Anisotropy in the absorption and scattering spectra of chicken breast tissue

Oblique incidence reflectometry is a simple and accurate method for measuring the absorption and the reduced-scattering coefficients of turbid media. We used this technique to deduce absorption and reduced-scattering spectra from wavelength-resolved measurements of the relative diffuse reflectance profile of white light as a function of source-detector distance. In this study, we measured the absorption and the reduced-scattering coefficients of chicken breast tissue in the visible range (400-800 nm) with the oblique incidence probe oriented at 0 degrees and 90 degrees relative to the muscle fibers. We found that the deduced optical properties varied with the probe orientation. Measurements on homogenized chicken breast tissue yielded an absorption spectrum comparable with the average of the absorption spectra for 0 degrees and 90 degrees probe orientations measured on the unhomogenized tissue. The reduced-scattering spectrum for homogeneous tissue was greater than that acquired for unhomogenized tissue taken at either probe orientation. This experiment demonstrated the application of oblique-incidence, fiber-optic reflectometry to measurements on biological tissues and the effect of tissue structural anisotropy on optical properties.