Proton dose deposition in heterogeneous media: A TOPAS Monte Carlo simulation study

Area of Science:

• Medical Physics
• Radiation Oncology

Background:

• Proton therapy offers precise dose delivery.
• Accurate dose calculation requires understanding tissue interactions.
• Tissue heterogeneity significantly influences proton beam dosimetry.

Purpose of the Study:

• To investigate the impact of tissue electron density on proton beam dose distribution.
• To quantify the relationship between electron density and dose parameters.
• To provide data for optimizing proton therapy treatment planning.

Main Methods:

• Utilized TOPAS Monte Carlo simulation for dose deposition analysis.
• Constructed heterogeneous tissue models with 14 distinct materials.
• Simulated a 169.23 MeV proton beam and analyzed dose parameters.

Main Results:

• Increased electron density correlated with higher local maximum dose.
• Higher electron density led to lower total dose and reduced Bragg peak depth/range.
• Electron density influenced penumbra width and Full Width at Half Maximum (FWHM).

Conclusions:

• Electron density is a critical factor in proton beam dose distribution.
• Variations in energy deposition due to electron density cause dose distribution changes.
• Findings offer a reference for precise dose calculation and proton therapy optimization.