A CRYOGEN-FREE OPEN SUPERCONDUCTING MAGNET FOR INTERVENTIONAL MRI APPLICATIONS

A 0.5T cryogen-free superconducting magnet with an open geometry has b een designed for use In MRI-guided minimally Invasive surgery and othe r interventional procedures. The magnet consists of a split pair of co ils to allow surgeons direct access to the patient within the field-of -view of the Imaging system. The magnet is wound using Nb3Sn tape cond uctor and is maintained at approximately 10K using a pair of Gifford-M cMahon refrigerators. High-Tc superconducting current leads have been used in order to minimize the heat leak to the magnet. A passive quenc h protection system was developed for this unique magnet geometry, Hig h quality MR images have been produced and used for interventional pro cedures. Descriptions of the design, fabrication, and test results of the magnet are presented.