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Proceedings Paper

System IRF impact on fluorescence lifetime fitting in turbid medium
Author(s): Guobin Ma; Niculae Mincu; Frederic Lesage; Pascal Gallant; Laura McIntosh
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Paper Abstract

Fluorescence lifetime imaging is independent of signal intensity and is thus efficient and robust. Additionally, lifetime can be used to differentiate fluorophores and sense fluorophore micro-environment change. A time-resolved optical system is usually used to measure fluorescent decay kinetics, and then one fits the decay to get lifetime. Since the system impulse response function (IRF) is finite, it impacts lifetime fitting. Deconvolution of the IRF can diminish its impact. In thick tissues, light diffusion due to scattering is also convolved with the fluorescence decay. One can recover the decay using an inversion algorithm. However, processing data in this way is computationally intensive and therefore not practical for real time imaging. We present here results of our studies on the IRF impact to fluorescence lifetime fitting in a turbid medium over a wide range of parameters, using a unique time-domain imaging system. Fluorophores were submerged inside a turbid medium that models tissue. Analytical analysis and computation show that when the lifetime is 1.5 times larger than the FWHM of system IRF, reasonable fluorescence lifetimes can be obtained by fitting the decay tail without taking into account IRF. For small source-fluorophore-detector separation, the effect of optical diffusion on the lifetime fitting is also negligible. This gives a guidance of system precision limit for fluorescence lifetime imaging by fast tail fitting. Experimental data using a fs laser with a streak camera and a pulsed diode laser with PMT-TCSPC for ICG, Cy5.5, and ATTO 680 support the theoretical results.

Paper Details

Date Published: 29 March 2005
PDF: 11 pages
Proc. SPIE 5699, Imaging, Manipulation, and Analysis of Biomolecules and Cells: Fundamentals and Applications III, (29 March 2005); doi: 10.1117/12.589338
Show Author Affiliations
Guobin Ma, Advanced Research Technologies, Inc. (Canada)
Niculae Mincu, Advanced Research Technologies, Inc. (Canada)
Frederic Lesage, Advanced Research Technologies, Inc (Canada)
Pascal Gallant, Advanced Research Technologies, Inc. (Canada)
Laura McIntosh, Advanced Research Technologies, Inc. (Canada)

Published in SPIE Proceedings Vol. 5699:
Imaging, Manipulation, and Analysis of Biomolecules and Cells: Fundamentals and Applications III
Dan V. Nicolau; Dan V. Nicolau; Jörg Enderlein; Ramesh Raghavachari; Robert C. Leif; Daniel L. Farkas, Editor(s)

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