Study on the Dose Enhancement of Gold Nanoparticles When Exposed to Clinical Electron, Proton, and Alpha Particle Beams by Means of Geant4.

Background: Various factors effecting deposited energy and dose enhancement ratio (DER) in the simplified model of cell caused by the interaction of a cluster of gold nanoparticles (GNPs) with electron beams were assessed, and the results were compared with other sources through Geant4 Monte Carlo simulation toolkit.

Method: The effect of added GNPs on the DNA strand breaks level, irradiated to electron, proton, and alpha beams, is assessed.

Results: Presence of GNPs in the cell makes DER value more pronounced for low-energy photons rather than electron beam. Moreover, the results of DER values did not show any significant increase in absorbed dose in the presence of GNP for proton and alpha beam. Moreover, the results of DNA break with GNPs for proton and alpha beam were negligible. It is demonstrated that as the sizes of the GNPs increase, the DER is enlarged until a certain size for 40 keV photons, while there is no striking change for 50 keV electron beam when the size of the GNPs changes. The results indicate that although energy deposited in the cell for electron beam is more than low-energy photon, DER values are low compared to photon.

Conclusion: Larger GNPs do not show any preference over smaller ones when irradiated through electron beams. It is proved that GNPs do not significantly increase single-strand breaks (SSBs) and double-strand breaks during electron irradiation, while there exists a direct relationship between SSB and energy.