FUNCTIONAL DESIGN-FEATURES AND INITIAL PERFORMANCE-CHARACTERISTICS OFA MAGNETIC-IMPLANT GUIDANCE-SYSTEM FOR STEREOTAXIC NEUROSURGERY

A helmet with a roughly cubic array of six superconducting coils is us ed to apply force on a small permanent magnet pellet in brain or in br ain phantom material. This apparatus, called the Magnetic Stereotaxis System, will be used to deliver drugs and other therapies directly int o deep brain tissues, under control of a computer and fluoroscopic ima ging system. This paper considers only the force application aspects o f the instrument. The primary design features of the helmet and power supply controls are presented, along with field plot data and single-a xis motion results. The field plot data show that agreement with the f inite-element iron-free field calculations is sufficiently high (>1%) for the instrument. These preliminary motion data indicate accuracy be tter than 2 mm for the impulsive pellet motion, even though the visual position observations had significantly greater error than the comple ted imaging system will have. The companion paper will take up analysi s of the control aspects of the motion, and our recent solutions to di fficulties found in the experimental work described here.