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Part 3

Part 3. IAEA Training Material on Radiation Protection in Nuclear Medicine. Principles of radiation protection and the international framework Regulatory requirements. Objective.

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Part 3

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  1. Part 3 IAEA Training Material on Radiation Protection in Nuclear Medicine Principles of radiation protection and the international framework Regulatory requirements

  2. Objective To become aware of the ICRP’sconceptual framework and the International Basic Safety Standards requirement (BSS) and related Safety Guides in radiation protection in medical field. Part 3. Principles of Radiation Protection

  3. Content • Principles of Radiation Protection • International Basic Safety Standards • Regulatory Control Part 3. Principles of Radiation Protection

  4. Part 3. IAEA Training Material on Radiation Protection in Nuclear Medicine Module 3.1. Basic principles of radiation protection

  5. Do we need radiation protection in nuclear medicine? Why? Part 3. Principles of Radiation Protection

  6. What can Radiation Do? Death Cancer Skin Burns Cataract Infertility Genetic effects Part 3. Principles of Radiation Protection

  7. What can RadiationDo? Deterministic effects death, skin burns, cataract, infertility Stochastic effects cancer, genetic effects Part 3. Principles of Radiation Protection

  8. Deterministic effects cataract infertility erythema epilation Cancer Genetic Prob  dose 500 mSv cataract 150 mSv for sterility (temporary-males) 2500 mSv for ovarian EFFECT Stochastic effects DOSE Part 3. Principles of Radiation Protection

  9. Objectives of Radiation Protection • PREVENTION of deterministic effect • LIMITING the probability of stochastic effect Part 3. Principles of Radiation Protection

  10. The Need for Protection Applies to all Dose Levels • It is generally assumed that even very small doses of ionizing radiation can potentially be harmful (linear no threshold hypothesis) • Therefore, persons must be protected from ionizing radiation at all dose levels Part 3. Principles of Radiation Protection

  11. Who should be Protected in Nuclear Medicine? • Patient • Members of his/her family • Worker • General public Part 3. Principles of Radiation Protection

  12. How should the people be protected? • Optimize protection • Justify the exposure • Dose limitations Part 3. Principles of Radiation Protection

  13. This is the system of radiological protection as defined by the ICRP (International Commission on Radiological Protection) Part 3. Principles of Radiation Protection

  14. What is the ICRP? A non-governmental professional organization established in 1928 by the International Congress of Radiology Part 3. Principles of Radiation Protection

  15. What is the ICRP? • A group of recognized leaders in the field of radiation protection • concerned with the protection of humans from ionizing radiation • official relationships with WHO, IAEA, ICRU • convenes task groups of experts to address particular issues • issues reports and recommendations Part 3. Principles of Radiation Protection

  16. Ionizing Radiation We live with 1-3 mSv/y Can kill 4000 mSv Is there a safe point?If not, how to deal with the problem? Part 3. Principles of Radiation Protection

  17. To protect the people taking into account the main objectives of radiation protection the system of protection should be based on: A.Individual-related system – dose limit (absolute maximum risk that society can accept), optimizationB. Source-related system – limitation on source, source related constraints – basic protection + environmental + individual protection (by shielding, protective clothing...) Part 3. Principles of Radiation Protection

  18. Part 3. Principles of Radiation Protection

  19. The ICRP Recommendations • ICRP publication 103 - 2007 • The recommended system of radiation protection is based upon 3 principles: • Benefit of a practice must offset the radiation detriment (justification) • Exposures and likelihood of exposure should be kept as low as reasonably achievable, economic and social factors being taken into account (optimization) • Dose limits should be set to ensure that no individual faces an unacceptable risk in normal circumstances Part 3. Principles of Radiation Protection

  20. ICRP 103 • Weighs all existing data to arrive at quantitative recommendations for risk, detriment, dose and dose rate weighting factors • Considers exposure to humans only • Considers exposure in three categories: occupational, medical, public Part 3. Principles of Radiation Protection

  21. IAEA BSS (2011) - glossary • Occupational Exposure: “All exposures of workers incurred in the course of their work, with the exception of exposures excluded from the Standards and exposures from practices or sources exempted by the Standards.” Part 3. Principles of Radiation Protection

