Abstract
This paper describes the relationship between the
ultrastructure of biological tissues and the observed macroscopic
optical scattering properties. A summary of the tissue absorption
spectrum is also presented. The scattering of soft tissues (liver,
prostate, etc.) and fibrous tissues such as dermis are considered. The
scattering of soft tissues is attributed to membranous structures and
modeled as Mie scattering from spheres in the 0.2-2-um diameter range,
where membrane lipids occupy about 1-20% of the cellular volume and the
refractive index mismatch is 1.46/1.35. The scattering of dermis is
modeled as scattering from collagen fiber bundles in the 2.8-um diameter
range occupying 21% of the dermal volume and the refractive index
mismatch is 1.38/1.35. The effects of a component of small-scale
particle scattering in the Rayleigh limit is also considered. The models
are compared with tissue values from the literature for the reduced
scattering coefficient, mus(1-g), and the anisotropy, g. The models
roughly match the absolute value and wavelength dependence of scattering
in the 300-1100 nm wavelength range.