Monte Carlo calculations of dose distribution for the treatment of gastric cancer with proton therapy

Proton therapy is a common form of external radiation therapy based on the manipulation of Bragg peak of this beam, it can treat the tumor by delivering high levels of doses to it, while protecting surrounding healthy tissues against radiation. In this work, the dose distribution of proton and secondary particles such as neutrons, photons, electrons and positrons in gastric cancer proton therapy have been studied. For this purpose, using a single-energy proton beam, the suitable energy range has been calculated for treating a tumor in the gastric tissue of a male adult male MRD-UF phantom. Then, the SOBP of the matrix method has been constructed using the dosimetry results. The primary and secondary doses were also examined in 12 surrounding healthy organs. The results show that the primary dose in healthy organs is much smaller than the dose received by the tumor. Although the secondary dose is small, but its amount in the stomach, spleen, pancreas and left kidney is higher than those in other organs. The results of the study show that the proton therapy of gastric cancer can represent an almost ideal radiation therapy by measuring the risk levels of secondary particle dose, in particular, the equivalent dose of neutrons.