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Optical medical tomography for the localization of oxygenation in the limb

Optical spectroscopy techniques are frequently used to non- invasively monitor various physiological functions such as tissue and blood oxygenation. It is desirable to develop a methods to localize these measurements and quantify the parameters of interest, e.g. oxygen saturation. An optical tomography system for imaging the oxygenation of the limb is presented. Initially, a rotate-translate optical imaging system was developed. Image reconstruction was performed using a conventional filtered back projection scheme. With this system the limits of spatial and contrast resolution as a function of the absorption and reduced scattering coefficients were investigated. The limiting factor was found to be contrast resolution. A second generation imaging system, using a rotate-rotate type scanning system, has been constructed. Data obtained with this system utilizes all the light emerging in the plane of measurement, and does not assume rectilinear propagation. The image reconstruction algorithm developed for this uses diffusion theory to model the light transport, and an iterative reconstruction algorithm. Results obtained with this model are presented. A further method to improve image quality is the use of a phase resolved technique, which uses amplitude modulation of the light source. An outline is given of the principle of this technique, and the system build for the measurement is discussed.