| Question 1: Which of the following changes in technique will decrease the image noise by a factor of 2 ? |
| Reference: | M. McNitt-Gray, “AAPM/RSNA Physics Tutorial for Residents:
Topics in CT: Radiation Dose in CT,†RadioGraphics 2002; 22:1541–1553. |
| Choice A: | Increase the slice thickness by a factor of 4 |
| Choice B: | Increase the slice thickness by a factor of 2 |
| Choice C: | Decrease the slice thickness by a factor of 2 |
| Choice D: | Decrease the mA by a factor of 2 |
| Choice E: | Decrease the tube potential by 20 kV |
| Question 2: For an AEC control that uses a Noise Index (NI) – or Standard Deviation (SD), if you change the kV from 120 to 80 and keep the NI or SD constant, how will the dose change? |
| Reference: | Reference: H. Brisse, “Automated exposure control in multichannel CT with tube current modulation to achieve a constant level of noise.†Med. Phys. 34 (7), July 2009. |
| Choice A: | Increase by about a factor of 1.5 |
| Choice B: | Increase by about a factor of 3 |
| Choice C: | Remain approximately the same |
| Choice D: | Decrease by about a factor of 1.5 |
| Choice E: | Decrease by about a factor of 3 |
| Question 3: Starting with a manual technique of 120 kV, 400 mA, 1.0 sec, 0.75 pitch, which is the best way to reduce the dose by a factor of 2? |
| Reference: | Reference: J Hsieh, Computed Tomography – Principles, Design, Artifacts, and Recent Advances (2009) |
| Choice A: | 120 kV, 200 mA, 1.0 sec, 0.75 pitch |
| Choice B: | 120 kV, 400 mA, 1.0 sec, 1.5 pitch |
| Choice C: | 120 kV, 400 mA, 0.5 sec, 0.75 pitch |
| Choice D: | 140 kV, 400 mA, 1.0 sec, 0.75 pitch |
| Choice E: | 140 kV, 400 mA, 1.0 sec, 1.5 pitch |
| Question 4: In the process of optimizing CT protocols, which of the following is NOT true? |
| Reference: | Reference: Sorantin E, et al. CT in children—dose protection and general considerations when planning a CT in a child. European Journal of Radiology Vol. 82, 1043-1049, 2013. |
| Choice A: | CT technologies with wide volumetric coverage and faster rotation can help reduce iodinated contrast usage. |
| Choice B: | A constant image noise level across all body sizes should be the goal as it produces consistent image appearance across all studies for radiologists. |
| Choice C: | Setting the tube potential lower may not be beneficial for patients of larger size. |
| Choice D: | The use of low tube voltage may be suboptimal when there are dense materials (highly concentrated iodinated contrast, metal, etc.) in the anatomy to be scanned. |
| Question 5: The primary reason(s) that we perform gonadal shielding in pediatric patients is to: |
| Reference: | ICRP Publication 121 (2013. www.imagegently.org |
| Choice A: | Reassure the patient and family members |
| Choice B: | Adhere to current regulatory requirements |
| Choice C: | Reduce radiation dose |
| Choice D: | Both a and b |
| Question 6: One reason that pediatric CT dose indices may be lower than analogous adult CTs when searching for tumors is: |
| Reference: | www.imagegently.org |
| Choice A: | Relatively larger primary tumors in children |
| Choice B: | Less motion artefact |
| Choice C: | Faster scans |
