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Proceedings Paper

Monitoring of benzoporphyrin derivative monoacid ring A (BPD-MA) in skin tumors by fluorescence during photodynamic therapy: preliminary observations
Author(s): Nikiforos Kollias; Harvey Lui M.D.; Joanne Wimberly; R. Rox Anderson M.D.
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Paper Abstract

The uptake and clearance of benzoporphyrin derivative - monoacid ring A (BPD-MA) in patients with primary and metastatic skin cancer were monitored using laser induced fluorescence in-vivo. These patients received systemic infusions of BPD-MA as part of a phase I clinical photodynamic therapy trial. The instrument used for photosensitizer detection consisted of two helium-neon (HeNe) lasers (612 and 633 nm) for fluorescence excitation and a phase sensitive detection system. The system was calibrated with various concentrations of BPD-MA using phantoms with scattering coefficients similar to that of skin. Measurements were carried out on unexposed normal skin near tumors, exposed normal skin immediately adjacent to tumors, and on the tumors themselves before drug infusion and at half hour intervals for up to three hours following infusion. Tumors were then exposed to 690 nm laser light for BPD-MA activation, during which time drug 'photobleaching' was followed by the loss of fluorescence. Following tumor irradiation, measurements were conducted for an additional two hours. Although fluorescence may be a useful means of monitoring photosensitizer concentration during photodynamic therapy, problems still remain. One is the linearity and the dynamic range of the response of the fluorescence detection device. Another is the uncertainty of the tissue depth probed by the fluorescence excitation source.

Paper Details

Date Published: 18 June 1993
PDF: 7 pages
Proc. SPIE 1881, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy II, (18 June 1993); doi: 10.1117/12.146329
Show Author Affiliations
Nikiforos Kollias, Massachusetts General Hospital (United States)
Harvey Lui M.D., Univ. of British Columbia (Canada)
Joanne Wimberly, Massachusetts General Hospital (United States)
R. Rox Anderson M.D., Massachusetts General Hospital (United States)

Published in SPIE Proceedings Vol. 1881:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy II
Thomas J. Dougherty, Editor(s)

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