X-ray detectable fiducial markers are associated with a stereotactic surgery frame. The frame is fixed with respect to a patient's anatomy and defines a predetermined three-dimensional coordinate system in which surgical devices may be precisely positioned. A desired target area of the anatomy is detected in a cross-sectional CT scanner depiction of the combined stereotactic frame and patient anatomy. The target's coordinates with respect to the frame are calculated based on three non-collinear fiducial points also located within the cross-section and having known coordinates both with respect to the frame and with respect to the target.
In the exemplary embodiment, detachable fiducial point-defining members are associated with a stereotactic surgical frame. For example, each member may be a plate having a series of parallel grooves or slots which progressively increase in length from one slot to the next. The frame coordinates of the end points of each slot are predetermined and known. Thus three fiducial points with respect to the frame can be determined by simply counting the number of slots or grooves contained within the cross-sectional depiction and thereby determining which end point is within such cross-section.