Dual Layered Models of Light Scattering in the Near Infrared B: Experimental Results with a Phantom

Intralipid emulsion is often used as optical model substance to mimic living tissue's strong scattering properties. As such it is of considerable importance to utilize realistic parameters for any type of simulation or calculation in context of Near Infrared Spectroscopy. We determined optical characteristics of diluted Intralipid solutions at often used, realistic volume concentrations ρil and at two wavelengths (780nm and 850nm) in a simple phantom setup featuring multiple sensors with different source-detector-separation (SDS) and penetration depths d. Both, phantom experiments and MC simulation showed qualitatively similar results and demonstrated the influence of the three major NIRS factors, namely the penetrated layer depth (d), the Intralipid concentration ρil and the source-detector separation (SDS). The results demonstrated that light reaching the detectors is inversely proportional to ρil and d. It corroborates the need for differential measurements with at least two SDS to account for superficial large angle scattering.