A fast and accurate moment method for the Fokker-Planck equation and applications to electron radiotherapy

This paper represents a first step toward a moment method for dose calculations in radiotherapy. Starting from a deterministic transport model for electron radiation and its Fokker-Planck approximation, a new macroscopic model is presented. We investigate several ways to simplify the deterministic model having two goals in mind, lower computation times on the one hand and high accuracy and model inherent incorporation of tissue inhomogeneities on the other hand. While being fast, the second property is lost in the often used pencil-beam models. We discuss the properties of well-known macroscopic models and design a new model, which combines their advantages. Several test cases, including the irradiation of a water phantom, are presented.