Generation of base data supporting a radiotherapeutic carbon dose engine using Monte Carlo methods.

Abstract

Detailed calculations of the physical dose and relative biological effect (RBE) of ionising radiation are vital in radiotherapy. This is generally done by the dose engine of a treatment planning system (TPS), which relies on base data sets consisting of integrated depth dose distributions (IDDs) and differential particle spectra. In this study, the Monte Carlo (MC)transport and interaction code FLUKA has been used to generate a new, optimised set of base data in support of the RayStation carbon dose engine. Firstly, it has been identified that the new data is more consistent and less subject to statistical fluctuations. Secondly, significant changes in physical and RBE weighted dose between treatment plans generated with the old and new base data were found. Since the changes in RBE weighted dose could exceed clinical uncertainty limits, clinics may have to reconsider their dose prescriptions. The new base data has been implemented in a development version of RayStation and may be released clinically in a future version. If so, the data will be used to calculate physical and RBE weighted dose in clinical applications.