Reflectance Spectrophotometric Investigation Of Tissue Response In Photodynamic Therapy Of Cancer

J. W. Feather; I. Driver; G. Leslie; M. Hajizadeh-Saffar; D. Gilson; P. R. King; B. Dixon

doi:10.1117/12.945272

21 June 1988 Reflectance Spectrophotometric Investigation Of Tissue Response In Photodynamic Therapy Of Cancer

J. W. Feather, I. Driver, G. Leslie, M. Hajizadeh-Saffar, D. Gilson, P. R. King, B. Dixon

Proceedings Volume 0906, Optical Fibers in Medicine III; (1988) https://doi.org/10.1117/12.945272
Event: 1988 Los Angeles Symposium: O-E/LASE '88, 1988, Los Angeles, CA, United States

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.

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J. W. Feather, I. Driver, G. Leslie, M. Hajizadeh-Saffar, D. Gilson, P. R. King, and B. Dixon "Reflectance Spectrophotometric Investigation Of Tissue Response In Photodynamic Therapy Of Cancer", Proc. SPIE 0906, Optical Fibers in Medicine III, (21 June 1988); https://doi.org/10.1117/12.945272

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