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Journal of Biomedical Optics

Local thermal coagulation due to laser-tissue interaction as irreversible phase transition
Author(s): Igor A. Lubashevsky; Alexander V. Priezzhev; Vasyl V. Gafiychuk; Meruzhan G. Cadjan
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Paper Abstract

A new mathematical model is proposed for the growth of a small necrosis domain in living tissue caused by local laser irradiation. Laser light is assumed to be delivered to a small internal region where its absorption causes the temperature to attain high values, leading to immediate tissue coagulation. The coagulation is treated in terms of irreversible phase transition, i.e., it is assumed to occur after the tissue temperature exceeds a certain threshold Tcg . The model considers tissue as involving two regions: the necrosis domain, where the blood perfusion rate is equal to zero, and the normal tissue, which responds to temperature variations by increasing the perfusion rate. The model takes into account the fact that in normal tissue changes in temperature are governed by the blood perfusion rate averaged on spatial scales over the length of the vessels directly controlling heat exchange between the tissue and blood rather than the true perfusion rate. Two alternative models, the developed one and a model allied to the classic approach to the mathematical description of local thermal coagulation, are compared. The effects of blood flow nonuniformity and the delay in vessel response on growth of the necrosis domain are analyzed in detail.

Paper Details

Date Published: 1 January 1997
PDF: 11 pages
J. Biomed. Opt. 2(1) doi: 10.1117/12.259665
Published in: Journal of Biomedical Optics Volume 2, Issue 1
Show Author Affiliations
Igor A. Lubashevsky, Moscow State Univ. (Russia)
Alexander V. Priezzhev, Moscow State Univ. (Russia)
Vasyl V. Gafiychuk, Institute for Applied Problems of Mechanics and Mathematics (Ukraine)
Meruzhan G. Cadjan, Institute of High Temperature (Russia)

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