Evaluation of Secondary Neutron Produced in Proton Therapy Using Phits

Abstract

Proton therapy uses high-energy proton beams to kill cancer cells while spare surrounding healthy tissues, due to their Bragg peak characteristics, which has become the choice treatment for many types of tumors. However, the production of secondary neutrons by the interactions of primary protons with the body and the environment might provide undesirable extra radiation outside the treatment volume, which could reduce the benefit of this over the traditional radiation therapy. The purpose of this research is to evaluate the secondary neutrons produced from a spot scanning beam in the soft tissue phantom and their contribution in terms of dose mainly to the distal of the Bragg peak, the flux, and energy spectra as well as evaluated using the Monte Carlo code, Particle and Heavy Ion Transport Code System (PHITS). According to this study, the contribution to the overall dose that occurred after the peak maximum was at least a thousand times lower. We concluded that this dose has no natural effect on a potentially application therapeutic.