A dynamic photo-thermal model of carbon dioxide laser tissue ablation.

A dynamic photo-thermal model of carbon dioxide (CO(2)) laser tissue ablation was developed, based on McKenzie's three-zone model, with the following improvements: (1) the laser-irradiated tissue from the surface to the inside was divided into a carbonized zone, a dried zone, a dehydrating zone, a thermally damaged wet (TDW) zone and an uncoagulated zone; (2) the carbonized and dried tissues were analyzed as porous media, with convection heat transfer between the vapor from the dehydrating tissue and the porous dried/carbonized tissue taken into account; (3) the interactions of temperature distribution, deposited laser energy distribution and dynamic changes in optical and thermal properties as well as blood perfusion rate were included. The finite difference method was used to solve numerically for the temperature and deposited laser energy fields, and the boundary positions of the zones.