A multi-institutional comparison of acceptance testing data for a 0.35 T MRI scanner

Area of Science:

• Medical Physics
• Radiotherapy Technology
• Magnetic Resonance Imaging

Background:

• Magnetic resonance-linear accelerators (MR-linacs) integrate magnetic resonance imaging (MRI) with linear accelerators for advanced radiation therapy.
• Standardized acceptance testing is crucial for ensuring the consistent performance of MR-linac imaging components.

Purpose of the Study:

• To quantify variability in acceptance testing data for the 0.35 T MR-linac imaging component.
• To establish benchmarks for imaging quality assurance and guide future MR-linac commissioning.

Main Methods:

• Described MR-linac vendor's acceptance testing protocol, equipment, and scanner parameters.
• Collected data on B-field homogeneity, signal-to-noise ratio (SNR)/uniformity, American College of Radiology (ACR) image quality, and spatial integrity from twelve institutions.
• Analyzed institutional variability in imaging performance metrics.

Main Results:

• B-field homogeneity showed gantry dependence but remained below 4 ppm.
• SNR and uniformity exceeded vendor thresholds with minimal institutional variation.
• All institutions passed ACR image uniformity tests; slice positional accuracy exhibited the largest variability (<2.1 mm at 175 mm radius).

Conclusions:

• Multi-institutional data provide a basis for setting tolerances and guidelines for MR-linac imaging quality assurance.
• Findings will aid in future MR-linac acceptance testing and commissioning processes.