Monte Carlo modeling of light propagation in highly scattering tissues. II. Comparison with measurements in phantoms

For pt.I see ibid., vol.36, no.12, p.1162-8 (1989). Measurements of the fluence-depth distributions and the diffuse reflectance of 633-nm light in liquid media with optical properties similar to soft tissues are discussed. The results are compared with predictions of Monte Carlo computer calculations in order to test the adequacy of Monte Carlo modeling of light transport in tissues. Except at extremely high albedo, the experimental data and the Monte Carlo results agree well for the depth dependence of the fluence as a function of incident light beam diameter and optical absorption and scattering, and for the dependence of the diffuse reflectance on the albedo. The absolute experimental values for the fluence must be renormalized by a factor which varies with the albedo in order to match the model values, and the possible sources of this discrepancy are discussed.