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Proceedings Paper

Time-delayed fluorescence imaging of a porphycene derivative
Author(s): Sarah L. Gundy; Wilhelm J.M. van der Putten; Andrew Shearer; Daniel J. Buckton; Alan G. Ryder; Michael Ball
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Paper Abstract

Porphycenes are currently under investigation for use in Photodynamic therapy, which is a promising treatment for cancer. These materials, which display preferential uptake in cancerous cells, also exhibit high fluorescence yields, and can be used for tumour detection. Problems with steady-state fluorescence techniques such as background autofluorescence can be eliminated by the use of time-resolved techniques. Improved contrast can be obtained with time-resolved techniques because of the differing fluorescence lifetimes between autofluorescence and longer-living exogenous photosensitisers. An imaging system was constructed using a fast (200 ps) gated CCD camera and a pulsed 635 nm laser diode. A tissue phantom composed of polymethyl methacrylate (PMMA) with thirty-six wells of varying diameter and depth (10 mm to 1 mm) was assembled to test the system. The system was used to record images of a porphycene derivative within the wells at differing concentrations in an organic solvent. A tissue imitator was placed on top of the PMMA block at varying thickness. 10-4 M zinc phthalocyanine tetrasulfonate was also placed on top of the block to mimic autofluorescence. The results indicate that the time-gated imaging system can prevent background excitation scatter and fluorescence from a shorter-lived fluorophore from distorting the fluorescence signal from a longer-lived photosensitiser.

Paper Details

Date Published: 13 June 2003
PDF: 10 pages
Proc. SPIE 4952, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XII, (13 June 2003); doi: 10.1117/12.473596
Show Author Affiliations
Sarah L. Gundy, National Univ. of Ireland Galway (Ireland)
Wilhelm J.M. van der Putten, Univ. College Hospital Galway (Ireland)
Andrew Shearer, National Univ. of Ireland Galway (Ireland)
Daniel J. Buckton, GE Medical Systems (Austria)
Alan G. Ryder, National Univ. of Ireland Galway (Ireland)
Michael Ball, National Univ. of Ireland Galway (Ireland)

Published in SPIE Proceedings Vol. 4952:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XII
David Kessel, Editor(s)

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