Chapter 17 Quality Assurance

1. Chapter 17Quality Assurance

2. An adequate QA program increased staffing and up-to-date equipment can be expensive the total cost of QA program in radiation therapy ~3% of the annual billing are QA programs voluntary? incentive for QA? a desire to practice good radiation therapy or avoid malpractice suits

3. QA: Goals the objective, systematic monitoring of the quality and appropriateness of patient care. is essential for all activities in RadOnc • Structure: staff, equipment and facility • process: the pre- and post-treatment evaluations and the actual treatment application • and outcome: the frequency of accomplishing stated objectives (TCP), and by the frequency and seriousness of NTCP all of which can be measured

4. A comprehensive QA program includes admin, clinical, physical, and technical aspects of rad onc Operationally, no single personnel has the expertise to cover all these areas teamwork is essential among admin, rad onc, nurses, med phys, and therapy techs For an effective QA program , all the staff must be well coordinated and committed to QA.

5. Minimum Personnel Requirements for Clinical Radiation Therapy

6. Additional personnel These recommendations are for clinical service only, do not include staffing for research, teaching, or administrative functions. Additional personnel required for • QA of modern imaging equipment (e.g., cone-beam computed tomography [CT] system, [EPID]), CT simulators, and (PET)/CT • Sophisticated and complex treatments (e.g., [IMRT], [IGRT], [HDR], prostate implants, SRS, tomo, proton therapy).

7. For example if 800 patients/y with 3 linacs, one 60Co, an orthovoltage, and one TPS: 2-3physicists A training program with eight residents, two tech students, and a graduate student: 1 to 1.5 full-time employees (FTEs). Administration of this group would require 0.5 FTE If the faculty had 20% time for research: a total of 5-6 physicists for direct patient care.

9. Training education and training of physics staffing of critical importance The greatest weakness in this regard has been the physicist's training Most physicists are hired with less than adequate clinical training Structured clinical training programs have been traditionally nonexistent

10. Training Certification boards residency-type clinical training nationally accredited residency programs before taking the board examinations or assuming independent clinical esponsibilitie the certifying board for radiological physicists—has decided that “Beginning in 2014… candidates must be enrolled in or have completed a accredited residency program.”

11. Radiation oncology physicist: Qualifications a M.S. or Ph.D. in physics, medical physics, or a closely related field and a certification in radiation oncology physics by the American Board of Radiology, the American Board of Medical Physics, or another appropriate certifying body.

13. Role of physicist: example At the University of Minnesota the physicist's consultation is made as important as other consultations, such as those sought from the medical oncologist, the surgeon, or the radiologist To prevent bypassing the physics consultation, each patient is assigned a physicist who is available at the time of simulation to assist the radiation oncologist in formulating the best possible treatment plan Subsequent physics work is the designated physicist's responsibility,although he or she may be assisted by the dosimetrist or other technical personnel. The final treatment plan is approved by the radiation oncologist after discussing the plan with the physicist. Also, the physicist is present at the time of first treatment and subsequent treatments, if needed, to ensure proper implementation of the plan.

14. Not all the clinical physics procedures performed by physicists Many of the technical tasks: by dosimetrists so that physicists can devote time to developmental activities Every rad onc department needs to develop new programs as well as revise the old ones to keep current with advancements in the field: Responsibility of the physicist

15. Acceptance Testing • To satisfy all the specifications and criteria contained in the purchase contract • To perform all the tests in accordance with the company’s procedure manual • Any equipment to be used for patients must be tested to ensure that it meets its performance specifications and safety standards

16. Radiation Survey • To evaluate the exposure levels outside the room will not exceed permissible limits, considering the dose rate output, machine on time, use factors and occupancy factors for the surrounding areas • A calibration of the machine output (cGy/MU) • Radiation protection survey • Head leakage • Area survey • Tests of interlocks, warning lights, and emergency switches

17. Coincidence • Collimator axis, light beam axis and cross-hairs • The light field edges • The intersection of diagonals and the position of cross-hair images • Light beam with x-ray beam • AAPM guidelines  3% (2%)

18. Mechanical Isocenter • The intersection point of the axis of rotation of the collimator and the axis of rotation of the gantry • Collimator rotation • 2 mm diameter circle • Gantry rotation • ±1 mm

19. Radiation Isocenter • Collimator2 mm diameter circle • Treatment table 2 mm diameter circle • Gantry 2 mm diameter circle

20. 1 2 1 2 Multiple Beam Alignment Check • Focal spot displacement • Asymmetry of collimator jaws • Displacement in the collimator rotation axis or the gantry rotation axis • The split-field test

21. X-ray Beam Performance • Energy • A central axis depth dose distribution • A suitable ion chamber in a water phantom • Small chamber (<3 mm) • For a larger chamber, the depth dose curve should be shift to the left (toward the source) by 3/4r. • Suitable depths for comparing depth dose ratios are 10 and 20 cm. • 1010, 100 cm SSD, and 10 cm depth  ±2%

23. X-ray Beam Performance • Field flatness • The variation of dose relative to the central axis over the central 80% of the field size at 10 cm depth • < ±3% • Within the region extending up to 2 cm from the field edge at a 10 cm depth • +3% ~ -5% • The diagonal flatness extending up to 2.8 cm from the 50% isodose curve in a plane at a 10 cm depth • +4% ~ -6%

25. X-ray Beam Performance • Field symmetry • To fold the profile at the field center and the two halves of the profiles to be compared • < 2% at any pair of points

27. Electron Beam Performance • Energy • TG-25 • Rp (Ep)0=C1+C2Rp+C3Rp2 • < ±0.5 MeV • Flatness and symmetry • TG-25 • flatness±5% (± 3%) • symmetry < 2%

29. Wedges • 1010 • ±2°

30. Miscellaneous Checks • Isocenter shift with couch motion up and down  < ±2 mm • ODI  < ±2 mm • Field size indicators  < ±2 mm • Gantry angle and collimator angles  < 1º • Laser lights aligned with the isocenter  < ±2 mm • Tabletop sag with lateral or longitudinal travel under a distributed weight of 180 lb  < 0.5 cm

31. Simulator • Checking of the geometric and spatial accuracies • Performance evaluation of the x-ray generator and the associated imaging system • Table 17.5

32. Brachytherapy • Intracavitary sources and applicators • Source identity • Physical length, diameter, serial No. • Source uniformity and symmetry • The superposition of the autoradiograph and transmission radiograph • Source calibration • A well ionization chamber • 5% • Applicator evaluation • Orthogonal radiographs • The ease of source loading and removal

33. Remote Afterloaders (1) • Operational testing of the afterloading unit • Radiation safety check of the facility • Checking of source calibration and transport • Checking of treatment planning software • Table 17.6

34. Remote Afterloaders (2) • Source positioning • The position of dummy sources and radioactive sources should correspond within ±1 mm. • Source calibration • A well ionization chamber • A cylindrical lead insert for a conventional well ionization chamber for calibrating HDR sources • Cylindrical ion chamber • A free air geometry • An interpolative method of obtaining exposure calibration factor

35. Commissioning • After all the necessary beam data have been acquired and adopted, the machine can be released or commissioned for clinical use.

36. Commissioning Data for a Linear Accelerator

37. Periodic QA of Linear Accelerator

38. Periodic QA of Simulators

39. Thank you for your attention!!