Temperature and Wavelength Dependent Scattering of Light during Slow Heating of Porcine Septal Cartilage

摘要

The response of cartilage tissue to thermal stress can be investigated indirectly by measuring changes in optical properties during heating. Temperature distributions in cartilage depend on the mode of heating. Laser irradiation of thick cartilage specimens results in non-uniform heating, causing asynchronous stress relaxation in different regions of the tissue. In contrast, slow heating of cartilage in a Rose chamber results in more uniform temperature profiles. In addition, the heating of tissue in a saline- (or mineral oil) filled Rose chamber eliminates dehydration effects that are commonly encountered during laser heating. The purpose of this investigation was to measure diffuse reflectance and diffuse transmittance of porcine septal cartilage tissue during slow heating. Diffuse reflectance and transmittance were measured using integrating sphere and lock-in detection techniques. Cartilage surface temperatures were estimated using a thermocouple and cold-junction compensator. Diffusely transmitted light was observed to decrease, plateau, and then increase whereas diffusely reflected light was observed to increase, plateau, and then decrease. The change in slope for both transmitted and reflected light occurred at cartilage front surface temperatures of between 45 and 50℃. The results suggest that changes in the optical properties of cartilage tissue occur due to a phase transformation during heating.