RESUMO
The recent progress in Nanotechnology has introduced Gold Nanoparticles (AuNPs) as promising radiosensitizing agents in radiation oncology. This work aims to estimate dose enhancement due to the presence of AuNPs inside an irradiated water region through Monte Carlo calculations. The GATE platform was used to simulate 6 MV photon histories generated from a TrueBeam® linear accelerator with and without a Flattening Filter (FF) and model AuNPs clusters. The AuNPs size, concentration and distribution pattern were examined. To investigate different clinical irradiation conditions, the effect of field size, presence of FF and placement of AuNPs in water were evaluated. The range of Dose Enhancement Factors (DEF = DoseAu/DoseWater) calculated in this study is 0.99 ± 0.01-1.26 ± 0.02 depending on photon beam quality, distance from AuNPs surface, AuNPs size and concentration and pattern of distribution. The highest DEF is reported for irradiation using un-flattened photon beams and at close distances from AuNPs. The obtained findings suggest that dose deposition could be increased in regions that represent whole cells or subcellular targets (mitochondria, cell nucleus, etc.). Nevertheless, further and consistent research is needed in order to make a step toward AuNP-aided radiotherapy in clinical practice.
RESUMO
PURPOSE: Over the last decades, Gold Nanoparticles (AuNPs) have been presented as an innovative approach in radiotherapy (RT) enhancement. Several studies have proven that the irradiation of tumors containing AuNPs could lead to more effective tumor control than irradiation alone. Studies with low kV photons and AuNPs conclude in encouraging results regarding the level of radioenhancement. However, experimental and theoretical studies with MV photons report controversial findings concerning the correlation between dose enhancement effect and tumor cell killing. The great variation in the experimental protocols and simulations complicates the comparison of their outcomes and depicts the need for limiting the variety of investigated parameters. Our purpose is to point out a possible direction for building realistic Monte Carlo (MC) models that could end up with promising results in MV photons RT enhancement. METHODS: We explored published in silico studies concerning AuNPs enhanced RT from 2010 to 2019. In this review, we discuss the different AuNPs and MV photon beams characteristics that have been reported and their effect in dose enhancement. RESULTS: AuNPs size, concentration, type of distribution along with photon beams energy and the presence of flattening filter in linear accelerators seem to be the major parameters that determine AuNPs radioenhancement in silico. CONCLUSIONS: Prior to AuNPs clinical translation in photon radiotherapy, in silico studies should emphasize on nanodosimetry and track structure codes than condensed history ones. Toxicity estimation and biological aspects should be implemented in MC simulations so as to achieve accurate and realistic modelling of AuNPs driven RT.