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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 7 Design of Facilities and Shielding

  2. Rationale In radiotherapy, a potentially lethal dose of radiation is delivered to patients. In order to avoid misadministration and exposure of other individuals (staff, visitors, general public) a radiotherapy facility must be appropriately designed. Shielding is an essential part of this design process. Part 7, lecture 1: Facility design

  3. Contents Lecture 1: Design of a radiotherapy facility • components of a radiotherapy department • design criteria Lecture 2: Shielding • general considerations • external beam radiotherapy • brachytherapy Part 7, lecture 1: Facility design

  4. Objectives - on completion, participants should • Understand the underlying principles for the design of a radiotherapy facility • Be familiar with the safety requirements for the design of radiotherapy facilities including interlocks, maze design and warning signs. • Be able to calculate the shielding thickness required for a particular barrier Part 7, lecture 1: Facility design

  5. Radiation Protection inRadiotherapy IAEA Training Material on Radiation Protection in Radiotherapy Part 7 Design of Facilities and Shielding Lecture 1: Facility Design

  6. Objectives of lecture 1 • Be familiar with components of a radiotherapy department • Understand the basic layout and design features of a radiotherapy department Part 7, lecture 1: Facility design

  7. Contents of lecture 1 1. Components of a radiotherapy department 2. Departmental planning and layout 3. Design considerations Part 7, lecture 1: Facility design

  8. 1. Components of a typical radiotherapy department • Diagnostic facilities (CT, MRI, …) • Simulator • Mouldroom • Treatment planning • External beam treatment units • Brachytherapy equipment • Clinic rooms, beds, ... Part 7, lecture 1: Facility design

  9. Outpatient areas Diagnostics Clinics Therapy Inpatient areas Oncology ward Brachytherapy Non-patient areas Components of a Radiotherapy Department Part 7, lecture 1: Facility design

  10. Radiotherapy is typically part of a large hospital • Use of other services: • Diagnostics • Nuclear Medicine • Maintenance • Domestic/kitchen • In patients/nursing • Administration Part 7, lecture 1: Facility design

  11. Areas not directly related to patient care • Offices • Workshops (physics, electronics, mechanics) • Storage • Teaching • Research Part 7, lecture 1: Facility design

  12. Areas not directly related to patient care which need to be considered from a radiation protection point of view • Offices • Workshops (physics, electronics, mechanics) • Storage (including isotopes) • Teaching • Research Part 7, lecture 1: Facility design

  13. Workshops • Physics workshop/lab: need to consider check sources for dosimetric equipment Part 7, lecture 1: Facility design

  14. Storage areas for sources • Hotlab • Source preparation area for interim storage of sources • Decay lab - decay of radioactive material (e.g. 192-Ir) prior to disposal Part 7, lecture 1: Facility design

  15. Research • Many different possibilities for radiation protection problems: • students participating in research and observation of practice (training?) • after hours work (confined spaces? Should there be more than one researcher?) • labs including radiobiological research • ethics - see part 9 on medical exposure Part 7, lecture 1: Facility design

  16. Components of the outpatient area • Reception area • Clinic rooms - new patients and review • Waiting area • Diagnostics - e.g. CT scanner, simulator, dark room • Treatment units - e.g. 60-Co, linacs, superficial/orthovoltage, HDR brachytherapy • Treatment planning including mould room • Dosimetry, physics and electronics labs • Office space and storage (!) Part 7, lecture 1: Facility design

  17. Flow chart for patient treatment... Part 7, lecture 1: Facility design

  18. Flow chart for data Part 7, lecture 1: Facility design

  19. Quick task Please try to follow a patient through the components on the previous slide. Label the components from 1 to 7 in the order as the data of a particular patient would be acquired and processed

  20. Outpatient data flow Part 7, lecture 1: Facility design

  21. 2. Layout of a department • Planning should include all components and allow for growth • Easy access is required for patients and ambulance - patient may be transported by wheelchair or on a trolley bed • Typically a radiotherapy department is part of a larger hospital complex - access must be ensured, in particular to: • diagnostics (X Ray, nuclear medicine) • oncology clinic and beds Part 7, lecture 1: Facility design

  22. Layout example Part 7, lecture 1: Facility design

  23. Components of a brachytherapy section • Different layout and components for • high dose-rate (HDR) brachytherapy • similar to external beam • usually outpatient facility • low dose-rate (LDR) or pulsed dose-rate (PDR) • in-patient procedure • treatment room in a ward Nucletron HDR unit Part 7, lecture 1: Facility design

  24. Patient flow in brachytherapy Treatment decision Ideal plan - determines source number and location Implant of sources or applicators in theatre Localization of sources or applicators (typically using X Rays) Treatment plan Commence treatment Part 7, lecture 1: Facility design

  25. Components of a brachytherapy suite in the ward • Operating theatre for placement of sources or applicators • Diagnostic facility to localize sources • Shielded room - consider manual and remote afterloading • Dosimetry and physics area • Source preparation may be required (e.g. 192-Ir wire cutting) • Source storage - include also case of emergency • Nurse station with patient intercom Part 7, lecture 1: Facility design

  26. Transport issues • Ideally, all these components should be close together - good departmental planning can ensure this. • In practice, often these components are far apart from each other leading to the need for patient transport (sources or applicators can move!) or transport of radioactive material through the hospital Part 7, lecture 1: Facility design

