The measurement of oxygen saturation SO2 is one of the vital signs relied on by the medical profession. Pulse oximeters are widely used in many branches of medicine; and are the most widely used method of assessing oxygen saturation. However they can only be applied to an extremity (usually a finger or toe), need calibration, and are known to be inaccurate under certain conditions. The object of this research was to develop an oximeter, that does not require a pulsatile signal, (and so can be used anywhere on the body); can be used in either transmission of reflective mode; does not require calibration; and does not suffer from the known problems of pulse oximeters. The instrument must work with reflected light, and so the first step was to develop a Monte Carlo simulation of the Attenuation spectra, for visible light, from a scattering media (tissue). A mathematical model of the attenuation surface had then to be found, and its effect on the absorbtion spectra of oxyhemoglobin HbO2 and de-oxyhemoglobin Hb understood. Then the oxygen saturation the ratio of HbO2 to total haemoglobin could be recovered. Methods of computing oxygen saturation from the raw reflectance spectra were devised and then tested with single reflection spectra, the results indicate that a low cost instrument could be developed. The technique was applied to images from a hyper-spectral camera, this instrument takes a full spectrum at each pixel of an image, and enabled an oxygen saturation map for large areas of the body to be produced. The technique is being used with AstraZenca Ltd as a bio marker skin for irritation studies.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:537669 |
| Date | January 2006 |
| Creators | Rodmell, Paul Irvin |
| Publisher | University of Nottingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://eprints.nottingham.ac.uk/31151/ |
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