photodynamic therapy

In medicine, therapy used to destroy cancer cells by the action of bright light and oxygen. PDT involves two stages: first a photosensitizer (light sensitive chemical) is injected into the body, where it accumulates in the tumour; the patient is then exposed to a bright light source which the photosensitizer absorbs and transfers as light energy to oxygen molecules within the cells. The energized oxygen (singlet oxygen) then destroys the tumour cells. The treatment is most successful in tumours easily exposed to a light source, such as those on the skin or in the mouth. PDT can eradicate 90% of skin tumours if applied at an early stage.