Endoscopic Laser Surface Scanner for Minimally Invasive Abdominal Surgeries

Minimally invasive surgery performed under endoscopic video is a viable alternative to several types of open abdominal surgeries. Advanced visualization techniques require accurate patient registration, often facilitated by reconstruction of the organ surface in situ. We present an active system for intraoperative surface reconstruction of internal organs, comprising a single-plane laser as the structured light source and a surgical endoscope camera as the imaging system. Both surgical instruments are spatially calibrated and tracked, after which the surface reconstruction is formulated as the intersection problem between line-of-sight rays (from the surgical camera) and the laser beam. Surface target registration error after a rigid-body surface registration between the scanned 3D points to the ground truth obtained via CT is reported. When tested on an ex vivo porcine liver and kidney, root-mean-squared surface target registration error of 1.28 mm was achieved. Accurate endoscopic surface reconstruction is possible by using two separately calibrated and tracked surgical instruments, where the trigonometry between the structured light, imaging system, and organ surface can be optimized. Our novelty is the accurate calibration technique for the tracked laser beam, and the design and the construction of laser apparatus designed for robotic-assisted surgery.