  22. IAEA BSS (2011) - glossary • Medical Exposure: “Exposure incurred by patients as part of their own medical or dental diagnosis or treatment; by persons, other than those occupationally exposed, knowingly while voluntarily helping in the support and comfort of patients; and by volunteers in a programme of biomedical research involving their exposure.” Part 3. Principles of Radiation Protection

  23. IAEA BSS (2011) - glossary • Public Exposure: “Exposure incurred by members of the public from radiation sources, excluding any occupational or medical exposure and the normal local natural background radiation but including exposure from authorized sources and practices and from intervention situations.” Part 3. Principles of Radiation Protection

  24. Justification • No use of ionizing radiation is justified if there is no benefit • All applications must be justified • This implies to even the smallest exposures that are potentially harmful and the risk must be offset by a benefit Part 3. Principles of Radiation Protection

  25. Risk/Benefit Analysis • Need to evaluate the benefits of radiation - an easy task in the case of nuclear medicine • Radiation is the diagnostic and therapeutic agent • Assessment of the risks requires the knowledge of the dose received by persons Part 3. Principles of Radiation Protection

  26. Optimization • When radiation is to be used then the exposure should be optimized to minimize any possibility of detriment. • Optimization is “doing the best you can under the prevailing conditions” • Need to be familiar with techniques and options to optimize the application of ionizing radiation - this is really the main objective of the present course Part 3. Principles of Radiation Protection

  27. Optimization (contd..) • Must take into account the resources available - this includes economic circumstances • Often a tricky question - where shall we stop, how much shielding should we really use? • Governed by the optimization principle Part 3. Principles of Radiation Protection

  28. Optimization Principle Part 3. Principles of Radiation Protection

  29. …very much in line with the rest of real life • Both justification and optimization are part of all strategies when handling potentially harmful substances or dealing with risks: • there must be a benefit • the risk should be kept as low as possible • Same for household chemicals, drugs, traffic, travel, sports, …. Part 3. Principles of Radiation Protection

  30. A comment on the optimization principle (As Low As Reasonably Achievable) • Issues which are often subject of discussion: • L … what is a low dose? • R … what is reasonable? Part 3. Principles of Radiation Protection

  31. What is Low? • It can be very costly to consider every dose level explicitly • Discussions are on-going about dose levels below ‘regulatory concern’ • A potential starting point are doses from natural background which are inevitable and one can assume organisms have adapted to them Part 3. Principles of Radiation Protection

  32. Average annual doses in mSv from natural sources in European countries Part 3. Principles of Radiation Protection

  33. What is Radon (222Rn)? • It is a radioactive gas that exists everywhere in the atmosphere • It is a member of the 238U series • It is formed by the decay of 226Ra Part 3. Principles of Radiation Protection

  34. What is Radon (222Rn)? • Half-life 3.82 days • It is an alpha emitter decaying to 218Po • 218Po is also an alpha emitter (T½ 3 min) • Other important decay products are 214Po (a, T½ 0.164 msec) and 214Bi (b, T½ 19.9 min) Part 3. Principles of Radiation Protection

  35. The hazard arises from the inhalation of its decay products which are not gaseous Most of the decay products become attached to aerosols in the atmosphere and are deposited in the conducting airways and in the lung during respiration. Why is Radon a Problem? Part 3. Principles of Radiation Protection

  36. Other important contributions to natural exposure: Potassium-40 • 40K constitutes 120 parts per million of stable potassium which is an essential trace element in every human body • 40K has a half-life of 1.28 x 109 years, decaying by beta emission (Emax 1.3 MeV) • An 80 kg adult male contains about 180 g of potassium -> 18 mg of 40K • This gives an annual internal effective dose of 170 µSv Part 3. Principles of Radiation Protection

  37. The cosmic rays contribution to the background radiation varies markedly with altitude. Note, that at cruising altitude in a Boeing 747 the dose rate is approximately 5 µSv/h Part 3. Principles of Radiation Protection

