Three-Dimensional Dosimetric Validation of a Magnetic Resonance Guided Intensity Modulated Radiation Therapy System

摘要: Purpose To validate the dosimetric accuracy of a commercially available magnetic resonance guided intensity modulated radiation therapy (MRgIMRT) system using hybrid approach: 3-dimensional (3D) measurements and Monte Carlo calculations. Methods Materials We used PRESAGE radiochromic plastic dosimeters with remote optical computed tomography readout to perform 3D high-resolution measurements, following novel dosimetry protocol. followed commissioning recommendations American Association Physicists in Medicine Task Group 119, adapted incorporate data. Preliminary tests ("AP" "3D-Bands") were delivered 9.5-cm usable diameter cylindrical treatment planning (TPS) for nonmodulated deliveries; assess sensitivity, uniformity, rotational symmetry dosimeters; test robustness Following this, 4 clinical MRgIMRT plans ("MultiTarget," "Prostate," "Head/Neck," "C-Shape") measured 13-cm dosimeters. For all plans, 3D-γ (3% or 3 mm global, 10% threshold) passing rates calculated maps examined. Point doses an IBA-CC01 ionization chamber validation absolute dose. Finally, by use in-house-developed, GPU-accelerated algorithm (gPENELOPE), we independently dose 6 119 compared against TPS. Results analysis yielded 98.7%, 99.2%, 98.5%, 98.0%, 90.7% AP, 3D-Bands, MultiTarget, Prostate, Head/Neck, C-Shape, respectively. Ion within average 0.5% (±1.1%) from TPS calculations demonstrated good agreement TPS, mean rate 98.5% ± 1.9% stricter 2%/2-mm criterion. Conclusions have validated commercial techniques. first time that is comprehensive feasible approach MRgIMRT. This may provide better sensitivity error detection standard 2-dimensional could be when implementing complex new technologies.