A fast numerical method for calculating the 3D proton dose profile in a single-ring wobbling spreading system

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Physics

Background:

• Accurate dose calculation is crucial for effective proton therapy.
• Secondary particles from nuclear interactions contribute to the total dose.
• Existing methods may lack speed or comprehensive secondary particle consideration.

Purpose of the Study:

• To develop and validate a fast numerical method for 3D proton dose distribution calculation.
• To quantify the dose contribution of secondary particles in proton beams.
• To assess the accuracy of the proposed method against established simulations and models.

Main Methods:

• Calculation of 3D dose distribution based on surface proton fluence in a water phantom.
• Inclusion of secondary particle dose contributions, assuming 60% local energy absorption.
• Validation using Geant4 simulations for dose beyond the Bragg peak and relative dose profiles.

Main Results:

• Secondary radiation accounts for approximately 16.8% of the total dose in the plateau region for 190 MeV protons.
• Dose beyond the Bragg peak is less than 0.02% of the maximum dose, primarily from secondary neutrons.
• The proposed method's dose profile agrees within 2% with Fermi Eyges and Geant4 simulation results.

Conclusions:

• The fast numerical approach accurately models proton dose distributions, including secondary particle effects.
• This method shows potential for integration into 3D deterministic treatment planning systems.
• It can aid in analyzing beamline modifications for optimized proton therapy.