IN-VITRO DOUBLE-INTEGRATING-SPHERE OPTICAL-PROPERTIES OF TISSUES BETWEEN 630 AND 1064 NM

The optical properties (absorption and scattering coefficients and the scattering anisotropy factor) were measured in vitro for cartilage, l iver, lung, muscle, myocardium, skin, and tumour (colon adenocarcinoma CC 531) at 630, 632.8, 790, 850 and 1064 nm. Rabbits, rats, piglets, goats, and dogs were used to obtain the tissues. A double-integrating- sphere setup with an intervening sample was used to determine the refl ectance, and the diffuse and collimated transmittances of the sample. The inverse adding-doubling algorithm was used to determine the optica l properties from the measurements. The overall results were comparabl e to those available in the literature, although only limited data are available at 790-850 nm. The results were reproducible for a specific sample at a specific wavelength. However, when comparing the results of different samples of the same tissue or different lasers with appro ximately the same wavelength (e.g. argon dye laser at 630 nm and HeNe laser at 632.8 nm) variations are large. We believe these variations i n optical properties should be explained by biological variations of t he tissues. In conclusion, we report an an extensive set of in vitro a bsorption and scattering properties of tissues measured with the same equipment and software, and by the same group. Although the accuracy o f the method requires further improvement, it is highly likely that th e other existing data in the literature have a similar level of accura cy.