Image-guided PDT for oral lesions: technology development, evaluation and translation

Oral cancer is the sixth most common cancer worldwide and mortality rates have increased steadily over the past three decades. Clinical studies by ourselves and others have shown that PDT is an effective non-surgical alternative for treatment of early-stage oral cancers and precancerous lesions, though a lack of any standardized protocols and robust enabling technologies have limited its adoption. In this proceedings report we briefly update on the status of new technology which integrates PDT light delivery into a handheld intraoral imaging device to enable simultaneous visualization and treatment guidance based on white light, tissue autofluorescence, and photosensitizer (ALA-induced protoporphyrin IX) fluorescence signals. This builds on earlier generation hardware for intraoral PDT involving separate light delivery and fluorescence imaging components. Here we briefly discuss how the integration of imaging and therapeutic light delivery into the same module allows for monitoring of photosensitizer photobleaching as a real-time dosimetry reporter. We also discuss recent extension of this capability using modified fluorescence optics to allow imaging of PpIX photoproduct formation as an additional dosimetry reporter.