Question 1: Monthly routine calibration of machine using a solid water phantom, there was no problem with photon beam, but a consistent difference of over 3% was noted in electron beam. What could be the problem?
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Reference: | Reference: Wrong slab was used that has uniform whole proving air gap around chamber. A possible ref: Ho A, Paliwal BR. Stopping-power and mass energy -absorption coefficient ratios for solid water. Med Phys 1986;13:403-404
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Choice A: | Temperature and pressure correction |
Choice B: | Change in SSD |
Choice C: | Changes in flatness & symmetry |
Choice D: | Wrong phantom slab for ion chamber |
Choice E: | Defective ion chamber |
Question 2: A patient with a centrally located glioblastoma is planned with non-coplanar vertex field. What should be considered for such a field?
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Reference: | Consider beam path passing through entire body thus giving significant dose to whole body: Das et al, Int J Radiat Oncol Biol Phys 1997;37:1023-1029. |
Choice A: | PTV coverage |
Choice B: | Estimation and proper evaluation of DVH |
Choice C: | Beam angle selection |
Choice D: | Age of patient |
Choice E: | Use of MLC |
Question 3: After implementation of an in-house online event recording system at the UCSD Cancer Center, were most linac issues resolve by clinic staff, clinic staff with remote assistance, or on-site by a vendor engineer?
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Reference: | Improving linear accelerator service response with a real-time electronic event reporting system. Hoisak JD, Pawlicki T, Kim GY, Fletcher R, Moore KL. J Appl Clin Med Phys. 2014 Sep 8;15(5):4807. doi: 10.1120/jacmp.v15i5.4807. |
Choice A: | Clinic staff |
Choice B: | Clinic staff with remote assistance |
Choice C: | On-site vendor engineer |
Choice D: | Comparable frequencies for each of the above |
Choice E: | None of above |
Question 4: Which of the following was not cited as an advantage of an online help desk system for linac problems at the Illawarra Cancer Care Centre?
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Reference: | Experience with an online helpdesk for equipment fault reporting in a radiation oncology department. McNamara J, Williams M, Carolan M. J Appl Clin Med Phys. 2013 Nov 4;14(6):4396. doi: 10.1120/jacmp.v14i6.4396 |
Choice A: | Eliminates the need for communication between the radiation therapists, physicists, and engineers. |
Choice B: | Allows access by multiple users simultaneously from any computer in the cancer center, which is an improvement over a fault logbook located at the linac. |
Choice C: | Observations such as smells and noises in the linac bunker that previously may have been discussed but were never written down are now documented. |
Choice D: | Field service reports (FSRs) are received in electronic format and can be input into the system immediately. |
Choice E: | All of above |
Question 5: Based on the TLD measured dose in the IROC Houston lung phantoms which of the following heterogeneity correction algorithms calculate a dose that has the closest agreement with the measured dose?
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Reference: | Kry SF, Alvarez P, Molineu A, Amador C, Galvin J, Followill DS. Algorithms Used in Heterogeneous Dose Calculations Show Systematic Differences as Measured With the Radiological Physics Center's Anthropomorphic Thorax Phantom Used for RTOG Credentialing. Int J Radiat Oncol Biol Phys 85(1):e95-e100, 1/2013. |
Choice A: | AAA |
Choice B: | Monte Carlo |
Choice C: | Convolution superposition |
Choice D: | Pencil beam |
Choice E: | Clarkson |
Question 6: Depending on the dosimeter used, the magnitude of the additional small field fluence correction, down to a 0.5 x 0.5 cm2 field size can be as much as:
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Reference: | Francescon et al. Med Phys, Vol. 38, No. 12, December 2011. |
Choice A: | 0% |
Choice B: | 2% |
Choice C: | 5% |
Choice D: | 8% |
Choice E: | 13% |