2021 AAPM Virtual 63rd Annual Meeting
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Session Title: Patient-Specific QA Devices/Software
Question 1: Which of the following is NOT being verified as part of patient-specific QA?
Reference:AAPM TG-218: Tolerance limits and methodologies for IMRT measurement-based QA, M. Miften, A. Olch, D. Mihailidis, J. Moran, T. Pawlickim A. Molineu, H. Li, K. Wijesooriya, J. Shi, P. Xia, N. Papanikolaou, D. Low, Medical Physics, Vol 45(4), pp e53-e83.
Choice A:The accurate transfer of DICOM-RT plan data from the treatment planning system to the treatment delivery system
Choice B:The deliverability of the clinical plan on the treatment delivery system
Choice C:The clinical plan’s sensitivity to heterogeneities
Choice D:The accuracy of the clinical plan dose calculations on the phantom geometry
Question 2: True or False? The dose difference test is appropriate for comparing dose distributions in low gradient regions but inappropriate for comparing dose distributions in high gradient regions.
Reference:AAPM TG-218: Tolerance limits and methodologies for IMRT measurement-based QA, M. Miften, A. Olch, D. Mihailidis, J. Moran, T. Pawlickim A. Molineu, H. Li, K. Wijesooriya, J. Shi, P. Xia, N. Papanikolaou, D. Low, Medical Physics, Vol 45(4), pp e53-e83.
Choice A:True
Choice B:False
Question 3: True or False? Evaluating the distance to agreement test alone can still yield clinically relevant information in a high dose, low gradient region of a plan.
Reference:AAPM TG-218: Tolerance limits and methodologies for IMRT measurement-based QA, M. Miften, A. Olch, D. Mihailidis, J. Moran, T. Pawlickim A. Molineu, H. Li, K. Wijesooriya, J. Shi, P. Xia, N. Papanikolaou, D. Low, Medical Physics, Vol 45(4), pp e53-e83.
Choice A:True
Choice B:False
Question 4: Two dose points in a low dose, low gradient region of a clinical dose distribution are being compared to each other as part of a dose difference test. In the reference data set, the point’s value is 1 cGy. In the evaluation data set, the point’s value is 2 cGy. The normalization dose, when applicable, is the maximum dose in the reference dataset which is 200 cGy. The dose difference criterion is 3%.
Reference:AAPM TG-218: Tolerance limits and methodologies for IMRT measurement-based QA, M. Miften, A. Olch, D. Mihailidis, J. Moran, T. Pawlickim A. Molineu, H. Li, K. Wijesooriya, J. Shi, P. Xia, N. Papanikolaou, D. Low, Medical Physics, Vol 45(4), pp e53-e83.
Choice A:Pass/Pass
Choice B:Pass/Fail
Choice C:Fail/Pass
Choice D:Fail/Fail
Question 5: A Farmer-type ionization chamber is used to measure a “point” dose in a cylindrical phantom for a clinical plan. The chamber is placed into a high dose, low gradient region at the centroid of the tumor target. Which of the following calculated quantities is the most appropriate for this measured dose to be compared to?
Reference:AAPM TG-120: Dosimetry tools and techniques for IMRT, D. Low, J. Moran, J. Dempsey, L. Dong, M. Oldham, Medical Physics, Vol 38(3), pp 1313-1338.
Choice A:The calculated dose at a point in the center of the ionization chamber
Choice B:The calculated dose averaged over the volume of the ionization chamber
Choice C:The calculated maximum dose to the tumor target
Choice D:The calculated average dose to the tumor target
Question 6: If an absolute dose precision better than 3% is required for a PSQA application, which of the following detectors would be most appropriate to use?
Reference:AAPM TG-120: Dosimetry tools and techniques for IMRT, D. Low, J. Moran, J. Dempsey, L. Dong, M. Oldham, Medical Physics, Vol 38(3), pp 1313-1338.
Choice A:TLDs
Choice B:Ionization Chambers
Choice C:Radiochromic Film
Choice D:Gel
Question 7: If a high-resolution measurement of the penumbra region is required for a PSQA application that is incompatible with a scanning water tank setup, which of the following detectors would be most appropriate to use?
Reference:AAPM TG-120: Dosimetry tools and techniques for IMRT, D. Low, J. Moran, J. Dempsey, L. Dong, M. Oldham, Medical Physics, Vol 38(3), pp 1313-1338.
Choice A:TLDs
Choice B:Ionization Chamber
Choice C:Radiochromic Film
Choice D:Diode Array
Question 8: TG-218 recommends which of the following for universal tolerance limits for the gamma analysis test using global normalization in absolute dose? Assume all tests require greater than 95% of total points to pass.
Reference:AAPM TG-120: Dosimetry tools and techniques for IMRT, D. Low, J. Moran, J. Dempsey, L. Dong, M. Oldham, Medical Physics, Vol 38(3), pp 1313-1338.
Choice A:3%/3mm with a 10% dose threshold
Choice B:3%/2mm with a 10% dose threshold
Choice C:7%/4mm with a 20% dose threshold
Choice D:3%/3mm with a 20% dose threshold
Question 9: True or False? The main goal of an independent secondary monitor unit calculation is to precisely reproduce the dose distribution from the treatment planning system and ensure that the two are identical.
Reference:IAEA TRS 430: Commissioning and quality assurance of computerized planning systems for radiation treatment of cancer
Choice A:True
Choice B:False
Question 10: One benefit of on treatment EPID-based transmission dosimetry is:
Reference:AAPM TG-120: Dosimetry tools and techniques for IMRT, D. Low, J. Moran, J. Dempsey, L. Dong, M. Oldham, Medical Physics, Vol 38(3), pp 1313-1338.
Choice A:The EPID is designed for absolute dosimetry
Choice B:It can detect errors before the beam is delivered
Choice C:It can detect patient setup errors
Choice D:It can eliminate the need to purchase additional QA equipment when establishing an IMRT QA program.
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