A macro Monte Carlo method for electron beam dose calculations

Abstract

The macro Monte Carlo (MMC) method is a fast Monte Carlo (MC) algorithm for high energy electron transport in an absorbing medium. Incident electrons are transported in large-scale macroscopic steps through the absorber. Electron parameters after each step are calculated from probability distributions. Transport of secondary electrons and bremsstrahlung photons is taken into account. For electron beam dose calculations, the energy, angular and spatial distributions of primary electrons have to be provided. The absorber geometry is represented by a 3D density matrix and the energy lost by the electrons along their paths is scored in a 3D dose matrix of user-definable resolution. Measurements in the beam of a Philips SL75-20 linear accelerator incident on homogeneous and simple inhomogeneous phantoms are in good agreement with MMC simulations.