Image reconstruction for optical tomography using photon density waves

Various investigations into the nature of light-tissue interaction have indicated that near infrared (NIR) light can be used to penetrate substantial depths of biological tissue. At near infrared wavelengths (700-1300 nm), scattering dominates absorption, which makes the calculation of the light distribution and therefore the reconstruction of absorption and scattering coefficients difficult. Several analytical and numerical approaches such as the diffusion theory and the Monte Carlo simulations have been used to calculate the light distribution in turbid media. In this paper the diffusion of photons is considered in the steady-state domain. The optical image reconstruction is based on the diffusion approximation and simulation is done using the finite element method. Results are given for the forward model, in both homogeneous and heterogeneous cases.