ABSTRACT
In contrast to most of the chapters of this handbook, this chapter will address a therapeutic, rather than diagnostic, application of biomedical optics. ™e therapeutic ežects of light have been appreciated since ancient times. Exposure to light has ežects on health ranging from mood and psychological ežects and production of vitamin D to UV damage and the induction of cancer. ™e majority of these ežects can be reproduced or enhanced with arti›cial light. ™e term photodynamic therapy, however, refers speci›cally to photochemical reactions mediated by a pharmacological or endogenously generated photosensitizer. Because photosensitizers are involved, these ežects are fundamentally dižerent from the majority of naturally occurring ežects expected from exposure to sunlight. ™is chapter will review the history of photodynamic therapy and the basic physics and optics underlying it, as well as the current clinical use of the modality.
