2019 AAPM Annual Meeting
Back to session list

Session Title: Alternative Strategies for Linac Beam Verification or Beam Data Collection Without Using a 3D Water Tank
Question 1: What is the preferred method for collection of TMR data.
Reference:N. C. Knutson et al., “Technical Note: Direct Measurement of Continuous TMR Data with a 1D Tank and Automated Couch Movements,” Med. Phys., vol. 44 no. 7 pp. 3861-3865,
Choice A:Conversion from measured PDDs
Choice B:Discrete measurements in solid water
Choice C:Direct continuous measurement in water
Choice D:I don’t measure TMRs because it is too hard
Question 2: Scanning speeds are limited by all but the following.
Reference:N. C. Knutson et al., “A Cost Effective Method for Collecting Commissioning Beam Scan Data with a 1D Tank and Automated Couch Movements,” JACMP vol 19 no. 6 pp. 60-67, 2018.
Choice A:Water motion
Choice B:Data point resolution
Choice C:Maximum couch speed
Question 3: How do you program a beam hold in a developer mode research beam
Reference:N. C. Knutson et al., “A Cost Effective Method for Collecting Commissioning Beam Scan Data with a 1D Tank and Automated Couch Movements,” JACMP vol 19 no. 6 pp. 60-67, 2018.
Choice A:Set the MU to zero
Choice B:Change MU from control point to control point
Choice C:Modify a machine parameter with a fixed MU
Choice D:Type “Pause” in XML
Question 4: Beam alignment and profile measurements in the presence of a magnetic field is primarily affected by
Reference:van Zijp et al. “Minimizing the magnetic field effect in MR-linac specific QA-tests: the use of electron dense materials”, PMB 2016,61(3)
Choice A:The change in dose distribution due to the B-field effect on the secondary electrons
Choice B:The change in dose reading due to the B-field effect on the detector
Choice C:The change in dose output due to the B-field effect on the linac
Choice D:B-field inhomogeneity within the bore.
Question 5: Setup of measurement equipment and beam alignment measurement on a MRI-Linac cannot make use of:
Reference:Barten et al., “Suitability of EBT3 GafChromic film for quality assurance in MR-guided radiotherapy at 0.35 T with and without real-time MR imaging” PMB 2018 63(16);
Choice A:Projections of the radiation field
Choice B:Gantry rotation
Choice C:Collimator rotation
Choice D:Position (difference) of well-defined objects (e.g. ball-bearings)
Question 6: Detector response curves to e.g. dose should at least be:
Reference:Raaymakers et al. “First patients treated with a 1.5 T MRI-Linac: clinical proof of concept of a high-precision, highfield MRI guided radiotherapy treatment”, PMB 2017 62 (41)
Choice A:Linear
Choice B:Accurately determined
Choice C:Not influenced by the magnetic field
Choice D:All of the above
Back to session list