Dosimetry of Photodynamic Therapy of Cancer: real time monitoring

Photodynamic therapy (PDT) is a non surgical cancer treatment modality successfully used as a primary therapy in hollow organs and body cavities, such as gastrointestinal tract, bladder, mouth, and abdominal cavity. PDT is the use of a photosensitizing agent that is activated by light to produce specific biological effects in cells or tissues. PDT is precise in tumor destruction due to the specific uptake of photoactive drugs by the malignancy and use of laser light to irradiate it. At the same time, the effective depth of treatment does not exceed one centimeter, so deeper tissue layers are spared. PDT is also a time efficient clinical procedure, allowing a single fraction treatment of the malignancy to reduce the treatment time that is important for both patient and oncologist.
In this lecture, an introduction into dosimetry aspects of PDT of cancer will be presented. The results of the real time spectroscopy studies of photodynamic reactions in vitro and in vivo will be discussed. The theoretical interpretation of the oxygen depletion monitoring during PDT will be suggested. Examples describing how spectroscopic results were implemented into research and commercially available imaging devices will be presented as well.