Photodynamic therapy. Basic concepts.

PDT method is based on the destruction of malignant tumours as a result of a series of photochemical reactions

in the interaction of laser radiation of a certain wavelength and tumourtropic photosensitizer previously introduced into the patient’s body.

In the mechanism of the cytotoxic effect the important role play oxidation and damage of vital cell structures due to excessive

formation of singlet oxygen and other radicals. In addition, the photosensitizers after the accumulation in the tumour, and

when irradiated with light of a specific wavelength, have properties of the fluorescence (FD), which allows to exactly identify

the location of the tumour and to determine the degree of local spread.

Stages of PDT

1. The introduction of a photosensitizer                (intravenously, topically, orally, pulmonary, etc.) 2. Accumulation of photosensitizer; 3. Fluorescent diagnostics (the identification and      definition of the tumour’s borders); 4. Photodynamic therapy of the tumour