Simulación del efecto de la interacción de fotones de 6MV con cristalino mediante GEANT4

Abstract

The aim of this research work was to simulate the effect of the interaction of 6MV photons on the crystalline lens using the Monte Carlo method. For this purpose, the simulation was developed in three stages: the first one consisted in the construction of the geometry of an approximate model of eyes with their crystalline lens located 100cm from the source and a usual model of an external beam radiotherapy accelerator composed of: a target, a primary collimator, a flattening filter, an ionisation chamber, and a model of jaws to define a field size of 10x10 cm2 for photons of 6MV energy. Detector geometries were also created. For the second stage, the geometries were parameterised to declare the detectors in the eye model and estimate the events and dose contribution in the simulated crystallites. In the third stage, the physical process generator and the physics required for the simulation were declared via user commands in an .in file of the GAMOS platform. For the dose analysis in the crystalline lens, Dose-Volume Histograms, Dose Profiles and absorbed dose values were generated by executing commands. The results showed that the absorbed dose varies according to the depth that the photons reach, contributing small amounts of dose per event and it is concluded that the total absorbed dose for the simulated right and left crystalline lens is 0.04 mGy and 0.05 mGy respectively, due to the physical parameters of the radiation beam. It is recommended to extend the study by simulating real clinical situations and realistic, non-idealised geometries.