| Question 1: For a cylindrical ion chamber with its center at depth d and radius r, the effective point of measurement is at depth: |
| Reference: | Gerbi, B. J., J. A. Antolak, et al. (2009). "Recommendations for clinical electron beam dosimetry: Supplement to the recommendations of Task Group 25." Medical Physics 36(7): 3239-3279 |
| Choice A: | d |
| Choice B: | d – 0.5*r |
| Choice C: | d + 0.5*r |
| Choice D: | d – 0.6*r |
| Choice E: | d + 0.6*r |
| Question 2: When measuring percent depth ionization with a cylindrical ion chamber, the following corrections are recommended when converting to percent depth dose: |
| Reference: | Gerbi, B. J., J. A. Antolak, et al. (2009). "Recommendations for clinical electron beam dosimetry: Supplement to the recommendations of Task Group 25." Medical Physics 36(7): 3239-3279 |
| Choice A: | Effective point of measurement |
| Choice B: | Effective point of measurement & stopping power ratio |
| Choice C: | Effective point of measurement, stopping power ratio & fluence correction |
| Choice D: | Stopping power ratio & fluence correction |
| Choice E: | Fluence correction |
| Question 3: The most significant impact of patient heterogeneity on lung dose in electron therapy of the post mastectomy chest wall is: |
| Reference: | Hogstrom KR 2004 Electron beam therapy: dosimetry, planning, and techniques Principles and Practice of Radiation Oncology ed C Perez et al (Baltimore, MD: Lippincott, Williams, & Wilkins) pp 252-282 |
| Choice A: | Increased penetration in lung due to low lung density |
| Choice B: | Scatter from an irregularly shaped chest wall surface |
| Choice C: | Scatter from closely spaced ribs |
| Choice D: | Scatter from the mediastinum in the IMC field to lung |
| Choice E: | Increased dose in region of where electron beams of differing energy abut |
| Question 4: Consider a PTV having a 5-cm diameter circular cross section and a maximum depth of 4 cm. For the distal 90% dose surface to contain the PTV, which of the following are the best initial estimates for beam energy (Ep,o) and field size? |
| Reference: | Hogstrom KR 2004 Electron beam therapy: dosimetry, planning, and techniques Principles and Practice of Radiation Oncology ed C Perez et al (Baltimore, MD: Lippincott, Williams, & Wilkins) pp 252-282 |
| Choice A: | 12 MeV, 5-cm diameter field |
| Choice B: | 12 MeV, 6-cm diameter field |
| Choice C: | 12 MeV, 7-cm diameter field |
| Choice D: | 13 MeV, 6-cm diameter field |
| Choice E: | 13 MeV, 7-cm diameter field |
| Question 5: All of the following are a clinical basis for skin collimation, EXCEPT: |
| Reference: | Hogstrom KR 2004 Electron beam therapy: dosimetry, planning, and techniques Principles and Practice of Radiation Oncology ed C Perez et al (Baltimore, MD: Lippincott, Williams, & Wilkins) pp 252-282 |
| Choice A: | Sharpening penumbra at ends of treatment area in arc therapy of chest wall |
| Choice B: | Improvement of dose in abutted electron beams in fixed beam therapy of chest wall |
| Choice C: | Protection of eye in treatment of nose |
| Choice D: | Restoration of penumbra under bolus |
| Choice E: | Small field for treating eyelid |
| Question 6: Currently, commercially available electron beam treatment planning technologies include: |
| Reference: | Kim MM, Kudchadker RJ, Kanke JE, Zhang S, and Perkins GH 2012 Bolus electron conformal therapy for the treatment of recurrent inflammatory breast cancer: a case report,Medical Dosimetry 37 208-213 |
| Choice A: | Modeling of eye blocks |
| Choice B: | Energy segmentation |
| Choice C: | Electron arc therapy |
| Choice D: | Pencil beam redefinition algorithm |
| Choice E: | Bolus electron conformal therapy |
| Question 7: Which of the following is the most appropriate use of uniform thickness bolus? |
| Reference: | Hogstrom KR 2004 Electron beam therapy: dosimetry, planning, and techniques Principles and Practice of Radiation Oncology ed C Perez et al (Baltimore, MD: Lippincott, Williams, & Wilkins) pp 252-282 |
| Choice A: | Placing around nose to remove surface irregularity and increase dose to septum |
| Choice B: | Placing in ear canal to protect inner ear from increased dose without bolus |
| Choice C: | Placing on chest wall to increase surface dose when using low energy electron beams or arc electron therapy |
| Choice D: | Placing on chest wall to conform 90% dose surface to distal chest wall PTV surface |
| Choice E: | Placing on lateral head to conform 90% dose surface to distal parotid PTV surface |
| Question 8: The primary purpose of bolus electron conformal therapy (BECT) is to: |
| Reference: | Kudchadker, R.J., K.R. Hogstrom, et al. (2002). “Electron conformal radiotherapy using bolus and intensity modulation.” Int J Radiat Oncol Biol Phys 53(4): 1023-1037 |
| Choice A: | Conform the 90% isodose surface to the distal surface of the PTV |
| Choice B: | Maintain dose uniformity (i.e. 90%-100%) inside the PTV |
| Choice C: | Minimize the maximum dose to less than 110% of the prescription |
| Choice D: | Provide surface collimation to improve the electron penumbra |
| Choice E: | Treat targets with uniform thickness and density. |
| Question 9: Bolus electron conformal therapy is ideally suited for clinical cases that exhibit: |
| Reference: | Hogstrom K.R., J.A. Antolak, et al. (2003). “Modulated Electron Therapy,” in Intensity-Modulated Radiation Therapy: The State of the Art, edited by J.F. Palta and T.R. Mackie (Medical Physics Publishing, Madison, WI, 2003) 749 - 786 |
| Choice A: | Irregular surfaces |
| Choice B: | Variable target depths |
| Choice C: | Critical structures immediately distal |
| Choice D: | Maximum target depth <6cm |
| Choice E: | All of the above |
| Question 10: The variable bolus thickness for BECT is generally designed: |
| Reference: | Low, D.A., G. Starkschall, et al. (1992). “Electron bolus design for radiotherapy treatment planning: Bolus design algorithms.” Med. Phys. 19(1):115-124 |
| Choice A: | Manually within any commercial treatment planning system. |
| Choice B: | Using stand-alone commercial software as the difference between the therapeutic range and target thickness |
| Choice C: | Using inverse optimization algorithms and dosimetric planning objectives |
| Choice D: | Independent of the depth of the target |
