Tissue-Dependent Efficacy of Gold Nanoparticles as Radiosensitizers: Implications of Personalized Tissue, Radiation Interaction Parameters, and Physical Dose Enhancement

In radiological practices, enhancement of radiation by the introduction of gold nanoparticles (GNPs) into biological tissues is expected to alter radiation parameters during radiation imaging and radiotherapy. These radiation parameters influence dosimetric evaluations in the overall radiological outcome. This study aims to provide a focused investigation on the effects of different concentrations of GNPs on the radiation interaction parameters and dose enhancement factor (DEF) in the prostate, lung, and blood tissues of an adult male referenced phantom.GNPs at concentrations of 0.1 mg/g, 10 mg/g, and 50 mg/g were added to prostate, lung, and blood tissues, followed by the determination of the resulting elemental weight composition. At different energies (0.01 to 15 MeV), the radiation interaction parameters: effective atomic number (Zeff), effective electron density (Neff), mass attenuation coefficient (μ/ρ), and energy absorption buildup factor (EABF) for the doped and undoped tissues were calculated using the PAGEX software. Finally, the DEF was evaluated based on the mass energy absorption coefficient.At lower photon energies (E ≤ 0.1 MeV), the addition of GNPs substantially increased the Zeff, Neff, and μ/ρ, with a concentration of 50 mg/g showing the most significant effect. On the contrary, the EABF decreased with higher concentrations of GNPs. The DEF was discovered to be highly dependent on the concentration of GNPs, photon energy, and tissue type, with a peak maximum at 40 keV and a distinct secondary peak at 80 keV corresponding to the K-absorption edge of gold. The maximum value reached 8.978 for prostate tissue and 8.049 for lung and blood tissues at a concentration of 50 mg/g. Above 1 MeV of energy, the DEF converged to around 1.01 for all tissues with and without the concentrations of the GNPs.The study demonstrated that the assumption of a uniform DEF across different tumor sites would lead to huge differences in dose calculation during treatment planning, which can compromise treatment outcomes. Thus, these findings stress the need for tissue-specific and energy-dependent dosimetry analysis in the optimization of nanoparticle-enhanced radiotherapy and radiation imaging.