On the validity of the anomalous diffraction approximation in light-scattering studies of soft biomedical tissues

Abstract

In simulations of light propagation in soft biomedical tissues, the tissue is generally modeled as a turbid medium. In one such model, suspended scatterers are assumed to be homogeneous spheres of size following a fractal size distribution law. In this paper, we examine, within the framework of this model, the accuracy of a well-known approximation known as the anomalous diffraction approximation. The deployment of this approximation allows the tissue scattering coefficient to be expressed in a closed analytic form. It is demonstrated that use of the anomalous diffraction approximation yields reasonably good results for the tissue scattering coefficient, the phase function and the asymmetry parameter. It is also shown that the experimentally observed wavelength dependence of the scattering coefficient follows analytically from the formulas obtained using this approximation. The results are important from the point of view of constructing more realistic tissue models which may include non-spherical scatterers.