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Commissioning of a 3.0T MR Simulator Dedicated for Radiation Oncology Application

C Wang

C Wang1*, F Yin1 , J Cai1 , O Craciunescu1 , A Faught2 , Z Chang1 , (1) Duke University Medical Center, Durham, NC, (2) University of Colorado School of Medicine, Denver, CO


SU-I-GPD-J-89 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: To commission a 3.0T MR simulator (MR-sim) dedicated for radiotherapy simulation.

Methods: The Siemens MAGNETOM Skyra 3.0T simulator is designed with a large 70cm-diameter bore size with XQ gradients and 64-channel RF architecture. It is configured with several radiotherapy-specific features including external laser system, flat-indexed couch top and multiple radiofrequency (RF) coils for flexible imaging positions. The commissioning of this simulator consists of 6 major component: 1) safety procedure and equipment test; 2) mechanical integrity of laser and couch motion; 3) image quality measurement and RF coil performance test following American College of Radiology (ACR) 2015 guideline; 4) MR compatibility check of radiotherapy-specific devices, including CIVCO immobilization package and Varian titanium gyn-brachytherapy applicators; 5) MR spatial accuracy configuration for intracranial (small field-of-view FOV) and abdominal (big FOV) imaging using dedicated phantoms; 6) development and optimization of site-specific scan protocols for radiotherapy planning and response assessment.

Results: All safety equipment functioned well. The accuracy of the laser and couch movement was less than ±1mm. All image quality tests passed the recommended tolerance of 3.0T scanner by ACR guideline. Baseline data for future periodic quality assurance (QA) sessions were established. The tested radiotherapy-specific devices were compatible with the MR-sim. The magnetic susceptibility effects of gyn-applicators demonstrated to be acceptable for clinical use and were consistent with those published in literature. The maximum geometric distortion for intracranial imaging using head coil was 1.08mm after distortion correction. For abdominal scans using inherent body coil and spine phase-array coil, the distortion at 20 cm away from bore center was 1.62mm after distortion correction. MR protocols for brain, breast, GI-abdominal, prostate and gyn-brachytherapy were successfully developed and demonstrated.

Conclusion: The commissioning data provided valuable insights and reliable evaluations on the characteristics of the new MR-sim. The systematically measured data might be useful for future reference

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