Effect of Gold Nanoparticles on Dose Enhancement in Brachytherapy Using a Polymer Gel Dosimeter

The objective of the present study was to measure and evaluate the effect of gold nanoparticles (GNPs) on dose enhancement in brachytherapy with and 192 Ir source using polymer gel dosimeters. To test the dose enhancement effect of GNPs during brachytherapy using 192 Ir radioisotope, we used gamma rays in the same amount to irradiate gel dosimeters containing different concentrations and sizes of GNPs to measure their doses. Radiation was applied to 10 polymer gel dosimeters and control gel dosimeters that contained GNPs with different sizes (10 nm and 100 nm) and concentrations (0.1, 0.2, 0.3, 0.4, and 0.5 mM) under the same conditions. Dose enhancement factors (DEFs) were found to be 1.011, 1.014, 1.015, 1.026, and 1.029 when the concentrations of GNP were 0.1, 0.2, 0.3, 0.4, and 0.5 mM, respectively, with the size of the GNPs at 10 nm. When the GNP size was increased to 100 nm, the DEFs were 1.070, 1.088, 1.1890, 1.212, and 1.244 when concentrations of the GNPs were 0.1, 0.2, 0.3, 0.4, and 0.5 mM, respectively, showing dose enhancements higher than those of 10-nm-sized GNPs. When GNP size was 100 nm and its concentration was 0.3 mM or higher, the DEFs were higher than 1.15. The bigger the GNP size and the higher the concentration were, the larger the dose enhancement effect was. Such a dose enhancement effect of GNPs obtained in the present study can be utilized as basic data for clinical applications to enhance treatment effects. If such data are utilized in a treatment plan system, a treatment plan taking dose enhancement effect into account can be established at the planning stage.