôùi U vôùi U ) *) * ++D(D(Tuûy xöông Tuûy xöông Lung) * Lung) *

++D(D(Tuûy xöông Tuûy xöông Tuûy xöông Tuûy xöông ) *) *

++D(D(Tuûy xöông Tuûy xöông Phaàn coøn laïi cuûa cô Phaàn coøn laïi cuûa cô theå theå ) *) *

* * Duøng caùc heä soá S ñieàu chænh theo khoái löôïng Duøng caùc heä soá S ñieàu chænh theo khoái löôïng

TÍNH LIEÀU HAÁP THUÏ TAÏI BIA Thuaät toaùn tính lieàu MIRD coù hieäu chænh Thuaät toaùn tính lieàu MIRD coù hieäu chænh

XAÏ HÌNH SPECT

ATTENUATIONAûnh Gan vôùi 99mTc-Phytate vaø aûnh U gan vôùi Re-188 lieàu thaùm saùt 5 mCi .

Aûnh truyeàn

qua Phoåi ,Ga

n

Aûnh

nguoàn

chuaån

Aûnh

u gan

Aûnh

Gan

Aûnh

toaøn thaân

Re-188 lieàu

thaùm saùt 5 mCi

Aûnh

nguoàn

chuaån

Detector

Re-188

Phantom nguoàn phaúng

Detector

Beänh nhaân

Nguoàn chuaån Re- Re-

188 188

Ghi hình

nguoàn chuaån

Re-188

Ghi hình nguoàn Re-188 trong Phantom phaúng truyeàn qua beänh nhaân

C.6. TÍNH LIEÀU XAÏ TRÒ BAÈNG EXCEL SPREADSHEET

THEO THUAÄT TOAÙN MIRD