Developing a Numerical Model for Determining the Distribution of the Depths of Electric Beam Doses in Modified Plastics

Abstract

Radiation therapy is a way of treating malignant tumors where ionizing radiation interacts with tumor cells, causing their destruction. However, there is inevitably a side effect on healthy cells during the radiation treatment of malignant tumors. An important task of beam therapy is therefore to ensure the optimum distribution of a dose in order to minimize the impact of radiation on healthy tissues and deliver the maximum dose to the tumor. A device that allows the distribution of a dose’s depth in a patient’s body is a bolus. Boluses for electron beam therapy can now be manufactured by means of three-dimensional printing. The aim of this work is to develop a numerical model for determining the distribution of the depth of an electron beam dose in plastics modified with metallic additives. The use of these materials would allow the creation of smaller boluses that could shorten the manufacturing stage and simplify the procedure for fixing the device on a patient’s body. Numerical models of an electron beam source and plastic boluses are developed using the GEANT4 toolkit. Numerical experiments are performed using the Monte Carlo technique. Distributions of the depths of electron beam doses with nominal energies of 6, 12, and 15 MeV are obtained in modified plastics with copper additives. In the future, the resulting data will allow the thickness of a forming device created from the studied plastics via three-dimensional printing to be selected according to the clinical task.