Optical changes of collagen due to thermal damage and biaxial loading /
Thermal denaturation can induce marked changes in the optical and mechanical properties of collagenous tissues. The optical properties are important in both therapeutic and diagnostic applications of lasers in medicine. Although mechanical stress can be caused by collagen shrinkage in laser-based...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2001.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=728908441&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Thermal denaturation can induce marked changes in the optical and mechanical properties of collagenous tissues. The optical properties are important in both therapeutic and diagnostic applications of lasers in medicine. Although mechanical stress can be caused by collagen shrinkage in laser-based therapies, how the mechanical loading state affects the optical properties is not well understood. We applied a new computer-controlled biaxial testing system to various loading conditions to subject bovine epicardium both before and after multiple levels of thermal damage. An integrating sphere technique was used to measure transmittance and diffuse reflectance, from which absorption and scattering coefficients were calculated using a Monte Carlo method. Results showed that the scattering coefficient increased with increasing mechanical load but decreased as the degree of thermal damage increased. There was no significant change in the absorption coefficient due to thermal damage over the ranges studied. The changes of polarization characteristic due to thermal denaturation were investigated by obtaining the Mueller matrix elements of collagen with the automated data acquisition system. Because the fiber orientation affects on the Mueller matrix of the collagen sample, the measurements were performed at different fiber orientations and multiple heating levels. Results showed that the changes of the Mueller matrix elements, caused by thermal denaturation, could be correlated with the changes of the scattering coefficients of the collagen sample. The role of fiber orientation on the Mueller matrix reduced as thermal damage increased, which could cause fiber folding and decrease the ordered structure of the collagen sample. |
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| Item Description: | Vita. "Major Subject: Biomedical Engineering". |
| Physical Description: | xiii, 105 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 91-101). |