The principle of photodynamic therapy (PDT) is based on the generation of reactive oxygen species, notably singlet oxygen, within cells and tissues. This is achieved by the administration of a photosensitiser, or a photosensitiser precursor, and subsequent illumination with (visible) light of an appropriate wavelength. The photosensitiser absorbs the energy of the photons and transfers it to molecular oxygen in the tissue. This photochemical reaction results in the formation of reactive oxygen species that cause damage to critical cellular and tissue structures. The characteristics of the photosensitiser determine their spatial distribution within cells and tissues which has a strong influence on the response to therapy. For this reason it is important to consider the study of specific photosensitisers and recognise the importance of their specific field of application. PDT has been used to treat various (pre-) malignant and non malignant conditions that range from skin cancer and psoriasis to age-related macular degeneration (AMD) and prostate cancer. In each case the specifics of the disease and photosensitiser are critical parameters for the successful application of the therapy.

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P.C. Levendag (Peter)
Erasmus University Rotterdam
The Dutch Cancer Society (KWF) Ocean Optics, Galderma Nederland SA, Sanyo E&E Europe B.V., AB Diets, Atol
Erasmus MC: University Medical Center Rotterdam

de Bruijn, H.S. (2008, June 12). Light Fractionated ALA-PDT. Erasmus University Rotterdam. Retrieved from