Collimated and non-collimated proton minibeam irradiation using SIRMIO: a simulation study.

Area of Science:

• Radiation Oncology
• Medical Physics
• Preclinical Research

Background:

• Clinical integration of proton MBRT requires understanding parameter-effect relationships.
• Small animal models are crucial for these investigations.
• A specialized platform is needed for precise spatial dose control in preclinical studies.

Purpose of the Study:

• To evaluate the SIRMIO beamline's capability for proton MBRT experiments.
• To assess dose delivery configurations with and without a multislit collimator.
• To investigate the impact of center-to-center spacing on dose fractionation.

Main Methods:

• In silico study using Geant4-based Monte Carlo simulations.
• Evaluated two beamline configurations: no collimator and with a brass multislit collimator (MSC).
• Simulated center-to-center spacings of 3, 4, and 5 mm, with a 1 mm slit width for the MSC configuration.

Main Results:

• SIRMIO generates effective spatially fractionated dose profiles with varying center-to-center (CTC) spacing.
• Sufficient dose contrast for pMBRT achieved with CTC ≥ 4 mm (PVDR 3.44-6.57) without collimator.
• MSC enhanced dose contrast significantly (PVDR 11.3-28.7) for CTC 3-5 mm.
• Interlacing beams demonstrated potential for uniform target dose with preserved normal tissue contrast.

Conclusions:

• The SIRMIO platform is a viable tool for preclinical proton MBRT research.
• The platform can deliver precisely controlled spatially fractionated doses.
• Simulations confirm its potential for advancing pMBRT investigations.