Demonstration of motion-compensated volumetric modulated arc radiotherapy on an MR-linac

Abstract

Intensity-modulated radiotherapy (IMRT) in combination with magnetic resonance imaging (MRI)-guided gated delivery represents the latest development in the treatment of abdominothoracic tumours on MR-linac. In contrast, volumetric-modulated arc therapy (VMAT) is typically used on conventional linacs due to its superior delivery efficiency and speed. Non-inferior VMAT plans were created in a research treatment planning system for eight lung cancer patients previously treated on an MR-linac. VMAT plans were delivered on a moving dosimeter using respiratory multi-leaf collimator (MLC) tracking. VMAT with MLC tracking achieved an average 2%/2 mm local gamma pass rate of 93% relative to planned dose with a delivery efficiency of 83%.