EFFECTS OF COMPRESSION ON SOFT-TISSUE OPTICAL-PROPERTIES

Tissue optical properties are necessary parameters for prescribing lig ht dosimetry in photomedicine, In many diagnostic or therapeutic appli cations where optical fiber probes are used, pressure is often applied to the tissue to reduce index mismatch and increase light transmittan ce, In this paper, we have measured in vitro optical properties as a f unction of pressure with a visible-IR spectrophotometer. A spectral ra nge of 400-1800 nm with a spectral resolution of 5 nm was used for all measurements, Skin specimens of a Hispanic donor and two Caucasian do nors were obtained from the tissue bank, Bovine aorta and sclera, and porcine sclera came from a local slaughter house, Each specimen, sandw iched between microscope slides, was compressed by a spring-loaded app aratus, Then diffuse reflectance and transmittance of each sample were measured at no load and at approximately 0.1, 1, and 2 kgf/cm(2), Und er compression, tissue thicknesses were reduced up to 78%, Generally s peaking, the reflectance decreased while the overall transmittance inc reased under compression, The absorption and reduced scattering coeffi cients were calculated using the inverse adding doubling method, Compa red with the no-load controls, there was an increase in absorption and scattering coefficients among most of the compressed specimens.