Estimation of the optical properties of two-layered tissue simulating phantoms from spatially resolved frequency-domain reflectance

Spatially resolved diffuse reflectance measurements of two-layer tissue simulating phantoms were performed in the frequency-domain. The measurements were fitted to a two-layer diffusion model of photon transport. The specific case of skin containing increasing amounts of exogenous absorber over homogeneous muscle tissue was simulated. The retrieved optical properties were compared with the known optical properties of the phantoms as well as with results obtained from Monte Carlo (M.C.) simulated data. It was found that in most cases, experimental factors that are yet to be accounted for rather than diffusion theory limitations determine the accuracy of retrieved optical properties. The absorption increase in the top layer could only be quantified for a layer thickness of 4mm. The errors in all other retrieved optical properties were in the 15-40% range with estimated uncertainties to the fitted parameter values being of similar magnitude.

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