Surface-based registration of CT images to physical space for image-guidedsurgery of the spine: A sensitivity study

This paper presents a method designed to register preoperative computed tom ography (CT) images to vertebral surface points acquired intraoperatively f rom ultrasound (US) images or via a tracked probe, It also presents a compa rison of the registration accuracy achievable with surface points acquired from the entire posterior surface of the vertebra to the accuracy achievabl e,vith points acquired only from the spinous process and central laminar re gions, Using a marker-based method as a reference, this work shows that sub millimetric registration accuracy can be obtained even when a small portion of the posterior vertebral surface is used for registration, It also shows that when selected surface patches are used, CT slice thickness is not a c ritical parameter in the registration process. Furthermore, the paper inclu des qualitative results of registering vertebral surface points in US image s to multiple CT slices, The method has been tested with US points and phys ical points on a plastic spine phantom and,vith simulated data on a patient CT scan.