Radiation Protection in Radiotherapy

1. Radiation Protection inRadiotherapy IAEA Training Material on Radiation Protection in Radiotherapy Part 15 Security of sources, and disposal of disused sources

2. BSS glossary: • A source is: “Anything that may cause radiation exposure, such as by emitting ionizing radiation or releasing radioactive substances or materials. For example, materials emitting radon are sources in the environment, a sterilization gamma irradiation unit is a source for the practice of radiation preservation of food, an X ray unit may be a source for the practice of radiodiagnosis, and a nuclear power plant is a source for the practice of generating electricity by nuclear power. A complex or multiple installation situated at one location or site may, as appropriate, be considered a single source for the purposes of application of the Standards.” Part 15: Security and disposal of sources

3. Objectives • Be able to apply the concept of a radiation source to radiotherapy • Understand how sources in radiotherapy can be made secure • Be familiar with appropriate ways to dispose of sources in radiotherapy Part 15: Security and disposal of sources

4. Contents 1. Sources in radiotherapy 2. Security of sources 3. Disposal of disused sources Part 15: Security and disposal of sources

5. 1. Sources in radiotherapy • X Ray equipment • Radioactive sources for external beam radiotherapy • Radioactive sources for brachytherapy • Other sources Part 15: Security and disposal of sources

6. Radiotherapy sources are HOT! A note on exempted sources • In general radioactive sources used in radiotherapy will NOT qualify for exemption according to BSS schedule I Part 15: Security and disposal of sources

7. X Ray equipment • Very common source of radiation in radiotherapy • Not of major concern for security of sources and disposal because no radiation is produced when the unit is turned off... Courtesy of Siemens Medical Part 15: Security and disposal of sources

8. Radioactive sources for external beam radiotherapy • In practice 137-Cs and more importantly 60-Co units need to be considered MDS Nordion Part 15: Security and disposal of sources

9. Radioactive sources for EBT • High activity (>100TBq (3000 Ci)) • Small (height and diameter a few centimeters) • Relatively long half life of 5.26 years for 60-Co and 30 years for 137-Cs • Has been source of a major radiation accident in the past… (Goiânia) Part 15: Security and disposal of sources

10. A teletherapy 60-Co source 120TBq 5cm Part 15: Security and disposal of sources

11. Radiation accident in Goiânia • End 1985 in Brazil • Private radiotherapy unit moved location leaving a 137-Cs unit in former premises • Authorities were not notified • Cs unit was scavenged as scrap metal Part 15: Security and disposal of sources

12. Goiânia accident • Source assembly sold to scrap yard • ‘Glow in the dark’ caused attraction • Parts of the source distributed widely... Part 15: Security and disposal of sources

13. Goiania accident • Several persons showed gastrointestinal symptoms due to irradiation • One affected person contacted public health department • A local physicist was involved in determining the extent of the accident and initiated evacuation of affected areas Part 15: Security and disposal of sources

14. Large scale accident Human Costs • 249 people contaminated • Four people died within 4 weeks Part 15: Security and disposal of sources

15. Environmental and financial costs • Lots of work • Lots of costs • Lots of waste Part 15: Security and disposal of sources

16. Radioactive sources for brachytherapy • Many different isotopes and forms as discussed in part 6 of the course • Brachytherapy isotopes are in radiotherapy practice the most likely cause of concern for security and disposal of sources Part 15: Security and disposal of sources

17. Other sources Part 15: Security and disposal of sources

18. Other sources • Check sources for dosimetric equipment • Check sources for shielding • Except for sources for unsealed source radiotherapy (dealt with in the course on nuclear medicine) all sources can be considered sealed In practice a small part of the radioactive inventory of a radiotherapy department - the considerations in regards to security and disposal for these sources are similar to brachytherapy sources Part 15: Security and disposal of sources

19. 2. Security of sources • BSS 2.34: “Sources shall be kept secure so as to prevent theft or damage and to prevent any unauthorized legal person from carrying out any of the actions specified in the General Obligations for practices of the Standards (see paras 2.7-2.9), by ensuring that: (a) control of a source not be relinquished without compliance with all relevant requirements specified in the registration or licence and without immediate communication to the Regulatory Authority, and when applicable to the relevant Sponsoring Organization, of information regarding any decontrolled, lost, stolen or missing source;” ... Part 15: Security and disposal of sources

20. ...and... (b) a source not be transferred unless the receiver possesses a valid authorization; and (c) a periodic inventory of movable sources be conducted at appropriate intervals to confirm that they are in their assigned locations and are secure.” Part 15: Security and disposal of sources

21. Security of sources • Not a problem for X Ray equipment if one assumes that • they are properly designed and maintained (compare part 10 of the course) • only authorized persons are able to operate the equipment • unit cannot be accessed by un-authorized persons Part 15: Security and disposal of sources

22. Linac Console Key required for operation Part 15: Security and disposal of sources

23. Security of sources • All radiation equipment must be locked when not in use... Part 15: Security and disposal of sources

24. Security of 60-Co sources • In teletherapy units: • Mainly a feature of equipment design • Treatment rooms must be locked • Source transfer only be done by qualified persons • Great care must be taken when disposing the source - it MUST be returned to an authorized person or company!!! Part 15: Security and disposal of sources

25. Must know the source housing and exposure mechanism design Source Exposure mechanism Hg pumped in and out Part 15: Security and disposal of sources

