Detection of Tumour in Biological Tissues by Laser Backscattering and Transillumination Signal Analysis

The onset of tumour in biological tissues affects their optical properties. In the present study Monte Carlo simulation of the diffuse surface reflectance and transmittance for detection of the inhomogeneities/tumour in control tissue is carried out. From the isolated heart, spleen and adipose tissues of goat digital phantoms are prepared. The virtual optical probe consists of a photon injection port (source), three ports placed along the x-axis at 2, 4 and 6 mm to collect backscattered photons and one port placed coaxially to the source port at the exit end to collect transmitted photons. Two types of inhomogeneities of diameter 2 mm are introduced in the phantoms - first a tissue of absorption coefficient 10% more than that of heart and same scattering coefficient; second, adipose or spleen tissue, embedded in heart phantoms, at depths 2, 4 and 6 mm. The inhomogeneity placed at depth 2 mm gives maximum normalized backscattered intensity (|NBI|) at the port placed at 2 mm. The maxima of low |NBI|s are also observed at ports located at 4 and 6 mm of inhomogeneities embedded at depths 4 and 6 mm. The signals due to high scattering and high absorption are positive and negative with reference to that of heart. The transmittance also shows respective variations with placement of tissues in the phantoms. The normalized transmitted intensity is maximum when the tissues are placed close to the exit surface. These are further characterized by the peak intensity and full-width at half maximum of signals. The data analysis provides details of their type, location and size. Inhomogeneities with minimal change in optical parameters are also identified.