| Question 1: IEC 62895 defines the size-specific dose estimate (SSDE) as the |
| Reference: | IEC 62895: Methods for Calculating Size Specific Dose Estimates (SSDE) for Computed Tomography |
| Choice A: | radiation output of the CT scanner for a given patient size |
| Choice B: | absorbed dose averaged across the whole scan volume |
| Choice C: | air kerma averaged across the whole scan volume |
| Choice D: | absorbed dose weighted by the patient size |
| Question 2: SSDE is especially important for the pediatric population because CTDIvol tends to overestimate the absorbed radiation dose for smaller patients |
| Reference: | AAPM Report 293 |
| Choice A: | True |
| Choice B: | False |
| Question 3: Why are the SSDE conversion factors consistently lower for head CT (Report 293) in comparison to body CT (Report 204). |
| Reference: | AAPM Report 293 |
| Choice A: | attenuation of the skull |
| Choice B: | head CT examinations always use a higher kV |
| Choice C: | attenuation of the ribs |
| Choice D: | none of the above |
| Question 4: Despite its wide usage, CTDI limitations have been in the spotlight in recent years. Which limitation of CTDI methodology is specifically addressed by the introduction of a long phantom as described in AAPM reports 111 and 200? |
| Reference: | McCollough CH, Leng S, Yu L, Cody DD, Boone JM, McNitt-Gray MF. CT dose index and patient dose: they are not the same thing. Radiology. 2011;259(2):311-316. doi:10.1148/radiol.11101800 |
| Choice A: | CTDI’s inability to accurately measure the scanner output |
| Choice B: | CTDI’s inability to mimic actual patient’s torso and generation of scattered radiation from entire scan length. |
| Choice C: | CTDI’s inability to reflect surface/skin dose in stationary (without table movement) settings. |
| Choice D: | CTDI’s inability to account for varying patient sizes in the z-plane. |
| Question 5: Which definition below is more appropriate for estimating dose from multiple stationary (without table movement) CT scans: |
| Reference: | Bauhs JA, Vrieze TJ, Primak AN, Bruesewitz MR, McCollough CH. CT dosimetry: comparison of measurement techniques and devices. Radiographics. 2008 Jan-Feb;28(1):245-53. doi: 10.1148/rg.281075024. PMID: 18203941 |
| Choice A: | Skin dose = Peak dose x N scans |
| Choice B: | Dose = Peak dose x N scans |
| Choice C: | Skin dose = CTDI100 |
| Choice D: | Skin dose = CTDI100 x n scans |
| Question 6: As CTDI100 excludes contributions from radiation scattered beyond the relatively short range of integration along z, it tends to ______ the cumulative dose at the midpoint of a scanning range. |
| Reference: | AAPM Report 111: Comprehensive methodology for the evaluation of radiation dose in x‐ray computed tomography. College Park, MD: American Association of Physicists in Medicine; 2010. |
| Choice A: | approximate |
| Choice B: | underestimate |
| Choice C: | overestimate |
| Question 7: The cumulative dose at the midpoint of a scanning range of length L normalized by the CTDIvol (the G(L) function) is nearly independent of kV. |
| Reference: | Report 87, Journal of the International Commission on Radiation Units and Measurements, Volume 12, Issue 1, April 2012 |
| Choice A: | True |
| Choice B: | False |
| Question 8: Which of the following is true regarding the helically-acquired CTDIvol estimation method? |
| Reference: | Leon SM, Kobistek RJ, Olguin EA, Zhang Z, Barreto IL Schwarz BC. (2020), The helically‐acquired CTDIvol as an alternative to traditional methodology. J Appl Clin Med Phys, 21: 263-271. |
| Choice A: | The helical measurement estimates the equilibrium dose, unlike the axial CTDIvol |
| Choice B: | The helical measurement does not incorporate the pitch value in the calculation |
| Choice C: | The helical measurement requires entering an advanced service engineer mode |
| Choice D: | The helical measurement calculation is normalized by collimation width instead of scan length |
| Question 9: A measurement of CTDI8 free-in-air can provide what information? |
| Reference: | Dixon, R. L., & Boone, J. M. (2010). Cone beam CT dosimetry: A unified and self-consistent approach including all scan modalities—With or without phantom motion. Medical Physics, 37(6), 2703–2718. https://doi.org/10.1118/1.3395578 |
| Choice A: | The value of 'NT' for a scan |
| Choice B: | Direct measurements of the aperture, 'a' |
| Choice C: | The relative variation between 'a' and 'NT' |
| Choice D: | A value to directly compare to the displayed scanner output |
| Question 10: Measuring the equilibrium dose pitch product free-in-air D(eq,air) can provide all of the following except: |
| Reference: | Dixon, R. L., Anderson, J. A., Bakalyar, D. M., Boedeker, K. L., Boone, J. M., Cody, D. D., Fahrig, R., Jaffray, D. a., Kyprianou, I., McCollough, C. H., McNitt-Gray, M. F., Morgan, H. T., Morin, R. L., Nakonechy, K. D., Payne, T., Pizzutiello, R. J., Schmidt, B., Seibert, J. A., Simon, W. E., … Vastagh, S. (2010). Comprehensive Methodology for the Evaluation of Radiation Dose in X-Ray Computed Tomography (AAPM Report). http://www.aapm.org/pubs/reports/RPT_111.pdf |
| Choice A: | A dose measurement proportional to the overbeaming factor |
| Choice B: | A value useful to check periodically for constancy measurements |
| Choice C: | The primary radiation component of the beam |
| Choice D: | The scattered radiation component of the beam |
