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Proceedings Paper

Simulation of laser induced thermo-mechanical changes in tissue using RF heating method
Author(s): Dmitriy E. Protsenko; Allison Zemek; Brian J. F. Wong M.D.
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Paper Abstract

Successful application of laser cartilage reshaping (LCR) for the in-situ treatment of structural deformities in the nasal septum, external ear and trachea requires a better understanding of the evolution of cartilage mechanical properties with temperature. We develop a method of Radio Frequency (RF) heating for reliable evaluation of mechanical changes in septal cartilage undergoing heating and used obtained data to model the mechanical changes in cartilage at steady state following laser heating. Cartilage specimens harvested from porcine septum were secured between two flat parallel copper platens connected to a surgical radiofrequency source. The current was user-selectable and controlled to achieve any desired heating rate mimicking heating rate obtained during laser irradiation. Surface and internal temperatures were monitored by an IR camera and embedding a small electrically insulated thermocouple inside the specimen. Cylindrical and rectangular samples were fashioned from the heated specimens and their equilibrium elastic modulus was measured in a step unconfined compression and tension experiments, respectively. Functional dependencies of the elastic modulus and maximum temperature were interpolated from the measurements. The calculated elastic modulus profiles were incorporated into a numerical model of uniaxial unconfined compression and tension of laser irradiated samples. The reaction force to a 0.1 strain was calculated and compared with the reaction force obtained in analogous mechanical measurements experiment. The results of the numerical simulation of uniaxial compression of laser heated samples demonstrate good correlation with experimentally obtained reaction force. Generalization of this methodology to incorporate orthogonal mechanical properties may aid in optimizing clinical LCR procedures.

Paper Details

Date Published: 10 February 2007
PDF: 6 pages
Proc. SPIE 6440, Thermal Treatment of Tissue: Energy Delivery and Assessment IV, 64400S (10 February 2007); doi: 10.1117/12.717859
Show Author Affiliations
Dmitriy E. Protsenko, Univ. of California/Irvine (United States)
Allison Zemek, Univ. of California/Irvine (United States)
Brian J. F. Wong M.D., Univ. of California/Irvine (United States)

Published in SPIE Proceedings Vol. 6440:
Thermal Treatment of Tissue: Energy Delivery and Assessment IV
Thomas P. Ryan, Editor(s)

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