Room: Exhibit Hall | Forum 4
Purpose: To computationally assess and validate dose enhancement to a tumor using different sizes and concentrations of gold nanoparticles at varying photon energies.
Methods: Monte Carlo simulation geometries were created in MCNP 6.2 for (1) An acrylic phantom designed in-house to measure dose enhancement with EBT3 film placed at 7.5 cm SSD from an Ir-192 HDR seed, and (2) The same phantom placed at 100 cm SSD from both a 6 MV and an 18 MV gantry head. The center of the EBT3 film was tallied to report dose delivered to a gold nanoparticle solution inside the acrylic phantom. The gold nanoparticle solution was modeled first as a solution of gold and water using atomic percent, and second using the repeating structures capability of MCNP 6.2. Data were analyzed using relative uncertainty and the results of the two models were compared with experimental measurements.
Results: For a 22 nM solution of gold nanoparticles 30 nm in diameter in the Ir-192 brachytherapy setup, the atomic percent method predicted a DEF of 1.059, while the repeating structure method predicted 1.045. For the same solution in the 18 MV external beam setup, the atomic percent method predicted a DEF of 1.021, while the repeating structure method predicted 1.012. Statistical uncertainty for all results was < 1%. Experimentally measured DEFs were 1.032 and 1.018, for the Ir-192 and 18 MV setups, respectively. Results of this study show that the model using an atomic percent of gold generally overestimated dose enhancement to the tumor volume, while the model using the repeating structures geometry more accurately predicted dose enhancement to the tumor.
Conclusion: This study shows that utilizing the repeating structures geometry in MCNP 6.2 is an accurate way of modeling and effectively predicting dose enhancement to a tumor using gold nanoparticles as dose enhancing agents.
Funding Support, Disclosures, and Conflict of Interest: San Antonio Medical Foundation; San Antonio Life Sciences Institute
Not Applicable / None Entered.