Poster - Thur Eve - 27: Scattering foil redesign for modulated electron radiotherapy

Area of Science:

• Medical Physics
• Radiation Oncology
• Accelerator Physics

Background:

• Modulated Electron Radiotherapy (MERT) can benefit from scattering-foil-free beamlines, similar to flattening filter-free photon therapy.
• Concerns exist regarding accelerator transmission ionization chamber function with narrow beams and limited field sizes in MERT.

Purpose of the Study:

• To design and optimize a custom scattering foil for MERT applications.
• To investigate foil parameters (material, thickness, shape) for creating minimally scattered beams.
• To preserve dosimetric advantages like higher dose rates and reduced bremsstrahlung tail contamination.

Main Methods:

• Utilized Monte Carlo modeling, verified against experimental data.
• Analyzed fluence profiles at the transmission ionization chamber level.
• Evaluated Percentage Depth Doses (PDDs) and beam profiles in a water phantom for various foil configurations.

Main Results:

• A simple slab geometry foil made of low-to-medium Z material was found to be effective.
• Foil thickness was optimized based on maximum field size and electron energy.
• The optimized foil produced a sufficiently scattered beam, retaining dosimetric benefits.

Conclusions:

• The developed custom scattering foil is suitable for MERT.
• It offers higher dose rates, reducing treatment time.
• Reduced bremsstrahlung tail dose minimizes radiation exposure to healthy tissues.