Abstract ID: 19 Validation of the Monte Carlo GATE platform for the dosimetry of ocular protontherapy

Abstract

The aim of this work consisted to validate the Monte Carlo GATE platform in dose distributions of a proton beam on a mathematical model of the human eye. As a first step, a recommended 62 MeV proton beam for the treatment of ocular melanoma was simulated with GATE to check its aptitude to reproduce experimental measurements. In the second step, this beam was applied to a mathematical model of the human eye was defined precisely with real dimensions and densities. Depth-dose profile, lateral profile, dosimetric parameters according to international recommendations, and absolute dose in tumor and each organ were calculated and compared to other therapeutic techniques and Monte Carlo codes. A total of 106 incident protons were simulated in 20 min on a single i5 3.2 GHz CPU. Relative comparisons of percentage depth-dose and lateral profiles, performed between measured beam data and the simulated, show an agreement of the order of 2% in dose and 0.1 mm in range accuracy. These comparisons carried out with and without beam-modifying device, yield results compatible to the required precision in ocular melanoma treatments. Doses distributions issued from calculations and measurements were also compared. GATE platform show better results compared to other Monte Carlo codes. Results obtained from this study show that protontherapy is the most suitable treatment for ocular melanoma due to the unique property of its beam (Bragg peak). The ease of use, reproducibility and speed of GATE allows it to be used as an integrated tool for modeling imaging, dosimetry and processing in the same simulation platform. Ocular protontherapy offers excellent levels of eye retention, even in unfavorable cases such as large tumors.