Penetration of Proton Beams through Water. 1. Depth-Dose Distribution, Spectraand LET Distribution

摘要

The penetration of protons through a water phantom was calculated with the MonteCarlo program PTRAN, which takes into account energy-loss straggling, multiple scattering, and nonelastic nuclear interactions. Calculations were done for incident proton beams incident with energies between 250 MeV and 50 MeV. The information obtained includes depth-dose curves as well as energy spectra of primary protons at various depth. Good agreement was found between calculated and measured relative depth-dose distributions, except at extreme depths. A systematic tabulation was made of various parameters that characterize the shape of the Bragg peak. The energy spectra were used to obtain LET distributions for primary protons. In addition, dose-averaged LET-values were obtained which include contributions from primary protons as well as from secondary charged particles produced in nuclear reactions.