CO 2 laser ablation of biological tissue

Abstract

ABSTRACT This paper presents a comprehensive review of the CO2 laser ablation of biological tissue. Based on energy balancefor modelling laser ablation, the thermal relaxation time and the ablation threshold are determined. Laser ablation ofbiological tissue is related to the spatial coherence of laser beams, so that the propagation of laser beams, the beam qualityand the focusability of laser beams are taken into consideration. To achieve the ablation threshold, the laser irradiance in thefocal zone is computed as a function of laser parameters. The advantages of pulsed operation of the CO2 laser for minimumresidual thermal damage of the tissue are stressed. The strengths and the weaknesses of the CO2 laser ablation are fmallydiscussed.Keywords: laser ablation, CO2 laser, biological tissue, laser irradiance and radiant exposure, thermal damage 1. INTRODUCTION Laser interaction with biological tissue has been a subject of ongoing research since the operation of the first laser inthe early sixties. Of the various laser systems currently used in medical practice, the CO2 laser has proved itself as one of themost efficient surgical instruments' .