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|Title:||Design and Testing of a Noninvasive Steady-State Device for the Measurement of Optical Properties of Tissues in the 900-1400nm Wavelength Region|
|Other Titles:||Device for Measurement of Optical Properties of Tissues: 900-1400nm|
|Abstract:||The measurement of the absorption coefficient, μₐ, and the transport scattering coefficient, μₛ', in tissue 𝘪𝘯 𝘷𝘪𝘷𝘰 has applications for blood analyte monitoring, dosimetry for laser therapeutics, and optical imaging techniques. The optical properties of human tissue 𝘪𝘯 𝘷𝘪𝘷𝘰 in the 900-1400 nm wavelength range are currently poorly characterized, even though this may be a useful wavelength range for biomedical optics applications. A system has been developed which is capable of performing steady-state spatially resolved diffuse reflectance measurements in the 900-1400 nm wavelength range, from which optical properties can be estimated. In this technique, light enters the sample in a pencil beam geometry, and reflected light is collected at several distances from the input location. The principal components of the system are a fibre optic probe, a broadband light source, an imaging monochromator, and an InGaAs photodiode array. A Monte Carlo model and a diffusion theory model have been applied to the. reflectance data to estimate optical properties. Both nonlinear regression and neural network techniques have been explored to fit the models to the reflectance data. Aqueous suspensions of monodisperse polystyrene spheres of known μₐ and μₛ' were measured to determine the accuracy of the technique in estimating optical properties. The features in the measured spectra compared well with the theoretical spectra for these phantoms, although large discrepancies between predicted and measured optical properties were observed. This disagreement may be a result of not accounting for a small mismatch in refractive index at the phantom-probe boundary, and not accounting for the limited collection angle of the detection fibres in the model. Several measurements were performed on human volunteers to demonstrate the capabilities of the instrument and the advantages of working in the 900-1400 nm wavelength range.|
|Appears in Collections:||Digitized Open Access Dissertations and Theses|
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