Fiducial registration for tracking systems that employ coordinate reference frames

摘要

An algorithm is presented that is designed for image-guidance systems that employ coordinate reference frames. It is common in image-guided surgery (IGS) to use a tracking system to determine the position of fiducial markers in physical space. Typically a "Coordinate Reference Frame" (CRF), is also employed, which is rigidly attached to the object being tracked. The positions of markers attached to the object are then measured in physical space relative to the CRF, and hence it is acceptable to allow the object to move during tracking. It is known that errors are introduced while localizing markers in image space and also while localizing markers in physical space using a probe. The use of a CRF causes additional error, which is anissotropic in nature and varies with the position of the marker being tracked relative to the CRF. This additional error has heretofore not been accounted for in the process of registering image space to physical space. We present in this paper a new rigid-body, point-based registration algorithm that accounts for the fiducial localization errors that arise in tracking systems that employ a coordinate reference frame. Simulations are presented that show that for such systems the new algorithm has the capability to perform better than the standard registration algorithm. The effect is enhanced for small CRFs and for marker configurations that are widely spaced relative to their mean distance from the CRF.