Calculated depth dose distributions for proton beams in some low-Z materials

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Dosimetry

Background:

• Clinical radiotherapy increasingly utilizes proton beams, necessitating precise dosimetry.
• Monte Carlo simulations are vital for studying proton dosimetry, similar to photon and electron beams.
• Existing proton Monte Carlo codes, like PTRAN, are limited to homogeneous water simulations.

Purpose of the Study:

• To enhance the PTRAN code for simulating proton transport in diverse materials beyond water.
• To investigate proton dosimetry in heterogeneous systems relevant to clinical applications.
• To compare depth dose distributions in low-Z materials with those in water.

Main Methods:

• Modified the PTRAN Monte Carlo code to include proton transport in various materials.
• Simulated proton transport in heterogeneous systems comprising different materials.
• Calculated and compared depth dose distributions for plastics (PMMA, polystyrene, A150), graphite, air, and aluminum against water.

Main Results:

• Depth dose characteristics in plastics (PMMA, polystyrene, A150) were comparable to water.
• Significant differences in depth dose distributions were observed for graphite, air, and aluminum compared to water.
• While differences in low-Z materials are small, they are critical for accurate proton dosimetry.

Conclusions:

• The enhanced Monte Carlo code accurately simulates proton transport in various materials.
• Material selection significantly impacts proton depth dose distributions, with plastics showing good agreement with water.
• Accurate dosimetry in proton therapy requires careful consideration of all materials present in treatment and phantom setups.