Determination of isotherms of thermal damage

We have previously reported isotherms for the boundaries between white coagulation and the red damage zone and between the red zone and normal tissue in livers of rats irradiated in vivo with cw Nd:YAG laser light (λ=1.064 microns) at constant times and powers. The isotherm temperatures were 68±5.0°C for the white/red boundary and 55±2.7°C for the red/normal tissue boundary. The present study was to determine the isotherm for tissue necrosis in rat livers irradiated under similar conditions. The hypotheses tested were 1) that the boundary of tissue necrosis, an indicator of the full extent of lethal thermal damage, is more peripheral than the boundary of red/normal tissue and 2) the isotherm at the boundary of tissue necrosis is less than that of the red/normal tissue