Dual Layered Models of Light Scattering in the Near Infrared A: Optical Measurements and Simulation

Intralipid emulsion is often used as optical model substance to mimick 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 properties of diluted Intralipid solutions at often used, realistic volume concentrations ρ_il and at two NIRS wavelengths (780nm and 850nm) in a double integrating Ulbricht-sphere setup. The results were used in Monte Carlo (MC) simulations of an experiment, described in our companion paper. Both, phantom experiments and MC simulation showed qualitatively similar results and demonstrated the effects of changing the three major NIRS factors, namely the penetrated layer depth (d), the Intralipid concentration ρ_il and the source-detector separation (SDS). The results demonstrated that light reaching the detectors was inversely proportional to ρ_il and d. It also showed that very low Intralipid concentrations do not follow the optical properties documented for Intralipid 20%.