A new concept of dose determination for treatment planning

Radiation transport programs applying Monte-Carlo and Ssub(N) methods have been adapted to simulate gamma-, electron- and neutron sources used in radiotherapy. After reproducing machine-dependent measured dose distributions in water we are free to change the material composition in the phantom and to simulate any inhomogeneity effect of interest in radiation therapy. Depth/dose distributions are given for gamma-rays, electrons and neutrons in homogeneous and inhomogeneous phantoms. Single field doses are stored in matrix form or analytically for use in the dose superposition code for treatment planning. For combined treatment with mixed high and low LET radiation, cell-survival models are of great value for simulating the total effect. Most of the various computer programs used have been connected to a central data storage from which each code gets the data needed and writes the results back. This represents a general program system for radiotherapy. (author)