Estimating the absorption coefficient of the bottom layer in four-layered turbid mediums based on the time-domain depth sensitivity of near-infrared light reflectance

Chie Sato; Miho Shimada; Yukari Tanikawa; Yoko Hoshi M.D.

doi:10.1117/1.JBO.18.9.097005

20 September 2013 Estimating the absorption coefficient of the bottom layer in four-layered turbid mediums based on the time-domain depth sensitivity of near-infrared light reflectance

Chie Sato, Miho Shimada, Yukari Tanikawa, Yoko Hoshi M.D.

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Journal of Biomedical Optics, Vol. 18, Issue 9, 097005 (September 2013). https://doi.org/10.1117/1.JBO.18.9.097005

Abstract

Expanding our previously proposed “time segment analysis” for a two-layered turbid medium, this study attempted to selectively determine the absorption coefficient (μ_a ) of the bottom layer in a four-layered human head model with time-domain near-infrared measurements. The difference curve in the temporal profiles of the light attenuation between an object and a reference medium, which are obtained from Monte Carlo simulations, is divided into segments along the time axis, and a slope for each segment is calculated to obtain the depth-dependent μ _a (μ^seg_a) . The reduced scattering coefficient (μ _s ′ ) of the reference is determined by curve fitting with the temporal point spread function derived from the analytical solution of the diffusion equation to the time-resolved reflectance of the object. The deviation of μ^seg_a from the actual μ_a is expressed by a function of the ratio of μ^seg_a in an earlier time segment to that in a later segment for mediums with different optical properties and thicknesses of the upper layers. Using this function, it is possible to determine the μ_a of the bottom layer in a four-layered epoxy resin-based phantom. These results suggest that the method reported here has potential for determining the μ_a of the cerebral tissue in humans.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Chie Sato, Miho Shimada, Yukari Tanikawa, and Yoko Hoshi M.D. "Estimating the absorption coefficient of the bottom layer in four-layered turbid mediums based on the time-domain depth sensitivity of near-infrared light reflectance," Journal of Biomedical Optics 18(9), 097005 (20 September 2013). https://doi.org/10.1117/1.JBO.18.9.097005

Published: 20 September 2013

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