FLUKA simulation of proton dose distribution in water and brain phantoms

In this study a dose simulation system was constructed based on the FLUKA Monte Carlo code to simulate proton dose distribution in homogeneous and CT phantoms. Conversion from Hounsfield unit of a patient CT image set to material information necessary for Monte Carlo simulation is based on Schneider’s approach. We used the NEU codes package to design a nozzle of proton therapy system, and we used FLUKA to simulate the transport of protons in the nozzle and a water phantom. Depth dose and SOBP dose distributions for homogeneous and CT head Phantoms for a 80 MeV proton beams were compared. Bragg peak in homogeneous and CT head phantoms were different about 6 mm. The result showed while for large fields these might be local effects, for very small fields in the head region these effects can potentially affect the majority of the treatment volume. Therefore treatment planning programs in proton therapy that water environment is considered, the results are less accurate for small field sizes. Also the simulation results showed that NEU code is a powerful tool in the design of passive-double scattering systems that constitute the basis of Proton therapy nozzles.