Optimization of reflectance pulse oximeter source-detector space using analytical model of light propagation in heterogeneous tissue to accurate diagnosis of Hypoxia tumoral tissue

Pulse oximetry is a very significant method in  medical monitoring . Due to the restriction in the use of the transmission pulse oximeter in high-density tissues, this research aims to focus on the study and development of the reflectance pulse oximeters, because it is able to show the blood oxygen saturation level (2SaO) in various densities. To this end, considering the benefits of photon diffusion theory over Beer-Lambert law, a new mathematical (analytical) method was developed to investigate the inensity reflective light propagation in a heterogeneous medium such as a fingerprint. Then, using the obtained analytical model, source-detector space was optimized so that by decreasing the sensitivity of the motion effects on light scattering the accuracy rate will increase. To verify the results obtained from the analytical model, Monte Carlo simulation results were used as a standard method compared to experimental data. This comparison showed the agreement of the analytical model with the results of these two methods with minor differences. By using the sensitivity function, the optimum distance of the detector from the light sourcewas obtained 4.8 mm and 2.8 mm for red and infrared lights, respectively. An overview of the results suggests that light propagation characteristics can be accurately assessed through an analytical model.