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Radiation Protection in Radiotherapy

Radiation Protection in Radiotherapy

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Radiation Protection in Radiotherapy

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  1. Radiation Protection inRadiotherapy IAEA Training Material on Radiation Protection in Radiotherapy Part 17 Protection of the Public

  2. Public Exposure • IAEA Safety Series 120 and glossary of BSS: “Exposure incurred by members of the public from radiation sources, excluding any occupational or medical exposure and normal background radiation but including exposure from authorized sources and practices from intervention situations.” Part 17: Protection of the public

  3. Context of part 17 • BSS Appendix III • Other important context: • Part 7 (“shielding”) of the present course • Part 16 (“discharge of patients”) Part 17: Protection of the public

  4. Objectives • To understand the concept of ‘public exposure’ in the context of a radiotherapy facility • To identify potential routes of exposure of the public through radiotherapy • To be able to optimize protection of the public and ensure relevant dose constraints are not exceeded Part 17: Protection of the public

  5. Contents 1. Radiotherapy and the Public 2. Potential routes of public exposure 3. Measures to minimize radiation exposure of the public Part 17: Protection of the public

  6. 1. Radiotherapy and the Public • Public: • People living around a radiotherapy facility • Visitors to the department • Relatives, friends and other persons who may be in contact with patients • Not necessarily: Partners and non-occupational persons who are involved in care or comforting the patient - this is “Medical Exposure” (compare part 9) Part 17: Protection of the public

  7. …public could also be: • Staff from other departments/divisions • Contractors • electricians • painters • plumbers Part 17: Protection of the public

  8. Responsibilities for Public Exposure BSS Appendix III.2. “Registrants and licensees shall be responsible, with respect to the sources under their responsibility, for the establishment, implementation and maintenance of: (a) protection and safety policies, procedures and organizational arrangements in relation to public exposure in fulfilment of the requirements of the Standards; (b) measures for ensuring: • (i) the optimization of the protection of members of the public ... • (ii) the limitation of the normal exposure of the relevant critical group, …” Part 17: Protection of the public

  9. In radiotherapy • Requires a radiation safety program • Written policies and procedures • These should include all potential areas of exposure - e.g. in the handbook for outside contractors some information on radiation must be included. • Most likely a radiation safety committee and a radiation protection officer Part 17: Protection of the public

  10. 2. Potential for Public Exposure in Radiotherapy 2 1 • External: • Facility shielding - for outside world (1) • Discharge of patients with radioactive implants (2) • Radioactive waste Part 17: Protection of the public

  11. Potential for Public Exposure in Radiotherapy • Internal: • Facility shielding - for visitors • Radioactive waste Part 17: Protection of the public

  12. Exposure of the Public to External Irradiation BSS Appendix III.6. “Registrants and licensees shall ensure that, if a source of external irradiation can cause exposure to the public: (a) prior to commissioning, the floor plans and equipment arrangement for all new installations and all significant modifications to existing installations utilizing such sources of external irradiation be subject to review and approval by the Regulatory Authority; (b) specific dose constraints for the operation of such a source be established to the satisfaction of the Regulatory Authority;” Part 17: Protection of the public

  13. In radiotherapy practice • Close collaboration with relevant authority • Shielding checked already in planning phase • Verification of the dose constraints used in calculations Part 17: Protection of the public

  14. Dose Limits for Public Exposure • BSS Schedule II (and ICRP 60) • Effective dose 1mSv/year • Under special circumstances 5mSv/year (but not more than 5mSv/5years) • Equivalent dose to eye: 15mSv/year • Equivalent dose to skin: 50mSv/year • May be different in your country!!! Part 17: Protection of the public

  15. Nuclear Medicine Radiology In radiotherapy practice Contributions to exposure can come from many sources - therefore designs of a facility must be shielded to restrict dose more than required by the dose constraint (typically: 1/3) • Close collaboration with relevant authority • Shielding checked already in planning phase • Verification of dose constraints Part 17: Protection of the public

  16. Means to minimize public exposure • Designation of areas as: • public • supervised • controlled • Compare part 8 on occupational exposure Part 17: Protection of the public

  17. Controlled Area A controlled area is an area where procedural controls are required in order to restrict radiation exposures. Restriction of Access Part 17: Protection of the public

  18. Controlled Area Requirements Work in a controlled area should be carried out in accordance with a written set of local rules. These apply not only to occupationally exposed persons but also to others, such as contractors. Therefore they must be in writing, easily accessible and regularly reviewed. Part 17: Protection of the public

  19. Supervised Areas A supervised area is one that does not require classification as a controlled area, but where exposure conditions should be kept under review. It could be accessible for the public, however, it requires: a delineated area routine monitoring work to be undertaken in accordance with local rules Part 17: Protection of the public

  20. Means to prevent public exposure • Access restriction • Shielding • Warning signs • Lights • Interlocks (e.g. door) • Written information Part 17: Protection of the public

  21. Means to prevent public exposure • Access restriction • Shielding - see part 7 of the course • Warning signs • Lights • Interlocks (e.g. door) • Written information - for staff and members of the public who could be at risk of exposure (e.g. contractors, allied health professionals) Part 17: Protection of the public

  22. Issues for public exposure: • Discharge of patients • Radioactive waste • Old teletherapy sources • Old brachytherapy sources Part 17: Protection of the public

  23. Discharge of patients with radioactive implants • Dealt with in part 16 • Rules are designed to keep public exposure limited • Written information must be available to the patient Part 17: Protection of the public

