Monte Carlo Simulation of Proton and Neutron Transport Based on the PENELOPE Code

This master thesis is a continuation of previous work done at Elekta Instrument AB for the joint objective of developing the Monte Carlo simulation program, Pegasos, for proton therapy. For this purpose, neutron transport with nuclear interactions has been implemented into the Pegasos framework. Nuclear data is provided from the TALYS nuclear code and for neutron-hydrogen nuclear interactions, the ENDF database, through the Los Alamos LA150 library, is used. Furthermore, angular distribution of neutron elastic scattering is implemented as well as neutron radiative capture to deuterium. Benchmarks of the Pegasos software, with implemented neutron as well as the initial Pegasos code, were executed against the Monte Carlo program Geant4 and against experimental data provided from Proton Therapy Center (PTC), Prague, and The Svedberg Laboratory (TSL), Uppsala. The results show a relatively good agreement for all benchmarks, except against PTC resulting from uncertainties in the proton beam’s energy spectrum. A small deviation of the Bragg peak’s position against Geant4 may result from the different databases used, which is called for further investigation. In addition, further implementation of angular distribution for proton nuclear reaction, including hydrogen and helium, and transport of heavier charged particles is recommended in future endeavours with the objective of simulating clinical cases.