title: Visual servoing for intraoperative positioning and repositioning of mobile C-arms.
abstract: The problem of positioning mobile C-arms, e.g. for down the beam techniques, as well as repositioning during surgical procedures currently requires time, skill and additional radiation. This paper uses a Camera-Augmented Mobile C-arm (CAMC) to speed up the procedure, simplify its execution and reduce the necessary radiation. For positioning the C-arm in down-the-beam position, the pre-operative diagnostic CT is used for defining the axis. Additional CT visible markers on patient's skin allow the CAMC's optical camera to compute the C-arm's pose and its required displacement for positioning. In the absence of electronically controlled mobile C-arms, the system provides step-by-step guidance to surgical staff until the final position is achieved. At this point, the surgeon can acquire an X-ray to ensure the correct positioning. In the case of intra-operative repositioning, no pre-operative CT is required. X-ray/Optical markers allow the visual servoing algorithm to guide the surgical staff in C-arm repositioning using CAMC's optical camera. This work paves the path for many possible applications of visual servoing in C-arm positioning and in surgical navigation. Experiments on phantom and a cadaver study demonstrate the advantages of the new methods.
authors.affiliation: TU Munich, Germany.
authors.forename: Nassir
authors.initials: N
authors.lastname: Navab
authors.forename: Stefan
authors.initials: S
authors.lastname: Wiesner
authors.forename: Selim
authors.initials: S
authors.lastname: Benhimane
authors.forename: Ekkehard
authors.initials: E
authors.lastname: Euler
authors.forename: Sandro Michael
authors.initials: SM
authors.lastname: Heining
mesh_terms: D000465:Algorithms; D000842:Ankle / Q000000981:diagnostic imaging; D001185:Artificial Intelligence; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D009038:Motion; D010363:Pattern Recognition, Automated / Q000379:methods*; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012371:Robotics / Q000379:methods*; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*