TOPAS Monte Carlo simulation for double scattering proton therapy and dosimetric evaluation

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Science

Background:

• Proton therapy offers precise dose delivery.
• Accurate dose calculation is crucial for effective proton therapy.
• Monte Carlo simulations provide detailed dose distributions.

Purpose of the Study:

• To develop and validate a TOPAS Monte Carlo model for a double scattering proton beam.
• To compare the dose accuracy of the TOPAS model against measured data and a treatment planning system (TPS).

Main Methods:

• A TOPAS Monte Carlo model was constructed based on manufacturer blueprints.
• Room-specific calibration data was used for nozzle setup and beam current modulation.
• The model was validated by comparing calculations of pristine peaks, spread-out Bragg peaks, and lateral profiles against measured data.

Main Results:

• TOPAS calculations showed high agreement with measured data for range and dose fall-off (within 0.05 cm).
• The model accurately reproduced lateral profiles and Bragg peaks.
• TOPAS demonstrated superior dose accuracy compared to TPS, particularly for range compensator calculations and in regions with dose gradients.

Conclusions:

• A validated TOPAS Monte Carlo model for double scattering proton therapy has been successfully commissioned.
• The TOPAS model offers improved dose accuracy over traditional TPS, especially for complex treatment scenarios.