Room: Exhibit Hall | Forum 4
Purpose: Gold nanoparticles (GNPs) can be used to amplify absorbed dose from radiation for a given treatment plan. The purpose of this study was to create a novel, cost effective, and clinically accessible method to measure the dose enhancement factor (DEF), the ratio of absorbed dose in GNP solution to that in water using an 192Ir source to irradiate the solution.
Methods: An acrylic apparatus was designed for these measurements. The acrylic apparatus housed a slot 7 cm from the base of the apparatus for a brachytherapy applicator. The base of the apparatus contained two regions that could be separated, between which EBT-3 film could be placed. Holes were drilled through these regions to hold the GNP solution. The film was cut into 2 cm squares and placed in the apparatus. The bottom hole was filled with 25 Î¼L of fluid, and the top hole was filled with 50 Î¼L of fluid. Film was irradiated in both GNP and water solutions, scanned, and analyzed by comparing the red color channel image intensity. GNPs 30 nm in diameter were used at concentrations of 8 nM, 16 nM, and 22 nM. A theoretical approach to determining DEF was also performed based on mass attenuation coefficients, the relative mass of gold in the solutions and the energy spectrum of 192Ir.
Results: The theoretical DEFs were determined to be 1.033, 1.024, and 1.012 for the 22nM, 16nM, and 8nM GNP solutions, respectively. The experimentally measured DEFs were 1.031 Â± 0.005, 1.023 Â± 0.010, and 1.013Â± 0.006 for the 22nM, 16nM, and 8nM solutions, respectively.
Conclusion: There is a way to physically measure DEF using materials readily available in a radiation oncology clinic. The method that was employed in this study confirms results from theoretical calculations.