Optical properties of native and coagulated human liver tissues at argon ion laser -- an in vitro study using the double-integrating-sphere technique

Abstract

We examine the optical properties of native and coagulated human liver tissues in vitro at four different wavelengths of argon ion laser, 476.5, 488, 496.5 and 514.5 nm, and the differences in the optical parameters of the tissues between 630nm and 790nm. The optical properties, &mu;_a, &mu;_s and g, of liver tissue were determined by measuring the diffuse reflectance, diffuse transmission and collimated transmission in a double integrating sphere set-up, and the inverse adding-doubling algorithm was used to calculate the optical properties from the measurements. The investigative results showed that there were significant differences respectively in the absorption coefficients, scattering coefficients and anisotropy factors between native and coagulated human liver tissues at the same laser wavelength (<i>P</i><0.01), these large differences of the absolute values in optical properties indicate that there were large differences in compositions and structures between both, and large differences in compositions and structures induce large differences in absorption and scattering properties between both, and these differences vary with a change of laser wavelength. The scattering coefficients for per tissue type exceed the absorption coefficients by at least one order of magnitude. Hence the conclusions may be helpful to diagnostics and therapeutic applications in liver tissue.