Proton beam simulation on selected tissue-mimicking phantoms using particle and heavy ion transport code system (PHITS)

Proton Beam Therapy has three (3) distinct advantages over Photon Beam Therapy. Proton Beams have more accurate dose deposition, absence of exit dose and the depth of the Bragg peak position is determined by the proton beam energy. Proton beam therapy offers more options for sculpting the dose distribution compared to conventional photon beam therapy. The general objective of this study is to develop a transport code to simulate the transport of proton beams within tissue-mimicking phantom using the Particle and Heavy Ion Transport System (PHITS). The interaction of proton energy beam levels ranging from 70 – 250 MeV were simulated on the different tissue mimicking phantoms. The proton beam energy level and their corresponding Bragg peaks were recorded for each of the eight (8) tissue phantoms simulated. The results shows an increasing variation between proton beam energy level and Bragg peak. Regression analysis show that the regression line follows an equation of the form y = Axp, where x is equal to the proton beam energy level and y is equal to the Bragg peak. The values of the constants A and P are specific and unique to the tissue phantom. The A and P values for Water are 0.0021 and 1.7806, respectively. Similarly, Lungs has A and P values of 0.002 and 1.7777; Prostate Gland has A and P values of 0.002 and 1.7795; Pancreas has A and P values of 0.0019 and 1.7792; Spinal Cord has A and P values of 0.0019 and 1.7771; Brain has A and P values of 0.0019 and 1.7816; Breast Gland has A and P values of 0.002 and 1.7784; and Liver has A and P values of 0.002 and 1.78227. Furthermore, the regression analysis results shows an exponential best fit line with a correlation R value greater than 0.999. The results highly suggest that the interaction of proton beam with matter follows the Bragg-Kleeman rule.