Exhibit Hall | Forum 2
Purpose: Although many studies have been done on Gold nanoparticle (AuNP) dose enhancement, the clinical translation has yet to be realized due to a lack of agreement among published work and practical implementation into current treatment methods. This study further characterizes AuNP mediated dose enhancement under clinically relevant conditions utilizing Monte Carlo (MC) simulations, the local effect model (LEM) and in vitro experiments.
Methods: Using the MC toolkit TOPAS and TOPAS-nBio, its radiobiology DNA-scale extension, a three-step process was used to determine the microscopic dose enhancement surrounding a 15 nm AuNP under 6 MV irradiation at various clinically relevant depths (1.5cm-30cm). These modular steps utilized condensed history (CH) and track structure (TS) physics lists to allow for high spatial resolution (nm). The dose enhancement ratio (DER) was used to calculate the dose to a cellular geometry containing 10 pg/cell of AuNPs, and cell survival fraction (SF) curves were calculated using the local effect model (LEM). SF curves were validated against clonogenic assay of LNCaP cells treated with 10 pg/cell AuNPs and irradiated using a 6 MV LINAC under varying thicknesses of solid water (1.5-30cm).
Results: DER increased with depth, with a maximum DER of ~5.7 at 1.5cm depth and ~8.1 at 30cm depth. DER was highest close to the AuNP surface with an appreciable range of ~200nm. The calculated SF curves closely matched the clonogenic assay derived SF curves, with an average sensitization enhancement ratio (SER) error of 4.0%.
Conclusion: The calculated SF curves closely matched the in vitro clonogenic assay derived SF, showing that MC simulations and the LEM can be used for AuNP-mediated radiotherapy studies in the future; however, caution is urged as each cell line is different and this model would need to be validated against other cell lines to be used generally.
Monte Carlo, Radiosensitivity, Radiobiology
TH- External Beam- Photons: Computational dosimetry engines- Monte Carlo