A new method for utilizing CT data in stereotactic surgery: measurement and transformation technique.

The proposed system is essentially based on the definition of a coordinate system, rigidly connected with the skull, by the introduction of three reference X-ray opaque points, secured into the bone of the skull. Target and reference points CT coordinates are given by the image display console. The three reference points are also identified on stereoradiographs, and their actual stereotactic coordinates are calculated by a geometrical approach which takes into account radiological distortion. A programmed computer links the target, identified on tomograms, to the three points system and calculates its stereotactic coordinates.