FAST ALGORITHM TO DETERMINE OPTICAL-PROPERTIES OF A TURBID MEDIUM FROM TIME-RESOLVED MEASUREMENTS

After analytical expressions for the time-resolved reflectance are int roduced from the diffusion approximation under the three most commonly used boundary conditions, a novel algorithm is demonstrated for deter mining the reduced scattering and the absorption coefficients from tim e-resolved reflectance (or backscatter) measurements at two positions on the surface of biotissue. The algorithm is straightforward and fast and involves only some simple mathematical operations, avoiding compl icated iterative nonlinear fitting to the time-resolved curve. The der ived reduced scattering coefficient is not affected by whatever bounda ry condition is applied. The algorithm was verified with time-resolved data from the Monte Carlo model. Both a semi-infinite medium and a tu rbid slab medium were tested. In contrast to the nonlinear fitting met hod, this algorithm allows both the scattering and the absorption coef ficients to be determined to a high accuracy. (C) 1998 Optical Society of America OCIS codes: 170.3600, 170.7050, 290.1990, 000.4430.