Phase-function corrected diffusion model for diffuse reflectance of a pencil beam obliquely incident on a semi-infinite turbid medium

Abstract

Oblique incidence reflectometry (OIR) is an established technique for estimation of tissue optical properties, however, a sensing footprint of a few transport mean-free paths is often needed when diffusion-regime-based algorithms are used. Smaller-footprint probes require improved light-propagation models and inversion schemes for diffuse reflectance close to the point-of-entry but might enable micro-endoscopic form factors for clinical assessments of cancers and pre-cancers. In this paper we extend the phase-function corrected diffusion-theory presented by Vitkin et al. (Nat. Comm 2011) to the case of pencil beams obliquely incident on a semi-infinite turbid medium. The model requires minimal computational resources and offers improved accuracy over more traditional diffusion-theory approximations models when validated against Monte Carlo simulations. The computationally efficient nature of the models may lend themselves to rapid fitting procedures for inverse problems.

Opto-Acoustic Image Reconstruction and Motion Tracking Using Convex Optimization

“…Thus, Φ λj = diag(ϕ λj ), where ϕ λj ∈ R nv is a vector representing the fluence profile. This is governed by the radiation transport equation and can be determined in several ways, including diffusion approximations [61]- [64], finite-element models [65], or Monte Carlo based methods [66], [67]. Our implementation uses analytic expressions based on the diffusion approximation [28], [63] with optical properties for breast tissue [4].…”

Non-Invasive Assessment of Dairy Products Using Spatially Resolved Diffuse Reflectance Spectroscopy

“…30 Recently, corrections have been proposed to include phase function dependencies by Zemp. 27 In addition, an improved analytical solution to the radiative transfer equation for a semi-infinite medium has recently been proposed by Liemert and Kienle. 31 These two approaches may individually reduce the coupling between the optical properties.…”

“…The presented method does not suffer from the same limitation due to the high spatial resolution of the presented camera-based instrumentation. The analysis is important in two regards: 27 (I) The previously suggested value may not be optimal.…”