Evaluation of proton therapy dose in breast cancer with boron agent based on GATE Monte Carlo code

Purpose: Proton Boron Capture Therapy (PBCT) has been introduced as a proposed method of increasing the proton therapy dose. The interaction mechanism of this reaction is p + 11B -> 3 alpha. This research was carried out to evaluate the dose of proton beams with boron agents. Methods: All the simulations were done with Monte Carlo GATE code. First, the proton beam and the breast phantom were simulated, and then different boron concentrations were created in the tumor area. Finally, using the dose actor, the amount of the deposited dose, the deposited energy, and the dose of secondary alpha particles in the tumor area were calculated. Results: The simulation results show that at a concentration of 65 ppm of 11B, the dose changes are less than 1% compared to the tumor area without boron, and the depth of the Bragg peak remains unchanged. By increasing the concentration of boron in the tumor area, the deposited dose and the depth of the Bragg peak decrease. In pure 11B, the deposited dose is reduced to half of the original amount. Conclusion: By placing different concentrations of boron agents, the physical aspects and simulation results did not show that boron is effective in increasing the dose in proton therapy. Therefore, 11B cannot be used as a doseenhancing agent in proton therapy.