  38. Example of Radiation Exposure to Aircrew to Cosmic Radiation Exposure of New Zealand aircrew International Routes • 1000 hours per year, with 90% of the time at an altitude of 12 km • 6.5 mSv annual dose from cosmic radiation Domestic Routes • 1000 hours per year, with 70% of the time at an altitude of 11 km • 3.5 mSv annual dose from cosmic radiation Adapted from L Collins 2000 Part 3. Principles of Radiation Protection

  39. Average Background DosesUNSCEAR 2008 Report WORLDWIDE AVERAGE DOSES Source Effective dose Typical range (mSv per year) (mSv per year) External exposure • Cosmic rays 0.4 0.3-1.0 • Terrestrial gamma rays 0.5 0.3-0.6 Internal exposure • Inhalation 1.2 0.2-10 • Ingestion 0.3 0.2-0.8 Total 2.4 1–10 Part 3. Principles of Radiation Protection

  40. What is ‘Reasonable’? • Depends on ‘prevailing conditions’ including • economic • cultural • Should be based on a risk/benefit analysis of the practice Part 3. Principles of Radiation Protection

  41. Dose Limitation • No dose limitation for medical exposure of the patient - it is always assumed that the benefits for the patient outweigh the risks • Limits need to be applied for public and occupational exposures Part 3. Principles of Radiation Protection

  42. Limits and Constraints • Dose limits are one of the three principles of protection as introduced by ICRP and BSS. Fixed dose limits are recommended by ICRP and often enforced by a national legal process (Radiation Protection Legislation). • Dose constraints are used in an optimization process to guide planning. Constraints and the importance thereof may be subject to change to achieve the optimum solution to a problem (Best practice guidelines). Part 3. Principles of Radiation Protection

  43. Optimization and Dose Limitation • It is NOT the aim to get close to the limit values - the aim is to get as low as reasonably achievable • Is part of risk management • Keeps the risks of dealing with ionizing radiation of the same order as other risks Part 3. Principles of Radiation Protection

  44. Part 3. IAEA Training Material on Radiation Protection in Nuclear Medicine Module 3.2. International Basic Safety Standards

  45. IAEA was established in 1957 and has the following functions: - Safeguards (verification of peaceful uses) - Technology (fostering the transfer of) - Safety Part 3. Principles of Radiation Protection

  46. IAEA RADIATION SAFETY FUNCTIONS Article III.A.6 of its Statute To service international conventions To establish standards of radiation safety To provide for the application of these standards Part 3. Principles of Radiation Protection

  47. BASIC SAFETY STANDARDS The purpose of the Standards is to establish basic requirements for protection against the risk associated with exposure to ionizing radiation and for the safety of radiation sources that may deliver such exposure. The Standards lay down basic principles and indicate the different aspects that should be covered by an effective radiation protection programme The Standards are aimed to serve as a practical guide for public authorities and services, employers and workers, specialized radiation protection bodies, enterprises and safety and health committees. 1996 2011 Part 3. Principles of Radiation Protection

  48. First Basic Safety Standards 1962 Revised Basic Safety Standards 1967 Revised and Joint with FAO, ILO, OECD/NEA, WHO 1982 ICRP published revised recommendations 1991 Consultants, Senior experts meetings, ad hocworking groups, technical committees 1991, 1992, 1993 6th draft circulated to all member states March 1994 7th Draft approved by IAEA Board of Governors Sept 1994 Publication of Interim Version S.S.115I 1994 Formal approval by co-sponsoring organizations 1994-1996 Publication of S.S.115 1996 Interim Revised BSS 2011 Tentative New BSS Publication 2012/2013 History Part 3. Principles of Radiation Protection

  49. BSS Jointly sponsored by: THE FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS(FAO) THE INTERNATIONAL ATOMIC ENERGY AGENCY(IAEA) THE INTERNATIONAL LABOUR ORGANIZATION(ILO) THE NUCLEAR ENERGY AGENCY OF THE OECD(NEA) THE PAN AMERICAN HEALTH ORGANIZATION(PAHO) AND THE WORLD HEALTH ORGANIZATION(WHO) Part 3. Principles of Radiation Protection

  50. The IAEA’s International Standards are basedon • estimates on radiation health effects made by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and • radiation protection recommendations of the International Commission on Radiological Protection (ICRP) Part 3. Principles of Radiation Protection

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