A Computational Method to Estimate the Effect of Gold Nanoparticles on X-Ray Induced Dose Enhancement and Double-Strand Break Yields

We report the effects of gold nanoparticles (GNP) on the enhancement of the dose effect and double-strand break (DSB) induction for X-ray monoenergies (10 keV-2 MeV). The overall relative biological effectiveness (RBE) was defined as the product of dose and DSB enhancement. The cellular doses and energy spectra were computed using the PENELOPE (PENetration and Energy LOss of Positrons and Electrons) code. The DNA damage yields were estimated using the MCDS (Monte Carlo damage simulation) code. Considering the production of Auger electrons induced by 7mg/ml GNP, we found that dose enhancement at the 30 keV was ~4.0 for cells with radius 4 μm. The DSB induction increased as GNP concentrations increased and was dependent on X-ray energy. These findings demonstrated that the maximum RBE was attained at 30-40 keV and therefore this energy range would be more efficient in cancer cell killing.