Reducing secondary particle dose in proton therapy for gastric tumors: a material optimization study

Proton therapy treats tumors by delivering high doses (in the form of Bragg peaks) to the target volume while protecting healthy tissue from radiation. However, secondary particles produce some dose, particularly neutrons, with high relative biological effects. This study used MCNPX code to investigate the impact of changing pre-collimator, snout, and diaphragm materials on the dose of secondary particles in proton therapy for gastric tumors. Results indicate that switching from brass to nickel reduces the total average dose of protons and secondary particles in most vital organs (excluding the tumor) by 44%. Additionally, the equivalent neutron dose to absorbed dose (H/D) in the brain decreased by 33%, and the average H/D in 14 vital organs dropped by approximately 12%. These findings demonstrate that changing collimator materials from brass to nickel can significantly reduce the harmful effects of secondary particle doses, particularly neutron doses, in gastric tumor treatment.