Thomas J. Dougherty: An Appreciation.

Without the efforts of Tom Dougherty, it is unlikely that photodynamic therapy would have been more than a minor biomedical curiosity. His contributions to the field not only involved demonstrating the clinical relevance of the procedure but organizing that eventually led to FDA approval. This report summarizes his contributions to the field and illustrates the scope of discoveries that became feasible after his work brought PDT to the attention of others and to assorted funding agencies.