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Proceedings Paper

Differentiation of tissue and kidney stones for laser lithotripsy using different spectroscopic approaches
Author(s): Birgit Lange; Jens Cordes; Ralf Brinkmann
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Paper Abstract

Holmium lasers are nowadays the gold standard for endoscopic laser lithotripsy. However, there is a risk of damaging or perforating the ureter or kidney tissue when the vision is poor. An automatic tissue/stone differentiation would improve the handling and safety of the procedure. To achieve this objective, an easy and robust real-time discrimination method has to be found which can be used to realize a feedback loop to control the laser system. Two possible approaches have been evaluated: White light reflectance and fluorescence spectroscopy. In both cases, we use the treatment fiber for detection and evaluate the possibility to decide whether the fiber is placed in front of tissue or calculus by the signal that is delivered by the surface in front of it. White light reflectance spectroscopy uses the standard light source for endourologic surgeries: Radiation of a Xenon light source is coupled to the ureteroscope via a liquid light guide. The part of the white light that is reflected back into the fiber is spectroscopically analyzed. In a clinical proof of concept study reflection signals were measured in vivo in 8 patients. For differentiation of stone and tissue via autofluorescence, excitation as well as detection was done via the treatment fiber. A suitable excitation wavelength was chosen with in vitro measurements (UV / visible) on several human renal calculi and porcine tissues. For verification of the positive results with green excitation in a clinical proof of concept study, a measurement set-up was realized which allows the recording of fluorescence signals during an endourological intervention.

Paper Details

Date Published: 15 July 2015
PDF: 9 pages
Proc. SPIE 9542, Medical Laser Applications and Laser-Tissue Interactions VII, 95420O (15 July 2015); doi: 10.1117/12.2183686
Show Author Affiliations
Birgit Lange, Medizinisches Laserzentrum Lübeck GmbH (Germany)
Jens Cordes, Univ. Schleswig-Holstein (Germany)
Ralf Brinkmann, Univ. zu Lübeck (Germany)


Published in SPIE Proceedings Vol. 9542:
Medical Laser Applications and Laser-Tissue Interactions VII
Lothar D. Lilge; Ronald Sroka, Editor(s)

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