Visualization and Photodynamic Therapy in Malignant Glioma - An Overview and Perspectives

Abstract

Photodynamic therapy (PDT) is a relatively new modality of cancer treatment. Actual ongoing clinical era started with the studies of Dougherty in the 1970s. PDT is based on the application of a so called photosensitizer (PS), which preferably enriches in the tumor tissue. The application of light at an appropriate wavelength excites the PS molecules from their ground state S0 to an electronically excited singlet state Sx. The energy of the excited state can be dissipated via several relaxation pathways. By this, so called cytotoxic reactive oxygen species (ROS) are generated. ROS react with various biomolecules inducing cell death by different mechanims.(Dougherty et al. 1998b)