Room: AAPM ePoster Library
Purpose: Nanoparticles and nano-sized molecules have the ability to act as contrast enhancement agents and possibly amplify the effect of radiation therapy procedures, if they contain a high-atomic number material. This study investigates the magnitude of dose enhancement by the presence of gold nanoparticles in a tumor.
Methods: The GATE Monte Carlo Simulations toolkit was used to simulate the radiation therapy treatment of the prostate gland. Simulations were run both for external beam radiotherapy (EBRT) and brachytherapy by modeling the radiation spectrum of a 6 MV LINAC and the 125I source. The XCAT mathematical anthropomorphic phantom was used throughout this study. When the LINAC was used, a four-field box irradiation technique was implemented. For prostate brachytherapy using 125?, a homogenous activity inside the gland was assumed.
Results: The in-silico EBRT study showed that the presence of gold, induced an average dose enhancement of 5% (range of 0-10% proportionally), when gold concentration ranges from 0-6.7% per weight of the prostate gland. For the brachytherapy modeling, the average dose enhancement was 175%, ranging from 0-230% logarithmically, for the same range of gold concentration. This outcome can be explained by the fact that low energy photons have a high rate of interaction with gold. Moreover, the brachytherapy simulation resulted to lower dose in neighboring organs, such as the rectum, which dose reduction was in average 65% (range 0-85% logarithmically).
Conclusion: The results showed that the presence of gold has a dose boosting effect to the tumor, both for EBRT and for brachytherapy procedures. Because of the higher cross section of interaction of the low energy gamma rays from 125I, the brachytherapy treatment offers significantly higher dose enhancement when compared to EBRT. This study needs to evolve in the modelling of brachytherapy sources and nanoparticles, and be evaluated with clinical data.