2017 AAPM Annual Meeting
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Session Title: In Memoriam of Michael Goitein: Milestones in Treatment Planning, Biophysical Modeling, and Delivery of Proton Therapy
Question 1: The concept of DVH was first used in:
Reference:Proton radiation as boost therapy for localized prostatic carcinoma. JAMA, Vol 241, p 1912-, 1979.
Choice A:3D CRT.
Choice B:IMRT.
Choice C:Proton Therapy .
Choice D:Electron beam therapy.
Question 2: The beam’s eye view is:
Reference:Goitein, M., et al. (1983). "Multi-Dimensional Treatment Planning: II. Beam's Eye-View, Back Projection, and Projection through CT Sections." International Journal of Radiation Oncology, Biology and Physics 9: 789-797.
Choice A:Required for determining multi-leaf collimator leaf sequences for the delivery of intensity-modulated radiotherapy.
Choice B:Used to select optimum beam directions maximizing avoidance of critical normal tissues.
Choice C:Used to define the planning target volume.
Question 3: A passively scattered beam of protons in a homogeneous medium has a range of 15 cm and a distal dose fall-off of 90% to 10% of 6 mm. The same beam through a complex heterogeneities of a head and neck patient will have a distal fall off of:
Reference:Urie, M., et al. (1986). "Degradation of the Bragg peak due to inhomogeneities." Physics in Medicine and Biology 31(1): 1-15.
Choice A:Less than 6 mm.
Choice B:Equal to 6 mm.
Choice C:Greater than 6 mm.
Question 4: Misalignment of range compensator and patient’s bony anatomy proximal to the target volume in passively-scattered proton therapy introduces uncertainty in the range of protons:
Reference:Urie, M., et al. (1984). "Compensating for heterogeneities in proton radiation therapy." Physics in Medicine and Biology 29(5): 553-566.
Choice A:It may be accounted for by smearing the compensator and enlarging the spread-out Bragg peak.
Choice B:It leads to overdosing at the distal portion of the target volume.
Choice C:It leads to greater sparing of normal tissues proximal to the target volume.
Question 5: Why have the studies to find recurrence within the cold-spot sub-volume of an inhomogeneously irradiated tumor been unsuccessful?
Reference:Reference: Goitein, M., et al. (1983). "Multi-Dimensional Treatment Planning: II. Beam's Eye-View, Back Projection, and Projection through CT Sections." International Journal of Radiation Oncology, Biology and Physics 9: 789-797.
Choice A:Imaging of tumor recurrence is not sensitive and accurate enough.
Choice B:Not true; there are studies clearly demonstrating that cold spot is responsible for tumor recurrence.
Choice C:Location of recurrence depends on the relative size and depth of the cold spot.
Choice D:Location of tumor recurrence cannot be explained by dose distribution.
Question 6: Suppose you are fitting a TCP model to a large clinical dataset consisting of 500 patients with 485 confirmed local controls and 15 local failures, and complete set of dose-volume, fractionation, and follow-up data. With such a large and rich dataset you are considering using a sophisticated TCP model with 7 parameters describing dose per fraction effect, repair mechanisms, and repopulation. Your friendly biostatistician is telling you that fitting this model to your dataset would represent serious overfitting with biased and unreliable parameter estimates. Why?
Reference:Reference: Goitein, M., et al. (1983). "Multi-Dimensional Treatment Planning: II. Beam's Eye-View, Back Projection, and Projection through CT Sections." International Journal of Radiation Oncology, Biology and Physics 9: 789-797.
Choice A:500 cases is not enough.
Choice B:485 cases with local control is not enough.
Choice C:15 cases with local failure is not enough.
Choice D:The friendly biostatistician is wrong.
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