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RADIATION PROTECTION IN RADIOTHERAPY

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  1. RADIATION PROTECTION IN RADIOTHERAPY IAEA Training Material on Radiation Protection in Radiotherapy Part 12: Quality Assurance PRACTICAL EXERCISE IAEA Post Graduate Educational Course Radiation Protection and Safe Use of Radiation Sources

  2. Objectives • To be familiar with the concepts of Quality Assurance as a multidisciplinary activity and its interrelation with radiation protection in radiotherapy. • To be familiar with Quality Assurance procedures as a tool for reviewing and assessing the overall effectiveness of a radiation protection program. • To be able to understand the need for and role of specific tests in the context of quality control and be able to identify appropriate national and international protocols for this task • To be aware of the need for involvement of professionals in a quality assurance program and for radiation protection Part 12, Practical 1

  3. Part 12: Quality Assurance IAEA Training Material on Radiation Protection in Radiotherapy Practical 1: Develop a Weekly QC Check List for an isocentric external beam irradiation device in the participant’s environment IAEA Post Graduate Educational Course Radiation Protection and Safe Use of Radiation Sources

  4. Why weekly? • Different frequencies may be possible and AAPM Task Group 40 recommends chiefly daily and monthly tests • Weekly checks are typically easy to schedule (e.g. each Friday at 4pm) • It is dependent on the user’s circumstances as to how often tests are performed Part 12, Practical 1

  5. Contents + Objective • Learn how to determine necessary checks and prioritize them • Understand how to design appropriate tests for a particular parameter • Develop a sheet which may be useful at the home institution Part 12, Practical 1

  6. What Minimum Equipment is Needed? • Paper • If checks are also to be performed in practice: • Radiographic film • Pointers • Graph paper Part 12, Practical 1

  7. How to start? • Think of three groups to test: • Mechanical/optical • Dosimetry • Safety Part 12, Practical 1

  8. How to decide on frequency for tests? • Likelihood of failure • Severity of the consequences if something goes wrong • Ease of the test - resources required A weekly check of an external beam irradiation unit typically takes about 2 hours Part 12, Practical 1

  9. Questions? Let’s get started... Part 12, Practical 1

  10. Some suggestions • Please don’t look before you try to produce your own list • Suggestions based on a document by C Blackwell and E McCullough for Mayo Clinic Part 12, Practical 1

  11. Weekly Mechanical Checks • Gantry angle readout • Collimator angle readout • Field size symmetric fields • Field size asymmetric fields • MLC field definition • Couch height • Couch angle • Physical wedge interlock • Electron applicators interlock Part 12, Practical 1

  12. Weekly optical checks • Optical distance indicator • Cross hair stability on collimator rotation • Cross hair stability on gantry rotation • Laser alignment to isocentre • Laser line orthogonality Part 12, Practical 1

  13. Weekly radiation checks • Output check photons • Output check electrons • Photon beam symmetry • Photon beam flatness • Light radiation field coincidence Part 12, Practical 1

  14. Weekly Safety Checks • Deadman switches • Door interlocks • Accessory mounts, trays, applicators • Emergency off buttons (one per week) • Touch guards Part 12, Practical 1

  15. Weekly other checks... • Film processor - if applicable • Electronic portal imaging • Data transfer for MLC • Record and verify system • Dynamic wedge factors and profiles • ... Part 12, Practical 1

  16. Handout Part 12, Practical 1

  17. Please check your handout • Do you want to add activities? • Can you suggest tolerances in the last column? Part 12, Practical 1