title: Hybrid diffusion and two-flux approximation for multilayered tissue light propagation modeling.
abstract: Accurate and rapid estimation of fluence, reflectance, and absorbance in multilayered biological media has been essential in many biophotonics applications that aim to diagnose, cure, or model in vivo tissue. The radiative transfer equation (RTE) rigorously models light transfer in absorbing and scattering media. However, analytical solutions to the RTE are limited even in simple homogeneous or plane media. Monte Carlo simulation has been used extensively to solve the RTE. However, Monte Carlo simulation is computationally intensive and may not be practical for applications that demand real-time results. Instead, the diffusion approximation has been shown to provide accurate estimates of light transport in strongly scattering tissue. The diffusion approximation is a greatly simplified model and produces analytical solutions for the reflectance and absorbance in tissue. However, the diffusion approximation breaks down if tissue is strongly absorbing, which is common in the visible part of the spectrum or in applications that involve darkly pigmented skin and/or high local volumes of blood such as port-wine stain therapy or reconstructive flap monitoring. In these cases, a model of light transfer that can accommodate both strongly and weakly absorbing regimes is required. Here we present a model of light transfer through layered biological media that represents skin with two strongly scattering and one strongly absorbing layer.
authors.affiliation: Laser Microbeam and Medical Program, Beckman Laser Institute, University of California, Irvine, 1002 Health Sciences Road, Irvine, California 92612, USA. yudovsky@uci.edu
authors.forename: Dmitry
authors.initials: D
authors.lastname: Yudovsky
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Durkin
mesh_terms: D006801:Humans; D008027:Light; D008954:Models, Biological; D009010:Monte Carlo Method; D055620:Optical Phenomena; D019339:Port-Wine Stain / Q000628:therapy; D012542:Scattering, Radiation; D012867:Skin / Q000033:anatomy & histology / Q000528:radiation effects