Ion beam transport in tissue-like media using the Monte Carlo code SHIELD-HIT

Area of Science:

• Medical Physics
• Computational Physics
• Radiation Biology

Background:

• Monte Carlo simulations are vital for modeling particle transport in biological tissues.
• Accurate simulation of heavy ion transport is essential for advancing radiation therapy techniques.
• Existing codes often require extensions to handle complex ion interactions and tissue heterogeneities.

Purpose of the Study:

• To describe the development and validation of the SHIELD-HIT (heavy ion transport) Monte Carlo code.
• To assess the code's capability in simulating proton and heavier ion transport in tissue-like media.
• To evaluate the code's accuracy against experimental data and other simulation models.

Main Methods:

• Development of the SHIELD-HIT code, extending the SHIELD code for heavy ion transport.
• Inclusion of ionization energy-loss straggling and multiple Coulomb scattering.
• Validation against experimental data and comparison with PTRAN, PETRA, and deterministic models.

Main Results:

• SHIELD-HIT accurately predicts energy deposition distributions for protons, 12C, and 20Ne ions in water.
• The code correctly models nuclear inelastic collisions and energy deposition beyond the Bragg peak.
• Good agreement was found for fragment production by 12C and 14N ions, and neutron spectra from 12C irradiation of Martian rock mimic.

Conclusions:

• SHIELD-HIT is a useful tool for Monte Carlo simulations in light ion radiation therapy.
• Accurate stopping power data for tissues is critical for precise dose delivery in radiation therapy.
• The code's predictions for energy deposition and fragment production demonstrate its potential for clinical applications.