dosimetry and radioenhancement comparison of gold nanoparticles in kilovoltage and megavoltage radiotherapy using magat polymer gel dosimeter

Background: numerous unique characteristics of the nanosized gold, includinghigh atomic number, low toxicity, and high biocompatibility make it one of the mostappropriate nanostructures to boost radiotherapy efficacy. many in-vivo and in-vitroinvestigations have indicated that gold nanoparticles (aunps) can significantlyincrease tumor injuries in low kilovoltage radiotherapy. while deep-lying tumorsrequire much higher energy levels with greater penetration power, and investigationscarried out in megavoltage energy range show contradictory results.objective: in this study, we quantitatively assess and compare dose enhancementfactors (defs) obtained through aunps under radiation of cobalt-60 source(1.25mev) versus iridium-192 source (380 kev) using magat gel dosimeter.material and methods: magat polymer gel in both pure and combinedwith 0.2 mm aunps was synthesized. in order to quantify the effect of energy ondef, irradiation was carried out by co-60 external radiotherapy and ir-192 internalradiotherapy. finally, readings of irradiated and non-irradiated gels were performedby mr imaging.results: the radiation-induced r2 (1/t2) changes of the gel tubes doped withaunps compared to control samples, upon irradiation of beams released by ir-192source showed a significant dose enhancement (15.31% ±0.30) relative to the co-60external radiotherapy (5.85% ±0.14).conclusion: this preliminary study suggests the feasibility of using aunps inradiation therapy (rt), especially in low-energy sources of brachytherapy. in addition,magat polymer gel, as a powerful dosimeter, could be used for 3d visualizationof radiation dose distribution of aunps in radiotherapy.