Estimation of absorption coefficient in bottom regions in multi-layered turbid media based on the time-domain depth sensitivity : a Monte Carlo investigation

摘要

We attempted to selectively determine the absorption coefficient (μ_a) of bottom regions in two- and four-layered models with time-domain near infrared measurement. The difference curve in the time-resolved reflectance between a target and a reference medium was divided into segments, and a slope of each segment was calculated to determine depth-dependent μ_a (μ_a~(seg)). The deviation of μ_a~(seg) in later time segments from the real μ_a of the bottom layer was expressed by a function of the ratio of μ_a~(seg) in an earlier time segment to that in a later one. Using this function, we could determine μ_a in the bottom layer for various target media with different conditions.