Promising application of nano-WO3/epoxy composite in intensity-modulated brachytherapy: a simulation study

Area of Science:

• Medical Physics
• Radiation Oncology
• Materials Science

Background:

• Intensity-modulated brachytherapy (IMBT) faces applicator dimension limitations, especially with high-energy sources like 60Co.
• Effective radiation shielding is crucial for protecting organs at risk (OARs) during brachytherapy procedures.

Purpose of the Study:

• To investigate the efficacy of a tungsten trioxide nanoparticle/epoxy composite as a shielding material for redesigned brachytherapy applicators.
• To evaluate the impact of this composite on radiation dose distribution in intensity-modulated brachytherapy (IMBT).

Main Methods:

• Monte Carlo simulations using Geant4 (version 9.0) were performed to model the shielding composite and IMBT.
• A voxelated patient-based phantom and 18 vaginal cancer patients were used for comparative analysis.
• Dose metrics (D90 for target, D2cc for OARs) were evaluated for 60Co and 192Ir sources with redesigned and conventional applicators.

Main Results:

• The redesigned applicator with the composite significantly reduced bladder and rectal doses: 11.1-12.8% for 60Co and 16.6-18.7% for 192Ir.
• No significant alteration in the D90 (target dose) was observed for either source.
• The composite effectively enhanced shielding properties within applicator size constraints.

Conclusions:

• Tungsten trioxide nanoparticle/epoxy composite offers a viable solution for radiation shielding challenges in IMBT.
• Improved OAR protection can be achieved without compromising therapeutic efficacy.
• This composite is a promising material for future brachytherapy applicator design.