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Relationship between damaged fraction and reflected spectra of denaturing tissues
Author(s) -
Yoshimura Hiroyuki,
Viator John A.,
Jacques Steven L.
Publication year - 2005
Publication title -
lasers in surgery and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 112
eISSN - 1096-9101
pISSN - 0196-8092
DOI - 10.1002/lsm.20240
Subject(s) - denaturation (fissile materials) , spectrometer , chemistry , reflectivity , spectral line , analytical chemistry (journal) , optical fiber , volume fraction , diffuse reflectance infrared fourier transform , thermocouple , materials science , biophysics , nuclear magnetic resonance , optics , chromatography , biochemistry , biology , nuclear chemistry , physics , photocatalysis , astronomy , catalysis , composite material
Background and Objectives During thermal therapy of tissue, such as induced by microwave heating, the initiation of denaturation should be monitored for proper thermal dosage. Additionally, denaturation should be confined to the pathologic volume, while preserving surrounding healthy tissue. The relationship between the damaged fraction and reflected spectra of denaturing tissues was investigated for a variation of the temperature of the tissues. Study Design/Materials and Methods Denaturation of muscle, liver, and milk was studied in vitro by measuring the temperature‐varying reflectance spectrum as heating occurs. A high‐resolution fiber optic spectrometer was used to measure the reflectance changes. Temperature was monitored using a thermocouple embedded within the tissue along the side of the optical fiber probe. Results The values of average free energy to initiate denaturation in muscle and liver at about 60°C were 94.8 and 96.3 kJ/mole, respectively. The reflectance spectra increased in amplitude for muscle and liver, and the peak shifted from approximately 700 to 720 nm in accordance with the damage fraction of tissue. The reflectance spectrum for milk was essentially unchanged. Conclusions Spectral changes from heated muscle and liver reflect denaturation of proteins contained therein. The spectral information at 800 nm can be used to determine the average free energy for the initiation of denaturation. Lasers Surg. Med. © 2005 Wiley‐Liss, Inc.