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[A new computed tomography-guided stereotactic instrument].

A new stereotactic system guided by computed tomography (CT) is reported. This instrument is composed of a square head frame, one arc frame, and a needle holder. The needle holder has a ball bearing function which does not limit the approach trajectories. The target point can be read out accurately from the CT image with dimension adjustable attachments. This system has the following advantages: 1) In spite of its simplicity, its mechanical accuracy is clinically satisfactory. 2) The entry point can be selected freely during operation. 3) Intraoperative manipulation is simplified by microcomputer calculation. 4) Three-dimensional relationship among target, entry point and the instrument is easily understood. 5) Surgical procedures in the CT room are made possible by using the plastic frame which gives little artifact.