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Proceedings Paper

Laser ablation of skull tissue using transverse excited 9.6-um CO2 lasers with pulse durations of 1-100 us
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Paper Abstract

Craniotomy using a drill and saw frequently results in fragmentation of the skull plate. Lasers have the potential to remove the skull plate intact. TE CO2 lasers operating at the peak absorption wavelength of bone ((lambda) equals 9.6 micrometer) and with pulse durations of 5 - 10 microseconds, approximately the thermal relaxation time in hard tissue, produced high ablation rates and minimal peripheral thermal damage. Both thick (2 mm) and thin (250 micrometer) bovine skull samples were perforated and the ablation rates calculated. Results were compared with Q-switched and free- running Er:YAG lasers ((lambda) equals 2.94 micrometer, (tau) p equals 150 ns and 150 microseconds). The CO2 laser perforated thick sections at ablation rates of 10 - 15 micrometer per pulse and fluences of approximately 6 J/cm2. There was no discernible thermal damage and no need for water irrigation during ablation. Pulse durations >= 20 microseconds resulted in significant tissue charring which increased with the pulse duration. Although the Er:YAG laser produced ablation rates of approximately 100 micrometer per pulse, fluences > 30 J/cm2 were required to perforate thick samples, and thermal damage measured 25 - 40 micrometer. In summary, the novel 5 - 10 microsecond pulse length of the TE CO2 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. Further studies with the TE CO2 laser are warranted for potential clinical application craniotomy procedures.

Paper Details

Date Published: 13 June 2000
PDF: 9 pages
Proc. SPIE 3914, Laser-Tissue Interaction XI: Photochemical, Photothermal, and Photomechanical, (13 June 2000); doi: 10.1117/12.388033
Show Author Affiliations
Nathaniel M. Fried, Johns Hopkins Univ. (United States)
Daniel Fried, Univ. of California/San Francisco (United States)

Published in SPIE Proceedings Vol. 3914:
Laser-Tissue Interaction XI: Photochemical, Photothermal, and Photomechanical
Jeffrey O. Hollinger; Donald Dean Duncan; Jeffrey O. Hollinger; Donald Dean Duncan; Steven L. Jacques, Editor(s)

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