Bismuth-based nanoparticles as radiosensitizer in low and high dose rate brachytherapy

Background: Recently bismuth-based nanoparticles have attracted increasing attention as a dose amplification agent in radiation therapy due to high atomic number, high photoelectric absorption, low cost, and low toxicity.

Objectives: This study aims to calculate physical aspects of dose enhancement of bismuth-based nanoparticles in the presence of brachytherapy source by Monte Carlo simulation and an analytical method for low mono-energy. Materials and methods: After simulation and validation brachytherapy sources (Iodine-125 and Ytterbium-169) by Monte Carlo code, bismuth-based nanoparticles (bismuth, bismuth oxide, bismuth sulfide, and bismuth ferrite) were modeled in the sizes of 50 nm and 100 nm for two concentrations of 10 and 20 mg/ml. Dose enhancement factors for the bismuth-based nanoparticles were measured at both brachytherapy sources. Furthermore, the dose amplification was calculated with an analytic method at 30 keV mono-energy.

Results: Dose enhancement factor was greatest with pure bismuth nanoparticles, followed by bismuth oxide, bismuth sulfide and bismuth ferrite for both radiation source and simulation methods. The dose amplification for the bismuth-based nanoparticles increased with increasing size and concentration of nanoparticles.

Conclusion: The physical aspect dose enhancement of the nanoparticles was shown by Monte Carlo and analytic method. The results have proved bismuth-based nanoparticles deserve further study as a radiosensitizer.