Assess the suitability of the technique for objective monitoring of laser tattoo removal by an extended treatment protocol.
One half of the tattoo in the first volunteer was treated with nanosecond ...and the other half with picosecond laser pulses at 1064 nm. In the second subject, four test areas were treated repeatedly using different radiant exposures from 1.5 to 6 J/cm
. Measurements of diffuse reflectance spectra and photothermal radiometric transients were performed 4-20 weeks after each treatment session. Inverse Monte Carlo analysis based on a three-layer model of tattooed skin was applied to assess the tattoo characteristics and analyze their changes.
The results clearly indicate a gradual reduction of the ink content and an increase of the subsurface depth of the tattoo layer with all treatments at a radiant exposure of 3 J/cm
or higher. The observed dependences on laser pulse duration, radiant exposure, and a number of treatments are in excellent agreement with visual fading of the tattoo.
The presented methodology enables noninvasive characterization of tattoos in human skin and objective monitoring of the laser removal treatment.
We analyze the influence of a person’s age on the thicknesses and reduced scattering coefficients of the epidermis and dermis in visible part of the spectrum. Their values were assessed using a ...non-invasive technique which combines pulsed photothermal radiometry and diffuse reflectance spectroscopy with Monte Carlo modeling of light transport in a four-layer model of skin. The analysis is affected by the strong influences of the melanin content on the reduced scattering coefficient of the epidermis, a epi , and blood content in the case of dermis ( a der ). Separating their contributions reveals a significant decrease of a der with the person’s age at an average rate of –0.25 mm –1 per decade, while the contribution of blood in the papillary dermis amounts to 1.0 mm –1 % –1 . Meanwhile, no influence of the person’s age was found on a epi and the thicknesses of the epidermis or dermis.
OBJECTIVESAssess the suitability of the technique for objective monitoring of laser tattoo removal by an extended treatment protocol.MATERIALS AND METHODSOne half of the tattoo in the first volunteer ...was treated with nanosecond and the other half with picosecond laser pulses at 1064 nm. In the second subject, four test areas were treated repeatedly using different radiant exposures from 1.5 to 6 J/cm2 . Measurements of diffuse reflectance spectra and photothermal radiometric transients were performed 4-20 weeks after each treatment session. Inverse Monte Carlo analysis based on a three-layer model of tattooed skin was applied to assess the tattoo characteristics and analyze their changes.RESULTSThe results clearly indicate a gradual reduction of the ink content and an increase of the subsurface depth of the tattoo layer with all treatments at a radiant exposure of 3 J/cm2 or higher. The observed dependences on laser pulse duration, radiant exposure, and a number of treatments are in excellent agreement with visual fading of the tattoo.CONCLUSIONSThe presented methodology enables noninvasive characterization of tattoos in human skin and objective monitoring of the laser removal treatment.
