A computerized tomography-computer graphics approach to stereotaxic localization

Abstract

The use of 3-dimensional computer graphics to display structures visible in computerized tomography (CT) scans and to accurately determine optimum stereotaxic probe placement relative to those structures was described. A prototype lucite stereotaxic frame designed for use in CT body scanners was fitted with a phantom consisting of small lucite spheres representing intracranial tumors with diameters of 6-19 mm. A series of CT scans was obtained of the frame and phantom together. Edge outlines of the spheres were extracted from each scan in the series. A 3-dimensional visual representation of the spheres was obtained by displaying their outlines from all CT scans. A superimposed visual simulation of the stereotaxic frame was adjusted interactively using several analog dials to simulate trajectory choice and probe depth before actual surgery. The frame settings and probe depth calculated by the graphical computer were then applied to the actual prototype frame to assess the accuracy of this combined CT-computer graphics approach to stereotaxic localization. The results of 22 such experiments and the implications for future clinical use of this new and prescise localization technique are discussed.