Abstract: This document discusses, among other things, a fiducial marker kit. In one example, the kit includes a fiducial marker assembly that includes a bone screw base for receiving an imageable marker or locatable divot. A valved protective sleeve prevents debris from accumulating in a receptacle portion of the base, which may otherwise degrade the accuracy of patient registration in an image-guided surgical procedure. In one example, the valve automatically opens or closes upon insertion or removal of a screwdriver or other tool, or a shaft portion of the imageable marker or locatable divot. Various bone screw base and receptacle combinations are also discussed.

Abstract: This document discusses, among other things, fiducial marker devices, tools, and methods. One example illustrates a combined computed tomography (CT) imagable fiducial locator head, an integral bone screw, and an integral divot for receiving a positioning wand of an image-guided surgical (IGS) workstation. A further example includes a fluid/gel-absorbing coating or cover into which a magnetic resonance (MR) imagable fluid is introduced, thereby permitting both CT and MR imaging. Protective caps and collars may be used to protect the fiducial marker from mechanical impact and/or to guide the fiducial marker during affixation. A bull's-eye or other template is used to select a center of a substantially spherical fiducial marker head on an image, such as for use during patient registration.