Calculation of the kinetics of heating and structural changes in the cartilaginous tissue under the action of laser radiation

A theoretical model is developed for the calculation of the temperature fields and determination of the size of a zone with structural changes in the cartilaginous tissue. The model is based on a simultaneous analysis of the heat and mass transfer processes and it takes into account the bulk absorpt...

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Bibliographic Details
Published in:Quantum electronics (Woodbury, N.Y.) N.Y.), 1998-07, Vol.28 (7), p.633-636
Main Authors: Sobol', E N, Kitai, M S
Format: Article
Language:English
Subjects:
ABSORPTION
ANIMAL TISSUES
BODY
CARTILAGE
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
CONNECTIVE TISSUE
DIFFUSION
DIMENSIONS
ELECTROMAGNETIC RADIATION
ENERGY DENSITY
EVAPORATION
HEATING
HYDROGEN COMPOUNDS
KINETICS
LASER RADIATION
MASS TRANSFER
MATERIALS SCIENCE
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
RADIATIONS
RELAXATION
SORPTION
STRESSES
SURFACES
TEMPERATURE DEPENDENCE
THICKNESS
WATER
WAVELENGTHS
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Summary:A theoretical model is developed for the calculation of the temperature fields and determination of the size of a zone with structural changes in the cartilaginous tissue. The model is based on a simultaneous analysis of the heat and mass transfer processes and it takes into account the bulk absorption of laser radiation by the tissue, surface evaporation of water, and temperature dependences of the diffusion coefficients. It is assumed that under the influence of a phase transition between free and bound water, caused by heating of the cartilage to 70{sup 0}C, the proteoglycans of the cartilage matrix become mobile and, as a result of such mass transfer, structural changes are induced in the cartilaginous tissue causing relaxation of stresses or denaturation. It is shown that the maximum temperature is then reached not on the irradiated surface but at some distance from it, and that the size of the zones of structural changes (denaturation depth) depends strongly on the energy density of the laser radiation and its wavelength, on the duration of the irradiation, and on the cartilage thickness. This model makes it possible to calculate the temperature fields and the depth of structural changes in laser-induced relaxation of stresses and changes in the shape of the cartilaginous tissue. (interaction of laser radiation with matter)
ISSN:1063-7818
1468-4799
DOI:10.1070/QE1998v028n07ABEH001281