Discrete-Ordinate Transport Simulations of Light Propagation in Highly Forward Scattering Heterogeneous Media

We implemented a delta-Eddington scheme in conjunction with a finite-difference, discrete-ordinate, radiative-transport code to accurately and efficiently simulate light propagation in highly-forward-scattering media. It is demonstrated that light propagation does only weakly depend on the anisotropy factor, g, as long as the reduced scattering coefficient, µ_s', is much larger than the absorption coefficient, µ_a. When µ_a - µ_s', the fluence rate decays faster in media with high g-values compared to isotropically scattering (g = 0) media. In heterogeneous media that contain void-like spaces, such as the cerebrospinal-fluid-filled ventricles in the brain, the choice of g barely affects the predicted light propagation. However, the diffusion approximation does not yield an accurate description of the light transport in these cases.