Determination of the optical properties of turbid media by measurement of the spatially resolved reflectance

The absorption and reduced scattering coefficients determine the radial dependence of the diffuse reflectance that is due to a point source. A system consisting of a HeNe laser source and a CCD camera was built for making remote measurements of spatially resolved diffuse reflectance. First, liquid tissue phantoms were made of Lipovenos and trypan blue. To determine the optical properties of the tissue phantoms a program code was implemented convolving the point-spread function of the camera with the solution of the diffusion equation and fitting the result to the measured data. We found that the prediction of mu(a) and mu(s)' was accurate within +/- 10 % and +/- 4 %. To check these results also measurements with a multiple fiber-optic detector in contact with the phantom surface at varying distances from the source were accomplished. The intensity signal was measured with twelve low noise photodiodes. We found good agreement between both approaches.