Dose optimization of extended collimators in boron neutron capture therapy

Area of Science:

• Medical Physics
• Radiation Oncology
• Biomedical Engineering

Background:

• Boron Neutron Capture Therapy (BNCT) is an advanced radiotherapy technique.
• Protecting healthy tissues and organs at risk from radiation dose is crucial in BNCT.
• Standard collimators in BNCT require enhancement to improve dose distribution.

Purpose of the Study:

• To design and evaluate extended collimators for BNCT.
• To reduce radiation dose to normal tissues and protect organs at risk.
• To compare the efficacy of different extended collimator designs.

Main Methods:

• Three types of extended collimators were designed: Type 1 (traditional), Type 2 (with PE(LiF)), and Type 3 (with Pb).
• Monte Carlo simulations were used to evaluate dose distribution in air, homogeneous phantom, and humanoid phantom.
• Neutron and gamma-ray fluxes, leakage doses, and organ doses were analyzed.

Main Results:

• Neutron and gamma-ray fluxes at the collimator outlet were similar across all designs.
• Type 2 collimators reduced neutron leakage dose by up to 57.14%, and Type 3 reduced gamma-ray leakage dose by up to 21.88%.
• Type 2 significantly reduced neutron doses to skin, thyroid, spinal cord, and left lung (approx. 16-26%). Type 3 reduced gamma-ray doses to thyroid, esophagus, and left lung (approx. 9-11%).

Conclusions:

• Extended collimators with PE(LiF) or Pb materials effectively suppress radiation dose distribution to patient organs.
• These findings provide valuable insights for designing improved collimators in BNCT.
• The enhanced collimators show potential for better patient outcomes by minimizing collateral radiation damage.