1 November 2005 Extraction of depth-dependent signals from time-resolved reflectance in layered turbid media
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J. of Biomedical Optics, 10(6), 064008 (2005). doi:10.1117/1.2136312
Abstract
We try a new approach with near-IR time-resolved spectroscopy, to separate optical signals originated in the upper layer from those in the lower layer and to selectively determine the absorption coefficient (µa) of each layer in a two-layered turbid medium. The difference curve in the temporal profiles of light attenuation between a target and a reference medium is divided into segments along the time axis, and a slope of each segment is calculated to determine the depth-dependent µa. The depth-dependent µa values are estimated under various conditions in which µa and the reduced scattering coefficient (µ′s) of each layer are changed with a Monte Carlo simulation and in phantom experiments. Temporal variation of them represents the difference in µa between two layers when µ′s of a reference is the same as that of the upper layer of the target. The discrepancies between calculated µa and the real µa depend on the ratio of the real µa of the upper layer to that of the lower layer, and our approach enables us to estimate the ratio of µa between the two layers. These results suggest the potential that µa of the lower layer can be determined by our procedure.
Chie Sato, Miho Shimada, Yoko Hoshi, Yukio Yamada, "Extraction of depth-dependent signals from time-resolved reflectance in layered turbid media," Journal of Biomedical Optics 10(6), 064008 (1 November 2005). http://dx.doi.org/10.1117/1.2136312
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KEYWORDS
Reflectivity

Monte Carlo methods

Photons

Scattering

Optical properties

Head

Picosecond phenomena

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