Influence of the laser-induced temperature rise in photodynamic therapy

Wolfgang Gottschalk; Joachim Hengst; Ronald Sroka; Eberhard Unsoeld

doi:10.1117/12.44117

1 June 1991 Influence of the laser-induced temperature rise in photodynamic therapy

Wolfgang Gottschalk, Joachim Hengst, Ronald Sroka, Eberhard Unsoeld

Proceedings Volume 1427, Laser-Tissue Interaction II; (1991) https://doi.org/10.1117/12.44117
Event: Optics, Electro-Optics, and Laser Applications in Science and Engineering, 1991, Los Angeles, CA, United States

Abstract

The influence of laser-induced temperature increase in transcutaneous PDT was examined in this study. First the subcutaneous temperature and the relative light intensity between tumor and skin were measured as a function of the applied power density in a series of studies. In a second experiment the influence of temperature on the effect of photodynamic therapy was studied. Determination of temperature and of relative light intensity was performed on three groups of mice: one group of C3H mice with macroscopically strong pigmentation, a second group of the same species with weak pigmentation and a third group of extensively unpigmented, homozygote nude mice of the NMRI family were used. For the second series of experiments the SSK2 fibrosarcoma was used as a tumor model on the C3H mouse. The photosensitized tumors from three animal groups, each with 5 animals, were irradiated subcuratively. In Group 1 the tumor surface was cooled in order to prevent laser- induced temperature effects. In Group 2 and 3 no cooling was used. Evaluation of the therapeutic effect was performed in respect to the regrowth delay time. With the use of transcutaneous PDT it could be shown that the temperature and the relative light intensity between tumor and skin depended essentially on the concentration of pigmentation of the skin above the tumor. Dependent on pigmentation and cooling, temperatures of more than 42 degree(s)C were established with irradiation at power densities starting at about 300 mW/cm². In the second series of experiments a clear prolongation of the regrowth delay time, i.e. a better therapeutic effect, was achieved in uncooled irradiated tumors. Curative therapy was successful only in uncooled irradiated tumors. For this reason the synergistic influence of laser-induced hyperthermia on the therapeutical result of PDT could be shown on the tumor model used.

Citation Download Citation

Wolfgang Gottschalk, Joachim Hengst, Ronald Sroka, and Eberhard Unsoeld "Influence of the laser-induced temperature rise in photodynamic therapy", Proc. SPIE 1427, Laser-Tissue Interaction II, (1 June 1991); https://doi.org/10.1117/12.44117

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