the impact of nano-sized gold particles on the target dose enhancement based on photon beams using by monte carlo method

objective(s): in this study we evaluate the impact of the different aspects of gold nano-particles (gnps) on the target absorptive dose enhancement factor (def) during external targeted radiotherapy with photon beams ranging from kilovolt to megavolt energies using monte carlo simulation. methods: we have simulated the interaction of photon beams with various energies of radiation using water solution containing gnps to be located in a tumor region and used mcnp5 code for initially, the water phantom in which a tumor dimensions of 1 × 1 × 1 cm3 was defined as the target, contained simulated gnps. then, themacroscopic def of gnps of different sizes, including 15, 50, and 100 nm, had been calculated at the target area with a fixed concentration of 7 mg/g during external beam radiotherapy with single-energy photon beams ranging from kev to mev. results: the tumor defs in the presence of gnps were obtained 1.69-2.66and 1.08-1.10 for kev and mev beams, respectively. the highest def was achieved by photon energy of 50 kev. by increasing the size of the gnps, the tumor dose factor raised too. conclusions: the factors calculated for enhancing the target dose of gnps were in good agreements with previous studies based on kev photon energies. for mev photon energies, after a reduction in the boundary between the two areas of water and the solution containing gnps, the dose factor was enhanced to its maximum value for 2 and 6 mev photon beams at the depths of 2.6 and 5.6 cm, respectively.