| Question 1: MR to MV transform test measures the alignment between the MR origin and the MV isocenter. Which statement is true about the MR to MV transform? |
| Reference: | Machine QA for the Elekta Unity system: A Report from the Elekta MR-Linac
consortium, accepted by Medical Physics (2021) |
| Choice A: | The MR origin overlaps with MV isocenter |
| Choice B: | The MR to MV transform values are very small and it can be ignored |
| Choice C: | The MR to MV transform values are fixed, no need to worry about it |
| Choice D: | The MR to MV transform is measured on machine installation, applied to the
treatment planning system and verified periodically |
| Question 2: The transverse magnetic field will induce which of the following? |
| Reference: | : Relative dosimetry with an MR-linac: Response of ion chambers, diamond, and diode detectors for off-axis, depth dose, and output factor measurements, Med.
Phys. 45 (2), (2018), 884-897 |
| Choice A: | A lateral shift in the crossline beam profile (perpendicular to the magnetic field) |
| Choice B: | A lateral shift in the inline beam profile (parallel to the magnetic field) |
| Choice C: | No lateral shift in either inline or crossline beam profile |
| Choice D: | lateral shift in both inline and crossline beam profiles |
| Question 3: Which of the following statements about the MRI gradient fields is false? |
| Reference: | Task Group 284 Report: Magnetic Resonance Imaging Simulation in
Radiotherapy: Considerations for Clinical Implementation, Optimization, and Quality
Assurance, accepted by Medical Physics (2021) |
| Choice A: | The gradient field encodes spatial information into MR signal |
| Choice B: | Accuracy of spatial mapping relies on the linearity of the gradient system |
| Choice C: | Imperfections in gradient linearity can cause geometric distortion |
| Choice D: | Imperfections in gradient linearity can reduce SNR |
| Question 4: Regarding treating a patient with a pacemaker on an 0.35T MRIgRT system, which of the following is true? |
| Reference: | Wilkoff, Bruce L., et al. "Magnetic resonance imaging in patients with a pacemaker system
designed for the magnetic resonance environment." Heart rhythm 8.1 (2011): 65-73. |
| Choice A: | MRI scanning is never allowed, a pacemaker is an absolute contraindication to MRI |
| Choice B: | If the pacemaker is FDA-cleared for 1.5T only, the manufacturer will support scanning at 0.35T because the lower field is less risky |
| Choice C: | If the patient is not pacemaker dependent, no additional actions are needed |
| Choice D: | Factors potentially affecting the safety of scanning include the field strength, slew rate, SAR, and location of the pacemaker with respect to the RF transmit coil isocenter |
| Question 5: Issues identified in commissioning a low-field MRI system include which of the following? |
| Reference: | Michael Gach, H., et al. "MRI quality control for low-field MR-IGRT
systems: Lessons learned." Journal of applied clinical medical
physics 20.10 (2019): 53-66. |
| Choice A: | Gantry-dependent field inhomogeneity changes |
| Choice B: | Image noise due to poorly shielded external RF sources |
| Choice C: | Image noise due to damaged RF coil components |
| Choice D: | All of the above |
| Question 6: Imaging isocenter variation of an 0.35T MRIgRT system has been observed to vary by up to how many mm with radiotherapy gantry rotation? |
| Reference: | Kim, Taeho, et al. "Characterizing MR imaging isocenter variation in MRgRT." Biomedical Physics & Engineering Express 6.3 (2020): 035009. |
| Choice A: | 0.18 mm |
| Choice B: | 0.98 mm |
| Choice C: | 1.80 mm |
| Choice D: | 2.80 mm |
| Question 7: Which of the following is false regarding reference dosimetry ion chamber
correction factors in an 0.35T external magnetic field? |
| Reference: | Krauss, Achim, Claudia Katharina Spindeldreier, and Sebastian
Klüter. "Direct determination of for cylindrical ionization chambers
in a 6 MV 0.35 T MR-linac." Physics in Medicine & Biology 65.23
(2020): 235049. |
| Choice A: | Larger chambers are expected to exhibit larger correction factors |
| Choice B: | Expected to be smaller than correction factors in a 1.5T field |
| Choice C: | At 1.5T, correction factors are small enough to be safety neglected in all situations |
| Choice D: | Correction factors depend on chamber orientation with respect to magnetic field lines |
| Question 8: During daily QA, MRI safety quality checks must be performed. Which of the following is recommended to be readily available as per ACR MR safety guidelines? |
| Reference: | ACR Committee on MR safety. ACR Manual on MR safety . Americal College of
Radiology. 1891 Preston White Drive, Reston, VA 20191 |
| Choice A: | A ferromagnetic detector |
| Choice B: | The presence of hearing protection device |
| Choice C: | The presence of MRI screening forms |
| Choice D: | All of the above |
| Question 9: The evaluation of spatial accuracy and geometric distortion should be performed on a monthly basis using a large phantom (>30 cm); what is the tolerance? |
| Reference: | Glide-Hurst C., Paulson E., McGee K., Tyagi N., Hu Y., Balter J., Bayouth J., Task Group 284 Report: Magnetic Resonance Imaging Simulation in Radiotherapy: Considerations for Clinical Implementation, Optimization, and Quality Assurance |
| Choice A: | 1 mm across the entire FOV |
| Choice B: | 2 mm across the entire FOV |
| Choice C: | 1 mm for distances less than 10 cm and 2 mm for distances up to 25 cm from isocenter |
| Choice D: | 2 mm for distances less than 15 cm and 3 mm for distances up to 35 cm from isocenter |
| Question 10: AAPM TG 142 provides guidance on quality assurance for linear accelerators, including tolerances for CBCT imaging and radiation coincidence. If similar
recommendations are to be adapted for MRI linac, the MR-RT isocenter coincidence tolerance should be which of the following? |
| Reference: | Reference: Klein EE, Hanley J, Bayouth J, et al. Task Group 142 Report: quality assurance of medical accelerators. Med Phys. 2009; 36: 4197– 4212. |
| Choice A: | 0.2 mm or less |
| Choice B: | 1 mm or less |
| Choice C: | 2 mm or less for non-SBRT, 1 mm or less for SBRT-capable machines |
| Choice D: | 3 mm or less for non-SBRT, 2 mm or less for SBRT-capable machines |
| Choice E: | None of the above |
