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Experimental and Monte Carlo Analysis of Gold Nanoparticle Dose Enhancement Using 6 MV and 18 MV External Beam Energies

T Gray1*, N Bassiri2, S David1, D Patel1, S Stathakis2, N Kirby2, K Mayer1, (1) The University of Texas at San Antonio, San Antonio, TX, (2) Mays Cancer Center - MD Anderson Cancer Center, San Antonio, TX

Presentations

(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose: The purpose of this study is to quantify the macroscopic dose enhancing effects of gold
nanoparticles (GNPs) at external beam energies of 6 MV and 18 MV both experimentally and through
Monte Carlo methods.


Methods: Nanoparticle dose enhancement factor (DEF) was measured experimentally using an acrylic dose measurement apparatus built in-house. Approximately 0.75 µL of GNP solution was placed inside the apparatus, with EBT3 film placed in the center of the solution to measure dose. Solution in the apparatus with an appropriate height bolus on top of the solution was positioned 100 cm source-to-surface distance and irradiated using 6 MV and 18 MV energies at a dose rate of 300 MU/min. The repeating structures capability of MCNP 6.2 was utilized in order to model the acrylic apparatus containing the GNP solution, modeled as an array of gold spheres inside the GNP volume. The dose enhancement factor (DEF) was determined for three combinations of GNP sizes and concentrations: 1.3% and 1% gold by mass solutions of 30 nm GNPs and 1% gold by mass solution of 100 nm GNPs. DEF was determined by dividing the dose delivered to the GNP solution by dose delivered to water only in a separate measurement of simulation.


Results: dose enhancement was observed for the 18 MV beam at the highest concentration of 30
nm GNP, at 1.3% gold. As the concentration of gold increased in solution, dose enhancement increased. As the size of the GNPs are increased, DEF increased. Uncertainties in both experimental and theoretical data were less than 1%.


Conclusion: this study we develop and verify a simple and cost-effective technique to measure and
validate dose enhancement for external beam energies. Significant dose enhancement is possible for 18 MV energies at relatively higher GNP concentrations in tumor.

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Keywords

Radiation Therapy, Monte Carlo, Dosimetry

Taxonomy

TH- External Beam- Photons: General (most aspects)

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