Monte Carlo FSPB Photon Dose Calculation In Accurate Radiotherapy

Radiotherapy is one of the most important means to treat tumors. Treatment Planning System (TPS) is a software tool, for which radiotherapy doctors and radiotherapy physicists can design and optimize the treatment plan before dose delivery. And dose calculation is one of the core functions in TPS, this study mainly focused on the key technologies, photon dose calculation based on the Monte Carlo Finite Size Pencil Beam (MCFSPB) in the ARTS project, and the prototype software of the MCFSPB method is also developed. And it also studies the influence of transition region's thickness on calculated time and precision of regional Monte Carlo dose calculation method - for the further study on combining the MCFSPB method and the Monte Carlo method.In the MCFSPB method, the taking of pencil beam kernel is one of the most important technologies. In this study, by analyzing the demerits of the clinical pencil beam dose calculation methods, it was developed a new pencil beam kernel model based on the MC simulation combining the reconstruction technology of medical accelerator energy spectrum. According to the axial symmetry principle, only part of simulation results was used for the data of pencil beam kernel, greatly reduced the data size of the pencil beam.Based on the above studies, we designed the MCFSPB method and programmed it. With several tests, the results met the challenge in clinic. So it can be expected to be used as a fast and accuracy dose engine for clinic TPS.Further, the influence of transition region's thickness on regional Monte Carlo dose calculation method was also discussed. The relationship was found in the influence of transition region's thickness on calculated time and precision in regional Monte Carlo dose calculation. It may give great help to the realization of MCFSPB and Monte Carlo hybrid dose calculation method based on region division.