Fast Dose Calculation for Stereotactic Synchrotron Radiotherapy

A hybrid approach is proposed to compute the dose deposited in cancerous and healthy tissues during stereotactic synchrotron radiotherapy treatment. In this approach the computation is divided into two parts: (1) the primary dose is calculated using a deterministic algorithm based on ray casting; (2) the secondary dose (due to scattering and fluorescence) is computed using a hybrid algorithm combining Monte Carlo and a deterministic method. The results obtained for test cases are compared to those obtained with the Monte Carlo method alone (Geant4 code) and found to be in excellent agreement. The proposed simulation scheme makes it possible to simulate dose maps with a single personal computer, with computation time and statistical fluctuations substantially reduced in comparison with conventional Monte Carlo simulations.