Clinical PD/PDT in North America: An historical review.

The healing properties of light have been appreciated for thousands of years. However, the harnessing of light energy to create a rigorous and reliable means to diagnose and treat human disease is only a relatively recent phenomenon. Despite outstanding results from ancient history and subsequent reemergence and refinement of this knowledge over the last 100 years, it took again the hand of serendipity to open the modern age of Photodiagnosis and Photodynamic Therapy. Based on the prescience and perseverance of a handful, the under appreciated observations of tumor fluorescence and photodynamic action have been brought to a worldwide audience. This review highlights the development of clinical Photodiagnosis and Photodynamic Therapy, emphasizing the significant events and milestones taking place in North America.