Sub-millimeter precision 3D measurement through a standard endoscope with time of flight

Endoscopic surgery has been widely adopted across specialties because it reduces patient trauma, risk, and recovery time as compared to open procedures. The foremost challenge of endoscopic surgery is the inability to see in three dimensions, a disadvantage that significantly increases procedure time and uncertainty by inhibiting depth perception as well as localization and measurement capability. State-of-the-art approaches in endoscopic 3D measurement are largely based on a combination of structured light and stereo vision, but are limited in their robustness and applicability to clinical workflow. Both approaches require a large baseline and are not supported by most handheld off-the-shelf endoscopes; stereo methods specifically are sensitive to scenes lacking features or containing disturbances such as smoke and specular reflections, which are common in surgery. To address these issues, we propose an alternative method for 3D measurement based on time-of-flight (TOF), a depth sensing modality which is inherently monocular and known to be insensitive to featureless scenes and many types of disturbances. Specifically, we develop a TOF imaging module adapter compatible with off-the-shelf endoscopes and demonstrate single-shot, sub-millimeter 3D measurement accuracy on animal tissue. These results are significant because they suggest widespread compatibility with existing operating room equipment and workflow and applicability to a wide variety of clinically relevant surgical tasks including measurement of tumors, hernias, and anastomoses, intra-operative registration of the surgical scene to high-quality static 3D imaging data, and control of surgical robots.