An experimental model for the photon depth statistics of re-emitted near-infrared light (Conference Presentation)

There is growing research on renal applications of near-infrared spectroscopy (NIRS), a non-invasive optical technique that measures tissue oxygen saturation. NIRS data can be more illuminating if clinicians know which anatomical structures it probes, but there is a lack of experimental data on the maximum and average photon depth of penetration in kidney tissue. Literature suggests that these parameters depend on the interoptode distance (IOD) between the light source and detector. To test these models, we made incremental cuts into a porcine renal sample secured on a NIRS sensor. We placed an opaque blade in the cut and graphed the attenuation of the optical signal. The maximum and average penetration depth was computed for 6 IODs between 16-40 mm. The maximum and the square root of the average depth of penetration had a linear relationship with the IOD, with an approximate slope of 0.25 and 0.02, respectively.