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Proceedings Paper

Reflectance Spectrophotometric Investigation Of Tissue Response In Photodynamic Therapy Of Cancer
Author(s): J. W. Feather; I. Driver; G. Leslie; M. Hajizadeh-Saffar; D. Gilson; P. R. King; B. Dixon
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Paper Abstract

Reflectance spectrophotometry has been used to investigate tumour and normal tissue responses to porphyrin mediated photodynamic therapy of cancer. Subcutaneously implanted isogenic fibrosarcomas were treated when they had grown to 10-12mm diameter. An Argon-ion pumped tunable dye laser provided 630nm cw light, which was delivered to the tumours either interstitially through a 200μm cleaved end fibre inserted into the centre of the tumour or transcutaneously through a 600μm cleaved end fibre mounted at distance from the overlying skin surface. A reflectance spectrophotometer employing fibre optic bundles to deliver light to and collect from the tissue was used to measure reflectance spectra (450-700nm) pre- and post-treatment in tumour and adjacent normal tissue of animals with and without photosensitiser. The reflectance data were converted to a parameter LIR (Logarithm of the Inverse Reflectance) whichmay be shown to be proportional to absorbance and therefore to tissue pigment concentration. Indices of total tissue haemoglobin and oxygen saturation levels have been derived based upon the differences in the shape of the LIR spectra of oxygenated and deoxygenated haemoglobin between 500 and 600nm. These indices provided information on the vascular state of tumours before treatment and the changes that occurred during and immediately after treatment. Preliminary results indicate a large decrease in tumour blood oxygenation during treatment with little recovery, at the dose level used, up to 2 hours post treatment in photosensitised animals, suggesting a decrease in tumour blood flow. After an immediate reduction in the haemoglobin index at the start of illumination, haemoglobin levels progressively rose throughout the treatment period and up to 2 hours post treatment. No significant changes occurred in non-photosensitised animals.

Paper Details

Date Published: 21 June 1988
PDF: 7 pages
Proc. SPIE 0906, Optical Fibers in Medicine III, (21 June 1988); doi: 10.1117/12.945272
Show Author Affiliations
J. W. Feather, University of Leeds (U.K)
I. Driver, University of Leeds (U.K)
G. Leslie, Cookridge Hospital (U.K)
M. Hajizadeh-Saffar, University of Leeds (U.K)
D. Gilson, University of Leeds (U.K)
P. R. King, University of Leeds (U.K)
B. Dixon, Cookridge Hospital (U.K)

Published in SPIE Proceedings Vol. 0906:
Optical Fibers in Medicine III
Abraham Katzir, Editor(s)

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