The GEANT4 toolkit for microdosimetry calculations: application to microbeam radiation therapy (MRT)

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Biology

Background:

• Microbeam radiation therapy (MRT) is an experimental radiotherapy using narrow x-ray beams.
• MRT's effectiveness relies on normal tissue's ability to repair vascular damage, unlike tumors.
• Accurate calculation of low-dose regions (valleys) is critical for MRT efficacy.

Purpose of the Study:

• To compute theoretical dose distributions for microbeam radiation therapy (MRT).
• To validate GEANT4 Monte Carlo (MC) simulation toolkit for MRT dose calculations.
• To compare GEANT4's simulation results with PENELOPE code for accuracy.

Main Methods:

• Utilized GEANT4 MC toolkit with specialized electromagnetic interaction packages.
• Simulated dose profiles for a cylindrical phantom irradiated with microbeam arrays.
• Employed superposition algorithms for microbeam array simulations.
• Compared GEANT4 results (evaluated data libraries and analytical models) against PENELOPE code.

Main Results:

• GEANT4's analytical model dose profiles closely matched PENELOPE code results.
• Noticeable differences were observed between GEANT4's evaluated data libraries and PENELOPE.
• Peak-to-valley dose ratios were computed for preclinical MRT assay scenarios.

Conclusions:

• GEANT4 is a viable tool for MRT dose distribution calculations, particularly its analytical model.
• The study highlights the importance of understanding MC code specifics for accurate MRT dosimetry.
• Further validation is needed for GEANT4's evaluated data libraries in MRT applications.