Flexible laser endoscope for minimally invasive photodynamic diagnosis (PDD) and therapy (PDT) toward efficient tumor removal.

Photodynamic diagnosis (PDD) provides valuable assistance in distinguishing tumor from the normal tissue using fluorescent colors. These colors are affected by the illumination and the photosensitizer, and PDD may be applied during operation. After the diagnosis, photodynamic therapy (PDT) could destroy tiny lesion without removing the tissue, something that considerably reduces the possibility of tumor recurrence. However, the present endoscope technologies cannot realize PDD and PDT using the same endoscope. The use of different endoscopes presents three main disadvantages. First, the intra-operation diagnosis cannot be realized unless endoscopes are the different during operation; use of different endoscopes further burdens of the surgeon and the patients. Second, it is very difficult to find the exact same area via the PDT endoscope, one that is confirmed as tumor or cancer by the PDD endoscope, when different endoscopes are used just as present applied. Third, the laser irradiation field cannot be controlled with present technologies, something that may hurt the surrounding healthy tissue or blood vessels, thus leading to serious complications. To resolve the above-mentioned problems, we propose a new flexible laser endoscope, which integrates PDD and PDT, and provides a controllable laser irradiation field for the surgeon. Experimental results proved that the resolution of both diagnosis and therapy images were five times higher than that of standard laparoscopy, the laser power density was high enough for PDT for a distance of 20 to 50 mm away from the target tumor, and the position accuracy of the presented system was half of the required errors. Moreover, the in-vitro experiments further verified the effectiveness of the laser endoscope system. Therefore, this new flexible laser endoscope is potentially suitable for future in-vivo experiments or clinical applications.