Comparative Assessment of Silver and Gold Nanoparticles for Dose Enhancement in Layered Skin Geometries: A Monte Carlo Sensitivity Study

This study quantifies nanoparticle-mediated dose modification in an idealized layered skin geometry using Monte Carlo (MCNP 6.3) (skin surface, epidermis ≈100 μm, dermis ≈500 μm, underlying skin). Homogeneous silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) at 5–30 mg/g were embedded in a 1 × 1 × 1 cm³ target, and energy-deposition tallies were converted to absorbed dose and reported as dose-enhancement factors (DEFs) normalized to 0 mg/g. Electron beams (6–12 Mega Electron Volt (MeV)) produced a near-linear DEF–concentration trend in the target with modest superficial gains; in contrast, low-energy photons (50/100 Kilo Electron Volt (keV)) yielded substantially higher enhancement, with AgNPs at 50 keV reaching ~560%, while adjacent normal-tissue sampling regions (OAR1–OAR6) remained near unity with mild, orientation-dependent anisotropy. Skin-layer summaries confirmed surface-weighted increases at low energies and more uniform depth profiles at higher MeV. Statistical uncertainties were