Monte Carlo-based calculation of nano-scale dose enhancement factor and relative biological effectiveness in using different nanoparticles as a radiosensitizer

Introduction Nowadays, some nanoparticles (NPs) are known and used as radiosensitizers in radiotherapy and radiobiology, due to their desired biological, physical, and chemical effects on cells. This study aimed to evaluate and compare the dose enhancement factor (DEF) and the biological effectiveness of some common NPs through EGSnrc and MCDS Monte Carlo (MC) simulation codes. Materials and methods To evaluate considered NPs' DEF, a single NP with 50 nm diameter was simulated at the center of concentric spheres. NP irradiations were done with 30, 60, and 100 keV photon energies. The secondary electron spectra were scored at the surface of considered NPs, and the dose values were scored at surrounding water-filled spherical shells which were distributed up to 4000 nm from the NP surface. The electron spectra were used in the MCDS code to obtain different initial DNA damages for the calculation of enhanced relative biological effectiveness (eRBE). Results By decreasing the photon energy, an increment of DEF was seen for all studied NPs. The maximum DEF at 30, 60, and 100 keV photon energies were respectively related to silver (Ag), gadolinium (Gd), and bismuth (Bi) NPs. The maximum double-strand break (DSB) related (eRBE(DSB)) values for the 30 keV photon belonged to Ag, while BiNPs showed the maximum values at other photon energies. The minimum eRBE(DSB) values were also related to iron (Fe) NPs at the entire range of studied photon energies. Conclusions The compared nanoscale physical and biological results of our study can be helpful in the selection of optimum NP as a radiosensitizer in future radiobiological studies. Bi, gold (Au), Ag, and platinum (Pt) NPs had great potential, respectively, as radiosensitizers relative to the other studied NPs.

Automated summary

This study evaluated and compared the dose enhancement factor (DEF) and biological effectiveness of common nanoparticles for radiosensitization using Monte Carlo simulation codes. The results showed that different nanoparticles had varying degrees of DEF at different photon energies, with silver (Ag), gadolinium (Gd), and bismuth (Bi) nanoparticles exhibiting the highest enhancements. Iron (Fe) nanoparticles had the lowest biological effectiveness values among the studied nanoparticles. Gold (Au), silver (Ag), and platinum (Pt) nanoparticles showed great potential as radiosensitizers compared to others.