  27. Designation of areas • Public • Supervised • operator console • Controlled • treatment rooms • brachytherapy source storage and preparation Part 7, lecture 1: Facility design

  28. Supervised Areas BSS Appendix I.24. “Registrants and licensees shall designate as a supervised area any area not already designated as a controlled area but where occupational exposure conditions need to be kept under review even though specific protection measures and safety provisions are not normally needed.” Part 7, lecture 1: Facility design

  29. Controlled areas • BSS appendix I.22.: “In determining the boundaries of any controlled area, registrants and licensees shall take account of the magnitudes of the expected normal exposures, the likelihood and magnitude of potential exposures, and the nature and extent of the required protection and safety procedures.” Part 7, lecture 1: Facility design

  30. Quick task Please identify the areas on the handout of the departmental plan which should be controlled or supervised

  31. Part 7, lecture 1: Facility design

  32. Controlled and supervised areas • Access restrictions • Require warning signs • Monitoring of staff • Interlocks where appropriate • Written procedures Part 7, lecture 1: Facility design

  33. Planning and lay-out • When planning a new facility assumptions must be clearly stated • Plan for the future - consider expansions and increase in workload • Megavoltage treatment rooms are typically in the basement • It is usually best to place bunkers together to use common walls • Size matters - bunkers should be generous Part 7, lecture 1: Facility design

  34. Advantage of large bunker • Distance is effective shielding • Consider special treatments such as TBI • Need storage space for accessories and patient immobilisation • Allows for future upgrades of equipment (FAD 80 ---> 100cm) and increases in shielding Part 7, lecture 1: Facility design

  35. Treatment bunkers require lots of storage space for patient treatment aids... Part 7, lecture 1: Facility design

  36. More design criteria: • Make use of landscape features (e.g. built bunkers into a hill) and consider adjacent buildings • Positioning the control room and the equipment within so that staff have a good view of • the treatment room • access corridors • entrance to the treatment room Part 7, lecture 1: Facility design

  37. …before planning and shielding • Check and document all assumptions • Verify them with authorities and colleagues • Plan size and workload of the facility - be conservative, the design should be adequate for the next 20 year including room for expansion Part 7, lecture 1: Facility design

  38. Typical assumptions for planning a new facility • 4000 new cases of cancer per year per million population • 50% will require radiotherapy at some stage • 400 to 500 cases per megavoltage unit per year • ...may depend on local conditions Part 7, lecture 1: Facility design

  39. Design considerations: External Beam Radiotherapy • Placement of the treatment unit • Primary beam direction • Operator location • Surrounding areas - should have low occupancy • Costs • can be reduced if the design is good • for extension is usually much larger than for allowing for expansion already during the building phase Part 7, lecture 1: Facility design

  40. Typical megavoltage room layout Part 7, lecture 1: Facility design

  41. Design criteria: External Beam treatment area • clear signs are required in areas leading to treatment units • patient and visitor waiting areas should be positioned so that patients are unlikely to enter treatment areas accidentally • patient change areas should be located so that the patient is unlikely to enter a treatment area accidentally • shielding/maze/doors discussed later Part 7, lecture 1: Facility design

  42. Megavoltage Room • Is a door needed? • Door interlocks • Protocol for closing the door and activating radiation • Door interlocks • Radiation warning signs are needed Part 7, lecture 1: Facility design

  43. Radiation Safety in Radiotherapy • the possibility of accidental exposure can be minimised by measures such as • positioning the control room and the equipment within so that staff have a good view of • the treatment room • access corridors • entrance to the treatment room Part 7, lecture 1: Facility design

  44. Control area • Spacious • Patient monitor • Clear view of surrounding area • Control of access to bunker Part 7, lecture 1: Facility design

  45. Radiation Safety in Radiotherapy • the possibility of accidental exposure can be minimised by measures such as positioning • clear signs in areas leading to treatment units • patient and visitor waiting areas so that they are unlikely to enter treatment areas accidentally • patient change areas so that the patient is unlikely to enter a treatment area accidentally Part 7, lecture 1: Facility design

  46. A note on ventilation • This should be reviewed for high energy accelerators > 15 MeV • There may be a build up of ozone and induced radioactive Oxygen-15 and Nitrogen-13 • 10 air changes per hour or greater should be satisfactory Part 7, lecture 1: Facility design

  47. Other irradiation units for external beam radiotherapy • Simulator and CT scanner - design of rooms similar to the design of a diagnostic radiology facility. This is dealt with in the course on diagnostic radiology • Protons, neutrons, pions,… beyond the scope of the present course • Superficial/orthovoltage units Part 7, lecture 1: Facility design

  48. Superficial/orthovoltage treatment room Part 7, lecture 1: Facility design

  49. Some comments • The movement of the X Ray tube may be restricted to prevent the primary beam from hitting areas which are not sufficiently shielded • A lead glass window is typically sufficient for viewing - its integrity must be checked Part 7, lecture 1: Facility design

  50. Brachytherapy • Source assembly area may be required • A secure storage area for the source safe and source transfer procedures may be required • In room area monitor • HDR • Principles are similar to megavoltage unit Part 7, lecture 1: Facility design