Representing Range Compensators in the Topas Monte Carlo System

Double scattering-based proton therapy systems often use patient-specific range compensators for beam modulation. Range compensators adjust the depth in the tissue at which protons reach their Bragg peak. Accurately representing range compensators in Monte Carlo particle transport simulations is a vitally important problem for clinical treatment planning. This paper proposes two new computational geometry range compensator representations. The authors have implemented the proposed range compensator representations in Tool for Particle Simulation (TOPAS) [1][2]. TOPAS aims at making Monte Carlo simulation faster and easier to use for clinicians and researchers. TOPAS employs the Geant4 [3] simulation toolkit for the underlying physics processes, and TOPAS offers numerous features that enable radiation therapy simulations. TOPAS includes a collection of customizable geometries for radiation therapy systems.