Quantification of dynamic changes in water absorption coefficient of water at Er:YAG and CO/sub 2/ laser wavelengths

Summary form only given. The number of clinical applications using erbium-based and CO/sub 2/ lasers continue to grow even though the mechanism(s) of the photoablation process are not well understood. The prediction(s) of laser-tissue interaction have been based upon the low intensity, room-temperature absorption spectrum data for water published by Hale and Querry. Since water constitutes 70-80% of virtually every type of soft tissue, it has been hypothesized that the absorption of IR radiation, particularly in the 3-/spl mu/m region, would lead to efficient cutting of tissue while minimizing residual thermal damage to the surrounding tissue. However, the room-temperature absorption spectrum of water does not accurately describe the absorption of IR radiation by tissue under high fluence levels. Studies employing a variety of lasers and techniques to generate short pulse radiation in the 2.7-3-/spl mu/m region have consistently reported the formation of deeper craters and wider zones of thermal damage than predicted by ablation models based on the low-intensity absorption spectrum of water. The objective of the present study was to quantify the dynamic changes in the absorption coefficient of water as a function of incident fluence at 2.94, 9.6, and 10.6-/spl mu/m.