2018 AAPM Annual Meeting
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Session Title: Technical and Professional Preparations for Medical Physicists in the Upcoming MRgRT Era
Question 1: For a medical physicist not trained in MRI, preparing to work on an MRI simulator should include:
Reference:M Cao, K Padgett, Y Rong, “Are in-house diagnostic MR physicists necessary for clinical implementation of MRI guided radiotherapy?”, JACMP, 18:5:6-9, 2017. M. Scmidt, G. Payne, “Radiotherapy planning using MRI”, Physics in Medicine and Biology, 60, R323-362, 2015.
Choice A:Training by the manufacturer.
Choice B:Seeking the services of a qualified MRI medical physicist.
Choice C:Understanding the challenges of using MRI in RT planning.
Choice D:A and C.
Choice E:A,B and C.
Question 2: Which of the following statement is INCORRECT about MRI distortion for RT application?
Reference:Weygand J, Fuller CD, Ibbott GS, et al. Spatial Precision in Magnetic Resonance Imaging-Guided Radiation Therapy: The Role of Geometric Distortion. Int J Radiation Oncol Biol Phys, Vol. 95, No. 4, pp. 1304e1316, 2016.
Choice A:Geometric distortion correction algorithms must be validated and properly assessed before being implemented for RT applications.
Choice B:MRI distortion is MR pulse sequence dependent.
Choice C:Precision within 2 mm is desired.
Choice D:Patient related geometric distortion is more problematic.
Choice E:None of them.
Question 3: When siting an MRI-Linac, what major difference(s) is/are recommended as compared to a conventional Linac?
Reference:Kanal, E., Barkovich, A.J., Bell, C., Borgstede, J.P., Bradley, W.G., Froelich, J.W., Gimbel, J.R., Gosbee, J.W., Kuhni‐Kaminski, E., Larson, P.A. and Lester, J.W., 2013. ACR guidance document on MR safe practices: 2013. Journal of Magnetic Resonance Imaging, 37(3), pp.501-530.
Choice A:Following American College of Radiology (ACR) MRI safety zones.
Choice B:Addition of a penetration panel.
Choice C:Elimination of reinforcing bars (rebar/steel) in the shielding.
Choice D:All of the above.
Question 4: The electron return effect may cause an increase in dose at air/tissue interfaces. What is one treatment planning strategy to mitigate this effect?
Reference:Raaijmakers, A.J.E., Raaymakers, B.W. and Lagendijk, J.J., 2005. Integrating a MRI scanner with a 6 MV radiotherapy accelerator: dose increase at tissue–air interfaces in a lateral magnetic field due to returning electrons. Physics in Medicine & Biology, 50(7), p.1363.
Choice A:Turn the magnetic field off during treatment.
Choice B:Disable inhomogeneity corrections during dose calculation.
Choice C:Use more beams in the treatment plan design.
Choice D:Avoid having the beam traverse air when treatment planning.
Question 5: Which of the following are the advantages of MRgRT system?
Reference:P Kupelian P, J-J Sonke, Magnetic Resonance–Guided Adaptive Radiotherapy: A Solution to the Future. Semin Radiat Oncol. 2014;24(3):227-232. doi:10.1016/j.semradonc.2014.02.01
Choice A:Improved soft tissue contrast
Choice B:Soft tissue based gated treatment
Choice C:Effective online adaptive therapy
Choice D:Onboard functional imaging capability
Choice E:All of the above
Question 6: The 5-Gauss line is:
Reference:E Kanal, JP Borgstede, AJ Barkovich, C Bell, WG. Bradley, JP Felmlee, JW Froelich, EM Kaminski, EK Keeler, JW Lester, EA Scoumis, LA Zaremba and MD Zinninge, American College of Radiology White Paper on MR Safety, American Journal of Roentgenology. 2002;178: 1335-1347. doi:10.2214/ajr.178.6.1781335
Choice A:A pixel line in the matrix
Choice B:The magnetic field line territory within which the magnetic field can become harmful
Choice C:A catheter inserted into the femoral artery
Choice D:A geometric theorem
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