Determination of optical properties and blood oxygenation in tissue using continuous NIR light

In this article, we introduce a simple method to characterize optical properties and blood oxygenation in tissue using spatially resolved, steady-state reflectance. The method considers multiple source-detector separations larger than 2 cm, i.e. 20 times the optical mean free path in tissue, and makes an approximation to linearize the relationship between the separation and reflectance. Simulation results show that errors of the algorithm due to the approximation are less than 10%. Using a calibration sample, we calculate from the slope and intercept the absorption and reduced scattering coefficients, mu a and mu's, of a tissue-like solution, and experimental results confirm the usefulness of the method for quantitation of haemoglobin saturation in tissue.