Figure 2. The First CT-Compatible Stereotactic Frame.

Brown designed and built this stereotactic frame in August 1978 in order to test the concept of the N-localizer [1]. Three N-localizers are attached to this frame and are merged end-to-end such that only seven rods are present. Because three points determine a unique plane in three-dimensional space, the locations of the centers of the three ellipses that the three N-localizers produce in a tomographic image precisely determine the position of the tomographic section with respect to the stereotactic frame [2].