Automatic determination of primary electron beam parameters in Monte Carlo simulation

Area of Science:

• Medical Physics
• Computational Dosimetry
• Radiotherapy Physics

Background:

• Accurate Monte Carlo simulations are crucial for medical linear accelerator (linac) photon beam modeling.
• Precise determination of primary electron beam parameters is fundamental for reliable simulations.

Purpose of the Study:

• To propose and validate a novel methodology for commissioning photon beams in Monte Carlo simulations.
• To ensure the reproducibility of clinically relevant field sizes and characteristics.

Main Methods:

• Accelerated Monte Carlo simulations were performed for various field sizes (2x2, 10x10, 20x20 cm²) at a source-surface distance of 100 cm.
• Simulations explored combinations of primary electron beam mean energy and radial full width at half maximum (FWHM).
• A simultaneous comparison with experimental measurements identified the optimal electron beam parameters.

Main Results:

• The proposed methodology successfully reproduced clinical photon beam characteristics for Siemens PRIMUS and Varian 2100 CD machines.
• Excellent agreement was achieved between simulated and measured data across a wide range of field sizes.
• The commissioning process was fully automated using precalculated profiles stored in databases.

Conclusions:

• The developed methodology provides an accurate and automated approach for Monte Carlo simulation commissioning of medical linac photon beams.
• The database-driven approach ensures reproducibility and facilitates characterization of accelerators across different sites.
• This method enhances the reliability of Monte Carlo simulations for radiotherapy applications.