System analysis of stereotactic neurosurgery based on CT scans


Stereotaxic localization of target points identified on single CT scan slices obtained using commercially available frame systems is widely available. These systems have intrinsic limitations imposed by the computational algorithms used to determine the stereotaxic frame settings for a desired approach to the target. The extant descriptions of stereotaxic frames are mathematically incomplete, confounding efforts to delineate the limitations of these devices and improve their versatility. This report provides a complete mathematical description for a commercially available device (Brown-Roberts-Wells stereotaxis system). This systems analysis was used to design and implement microcomputer-based (Apple Macintosh) interactive graphics software providing enhanced versatility in locating target points, selecting approach directions, and handling sequences of frame settings needed in procedures where multiple interventions are required. Application of this new software in neurosurgical procedures to uniformly distribute interstitial radiotherapy sources through tumor masses is described.