Effects of heterogeneous absorption of laser radiation in biotissue ablation: characterization of ablation of fat with a pulsed CO2 laser.

Background And Objective: Physicians encounter several clinical situations in which fat must be removed. In this study, the characterization of fat ablation produced by a pulsed CO2 laser is reported.

Study Design/materials And Methods: An RF excited 800 microns pulsed CO2 laser operating at 10.6 microns was used to ablate fresh porcine fat. The heat of ablation and ablation threshold were determined using a mass loss technique. Absorption coefficients for fat and dermis were determined by attenuated total reflection spectroscopy.

Results: Threshold radiant exposure and heat of ablation for fat were calculated from the mass loss measurements to be 1.05 J/cm2 and 2.4 J/cm3, respectively. The absorption coefficients of fat and dermis at 10.6 microns were 250 and 780 cm-1, respectively. Pulsed CO2 laser ablation of fat caused ejection of fat droplets, which ignited after high fluence pulses.

Conclusion: A pulsed CO2 laser can effectively ablate fat with a threshold fluence and efficiency comparable to other soft tissues. Our data suggest that fat ablation occurs primarily through the ejection of intact fat particles via the explosive vaporization of intervening water "lakes".