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Proceedings Paper

Fluorescence measurement of localized deeply embedded physiological processes
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Paper Abstract

Intrinsic and exogenous fluorescent molecules may be used as specific markers of disease processes, or metabolic status. A variety of fluorescent markers have been successfully used for transparent tissue, in-vitro studies, and in cases where the markers are located close to the tissue surface. For example, given fluorescence lifetime measurements of a fluorophore such as bis(carboxylic acid) dye, the known relationship of pH on its lifetime may be used to determine the pH of tissue at the fluorophore's location. For fluorophore depths greater than approximately one millimeter in normal tissue, such as might be encountered in in vivo studies, multiple scattering makes it impossible to make direct measurements of characteristics such as fluorophore lifetime. In a multiple scattering environment, the collected intensity depends heavily on the scattering and absorption coefficients of the tissue at both the excitation and emission frequencies. Thus, to obtain values for specific fluorophore characteristics such as the lifetime, a theoretical description of the complex photon paths is required. We have applied Random-walk theory to successfully model photon migration in turbid medias such as tissue. We show how time-resolve intensity measurements may be used to determine fluorophore location and lifetime even when the fluorophore site is located many mean photon scattering lengths from the emitter and detector.

Paper Details

Date Published: 20 April 2000
PDF: 6 pages
Proc. SPIE 3978, Medical Imaging 2000: Physiology and Function from Multidimensional Images, (20 April 2000); doi: 10.1117/12.383419
Show Author Affiliations
David W. Hattery, National Institutes of Health and George Washington Univ. (United States)
Victor V. Chernomordik, National Institutes of Health (Israel)
Israel Gannot, Tel Aviv Univ. (Israel)
Murray H. Loew, George Washington Univ. (United States)
Amir H. Gandjbakhche, National Institutes of Health (Israel)

Published in SPIE Proceedings Vol. 3978:
Medical Imaging 2000: Physiology and Function from Multidimensional Images
Chin-Tu Chen; Anne V. Clough, Editor(s)

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