| Question 1: Which of the following approaches perform multi energy CT by scanning at two different tube voltages? |
| Reference: | Johnson, T.R., 2012. Dual-energy CT: general principles. American Journal of Roentgenology, 199(5_supplement), pp.S3-S8.
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| Choice A: | Rapid-voltage switching. |
| Choice B: | Dual-source CT. |
| Choice C: | Multi-layer detector. |
| Choice D: | (a) and (b). |
| Question 2: Increasing the spectral separation or distinctiveness between multi-energy measurements improves dose efficiency. In some multi-energy CT approaches, spectral separation can be improved by..... |
| Reference: | Johnson, T.R., 2012. Dual-energy CT: general principles. American Journal of Roentgenology, 199(5_supplement), pp.S3-S8. |
| Choice A: | Increasing the scan time. |
| Choice B: | Increasing the number of projections. |
| Choice C: | Adding filters to the x-ray beam. |
| Choice D: | Reducing the helical pitch. |
| Question 3: The theoretical advantage of projection-space decomposition over image-space method is: |
| Reference: | dual- and multi-energy Ct: Principles, Technical Approaches, and Clinical Applications, Cynthia McCollough, et al, Radiology, 276 (3), 2015 |
| Choice A: | Less image noise. |
| Choice B: | Less beam-hardening artifact. |
| Choice C: | Faster reconstruction. |
| Choice D: | Better spatial resolution |
| Question 4: Three material decomposition in dual-energy CT usually requires additional assumption. The commonly used assumption includes: |
| Reference: | dual- and multi-energy Ct: Principles, Technical Approaches, and Clinical Applications, Cynthia McCollough, et al, Radiology, 276 (3), 2015 |
| Choice A: | Mass conservation. |
| Choice B: | Volume conservation. |
| Choice C: | (a) and (b). |
| Choice D: | None of above. |
| Question 5: ( T/F) Image-based methods for material suppression requires two basis materials and determining the density maps from the linear combination of the mass attenuation coefficients at high and low energy scans..... |
| Reference: | L. Yu, Dual Energy CT-Based Monochromatic Imaging, AJR, 199, 2012. |
| Choice A: | True. |
| Choice B: | False. |
| Question 6: Projection based dual-energy based material decomposition algorithms are primarily limited by which of the following: |
| Reference: | Dual energy CT in radiotherapy: Current applications and future outlook, W. van Elmpt, et al, Radiotherapy and Oncology, 119(1), 2016. |
| Choice A: | Beam hardening effects. |
| Choice B: | Data consistency between the high and low energy projections. |
| Choice C: | Noise from the low energy projections. |
| Choice D: | Spatial resolution. |
