Evaluating the effect of skin tone on quantitative hybrid frequency-domain and broadband diffuse optical spectroscopy

Skin pigmentation reduces the signal-to-noise ratio of diffuse optical spectroscopy (DOS) measurements of tissue. This increases the error in optical property estimation of the underlying tissue, e.g. if a single-layer geometry model is used, leading to errors in the derived concentration of tissue absorbers. Recent efforts have modeled skin pigmentation with polyurethane-and-silicone-based skin-mimicking phantoms, in order to observe the effect of skin pigmentation on the estimation of the optical properties of the target internal tissue. We employ previously-reported skin-mimicking, polyurethane-film phantoms of various opacity levels on a breast-tissue silicone phantom. We report on hybrid multifrequency frequency-domain and broadband DOS measurements processed with either single-distance or multidistance methods. The optical property estimations of the underlying breast-tissue phantom erroneously increased with skin phantom opacity using the single-distance method, while they retained +/-10% accuracy when obtained with the multidistance method. This underlines the potential of the multi-distance method to process DOS measurements to accurately measure the optical properties of internal tissue across a population with various skin-pigmentation levels.