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iii Abstract A Monte Carlo model of steady-state light transport in multi-layered tissue (mcml) and the corresponding convolution program (conv) have been coded in ANSI Standard C. The programs can therefore be executed on a variety of computers. Dynamic data allocation is used for mcml, hence the number of tissue layers and the number of grid elements of(More)
A model based upon steady-state diffusion theory which describes the radial dependence of diffuse reflectance of light from tissues is developed. This model incorporates a photon dipole source in order to satisfy the tissue boundary conditions and is suitable for either refractive index matched or mismatched surfaces. The predictions of the model were(More)
Using spatially resolved, steady state diffuse reflectometry, a directional dependence was found in the propagation of visible and near infrared light through human skin in vivo. The skin's reduced scattering coefficient mu(s)' varies by up to a factor of two between different directions of propagation at the same position. This anisotropy is believed to be(More)
Most instruments used to measure tissue optical properties noninvasively employ data-analysis algorithms that rely on the simplifying assumption that the tissue is semi-infinite and homogeneous. The influence of a layered tissue architecture on the determination of the scattering and absorption coefficients has been investigated in this study. Reflectance(More)
Photon diffusion theory was used to model photobleaching and tissue necrosis resulting from broad-beam therapeutic light irradiation of tissue containing a photosensitizer. The photosensitizer fluorescence signal at the tissue surface was simulated with both broad-beam and pencil-beam excitation. The relationship between the decreasing fluorescence signal(More)
Diabetics would benefit greatly from a device capable of providing continuous noninvasive monitoring of their blood glucose levels. The optical scattering coefficient of tissue depends on the concentration of glucose in the extracellular fluid. A feasibility study was performed to evaluate the sensitivity of the tissue reduced scattering coefficient in(More)
We have examined the possibility of determining the optical properties of a two-layer medium by using a diffusion approximation radiation transport model [Appl. Opt. 37, 779 (1998)]. Continuous-wave and frequency-domain (FD) low-noise Monte Carlo (MC) data were fitted to the model. Marquardt-Levenberg and a simulated annealing algorithm were used and(More)
The performance of a simple approach for the in vivo reconstruction of bioluminescent point sources in small animals was evaluated. The method uses the diffusion approximation as a forward model of light propagation from a point source in a homogeneous tissue to find the source depth and power. The optical properties of the tissue are estimated from(More)
A dual wavelength time-resolved reflectance system was developed for monitoring haemoglobin saturation noninvasively. At each wavelength, the time-resolved reflectance data were fitted to a diffusion model of light propagation in a homogeneous, semi-infinite medium to yield the absolute scattering and absorption coefficients. The absorption coefficients(More)