Lasers and light sources for PDT: past, present and future.

The more recent use of Photodynamic therapy in Oncology dates to the early 1970's, when Dr. Thomas J. Dougherty, began his investigations into the mechanisms and clinical uses hematoporphyrin derivative (HpD). Since then the therapy has found its way through the regulatory process in numerous countries throughout the world. In many of these locales as it was in the United States, this was the first drug device approval, for oncology, that had been undertaken and ultimately approved, by the regulatory agencies in the respective countries. Throughout this time changes occurred in the formulation of HpD as well as the development of other photosensitizers. The more difficult aspect, however, of this modality has been the availability of reliable, affordable and appropriate devices for the production and delivery of light to the targeted areas. In the last 10 years, however, there has been a slow yet improving landscape in the development of devices for PDT that ultimately will provide the impetus for greater acceptance of PDT in the medical community.