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Journal of Biomedical Optics

Ex vivo comparison of the tissue effects of six laser wavelengths for potential use in laser supported partial nephrectomy
Author(s): Wael Khoder; Katja Zilinberg; Raphaela M. Waidelich; Christian G. Stief; Armin Becker; Thomas Pangratz; Georg Hennig; Ronald Sroka
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Paper Abstract

Laparoscopic/robotic partial nephrectomy (LPN) is increasingly considered for small renal tumors (RT). This demands new compatible surgical tools for RT-resection, such as lasers, to optimize cutting and coagulation. This work aims to characterize ex vivo handling requirements for six medically approved laser devices emitting different light wavelengths (940, 1064, 1318, 1470, 1940, and 2010 nm) amenable for LPN. Incisions were made by laser fibers driven by a computer-controlled stepping motor allowing precise linear movement with a preset velocity at a fixed fiber-tip distance to tissue. Optical parameters were measured on 200 μm tissue slices. Cutting quality depended on power output, fiber velocity and fiber-tip distance to tissue. Contact manner is suitable for cutting while a noncontact manner (5 mm distance) induces coagulation. Ablation threshold differs for each wavelength. Ablation depth is proportional to power output (within limit) while axial and superficial coagulation remains mostly constant. Increased fiber velocity compromises the coagulation quality. Optical parameters of porcine kidney tissue demonstrate that renal absorption coefficient follows water absorption in the 2 μm region while for other spectral regions (900 to 1500 and 1 μm) the tissue effects are influenced by other chromophores and scattering. Tissue color changes demonstrate dependencies on irradiance, scan velocity, and wavelength. Current results clearly demonstrate that surgeons considering laser-assisted RT excisions should be aware of the mentioned technical parameters (power output, fiber velocity and fiber-tip tissue-distance) rather than wavelength only.

Paper Details

Date Published: 12 June 2012
PDF: 10 pages
J. Biomed. Opt. 17(6) 068005 doi: 10.1117/1.JBO.17.6.068005
Published in: Journal of Biomedical Optics Volume 17, Issue 6
Show Author Affiliations
Wael Khoder, Ludwig-Maximilians-Univ. München (Germany)
Katja Zilinberg, Ludwig-Maximilians-Univ. München (Germany)
Raphaela M. Waidelich, Ludwig-Maximilians-Univ. München (Germany)
Christian G. Stief, Ludwig-Maximilians-Univ. München (Germany)
Armin Becker, Ludwig-Maximilians-Univ. München (Germany)
Thomas Pangratz, Laser-Forschungslabor (Germany)
Georg Hennig, Laser-Forschungslabor (Germany)
Ronald Sroka, Laser-Forschungslabor (Germany)


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