ABSTRACT
In the early 1980s Radionics, Inc. (Burlington, MA) was approached with a design for an innovative stereotactic frame that used computed tomography (CT) to directly target points within the brain. This device, the BrownRoberts-Wells (BRW) frame, used a polar coordinate concept to define stereotactic space. A small computer with a simple menu was part of the system, thereby eliminating the need for strict orthogonality of the CT scan (a requirement of the Leksell arc-centered concept). The ‘‘picket-fence’’ configuration of the localizer was the key feature in this regard, as it allowed for calculation of the Z-coordinate (the height from the frame base, as opposed to the X and Y coordinates, which can be derived directly from a CT image).
