Characterizing long lived intralipid-infused tissue phantoms scattering using imaging sensors

Since regular biological tissue’s optical characteristics are unstable building long lived test phantoms that simulate their scattering characteristics are needed for testing optical methods of imaging through tissue. Our ongoing work developed a methodology to build long term stable phantoms with lifetimes >6 years which can be tuned to maintaining optical characteristics mimicing skin characteristics and a rapid technique to measure the scattering coefficients μs and anisotropy factor g. Our test phantoms employ intralipid-infused agar layers 1 to 8 mm thick. Agra can take a wide range of intralipid concentrations enabling the building phantoms of a large range of scattering parameters with typical values of μs=20cm-1, g=0.95. Encapsulating the intralipid-infused agar within a clear polymer has proved to stabilize these for long lifetimes and allows creation of varying thicknesses, scattering characteristics and shapes. We developed a rapid technique where the light from a laser beam passing perpendicular through the test phantom is captured using a 36×24mm digital camera sensor. This gathers ~6×106 measurements over a ±12° range, giving ~20,000 points each at 2300 angular bins of 0.005° . A Matlab program identifies the scattering center and data points for each angular position. Using a HenyeyGreenstein two-term model a nonlinear curve fitting extracts pairs of HG weighing factors, µs and g parameters. Fit results show extremely high statistical significance with exceedingly small deviation from the HG model for multiple wavelengths (currently 533, 632, 670 nm lasers and a supercontinuum laser at 650, 700,750 nm) for several test phantoms.