Microdosimetric analysis of proton boron capture therapy using microdosimetric kinetic model

Area of Science:

• Medical Physics
• Radiation Oncology
• Nuclear Medicine

Background:

• Proton boron fusion therapy (PBFT) utilizes alpha particles from proton-induced reactions with Boron-11.
• Early studies suggested significant dose enhancements, but feasibility concerns arose due to low reaction rates and high boron concentration requirements.

Purpose of the Study:

• To evaluate the relative biological effectiveness (RBE) enhancement in PBFT.
• To analyze microdosimetric data across a range of Boron-11 concentrations.

Main Methods:

• Employed Monte Carlo simulations using the PHITS package.
• Integrated the Microdosimetric Kinetic Model to quantify physical and biological dose.
• Analyzed dose enhancements at 100, 1000, and 10,000 ppm Boron-11 concentrations.

Main Results:

• Protons dominated the total dose, while alpha particles contributed more to higher linear energy deposition regions.
• RBE enhancement factors for HSG cells were 1.0011, 1.0080, and 1.1275 at 100, 1000, and 10,000 ppm Boron-11, respectively.
• Enhancements were negligible at lower concentrations but showed a modest increase at very high boron levels.

Conclusions:

• Alpha particles from the p +11B reaction deposit high-LET energy but result in minimal overall biological dose enhancement.
• The therapeutic benefit of PBFT is likely limited under clinically achievable boron concentrations.