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|Title:||Dual Wavelength Time Resolved Reflectance Measurements for the Determination of Hemoglobin Oxygenation in Tissue|
|Other Titles:||Measuring Hemoglobin Oxygenation by Time Resolved Reflectance|
|Abstract:||The aim of this work was to develop and test a system to measure the optical properties of tissue 𝘪𝘯 𝘷𝘪𝘷𝘰, with the specific goal of monitoring hemoglobin oxygenation in tissue. Since it is desirable to determine these properties noninvasively, it is necessary to use the information retained in the light that is scattered out of the tissue, i.e. the reflectance, to estimate values for the scattering and absorption coefficients of the tissue. It is possible to use these properties to study many physiological functions, including hemoglobin saturation and tissue metabolism. Methods for the indirect measurement of tissue optical properties fall into three categories: continuous wave (cw), frequency domain and time domain techniques. Regardless of which technique is used to measure the reflectance, a suitable model of light transport is needed to provide the best estimates of the optical properties of the medium investigated. The diffusion equation has been shown to have good agreement with both phantom measurements and Monte Carlo simulations under certain conditions. This thesis discusses a two wavelength system which operates in time-correlated single photon counting mode to measure noninvasively the optical properties of tissue. By exploiting the known differences in absorption between oxyhemoglobin and deoxyhemoglobin at 750 nm and 810 nm, this system will be used to monitor hemoglobin saturation. However, prior to performing oxygenation measurements, the performance of the system was compared to a continuous wave (cw) and a frequency domain system in our lab. This thesis will outline the instrumentation of the time-resolved system, results from fitting Monte Carlo data and the results of various measurements which investigate the response of the system to different factors. The two main experiments study the ability of the system to predict variations in either the scattering or the absorption coefficient. Following the success of the system in predicting optical properties of tissue simulating phantoms, 𝘪𝘯 𝘷𝘪𝘷𝘰 measurements were performed on the palm of the hand. The system proved sensitive enough to reflect changes in oxygenation induced in the tissue.|
|Appears in Collections:||Digitized Open Access Dissertations and Theses|
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