Building long lived test phantoms that simulate the scattering characteristics of biological tissue is needed in for testing optical methods targeted at imaging through tissue. Test phantoms are needed as real tissue samples optical characteristics (scattering coefficients µs and anisotropy factor g) varies greatly between samples and change rapidly with time. Our ongoing work has created long term stable phantoms with lifetimes of more than 6 years and maintaining consistent optical characteristics which mimic skin characteristics. These stable test phantom are created by an intralipid-infused agar layers 1 to 6 mm thickness Varying the intralipid concentration allows control of the scattering parameters with typical values of µs = 20/cm, g = 0.95. By encapsulating the intralipid-infused agar within a clear polymer it stabilizes for long lifetimes and allows creation a varying thicknesses, scattering characteristics and shapes. To characterize these test phantom we developed an enhanced technique where the scattered light from a laser beam passing through the test phantom is captured using a 36x24mm digital camera sensor to capture. This gives over 6 million measurements over a +/- 12 degree range, with typically 20,000 measurements at 2300 angular bins of 0.005 deg. For analysis these measurements of scattering values at a wide range of angles used a Matlab program to identify the scattering center and the angular positions. Fitted scattering models extracted the µs and g parameters for each test phantom Consistent results were obtained using a Henyey-Greenstein two-term model, probably because the Agar and intralipid impacted the scattering separately.
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