Abstract

A new micro measurement system - according to the principle of the EMPHO-System - has been developed to record tissue remission spectra within the range of 510 to 590 nm. The device hardware basically involves a white LED, optical fibers, and a miniaturized grating spectrometer. In general, exact computation of blood oxygen saturation and relative hemoglobin concentration from these tissue remisson spectra is not possible. The main reason is that - except for oxyhemoglobin and desoxyhemoglobin - many other light-scattering and light-absorbing substances such as dopa-melanin and bilirubin cause measurement errors. A new algorithm for the determination of local blood oxygen saturation and relative hemoglobin concentration from tissue remisson spectra is presented. This method is based on the probability of light photons propagation and reference coefficients. In addition, the algorithm also takes other light-scattering and light-absorbance substances in biological tissue into consideration. The method is compared with the standard procedure of Kubelka and Munk. Among others these two approaches are applied to the tissue remission spectra of ischaemia with subsequent reactive hyperemia. The calculated blood oxygen saturation and relative hemoglobin concentration of both methods are presented and discussed.

© 2003 SPIE