| Question 1: Which of the following statement about specialized platforms is true at present? |
| Reference: | Real-time intrafraction motion monitoring in external beam radiotherapy, Bertholet et al. Phys Med Biol, Vol 64, pp 15TR01, 2019 |
| Choice A: | Hybrid monitoring (e.g. on Cyberknife) imposes no ionizing radiation |
| Choice B: | MR imaging allows real-time 3D soft tissue monitoring |
| Choice C: | Hybrid monitoring only works for respiratory motion |
| Choice D: | The RTRT system can be used to mitigate motion with tracking |
| Question 2: Currently available methods using ultrasound and electromagnetic transponders: |
| Reference: | Real-time intrafraction motion monitoring in external beam radiotherapy, Bertholet et al. Phys Med Biol, Vol 64, pp 15TR01, 2019 |
| Choice A: | Both impose additional ionizing radiation |
| Choice B: | Both provide internal target monitoring |
| Choice C: | Both can be used for any treatment site |
| Choice D: | Both are compatible with any treatment machine |
| Question 3: Real-time motion monitoring using 2D imaging is only feasible when the axis of imaging is the same as the axis of treatment |
| Reference: | Real-time intrafraction motion monitoring in external beam radiotherapy, Bertholet et al. Phys Med Biol, Vol 64, pp 15TR01, 2019 |
| Choice A: | True |
| Choice B: | False |
| Question 4: Accurate real-time monitoring of the tumor position using two-dimensional kV or MV imaging requires all of the following EXCEPT |
| Reference: | The clinical and dosimetric impact of real-time target tracking in pancreatic SBRT. Vinogradskiy et al. International Journal of Radiation Oncology*Biology*Physics, Vol 103, pp 268-275, 2019 |
| Choice A: | Agreement between the observed and reference position of the tumor and/or surrogate |
| Choice B: | Ability to quickly detect changes in soft-tissue anatomy near the target |
| Choice C: | Agreement between the timing of the in-treatment imaging and the reference position |
| Choice D: | Ability to quickly localize the tumor and/or surrogate |
| Question 5: What do the MR-linac systems not provide? |
| Reference: | The present MR-linac systems do not provide a cone-beam CT. (a) and (b) are already implemented in the clinical workflow. Groups are working hard on the image registration, dose accumulation and fast dose optimization to implement (c) |
| Choice A: | Real-time soft tissue visualization during the actual treatment |
| Choice B: | Online treatment adaptation |
| Choice C: | The potential for intra-fraction dose optimization |
| Choice D: | Online and real-time cone-beam CT |
| Question 6: Currently, true real-time 3D MRI with 100 ms temporal resolution for motion estimation: |
| Reference: | Niek R F Huttinga, Cornelis A T van den Berg, Peter R Luijten, Alessandro Sbrizzi, MR-MOTUS: Model-Based Non-Rigid Motion Estimation for MR-guided Radiotherapy Using a Reference Image and Minimal K-Space Data, Phys. Med. Biol. 2020 10; 65(1):015004.
(b) does not provide real-time 3D images, but selects a 3D anatomy out of a respiratory sorted image library. While these methods are useful for motion estimation applications, they are not able to account for movements that are not captured in the library (e.g. drifts). (c) could enable acquisition times in the order of 100 ms for small field-of-views, however requires substantial reconstruction time that largely exceed the time constraint. (d) is the right answer, estimating motion fields directly from k-space data is the only method (so far) that can estimate 3D motion within 100 ms. |
| Choice A: | Is not possible |
| Choice B: | Can only be provided with the combination of 4D binning and real-time navigators |
| Choice C: | Can only be provided with efficient 3D k-space trajectories (e.g. 3D cones) in combination with parallel imaging and compressed sensing reconstruction |
| Choice D: | Can only be provided by directly estimating motion fields from k-space data |
