Variability of tissue optical properties in cancer patients receiving photodynamic therapy

Photodynamic Therapy (PDT) uses light to activate photosensitive drug to yield oxidative injury to targeted tissues such as cancer. The ability of treatment light to penetrate a tissue and activate the drug that has accumulated in a target tissue depends on the tissue optical properties, especially the blood perfusion. An endoscopic spectroscopic probe was developed for monitoring esophageal and lung tissues and tested in patients in a pilot clinical study.