Abstract

To develop and validate a reliable mathematical model for prediction of tissue response to high-power laser irradiation, we utilized a 2-D axially symmetric optothermal model that uses the delta-Eddington approximation to calculate light distribution and the heat diffusion equation to estimate temperature distribution in tissue. Scattering and absorption coefficients of selected aortic human specimens were obtained from spectrophotometric data of tissue reflectance and transmission by an inverse solution to the radiative transfer equation. These values and the reported values for the thermal properties of normal aorta were used to predict tissue response during argon laser irradiation. Experimentally, the thermal response of tissue to laser irradiation was quantified by monitoring surface temperature during argon laser irradiation of human aortic samples via a thermographic technique. In the range of 25–100°C, and for similar irradiation parameters, calculated values of tissue surface temperature during laser irradiation were up to three times higher than the experimental values that were measured thermographically. However, for purely absorbing materials, excellent correlation between measurements and predictions was observed. Careful analysis of the data raised concerns about the accuracy of the methods for optical property measurement.

© 1991 Optical Society of America