Diffuse reflection measurements determining optical properties of tissues

A reiteration method based on a modified discrete lattice model is presented to determine the absorption and transport scattering coefficients according to the fit of the calculated radial distribution curve of diffuse reflectance to the measured one. The modified discrete lattice model which includes the effects of specular reflection and the reduced incident intensity serves to exactly calculate the probability P(x,y,m) that a normally incident photon is emitted from the lattice point(x,y) at mth step on the surface of a semi-infinite medium with the index of refraction n before reiteration. In the reiteration procedure, various parameters to absorption and transport scattering coefficients as input data in an optimal sequences are used to calculate the radial distribution of diffuse reflectance R((rho) ) on the basis of P(x,y,m). The parameters correspondent to the radial distribution of diffuse reflectance which fits the measured curve are adopted to be the absorption and transport scattering coefficients of the medium. Steady state diffuse reflectance measurements are performed on Intralipid/ink phantoms with various concentrations. It costs only a few minutes to determine the absorption and transport scattering coefficients from the radial distribution of diffuse reflectance by this method in a personal microcomputer. The good agreement between the results of this method and those obtained from the transmission measurements of scattering and absorption demonstrates the potential of this technique in clinical applications.