26. Security of brachytherapy sources • Some info in part 6 on sources • May affect all aspects of source utilization: • receipt of sources • storage • handling • use on patients • disposal 125-I seeds - Courtesy Mentor Part 15: Security and disposal of sources

27. Safety Assessment • Identification of the mechanisms for exposure (both routine and accidents) • Realistic estimate of doses and likelihood of occurring • Identification of possible safety system failures • Identification of protection measures needed Part 15: Security and disposal of sources

28. Source Storage Source stores must: • provide protection against environmental conditions • be only for radioactive materials • provide sufficient shielding • be resistant to fire • be secure Part 15: Security and disposal of sources

29. Features of source storage • Secure (lock and key) • Labels • Different compartments • Shielding • Easy access • Well organized Part 15: Security and disposal of sources

30. Important to keep a good log book • Update with every source movement • Clear labels • Identify all sources • A drawing of the safe outline may be useful Part 15: Security and disposal of sources

31. Source transport • Always accompanied by qualified person • Details in part 14 of the course Part 15: Security and disposal of sources

32. Accountability of sources • Receipt, storage, use and all movements of a source must be recorded Part 15: Security and disposal of sources

33. Accountability of Sources Source accountancy records should contain: • radionuclide and activity of sources • location and description of sources • disposal details The records should be updated regularly, and the location of the sources checked. Part 15: Security and disposal of sources

34. Testing and Maintenance • Testing of safety systems • Calibration and testing of radiation monitors • Leak tests of sealed sources • Periodic examination of safety critical components Part 15: Security and disposal of sources

35. Testing and Maintenance • Documentation must exist for all procedures: • How to be done • Who is responsible • How often to be done Records of results must be kept Part 15: Security and disposal of sources

36. A lost source... • A major concern for radiation protection • Possible in case of: • Discharge of patients with temporary implants not completely removed • In theatre during implant of radioactive seeds Seeds are small Part 15: Security and disposal of sources

37. A lost source • In theatre a physicist should be present to identify a lost source immediately • Can be located often best using a radiation detector Part 15: Security and disposal of sources

38. A lost source in the ward • Notify physicist or radiation safety officer immediately • Have a plan for the search... Part 15: Security and disposal of sources

39. A lost source? Main actions • Need an emergency plan Part 15: Security and disposal of sources

40. 3. Disposal of disused sources • A potential for accidents • Disposal routes should already be considered when ordering sources • Accounting for sources includes their disposal • Responsibility for sources only ends after they have been safely disposed and disposal has been documented Part 15: Security and disposal of sources

41. BSS Appendix III: PUBLIC EXPOSURE - Radioactive Waste • 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; and (b) segregate, and treat separately if appropriate, different types of radioactive waste where warranted by differences in factors such as radionuclide content, half-life, concentration, volume and physical and chemical properties, taking into account the available options for waste disposal. Part 15: Security and disposal of sources

42. Radiotherapy X Ray equipment • In practice usually not a problem • as no parts of the equipment are activated • if the unit is properly ‘decommissioned’ • the unit is disposed off either in a condition which renders it unusable or sold to an appropriately licensed person - this also includes donations • the regulatory authority is informed Part 15: Security and disposal of sources

43. Disposal of teletherapy sources • Due to their high activity (even when not anymore fit for use on patients) the disposal of these sources poses a potential risk for severe accidents… • In practice this should not a be major problem if the source is replaced - in this case the manufacturer of the source shall also accept the source to be disposed Part 15: Security and disposal of sources

44. Potentially a problem if the teletherapy unit is decommissioned • The source should be disposed to an operator licensed to do so • this could be expensive… but is cheaper than an accident • Appropriate transport containers must be used Part 15: Security and disposal of sources

45. Please note • A hospital is NOT a suitable place for long term storage of high activity sources • The source housing is usually NEITHER suitable for transport NOR for long term storage of the source Part 15: Security and disposal of sources

46. Brachytherapy source disposal • Permanent implants ‘walk out with the patient’ • remaining sources must be disposed of appropriately • For temporary implant sources the disposal depends on activity and half life: • short/medium half life, low/medium activity (e.g. 192-Ir LDR sources) can be stored until decayed to an activity which is below limit values specified by the regulatory authority • this strategy does not work for high activity 192-Ir HDR sources or 137-Cs Part 15: Security and disposal of sources

47. 192-Ir HDR sources • Typically exchanged • Need trained personal for exchange • Storage not recommended Part 15: Security and disposal of sources

48. 137-Cs sources • Despite half life of 30 years most manufacturers only specify a useful life of 10years. This is mainly due to: • risk of damage to the encapsulation • e.g. Cs pellets in Microselectron ‘bump’ into each other during loading of the applicators • Wipe tests required • Disposal only to person authorized to accept sources Part 15: Security and disposal of sources

49. A note on the role of suppliers • BSS appendix IV.9. “In addition, and where applicable, registrants and licensees shall make suitable arrangements with suppliers of sources: (a) to establish and maintain mechanisms for suppliers to obtain information from the registrants and licensees or other users on the use, maintenance, operating experience, dismantling and disposal of sources, and in any particular normal or abnormal operating conditions that may be important for the protection of individuals or the safety of the source;…” Safety and security of sources is everyone's responsibility Part 15: Security and disposal of sources

50. Summary • Safety and security must be considered for all sources in radiotherapy • Security of sources relies on a system of accounting for sources • Disposal of sources is a major responsibility of the licensee - sources must only be disposed to an authorized person or company Part 15: Security and disposal of sources