short induction
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Do not adjust your set
Radiation Safety Induction
for Radiology Registrars
John SaundersonRadiation Protection Adviser
TPRH ext 6690
Ionising radiations• x-rays gamma rays (-rays) beta particles () electron beams
Not ionising radiations
• lasers ultraviolet (UV) infrared (IR) ultrasound MRI
Ionising / Non-ionising
Part 1 Physics Lectures
• Basic Physics (4h)– Trevor Davies (Nuclear Medicine Physicist)– CHH ext 2119 / 2125 trevor.davies@hey.nhs.uk
• Radiation hazards and dosimetry (10h)– John Saunderson (Consultant Physicist/Radiation Protection Adviser)– PRH ext 6690 john.saunderson@hey.nhs.uk
• Diagnostic radiology (10h)– Jenny Wilson (Radiation Physicist)– PRH ext 6693 jenny.wilson@hey.nhs.uk
• CT (2h)– Craig Moore (Radiation Physicist)– PRH ext 6808 craig.moore@hey.nhs.uk
• Radionuclide Imaging (2h)– Graham Wright (Nuclear Medicine Physicist)– CHH 2125 / 2115 graham.wright@hey.nhs.uk
• + 9h radiographer sessions
Exam
11 Dec 2006
Wilhelm Roentgen
• Discovered X-rays on 8th November 1895 .
Frau Roentgen’s hand,
1895Colles’ fracture 1896 .
Mihran Kassabian (1870-1910)
Dose Reduction Precautions
• X-ray tubes shielded• Collimation• Aluminium filters• Weekly exposure limits
introduced
Radiation Effects
• Acute radiation syndrome• Including vomiting, diarrhea, reduction in the
number of blood cells, bleeding, epilation (hair loss), temporary sterility in males, and lens opacity (clouding )
• Late 1940’s Dr Takuso Yamawaki noted an increase in leukaemia
• 20% of radiation cancers were leukaemia (normal incidence 4%)
• Incidence peaked at 6-8 years• Solid cancers – excess seen from 10
years onwards.
• Early X-ray pioneers – Acute effects– Precautions introduced
• Atomic bomb survivors– Acute effects similar in nature to pioneers– Some increased cancer risk
• But what about radiology today?
Cancer Risk• 1 in 20,000 risk of fatal cancer per
millisievert– Chest x-ray: 0.02mSv ► 1 in a million risk– Abdomen x-ray: 1mSv ► 1 in 20,000– Barium meal: 3mSv ► 1 in 7,000– CT abdomen: 10mSv ► 1 in 2,000– (Typical interventional radiologist dose < 3 mSv/y)
• Small risk compared to natural cancer risk
• Why worry?
700 CANCER CASES CAUSED BY X-RAYS
X-RAYS used in everyday detection of diseases and broken bones are responsible for about 700 cases of cancer a year, according to the most detailed study to date.
The research showed that 0.6 per cent of the 124,000 patients found to have cancer each year can attribute the disease to X-ray exposure. Diagnostic X-rays, which are used in conventional radiography and imaging techniques such as CT scans, are the largest man-made source of radiation exposure to the
general population. Although such X-rays provide great benefits, it is generally accepted that their use is associated with very small increases in cancer risk.
30 January 2004
Average X-ray examination dose = 0.5mSv ► 1 in 40,000 risk
UK Radiology = 41.5 million X-rays per year
Basic Principals of Radiation Protection
• Justification– Benefit > risk
• Optimisation– Doses as low as reasonably achievable
• Limitation– Absolute legal limits for staff and public– Reference levels as guidance for patients.
Regulations
• Ionising Radiations Regulations 1999 (IRR99)– Local rules, radiation protection supervisors
• Ionising Radiation (Medical Exposures) Regulations 2000 (IRMER2000)– Referrers, practitioners, operators– Justification & optimisation
• Medicines (Administration of Radioactive Substances) Regs 1978 (ARSAC)– Nuclear medicine
Organising radiation safety
Controlled Areas
Local Rules
Radiation Protection Supervisor
Radiation Protection Adviser
Radiographer.
IRMERIonising Radiation (Medical Exposures) Regulations 2000
• Referrers – allowed to request medical exposure– Trust decides who can e.g. GP, consultant, etc.
• Practitioners– Justifies X-ray - decides there is net benefit– Trust decides who can e.g. radiologist
• Operator– Performs “practical aspects”– Trust decides who can e.g. radiographer, technician
.
19
Medicines (Administration of Radioactive Substances) Regs 1978
(“MARS” / “ARSAC”)
• “No person shall administer to a human being (otherwise than to himself) any radioactive medicinal product unless he is doctor or dentist holding a certificate issued by the Health Minister for the purposes of section 60 of the Act in respect of radioactive medicinal products (hereinafter referred to as a “certificate”) or a person acting in accordance with the directions of such a doctor or dentist.” .
Radiation in hospitals
• Radioactive substances– nuclear medicine– pathology– radiotherapy
• X-ray sources– Radiology– Radiotherapy– Pathology .
X-ray tube
Primary beam
Scattered radiation
Patient
Leakage
Basic Principles
Time
Distance
Shielding
Distance
•Double distance = 1/4 dose
•Triple distance = 1/9th dose.
Shielding
Shielding
Typical Transmission through Shielding (90 kV)
• 0.25 mm lead rubber apron 8.5%• 0.35 mm lead rubber apron 5%• 2 x 0.25 mm apron 2.5%• 2 x 0.35 mm apron 1.0%
•Double brick wall 0.003%•Plasterboard stud wall 32%•Solid wooden 1” door 81%•Code 3 lead (1.3 mm) 0.1%.
Lead Apron Storage
• Always return to hanger• Do not
– fold– dump on floor and run
trolleys over the top of them!!!
• X-ray will check annually• But if visibly damaged,
ask X-ray to check them.
First Physics lectures
• Tuesday 12 September• 2pm start (please be prompt)
• The Princess Royal Hospital, Saltshouse Road
The End
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