Experimental Simulation of Volume Repainting Technique at Proton Synchrotron in Context of Spot Scanning Proton Therapy release_kqqhz4j7brcibkwfjx7c4hmnvq

Abstract

Background: Reduction the influence of respiration-induced intrafractional motion of tissues is one of the main tasks of proton therapy with a scanning beam. Repainting is one of the techniques of motion compensation. It consists in multiple repeated irradiations of the entire volume or individual iso-energy layers with a dose that is a multiple of the prescribed dose. As a result, the dose is averaged, which leads to an increase in the uniformity of the dose field. Purpose: Experimental simulation of volume sequential repainting and dosimetric estimation of its capabilities in the context of spot scanning proton therapy (SSPT) using dynamic phantom. Materials and Methods: Simulation of respiration-like translational motion is performed using the non-anthropomorphic water dynamic phantom. Target of this phantom is compatible with EBT-3 films. Estimation of repainting technique is based on the analysis of average dose, dose uniformity in region of interests located within planning target volume, and dose gradients. Results: Repainting was estimated for motion with amplitudes of 2, 5, 10 mm with different number of iterations up to 10 at the prescribed dose of 6 Gy. This one increased the uniformity of the dose field from 85,9% to 96,0% at an amplitude of 10 mm and 10 iterations. Conclusions: Volume repainting improves the uniformity of dose distribution. However, the irradiation time increases, and the dose gradients deteriorate in proportion to the amplitude of motion.
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