| Question 1: Is it feasible to perform MR imaging during beam delivery? |
| Reference: | Jackson S et al. Phys Med Biol. 2019 Jun 10;64(12):12NT01. doi: 10.1088/1361-6560/ab231a. |
| Choice A: | No, not during beam delivery, only when the radiation beam is off, otherwise the MRI data is geometrically distorted |
| Choice B: | No, the current systems are designed to perform MRI only prior to beam delivery to enable daily plan adaptation |
| Choice C: | Yes, as there is no interaction at all between the radiotherapy part and the MRI part of the hybrid systems |
| Choice D: | Yes, but one has to check that the MR sequence used is not geometrically distorted by the treatment in off-line QA |
| Question 2: Is MRI fast enough to provide input for gating? |
| Reference: | First clinical implementation of real-time, real anatomy tracking and radiation beam control.
Green OL et al. Med Phys. 2018 May 28. doi: 10.1002/mp.13002. |
| Choice A: | Yes, absolutely, gating on 4Hz 2D MRI is in clinical use |
| Choice B: | Yes, but only on 1D navigators |
| Choice C: | Yes, but not for respiratory motion, only for exception gating on bulk patient motion |
| Choice D: | No, although MR acquisition is fast enough, the image reconstruction too time consuming to enable gating |
| Question 3: Can you reconstruct the intra-fraction time evolution of the dose distribution if there is also anatomical motion? |
| Reference: | Bosma LS et al Phys Med Biol. 2021 Mar 2;66(6):065002. doi: 10.1088/1361-6560/abe02a. |
| Choice A: | No, the log files can provide the fluence as function of time, but that only provides snapshots of dose distributions which cannot be accumulated. |
| Choice B: | No, MRI is simply not fast enough for repeated volumetric imaging on an intra-fractional time scale. |
| Choice C: | Yes, the log-files can provide the fluence as function of time, the MRI is acquired as function of time, so for each anatomical state you have the dose and then you simply add it up to get the time trace of the dose distribution |
| Choice D: | Yes, as in c) but only when a validated non-rigid image registration is available for that specific anatomical location. |
| Question 4: In addition to breathing motion (mitigated by gating), the problem of non-periodic motion (e.g., peristalsis) can be mitigated by which of the following? |
| Reference: | Lagerwaard, Frank, et al. "Combined inter-and intrafractional plan adaptation using fraction partitioning in magnetic resonance-guided radiotherapy delivery." Cureus 10.4 (2018). |
| Choice A: | Compression device |
| Choice B: | Breathhold-based treatment |
| Choice C: | Mid-fraction volumetric imaging with adaptation |
| Choice D: | Pharmaceutical intervention |
| Question 5: What is online adaptive radiation therapy? |
| Reference: | XA Li, ed. Adaptive Radiation Therapy. Phys. Taylor & Francis, 2011. |
| Choice A: | Creating a boost plan |
| Choice B: | Modifying patient contours mid-treatment |
| Choice C: | Modifying radiation plans during treatment to account for patient weight loss |
| Choice D: | Creating a new plan based on image of the day and delivering the plan on the day without moving the patient |
| Choice E: | Adapting imaging procedures to improve anatomical visualization |
| Question 6: What is the range of typical online replanning times, including recontouring and plan generation and QA, in the current clinical practice of MRgART for abdominal tumors? |
| Reference: | Paulson ES, Ahunbay E, Chen X, Mickevicius NJ, Chen GP, Schultz C, Erickson B, Straza M, Hall WA, Li XA. 4D-MRI driven MR-guided online adaptive radiotherapy for abdominal stereotactic body radiation therapy on a high field MR-Linac: Implementation and initial clinical experience. Clin Transl Radiat Oncol. 2020 May 15;23:72-79. doi: 10.1016/j.ctro.2020.05.002. Erratum in: Clin Transl Radiat Oncol. 2021 Jan 29;27:96-97. PMID: 32490218; PMCID: PMC7256110. |
| Choice A: | 0-5 min |
| Choice B: | 5-20 min |
| Choice C: | 10-20 min |
| Choice D: | 30-60 min |
| Choice E: | 70-100 min |
| Question 7: Which of the following is the greatest challenge in the current MR-guided online adaptive radiation therapy? |
| Reference: | Lamb J, Cao M, Kishan A, Agazaryan N, Thomas DH, Shaverdian N, Yang Y, Ray S, Low DA, Raldow A, Steinberg ML, Lee P. Online Adaptive Radiation Therapy: Implementation of a New Process of Care. Cureus. 2017 Aug 27;9(8):e1618. doi: 10.7759/cureus.1618. PMID: 29104835; PMCID: PMC5663325. |
| Choice A: | poor daily image quality |
| Choice B: | Long recontouring time |
| Choice C: | Long plan re-optimization time |
| Choice D: | Long plan evaluation time |
| Choice E: | Long radiation delivery time |
| Question 8: Which of the following is a promising solution to substantially speed up online adaptation? |
| Reference: | Cardenas CE, Yang J, Anderson BM, Court LE, Brock KB. Advances in Auto-Segmentation. Semin Radiat Oncol. 2019 Jul;29(3):185-197. doi: 10.1016/j.semradonc.2019.02.001. PMID: 31027636. |
| Choice A: | A better plan optimization algorithm |
| Choice B: | A more accurate dose calculation engine |
| Choice C: | A deep learning based auto-segmentation method |
| Choice D: | An atlas based auto-segmentation tool |
| Question 9: All of the following quantitative/functional imaging techniques have been
demonstrated to be feasible on MR-guided radiotherapy systems, except which of these? |
| Reference: | Kooreman et al. Radiother Oncol. 2019 Apr;133:156-162; Nejad-Davarani et al. Med Phys 2020 May 20. doi: 10.1002/mp.14251 |
| Choice A: | Imaging of micro-anatomy and perfusion with IntraVoxel Incoherent Motion MRI |
| Choice B: | Imaging of metabolism with MR Spectroscopic Imaging |
| Choice C: | Imaging of perfusion/permeability with Dynamic Contrast-Enhanced MRI |
| Choice D: | Imaging of hypoxia with R2* mapping |
| Question 10: How can we ensure that the results of an MRI biomarker study on an MR-linac can be translated to diagnostic scanners and other MR-guided radiotherapy platforms? |
| Reference: | O’Connor JPB et al. Nat Rev Clin Oncol 2016;14:169–86; Shukla‐Dave A et al. J Magn Reson Imaging 2019;49:e101–21. |
| Choice A: | By conducting phantom measurements prior to the inclusion of patients in the trial |
| Choice B: | By conducting a test-retest measurement of the quantitative MRI sequence on the MR-linac prior to the start of treatment |
| Choice C: | By conducting an MRI exam with the quantitative MRI sequence on a diagnostic scanner as well as on the MR-linac |
| Choice D: | By conducting multi-center studies which includes centers with both available MRI-guided MR-linac platforms |
