Monte carlo electron source model validation for an Elekta Precise linac.

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Biology

Background:

• Electron beam radiation therapy is vital for superficial tumors, especially when kilovoltage units are unavailable.
• Accurate dose calculation is critical for head and neck sites to protect sensitive structures like the optic nerve and parotid gland.
• Monte Carlo simulations offer precise electron transport modeling for complex geometries.

Purpose of the Study:

• To validate a two point-source electron beam model for an Elekta Precise linear accelerator.
• To assess the model's accuracy in calculating dose distributions using Monte Carlo simulations.
• To compare simulation results with experimental measurements and a commercial treatment planning system.

Main Methods:

• Validated a two point-source electron beam model against water tank and film measurements.
• Used Monte Carlo simulations (BEAMnrc/DOSXYZnrc) for dose calculations.
• Compared results with a CMS XiO treatment planning system for a paranasal sinus case.

Main Results:

• The model accurately replicated percentage depth dose and beam profile data (within 2%/2 mm to 3%/3 mm) across energies (4-15 MeV) and distances (95-110 cm).
• Penumbra data agreed within 2 mm for a 20x20 cm2 field.
• Good agreement (gamma index 2%/2 mm) was observed between Monte Carlo simulations, film measurements, and the XiO system for a complex treatment case.

Conclusions:

• The validated electron beam model provides accurate dose distribution calculations for radiation therapy.
• The model's ease of implementation in Monte Carlo codes facilitates efficient dose calculations in complex geometries.
• This enhances the precision of electron radiation therapy, particularly for head and neck treatments.