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Proceedings Paper

Three-dimensional localization of discrete fluorescent inclusions from multiple tomographic projections in the time-domain
Author(s): Julien Pichette; Éric Lapointe; Yves Bérubé-Lauzière
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Paper Abstract

We introduce a novel approach for localizing a plurality of discrete fluorescent inclusions embedded in a thick scattering medium using time-domain (TD) experimental data. It relies on numerical constant fraction discrimination (NCFD), a signal processing technique for extracting in a stable manner the arrival time of early photons emitted by one or many fluorescent inclusions from measured photons time of flight (TOF) distributions. Our experimental set-up allows multi-view TD data acquisition from multiple tomographic projections over 360 degrees without contact with the medium. Fluorescence time point-spread functions (FTPSFs) are acquired all around the medium with ultra-fast time-correlated single photon counting (TCSPC) after short pulse laser excitation. From these FTPSFs, the early photons arrival time (EPAT) of a fluorescent wavefront at a detector position is extracted with our NCFD technique. The key to our localization algorithm is to combine EPATs from several detection positions and projections to form 3D surfaces. The digital analysis of the concavities of the surfaces allows to find the 3D positions of an a priori unknown number of fluorescent inclusions located in the medium. Indocyanine green (ICG; absorption peak = 780nm, emission peak = 830nm) is used for the inclusions. Various experiments were conducted, and we show localization results on experimental data for up to 5 discrete inclusions distributed at arbitrary positions in the medium. We expect to extend our method to continuous distributions of fluorescence (rather than discrete inclusions) in a near future.

Paper Details

Date Published: 12 February 2009
PDF: 10 pages
Proc. SPIE 7174, Optical Tomography and Spectroscopy of Tissue VIII, 71741A (12 February 2009);
Show Author Affiliations
Julien Pichette, Univ. de Sherbrooke (Canada)
Éric Lapointe, Univ. de Sherbrooke (Canada)
Yves Bérubé-Lauzière, Univ. de Sherbrooke (Canada)

Published in SPIE Proceedings Vol. 7174:
Optical Tomography and Spectroscopy of Tissue VIII
Bruce J. Tromberg; Arjun G. Yodh; Mamoru Tamura; Eva M. Sevick-Muraca; Robert R. Alfano, Editor(s)

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