Optical Characterization of Abnormalities in Various Size and Shape in Tissue Equivalent Phantoms

Tissue equivalent phantoms were made by mixing various combinations of wax colors with paraffin wax. Abnormalities of various size and shape were embedded into the tissue equivalent phantoms at different locations and depths to simulate real life abnormalities of tissues. The normalized back-scattered intensity (NBI) profiles at various locations on the tissue equivalent phantoms were obtained by multi-probe laser reflectometer. The laser radiations are guided by an optical fiber onto the phantoms and the backscattered radiations are collected by three optical fibers placed at a distance of 3 mm, 5 mm and 7 mm from the input fiber. The data after digitization, interpolation and filtering, are gray color-coded and displayed on the outline of the phantom. These NBI pattern vary depending on the optical characteristics of the phantom at various locations. For optical characterization the optical parameters, scattering (mu₃) and absorption (mu₂) coefficients and the anisotropy parameter (g) at each location on the phantom, by matching of reflectance profiles with that as simulated by a Monte Carlo simulation (MCS) procedure were determined. From the surface profile the size, location and depth of the abnormality were obtained.