US Patent 11389252 Rotating marker for image guided surgery

A marker for image guided surgery, consisting of a base, having a base axis, connecting to a clamp; and an alignment target. The alignment target includes a target region having an alignment pattern formed thereon, and a socket connected to the target region and configured to fit rotatably to the base, whereby the alignment target is rotatable about the base axis. The alignment target also includes an optical indicator for the socket indicating an angle of orientation of the alignment target about the base axis.