Comparison of Er:YAG and 9.6-μm TE CO2 lasers for ablation of skull tissue

✍ Scribed by Nathaniel M. Fried; Daniel Fried

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 326 KB
• Volume: 28
• Category: Article
• ISSN: 0196-8092
• DOI: 10.1002/lsm.1059

✦ Synopsis

Background and Objective: Craniotomy by using a drill and saw frequently results in fragmentation of the skull plate. Lasers have the potential to remove the skull plate intact, simplifying the reconstructive surgery. Study Design/Materials and Methods: Transverseexcited CO 2 lasers operating at the peak absorption wavelength of bone (l 9.6 mm) and with pulse durations of 5±8 msec, approximately the thermal relaxation time in hard tissue, produced high ablation rates and minimal peripheral thermal damage. Both thick (2 mm) and thin (250 mm) bovine skull samples were perforated and the ablation rates calculated. Results were compared with Q-switched and free-running Er:YAG lasers (l 2.94 mm, t p 0.5 msec and 300 msec). Results: The CO 2 laser produced ablation rates of up to 60 and 15 mm per pulse for thin and thick sections, respectively, and perforated thin and thick sections with ¯uences of less than 1 J/cm 2 and 6 J/cm 2 , respectively. There was no discernible thermal damage and no need for water irrigation during ablation. Pulse durations ! 20 msec resulted in signi®cant tissue charring, which increased with the pulse duration. Although the free-running Er:YAG laser produced ablation rates of up to 100 mm per pulse, ¯uences of 10 J/cm 2 and 30 J/cm 2 were required to perforate thin and thick samples, respectively, and peripheral thermal damage measured 25±40 mm. Conclusion: In summary, the novel 5-to 8-msec pulse length of the TE CO 2 laser is long enough to avoid a marked reduction in the ablation rate due to plasma formation and short enough to avoid peripheral thermal damage through thermal diffusion during the laser pulse. Furthermore, in vivo animal studies with the TE CO 2 laser are warranted for potential clinical application in craniotomy and craniofacial procedures.