Simulating dose and cancer risk due to low-dose neutron background in proton beam therapy

Abstract

In proton therapy secondary neutrons are produced due to protons undergoing nuclear interactions with the treatment head and the patient. The neutron contribution to various organs is difficult to measure but can be simulated using Monte Carlo methods and whole-body computational phantoms. For this study we considered a proton therapy treatment field to treat a CTV in the central spine, thus exposing the whole body to a low-dose neutron background. In order to mimic the treatment of a pediatric case, we have implemented phantoms resembling an 11-year old and a 14-year old patient. We considered six treatment fields with varying treatment volumes and depths. The results show that the cancer risk for most organs is lower than the natural baseline risk assuming risk models based on the BEIR VII report [1] and radiation weighting factors given by the ICRP [2]. © 2009 Springer-Verlag.