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Proceedings Paper

Selective tumor destruction with photodynamic therapy: exploitation of photodynamic thresholds
Author(s): Hugh Barr
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Paper Abstract

The uptake and distribution of the photosensitizer aluminum sulphonated phthalocyanine (AlSPc) has been studied. In a variety of experimentally induced gastrointestinal tumors the photosensitizer is retained between 24 - 48 hours after intravenous administration compared with the adjacent normal tissue in which the tumor arose. However, the maximum tumor-to- normal-tissue ratio was only 2:1. Quantitative fluorescence photometry using digital image processing, with a CCD camera and helium neon laser, was used to probe the microscopic localization of the photosensitizer in tissue sections of tumor and normal tissue. Selective localization of the photosensitizer was nonspecific in tumor stroma and there was never any significant difference between normal and neoplastic cells. Exploitation of the small differences in photosensitizer concentration, photodynamic threshold effects, and photosensitizer photodegration allows up to 2 mm of selective tumor damage to be produced in a tumor, when a similar light dose will produce no damage in adjacent normal tissue. However, selective eradication of a tumor without adjacent tissue damage will not be possible by using these methods. This paper reviews this previously reported data.

Paper Details

Date Published: 1 November 1991
PDF: 10 pages
Proc. SPIE 1525, Future Trends in Biomedical Applications of Lasers, (1 November 1991); doi: 10.1117/12.48201
Show Author Affiliations
Hugh Barr, John Radcliffe Hospital and Univ. College London (United Kingdom)


Published in SPIE Proceedings Vol. 1525:
Future Trends in Biomedical Applications of Lasers

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