Analysis of photochemical oxygen consumption effects in photodynamic therapy (Invited Paper)

Thomas H. Foster; Scott L. Gibson; Yongli Gao; Russell Hilf

doi:10.1117/12.60933

1 June 1992 Analysis of photochemical oxygen consumption effects in photodynamic therapy (Invited Paper)

Thomas H. Foster, Scott L. Gibson, Yongli Gao, Russell Hilf

Proceedings Volume 1645, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy; (1992) https://doi.org/10.1117/12.60933
Event: OE/LASE '92, 1992, Los Angeles, CA, United States

Abstract

Type II photo-oxidation depends on and consumes oxygen. Several factors, including the concentration of photosensitizer and the radiation fluence rate, determine the rate of oxygen consumption in tissue undergoing Photodynamic Therapy. If the tissue capillary density is sparse, as it is in many human tumors, our calculations indicate that for cells sufficiently distant from the nearest capillary, fluence rates commonly used in PDT (50 - 200 mW/cm²) deplete ³O₂ levels below those necessary for ¹O₂ formation. The calculations suggest that under these conditions reduced fluence rates and radiation dose fractionation should be more effective than continuous radiation at high fluence rates in producing ¹O₂ throughout the treated tissue volume. These predictions are supported by results obtained in vivo. The data and their interpretation have implications for PDT dosimetry and offer the possibility of improved therapeutic ratio.

Citation Download Citation

Thomas H. Foster, Scott L. Gibson, Yongli Gao, and Russell Hilf "Analysis of photochemical oxygen consumption effects in photodynamic therapy (Invited Paper)", Proc. SPIE 1645, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy, (1 June 1992); https://doi.org/10.1117/12.60933

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