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Proceedings Paper

Optoacoustic monitoring of cutting and heating processes during laser ablation
Author(s): Erwin Bay; Alexandre Douplik; Daniel Razansky
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Paper Abstract

Laser-tissue interaction during laser surgery can be classified into two biophysical processes: tissue removal in the focal zone of the laser beam and heating in the surrounding tissue. In order to ensure a precise cut and minimal collateral thermal damage, the surgeon has to control several parameters, such as power, repetition rate and fiber movement velocity. In this study we propose utilizing optoacoustics for providing the necessary real-time feedback of cutting and heating processes. A single Q-switched Nd-YAG laser (532nm, 4 KHz, 18 W, pulse duration 7.6ns) was used for ablation and generation of optoacoustic signals in fresh bovine tissue samples. Both shockwaves, generated due to tissue removal, as well as normal optoacoustic responses from the surrounding tissue were detected using a single 10MHz piezoelectric transducer. It has been observed that rapid reduction in the shockwave amplitude occurs as more material is being removed from the focal zone, indicating decrease in cutting efficiency of the laser beam, whereas gradual decrease in the optoacoustic signal likely corresponds to coagulation around the ablation crater. Further heating of surrounding tissue leads to carbonization accompanied by a significant shift of spectral components of the optoacoustic signal. Our results hold promise for real-time monitoring of cutting efficiency and collateral thermal damage during laser surgery.

Paper Details

Date Published: 4 March 2013
PDF: 10 pages
Proc. SPIE 8581, Photons Plus Ultrasound: Imaging and Sensing 2013, 85813X (4 March 2013); doi: 10.1117/12.2005027
Show Author Affiliations
Erwin Bay, Technical Univ. of Munich and Helmholtz Ctr. Munich (Germany)
Alexandre Douplik, Ryerson Univ. (Canada)
Friedrich-Alexander Erlangen-Nuremberg Univ. (Germany)
Daniel Razansky, Technical Univ. of Munich and Helmholtz Ctr. Munich (Germany)

Published in SPIE Proceedings Vol. 8581:
Photons Plus Ultrasound: Imaging and Sensing 2013
Alexander A. Oraevsky; Lihong V. Wang, Editor(s)

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