Light propagation in tissues with forward-peaked and large-angle scattering

Abstract

We study light propagation in tissues using the theory of radiative transport. In particular, we study the case in which there is both forward-peaked and large-angle scattering. Because this combination of the forward-peaked and large-angle scattering makes it difficult to solve the radiative transport equation, we present a method to construct approximations to study this problem. The delta-Eddington and Fokker-Planck approximations are special cases of this general framework. Using this approximation method, we derive two new approximations: the Fokker-Planck-Eddington approximation and the generalized Fokker-Planck-Eddington approximation. By computing the transmittance and reflectance of light by a slab we study the performance of these approximations.

Transillumination of highly scattering media by polarized light

“…This simple approximation is best suited to analytical treatment and semi-quantitative description of wave propagation and depolarization in media with highly forward scattering [70,71]. Within the framework of Eq.…”

“…(7.54)-(7.56) we take advantage of the results obtained within the smallangle Fokker-Planck approximation [69]. This approximation takes into account highly forward scattering (1 − cos γ 1) of light in biological tissues and tissuelike media [70,71] and enables us to elaborate simple semi-quantitative model of propagation of polarized light .…”

One-way radiative transfer

“…Therefore, a number of useful approximations have been derived to deal with this scenario. In particular, the asymptotic limit of sharply forward-peaked scattering has been studied extensively leading to the Fokker-Planck approximation [6,7] and its generalizations [8][9][10][11]. However, these approximations all lead to the same kind of boundary value problem as for the RTE.…”

Combining diffuse optical tomography and spectroscopy to detect and characterize lesions in two-layered tissues

“…This difference between optical properties is necessary to model accurately light propagation through tissues consisting of epithelial and stromal tissue layers. Furthermore, to account for sharply peaked forward scattering in tissues, we use the generalized Fokker-Planck-Eddington approximation [10] to the radiative transport equation.…”