Radiative transfer through multilayered medium: high-frequency experiments and theory

Development of efficient analytical and numerical techniques for the determination of optical parameters of biotissues on the base of measured data is a crucial part of successful implementation of non- invasive diagnostic techniques in clinical conditions. Widely used approximations, like diffusion approximation (DA), were shown to fail in most real-life circumstances due to simplifications of modeling or neglect of various involve phenomena, like boundary effects, tissue inhomogeneity, skin roughness and deviations of optical properties of skin in time due to physiological effects. In this work we compare experimental results with results of numerical simulations. For our measurements, we used both spatial-resolved and frequency-domain techniques. To describe propagation of photons we numerically solved the radiatve transfer equation (RTE). We found that the Monte-Carlo method (MC) is too time-consuming for large source- detector separations. We achieved flexibility in preparation of experimental medium with tissue simulating sample containing several homogeneous layers. Our objective is the investigation of accuracy in determining unknown structures and optical coefficients from measured data, based on the realistic model of the tissue described in the RTE.