Two-step excitation in photosensitized tumor therapy

Ricardas Rotomskis; Valentinas Mickunaitis; Darius Juodzevicius; Algis S. Piskarskas

doi:10.1117/12.199136

12 January 1995 Two-step excitation in photosensitized tumor therapy

Ricardas Rotomskis, Valentinas Mickunaitis, Darius Juodzevicius, Algis S. Piskarskas

Proceedings Volume 2325, Photodynamic Therapy of Cancer II; (1995) https://doi.org/10.1117/12.199136
Event: International Symposium on Biomedical Optics Europe '94, 1994, Lille, France

Abstract

The primary process in the usual photosensitized tumor therapy is sensitization from the sensitizers lowest triplet state. Alternatively, the laser light can be pulsed so that excitation occurring over short interval at high peak power can induce two-photon excitation of sensitizers via nonresonant absorption and initiate photodynamic action. The theoretical model has been developed and laser pulse parameters that ensure efficient two-step process have been calculated. In addition, the threshold that separates the two-step process through singlet manifold or triplet manifold was estimated. Both two-step excitation regimes should be initiated with tailored laser pulses. In this work we focus our attention on the characterization of the parameters (the lifetime of excited singlet state, quantum yield of interconversion to the triplet state, etc.) of the most suitable sensitizers for the proposed two-step excitation scheme. On the basis of our model the parameters of the laser pulse and the parameters of the most efficient sensitizer in two-step photosensitization process could be selected.

Citation Download Citation

Ricardas Rotomskis, Valentinas Mickunaitis, Darius Juodzevicius, and Algis S. Piskarskas "Two-step excitation in photosensitized tumor therapy", Proc. SPIE 2325, Photodynamic Therapy of Cancer II, (12 January 1995); https://doi.org/10.1117/12.199136

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