Development and validation of commissioning tests for volumetric modulated arc therapy on the 1.5T MR-linac

BACKGROUND: The MR-Linac enables adaptive radiotherapy using MRI guidance. Volumetric modulated arc therapy (VMAT) has been shown to be feasible on the MR-Linac and offers many advantages, but commissioning tests are needed. PURPOSE: This study establishes and demonstrates a framework of commissioning tests to facilitate clinical implementation of VMAT on the MR-linac. METHODS: mapping, geometric fidelity phantoms, and isocenter alignment tests. All tests were performed on two MR-linacs to demonstrate feasibility. RESULTS: variations, and geometric fidelity was within tolerances. No degradation in image quality was observed during gantry rotation. CONCLUSIONS: The presented tests provide a foundation for VMAT commissioning for the MR-linac that verifies the stability of the mechanical, radiation, and imaging components.