Question 1: Using the EPID for in-treatment target position assessment has the benefit that: |
Reference: | Rottmann et al 2010, Phys Med Biol Vol. 55(18), pp. 5585-5598
http://dx.doi.org/10.1088/0031-9155/58/12/4195
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Choice A: | The BEV perspective captures both directions of steep dose gradient. |
Choice B: | MV image contrast formation is dominated by the photoelectric effect. |
Choice C: | The additional patient dose is negligible if the EPID is placed >15cm away from the patient. |
Choice D: | A and C |
Choice E: | None of the above |
Question 2: What are the requirements to generate in-treatment fluoroscopic 3D images from in-treatment fluoroscopic (2D) EPID images? |
Reference: | Mishra et al 2014, Med. Phys. 41, 081713
http://dx.doi.org/10.1118/1.4889779
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Choice A: | The gantry has to rotate for a minimum of 180° during treatment delivery. |
Choice B: | A patient specific motion model derived from pre-treatment imaging (4DCT). |
Choice C: | Optimization of motion model parameters to generate the DRR best matching the current EPID image. |
Choice D: | B and C |
Choice E: | None of the above |
Question 3: Transit dose is measured through different phantom thicknesses with an EPID. To determine the dose that would be measured by an ion-chamber in solid water at the same position, a non-linear mapping from EPID signal to dose is required. Assuming that this is only due to primary dose i.e. ignoring scatter, what is the main physical mechanism for the difference in EPID response to ion-chamber? |
Reference: | Chen et al. Med. Phys 33(3), 584-594, 2006 |
Choice A: | Attenuation of the beam |
Choice B: | Settings of the EPID acquisition |
Choice C: | Energy-dependent response of the EPID |
Choice D: | Different size of the EPID |
Question 4: The major difference for an EPID backprojection method for VMAT compared to IMRT is: |
Reference: | Mans et al. Radiother. Oncol. 94, 181-187, 2010 |
Choice A: | Dose calculation method |
Choice B: | Requirement for cine-mode imaging |
Choice C: | Increase in EPID sensitivity |
Choice D: | EPID sag/flex correction |
Question 5: What is the typical Detective Quantum Efficiency of current flat-panel electronic portal imaging devices? |
Reference: | Antonuk LE: Electronic Portal Imaging Devices: A Review and Historical Perspective of Contemporary Technologies and Research. Phys. Med. Biol. 47(6), R31-R65, 2002. PMID: 11936185
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Choice A: | 1-2% |
Choice B: | 30-35% |
Choice C: | 60-70% |
Choice D: | 80-100% |
Question 6: It is possible to significantly improve the Detective Quantum Efficiency of flat-panel electronic portal imaging devices while largely preserving spatial resolution. |
Reference: | Wang Y, Antonuk LE, Zhao Q, El-Mohri Y and Perma L: High-DQE EPIDs based on thick, segmented BGO and CsI:Tl scintillators: Performance evaluation at extremely low doses. Med. Phys. 36(12), 5707-5718, 2009. PMID: 20095283 PMCID: PMC2797046
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Choice A: | True. |
Choice B: | False. |