2016 AAPM Annual Meeting
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Session Title: Basics of Proton Therapy
Question 1: Which statement is True about the use of CBCT in proton therapy?
Reference:Y-K-Park et al, Med Phys 42 4449 (2015), C Veiga et al, IJROBP 95 549 (2016).
Choice A:Photon scatter affects the image quality of CBCT images but have minimal impact on the accuracy of proton dose calculation.
Choice B:Deformable image registration alone between simulation CT and CBCT can model all complex anatomical change.
Choice C:The accuracy of Hounsfield units in CBCT is not affected by beam hardening.
Choice D:CBCT can be used for the qualitative assessment of anatomical change.
Question 2: Range uncertainty of a proton beam:
Reference:Moyers MF, et.al. : Med Dosim. 2010 Autumn;35(3):179-94. doi: 10.1016/j.meddos.2009.05.004. Yang M, et.al : Phys Med Biol. 2012 Jul 7;57(13):4095-115. doi: 10.1088/0031-9155/57/13/4095. Paganetti, H : Phys Med Biol. 2012 Jun 7;57(11):R99-117. doi: 10.1088/0031-9155/57/11/R99.
Choice A:Will produce less normal tissue complications.
Choice B:Will lead to greater tumor control rates for proton patients when compared to photons.
Choice C:Can be addressed by using a beam specific margins in the distal and proximal directions.
Choice D:Eliminate the benefits of decreased integral dose given to the patient.
Choice E:Has been poorly researched and is not quantifiable.
Question 3: Which statement concerning image guidance for proton therapy is NOT true?
Reference:1. Chen G et al. A review of image-guided radiotherapy. Radiol Phys Technol. 2:1-12, 2009. 2. Dong L. Image guidance to reduce setup error. 2011 AAPM summer school. https://www.aapm.org/education/VL/vl.asp?id=2158 3. Seco J and Spadea MF. Imaging in particle therapy: state of the art and future perspective. Acta Oncologica. 54:1254-1258, 2015. 4. Poludniowski G et al. Proton radiography and tomography with application to proton therapy. Br J Radiol. 88:20150134, 2015.
Choice A:Currently the majority of proton centers rely on 2D X-ray imaging with or without fiducials to verify patient position.
Choice B:Registering 2D X-ray images to 3D planning CT dataset in 2D-3D mode may allow determining the required set up correction in translation and rotation.
Choice C:KV CBCT has become commercially available and has been installed in several proton centers worldwide.
Choice D:Volumetric image guidance can be accomplished with gantry mounted CBCT, robotic C-arm CBCT, or CT-on rail.
Choice E:The major barrier to clinical use of proton CT in treatment planning and verification is the unduly high dose to patient.
Question 4: Which statement is True about cyclotron and synchrotron?
Reference:Godfrey D, Das S. K., Wolbarst A. B., Advances in Medical Physics, Medical Physics Publication, Vol. 5, 2014
Choice A:In cyclotron, as the proton energy is increased, the magnetic field is also increased.
Choice B:Proton energy increases by increasing the magnetic fields in synchrotron.
Choice C:As the energy increases, the proton radius increases in synchrotron.
Choice D:Magnetic field strength and energy are increased simultaneously to keep protons in the same orbits in synchrotron.
Question 5: Which is true for different delivery systems?
Reference:Paganetti H, Proton therapy physics. CRC press N.Y. 2012
Choice A:Double scattering uses energy stacking to produce spread out Bragg peak.
Choice B:Uniform scanning uses modulation wheels to produce spread out Bragg peak.
Choice C:To produce spread out Bragg peaks, energy of protons needs to be changed.
Choice D:Scanning delivery systems do not produce spread out Bragg peaks.
Question 6: Regarding proton beams characteristics:
Reference:Principles and Practice of Proton Beam Therapy, I. Das, H. Paganetti, AAPM summer school 2015.
Choice A:250 MeV proton beams spread laterally more than 70 MeV proton Beams.
Choice B:70 MeV proton beams suffer higher straggling than 250 MeV proton beams.
Choice C:Proton beams provides a finite range and sparing of distally organ at risk to the target.
Choice D:Have lower linear energy transfer (LET).
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