Estimation of light transport parameters in tissues using coherent backscattering : A revaluation of the method

The suitability of using the angular peak shape of the coherent backscattered light for estimating the light transport parameters of tissues has been investigated. Milk and methylene blue doped milk were used as tissue phantoms for the measurements carried out with a He-Ne laser (632.8nm). Results indicate that while the technique accurately estimates the transport length, it can determine the absorption coefficient only when the absorption is moderate (α > 1cm) for the long transport lengths typical of tissues. Further, the possibility of determining the anisotropy factor by estimating the single scattering contribution to the diffuse background is examined. It is shown that the anisotropy factor can be estimated reasonably well, provided it is lesser than a limit set by the accuracy of the intensity measurement ( g < 0.6 for our setup). The anisotropy factor is accurately estimated by corroborating the coherent backscattering measurements with transmission measurements and independently by angle-resolved scattering measurements.