Simulation of Particle Interactions with Matter Using PHITS Monte Carlo Code: Physical Aspects of Bragg Curve for Carbon Ion Therapy

In recent times, Monte Carlo simulations are gaining widespread recognition as the most precise tool for calculating particle interactions with matter. In this study, we investigated two primary aspects. Firstly, we examined how the average excitation energy of water \((I_{W})\) influences the location of the Bragg peak (BP). Secondly, we used the particle and heavy ion transport code system (PHITS) to study the Bragg curve of \({}^{12}\)C ion beam having an energy of 200 MeV/u in three different mediums: water, soft tissue, and bone. Lastly, we examined the impact of secondary particles on the overall dose. Our findings indicate that the average excitation energy of water strongly influences the position of the BP. The tail dose beyond the BP primarily results from secondary fragments of the primary carbon ion beams. Furthermore, the PHITS code accurately reproduces the measured Bragg curves.