In vitro spectral analysis of tattoo pigments.

Area of Science:

• Dermatology
• Optical Engineering
• Materials Science

Background:

• Tattoo pigment absorption spectra and their reaction to specific laser wavelengths (532 nm and 752 nm) are crucial for selecting optimal laser devices for tattoo removal.
• Understanding the correlation between pigment composition (titanium and iron) and laser interaction is essential for predicting treatment efficacy.

Purpose of the Study:

• To determine the absorption spectra of common tattoo pigments and India ink.
• To evaluate the response of these pigments to laser irradiation at 532 nm and 752 nm.
• To correlate pigment spectral properties and laser responses with their elemental composition.

Main Methods:

• Spectrophotometric analysis of 28 tattoo pigments and India ink mixed in agar.
• Irradiation of pigment-laden agar plates using Q-switched laser wavelengths of 532 nm and 752 nm.

Main Results:

• Red pigments showed highest absorbance in the complementary spectrum; blue, yellow, and orange pigments peaked in adjacent visible light regions.
• Variability in absorbance was observed for green tattoo pigments.
• Iron-containing pigments (except black) exhibited darkening at both wavelengths; titanium-containing pigments showed variable responses.
• Pigments cleared or darkened at 532 nm, with a more limited response observed at 752 nm.

Conclusions:

• Tattoo pigment absorption spectra provide insight into color resistance during tattoo removal.
• Pigment darkening is a complex phenomenon influenced by laser-tissue interaction and pigment composition.