Dual wavelength excitation pulsed photothermal radiometry for enhanced depth profiling of human skin

Abstract

Pulsed photothermal radiometry (PPTR) has been applied to depth profiling of port wine stain birthmarks in human skin with the aim to improve the laser therapeutic outcome. In this study, we investigate experimentally temperature depth profiling using PPTR in three polyacrylamide skin phantom models. We utilize in vitro polyacrylamide gel phantoms and ex vivo human epidermis, to provide quantitative experimental assessment of the ability of PPTR to discriminate between the epidermis and subsurface chromophores when they are in close proximity to one another. Experimentally determined temperature profiles are compared with results from Monte Carlo simulation. Using the conventional PPTR profiling method, specific geometrical characteristics can be determined only when the epidermal and subsurface chromophore layers are separated by a non-absorbing layer. Application of the dual wavelength excitation method enables discrimination between the epidermis and subsurface chromophore layer even when the two are in close proximity to one another.