Fig 1.
Schematic illustration of the irradiation setup used in the Monte Carlo simulations.
Table 1.
Tattoo-dermis mixture densities used in the Monte Carlo simulations at different volume fractions.
Table 2.
Elemental composition of selected Intenze tattoo inks compared to EU REACH regulatory limits. Multiple toxic metals, including Cr, Ni, Co, and Pb, exceed allowable thresholds in brown and orange inks, with Cr contamination observed across all three formulations. The brown ink exhibits the highest overall metal loading (Fe2O3-dominant at 88,400 ppm Fe, wet weight) and broadest compositional diversity, representing a conservative upper-bound scenario for dosimetric modeling.
Fig 2.
Modality- and energy-dependent dose enhancement factors (DEF) for Fe2O3-dominant brown tattoo pigment.
(a) 6 MeV and (b) 18 MeV electrons, and (c) 6 MV and (d) 18 MV photons. Electron beams produce modest perturbations, with 6 MeV showing enhancement (peak DEF ~ 1.07) while 18 MeV exhibits dose deficits (DEF < 1.0). In contrast, photon beams generate pronounced enhancement (peak DEF ~ 2.2–2.5) driven by high-Z-mediated secondary electron production. Curves shown here for 5%, 10%, 25%, 50%, 75%, and 100% pigment loading.
Fig 3.
Composition-dependent depth-dose profiles for three inks under 6 MeV electron and 6 MV photon irradiation.
(a, d) brown (Fe2O3-rich), (b, e) orange (Al-containing), and (c, f) black (carbon-based). Under electron irradiation, all pigments show shallow, localized perturbations with total skin-integrated dose differing by <2.5% from control. Under photon irradiation, dose perturbations follow the trend brown > orange > black, reflecting each ink’s high-Z metal content. Pigment loadings: 0%, 5%, 10%, 25%, 50%, 75%, and 100%.
Fig 4.
Electron-beam spatial dose distributions for a multi-color tattoo geometry (1 × 1 cm2, four 0.5 × 0.5 cm2 quadrants).
No ink (top-left), black (top-right), orange (bottom-left), and brown (bottom-right). Dose maps shown for 6 MeV(a–c) and 18 MeV (d–f) electron at 0%, 50%, and 100% pigment loading. Electron irradiation produces laterally uniform dose distributions.
Fig 5.
Photon-beam spatial dose distributions for a multi-color tattoo geometry (1 × 1 cm2, four 0.5 × 0.5 cm2 quadrants).
No ink (top-left), black (top-right), orange (bottom-left), and brown (bottom-right). Dose maps shown for 6 MV (a–c) and 18 MV (d–f) photon at 0%, 50%, and 100% pigment loading. Photon irradiation shows clear geometry-correlated enhancement patterns, but perturbations remain spatially confined to tattooed regions without lateral propagation.