Characterisation and application of three-dimensional silicone-based radiochromic dosimetry in 1.5 T magnetic resonance imaging-guided radiotherapy

Abstract

Abstract The magnetic field in magnetic resonance imaging-guided radiotherapy (MRgRT) systems influences the three-dimensional (3D) dose deposition and hence the delivered dose distributions. The aim of this study was to investigate the dose-rate dependency and dose response of silicone-based radiochromic dosimeters for photon irradiation in the precense of a magnetic field using a 1.5 T MRgRT system. Additionally, the study aimed to provide a proof of the concept of radiotherapy treatment based on a treatment plan calculated on magnetic resonance imaging rather than a computed tomography (CT) scan. The delivered dose was read out in 3D with an optical CT scanner and the dose distribution was verified using gamma analysis. We found an insignificant dose-rate dependency for dose rates ranging from 3.2 to 5.1 Gy/min and a linear dose response up to 20 Gy. A 3D 3%/3mm gamma analysis showed a pass rate of 95.1%. The dosimeter showed clinical potential for 3D dose verification of MRgRT delivery.