Modelling and verification of melanin concentration on human skin type

Abstract

Lasers are used in the minimalistic or noninvasive diagnosis and treatment of skin disorders. Less laser light reaches the deeper skin layers in dark skin types, due to its higher epidermal melanin concentration compared with lighter skin. Laser–tissue interaction modeling software can correct for this by adapting the dose applied to the skin. This necessitates an easy and reliable method to determine the skin’s type. Noninvasive measurement of the skin’s melanin content is the best method. However, access to samples of all skin types is often limited and skin-like phantoms are used instead. This study’s objective is to compare experimentally measured absorption features of liquid skin-like phantoms representing Skin Types I–VI with a realistic skin computational model component of ASAP®. Sample UV–VIS transmittance spectra were measured from 370 to 900 nm and compared with simulated results from ASAP® using the same optical parameters. Results indicated nonmonotonic absorption features towards shorter wavelengths, which may allow for more accurate ways of determining melanin concentration and expected absorption through the epidermal layer. This suggests possible use in representing optical characteristics of real skin. However, a more comprehensive model and phantoms are necessary to account for the effects of sun exposure.