BIOLOGICAL CONSEQUENCE OF GOLD NANOPARTICLES INDUCED BY IONIZING IRRADIATION: MONTE CARLO STUDY

In recent years, gold nanoparticles have been widely used in small animal experiments as a contrast agent in x-ray based imaging or does enhancement in radiation therapy. To better evaluate the potential biological consequences of gold nanoparticles used in small animal research, we integrated a Monte Carlo radiation transport code and fast Monte Carlo damage simulation program (MCDS) to compute DNA damage yields induced by different monoenergetic ionizing irradiation photons in the settings similar to cell experiments. The Monte Carlo radiation transport code was used to tally the initial electron particles produced by the photon interactions in the homogeneous cell medium phantom and the electron fluence was then transferred to MCDS for DNA damage yield calculations including double-strand and single-strand breaks. An iodinated contrast medium (eXIA 160) used in small animal imaging was included in our DNA damage investigation for comparisons with gold nanoparticles. We also calculated physical quantities including absorbed dose and scatter-to-primary ratios (SPR) for the cell phantom used in our simulation. Our results established a strong correlation relation between physical interaction processes in matters for ionizing photon particles and their corresponding biological consequences. The study helps us understand the biological effect of gold nanoparticles induced by ionizing irradiation.