A COMPUTATIONAL ASSESSMENT OF THERMAL DAMAGE IN PERFUSED TISSUE DUE TO LASER IRRADIATION

A computational assessment of in vivo thermal due to laser irradiation damage is presented as a function of the laser applicator length, total effective absorption coefficient, and heating duration for the peak tissue temperature of 100 degrees C. Spatio-temporal tissue heating is computed by solving the Generic Bioheat Transfer Model (GBHTM), a first principles based model that has been shown to estimate tissue heating more accurately compared to Pennes Model. Damage is estimated by computing thermal dose per Cumulative Equivalent Minutes at 43 degrees C (CEM43) and the Arrhenius integral with damage thresholds as CEM43 >= 60 minutes and Omega = 1, respectively. Results show that the damage increases as a function of the applicator length and heating duration but decreases as a function of the absorption coefficient. While ablation shape is generally ellipsoidal, sphere factor (ratio of the maximum damage along the applicator and normal to the applicator) increases as a function of heating duration, but decreases as a function of applicator length. The maximum damage diameter varies between 2-3 cm. The damage estimated per CEM43 >= 60 was similar to 40%-60% larger relative to the damage estimate per Omega >= 1.