title: Gradient-based 2-D/3-D rigid registration of fluoroscopic X-ray to CT.
abstract: We present a gradient-based method for rigid registration of a patient preoperative computed tomography (CT) to its intraoperative situation with a few fluoroscopic X-ray images obtained with a tracked C-arm. The method is noninvasive, anatomy-based, requires simple user interaction, and includes validation. It is generic and easily customizable for a variety of routine clinical uses in orthopaedic surgery. Gradient-based registration consists of three steps: 1) initial pose estimation; 2) coarse geometry-based registration on bone contours, and; 3) fine gradient projection registration (GPR) on edge pixels. It optimizes speed, accuracy, and robustness. Its novelty resides in using volume gradients to eliminate outliers and foreign objects in the fluoroscopic X-ray images, in speeding up computation, and in achieving higher accuracy. It overcomes the drawbacks of intensity-based methods, which are slow and have a limited convergence range, and of geometry-based methods, which depend on the image segmentation quality. Our simulated, in vitro, and cadaver experiments on a human pelvis CT, dry vertebra, dry femur, fresh lamb hip, and human pelvis under realistic conditions show a mean 0.5-1.7 mm (0.5-2.6 mm maximum) target registration accuracy.
authors: School of Engineering and Computer Science, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors: Harel
authors: H
authors: Livyatan
authors: Ziv
authors: Z
authors: Yaniv
authors: Leo
authors: L
authors: Joskowicz
mesh_terms: D000465:Algorithms; D000818:Animals; D002102:Cadaver; D005269:Femur / Q000000981:diagnostic imaging; D005471:Fluoroscopy / Q000379:methods*; D006621:Hip Joint / Q000000981:diagnostic imaging; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007430:Intraoperative Care / Q000379:methods; D010388:Pelvis / Q000000981:diagnostic imaging; D011300:Preoperative Care / Q000379:methods; D011856:Radiographic Image Enhancement; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012756:Sheep; D013382:Subtraction Technique; D025321:Surgery, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*