KEYWORDS: Luminescence, Monte Carlo methods, Sensors, Reconstruction algorithms, Signal to noise ratio, Atrial fibrillation, Diffuse optical tomography, Detection and tracking algorithms, Finite element methods, Photon transport
An image reconstruction scheme for time-domain fluorescence diffuse optical tomography is proposed using a
reflection-mode for a semi-infinite turbid geometry. The method is based on a generalized pulse spectrum technique that
employs analytic expressions of the Laplace-transformed time-domain photon-diffusion model to construct a Born
normalized inverse model, and a pair of real domain transform-factors to separate distributions of the fluorescent yield
and lifetime. The methodology is validated with a specifically-developed fluorescent Monte-Carlo simulator or
finite-element-based methods and its robustness to the background uncertainties is investigated.
In this paper, a Monte Carlo (MC) based model of diffuse reflectance is introduced to retrieval the light absorption and scattering
coefficients of multi-layered tissue. The absorption and transport scattering coefficients of biological tissues determine the radial
dependence of the diffuse reflectance that is due to a point source. The MC model of diffuse reflectance consists of a forward part and an
inverse one. The forward refers to a multi-layered MC simulation at a certain source detector separation, which results a time-resolved
profile. The inverse one is a fitting procedure based on Levenberg-Marquardt algorithm using forward model in iteration, and the
normalized intensity in each time bin is fitted. Tests with independent MC simulations show the errors in the deduced absorption and
reduced scattering coefficients. Although a high amount of computation time is needed, compared with investigation methods using
diffuse approximation to the transport equation, this model is valid for a wider range of optical properties and is easily adaptable to
exiting probe geometries.
In this article, we briefly described a time-correlated single photon counting (TCSPC) system specifically designed
for extracting the optical properties in turbid medium. This system was evaluated by use of two sets of liquid
tissue-simulating phantoms containing different concentrations of Intralipid-10% as scatters and India ink as
absorbers. With the distribution of times of flight (DTOF) of photons measured by the TCSPC system, some
featured parameters, such as the mean time of flight and the variance of DTOF were calculated. Based on these
parameters, we developed a simple and fast method to obtain the absorption coefficient μa and reduced scattering
coefficient μs
of the turbid medium. Furthermore, the accuracy of the method was validated using the Monte Carlo
simulations. It was found that the optical properties could be extracted with this method, which was much faster
than the conventional curve-fitting procedure. Our method could be useful in on-line monitoring of optical
properties of biological tissue.
In this paper, a Monte Carlo based model of diffuse reflectance is introduced to retrieve the light absorption and
scattering coefficients of multi-layered tissue. The model consists of a forward part and an inverse one. The forward
refers to a multi-layered Monte Carlo simulation at a certain source-detector separation, which lead to a time-resolved
profile. The inverse one is a fitting procedure based on Levenberg-Marquardt algorithm using forward model in iteration,
and the intensity in time bins is fitted. The model was tested with independent Monte Carlo simulations and
fiber-optic-based measurement in the deduced absorption and reduced scattering coefficients. Although a high amount of
computation time is needed, this model is developed as a verification standard to these investigation methods using
diffuse approximation to the transport equation. Furthermore, it is adaptable to the complex fiber-optic probe geometries.
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