  24. Radioactive Waste BSS appendix III.8: “Registrants and licensees shall: (a) ensure that the activity and volume of any radioactive waste that results from the sources for which they are responsible be kept to the minimum practicable, and that the waste be managed, i.e. collected, handled, treated, conditioned, transported, stored and disposed of, in accordance with the requirements of the Standards and any other applicable standard” Part 17: Protection of the public

  25. The problem of waste in radiotherapy • Mainly a problem with radioactive sources no longer used for treatment. • These could be: • teletherapy sources (60-Co, 137-Cs) • old and no longer usable brachytherapy sources with long half life (226-Ra, 137-Cs) • short/medium lived sources with activity too low for treatment Part 17: Protection of the public

  26. Old teletherapy sources • High activity • Regulatory authority must be informed • Requires specialized transport and storage container • Disposal • could be very costly • should be part of initial purchase or source replacement contract with manufacturer • documentation (i.e. source certificate) essential Part 17: Protection of the public

  27. Watch depleted uranium which may have been used as shielding material in telecurie treatment units Example: schematic drawing of treatment head of a 60-Co unit Part 17: Protection of the public

  28. Long lived brachytherapy sources • May leak • Disposal pathway MUST be approved by authority • Documentation essential Part 17: Protection of the public

  29. Short/medium half life brachytherapy sources • Examples: 198-Au, 192-Ir, 125-I, 103-Pd • A protocol must be in place for disposal • Store in suitable location until activity below the prescribed limit value • Return to manufacturer - may be required by law to accept the sources Part 17: Protection of the public

  30. Waste - unsealed isotopes • Not part of this training course • Covered in the companion course on Radiation Safety in Nuclear Medicine Part 17: Protection of the public

  31. 3. Measures to minimize radiation exposure of the public • Thinking ahead - what could happen • Shielding and safe design • Access restriction and sign posting • Procedures and a radiation safety program • Information sheets for public Part 17: Protection of the public

  32. Visitors = general public • BSS Appendix III: PUBLIC EXPOSUREdeals explicitly with “CONTROL OF VISITORS”: III.5. Registrants and licensees, in co-operation with employers when appropriate, shall: (a) ensure that visitors be accompanied in any controlled area by a person knowledgeable about the protection and safety measures for that area; (b) provide adequate information and instruction to visitors before they enter a controlled area so as to ensure appropriate protection of the visitors and of other individuals who could be affected by their actions; and (c) ensure that adequate control over entry of visitors to a supervised area be maintained and that appropriate signs be posted in such areas. Part 17: Protection of the public

  33. Information for visitors • Written information and signs • May be accompanied by trained staff at all times when visiting a patient with radioactive implants in place • the same applies to other hospital staff (e.g. maintenance, porters, catering,…) Part 17: Protection of the public

  34. Transport and storage of sources • Covered in part 14 • Within the hospital: • Secure storage (locks, interlocks) • When in transport (e.g. from hot lab to treatment area or operating theatre) sources MUST be under constant surveillance. Part 17: Protection of the public

  35. Monitoring of Public Exposure BSS appendix III.13: “Registrants and licensees shall, if appropriate: (a) establish and carry out a monitoring programme sufficient to ensure that the requirements of the Standards regarding public exposure to sources of external irradiation be satisfied and to assess such exposure; (b) establish and carry out a monitoring programme sufficient to ensure that the requirements of the Standards for discharges of radioactive substances to the environment … be satisfied.” Part 17: Protection of the public

  36. Monitoring • Relevant areas (at least all controlled and supervised areas) must be regularly monitored for radiation exposures • Contractors may be subject to temporary personal monitoring Part 17: Protection of the public

  37. Monitoring • Monitor and document workload • All outgoing radioactivity must be accounted for - monitor compliance Part 17: Protection of the public

  38. BSS Appendix III. 13: PUBLIC EXPOSURE (cont.) • MONITORING OF PUBLIC EXPOSURE • “Registrants and licensees shall, if appropriate: (c) keep appropriate records of the results of the monitoring programmes; (d) report a summary of the monitoring results to the Regulatory Authority at approved intervals; (e) report promptly to the Regulatory Authority any significant increase in environmental radiation fields or contamination that could be attributed to the radiation or radioactive discharges emitted by sources under their responsibility;” Part 17: Protection of the public

  39. BSS Appendix III. 13: PUBLIC EXPOSURE (cont.) • MONITORING OF PUBLIC EXPOSURE • “Registrants and licensees shall, if appropriate: (f) establish and maintain a capability to carry out emergency monitoring, in case of unexpected increases in radiation fields or radioactive contamination due to accidental or other unusual events affecting sources under their responsibility; and (g) verify the adequacy of the assumptions made for the prior assessment of radiological consequences of the discharges.” Part 17: Protection of the public

  40. A last note on all monitoring • Done prospectively and with a purpose • Is quantitative • Is documented • Action levels are usually established • Potential actions are thought of beforehand and they are documented Part 17: Protection of the public

  41. A note on action levels • Without them monitoring would be less useful • Need to be established and discussed by all people involved • Helps tremendously to speed up a reaction Part 17: Protection of the public

  42. Summary • If a radiotherapy department is designed well, the risk of public exposure is usually very small • Procedures must be established and be available in writing • Information of staff and the public about potential risks is essential. Part 17: Protection of the public

  43. Where to Get More Information • Parts 7 (shielding), 8 (occupational exposure) 14 (transport) and 16 (discharge of patients) • BSS appendix III Part 17: Protection of the public

  44. Any questions?

  45. Question: Discuss why the dose constraint for public exposure is smaller than for occupational exposure.