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Proceedings Paper

In-vitro measurement of two-dimensional temperature distribution during laser-induced interstitial thermotherapy (LITT) and comparison with theoretical calculations
Author(s): Andre Roggan; Ingolf Mesecke von Rheinbaben; Stephan Schruender; Gerhard J. Mueller
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Paper Abstract

Laser-induced thermotherapy is a method to treat pathologic sites of inner organs and oblique tissues with laser radiation. The radiation is transmitted via optical fibers and applied using specially designed laser applicators which are mounted to the distal fiber end. Different types of applicators have been developed recently for an effective treatment of large lesions in short periods of time. Two experimental set-ups are presented to measure the optical and thermal applicator patterns at various wavelengths and tissues. One set-up applies the integrating sphere technique to characterize the axial radiation distribution of LITT-applicators. The second set-up was developed to measure two-dimensional temperature distributions in-vitro during a laser application. It consists of a tissue phantom which could be opened like a book and enabled the uptake of thermocamera measurements. The applicator of interest was fixed between both slabs of the phantom. Measurements were carried out with various types of applicators (bare-fiber, diffusing tip, ring-mode, scattering-dome, internally cooled applicator) with a Nd:YAG laser (1064 nm) and a diode laser (980 nm). The results showed that the applicator designs yielded various maximum temperatures between 90 degrees Celsius and 260 degrees Celsius. The measurements for an internally cooled applicator were compared with theoretical calculations of photon- and heat diffusion in scattering media, applying Monte- Carlo simulations and finite difference methods. The measurements corresponded well with the theoretical simulations.

Paper Details

Date Published: 19 January 1996
PDF: 17 pages
Proc. SPIE 2623, Medical Applications of Lasers III, (19 January 1996); doi: 10.1117/12.230337
Show Author Affiliations
Andre Roggan, Laser- und Medizin-Technologie gGmbH (Germany)
Ingolf Mesecke von Rheinbaben, Laser- und Medizin-Technologie gGmbH (Germany)
Stephan Schruender, Laser- und Medizin-Technologie gGmbH (Germany)
Gerhard J. Mueller, Laser- und Medizin-Technologie gGmbH (Germany)

Published in SPIE Proceedings Vol. 2623:
Medical Applications of Lasers III
Stephen G. Bown; Herbert J. Geschwind M.D.; Raimund Hibst; Frederic Laffitte; Giulio Maira; Roberto Pini; Hans-Dieter Reidenbach; Hans H. Scherer M.D.; Pasquale Spinelli, Editor(s)

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