Anisotropic light propagation: models and numerical experiments

Jenni Heino
Helsinki University of Technology

Authors: Jenni Heino, Simon Arridge, Jan Sikora and Erkki Somersalo

In medical optical tomography, light propagation in tissue is
commonly modeled using the diffusion equation due to the strongly
scattering nature of most biological tissues. Some tissues such as
muscles or the white matter of the brain have structural anisotropic
characteristics, which also affect light propagation. The
anisotropies are generally not well known, though one may obtain
some prior information using, e.g., anatomical information or
some other imaging modality. Proper modeling of anisotropies
may provide valuable information for imaging.

In the diffusion framework, anisotropic light propagation
can be modelled using an anisotropic diffusion equation.
Here, we start from a possible model for anisotropic scattering
within the radiative transfer equation. From this model,
the corresponding anisotropic diffusion equation can be derived
in a simple case. For numerical experiments, we present an
anisotropic Monte Carlo simulation based on the radiative
transfer model, and finite element and boundary element
solutions of the anisotropic diffusion equation, and compare
the results of the numerical simulations from these methods.


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