Abstract

Photodynamic Therapy (PDT) means tumor treatment achieved through tumor-specific photosensitizer and photoradiation excitation. The basic concept of photoluminescence was already known at the beginning of this century. However, recent developments in photobiology, endoscopy, laser equipments and medical electronics have resulted in rapid progress. The mechanism of the cytocidal effects of PDT is considered to be as follows: when photosensitizer absorbed by a tumor is exposed to light, it absorbs light energy and enters an unstable excited singlet state. When returning from this unstable excited state to the stable ground state, the energy of the triplet status of photosensitizer is transferred to the oxygen in tissue, the excitation of which produces excited singlet oxygen. Singlet oxygen has toxic effects on tissue, thus making it possible to treat tumors.

© 1995 IEEE