Deriving optical properties in the near infrared using an inverse Monte Carlo program

Abstract

An Inverse Monte Carlo program was developed based on a scaleable Monte Carlo algorithm. This program determines the skin optical (µ_a and µ_s) properties in vivo using reflectance and thermal measurements as inputs from different skin types, very light to very dark. Some basic assumptions are made: (1) epidermal thickness is close to 100 µm, (2) the scattering in the epidermis is the same or similar to the dermal scattering, (3) the dermal absorption and scattering coefficients are similar between individuals. Experimental measurements of reflectance and temperature were taken. These were input in a pair of Inverse Monte Carlo programs that generated the optical properties for the different skin types. A single layer Inverse Monte Carlo model was employed to determine the optical properties of the dermis. A 2-layer Inverse Monte Carlo program was used to determine the epidermal optical properties.