MAGNETIC GENERATOR FOR SUPERCONDUCTING TYPE MRI

摘要

PURPOSE:To constitute the magnetic field generator in such a manner that the high uniformity of magnetic fields necessary for medical treatment purposes is satisfied and that an aperture is large and expansive to avoid imparting a mentally compressive feel to a testee by adopting the constitution to circumferentially provide a superconducting coil only at one of a pair of magnetic pole pieces arranged to face each other. CONSTITUTION:The aperture is constituted extremely large and expansive by arranging a pair of yoke plates 1, 2 mounted and provided with the magnetic pole pieces 7, 8 by means of four pieces of columnar yokes 5 in such a manner that these plates face each other. The diameter of the lower magnetic pole piece 8 circumferentially provided with the superconducting coil 6 is formed larger than the diameter of the upper magnetic pole piece 7 not provided with the superconducting coil 6 to improve the unbalance of the magnetic fields. An annular projection 8a having the outside diameter larger than the outside diameter of the upper magnetic pole piece 7 is provided and the superconducting coil is circumferentially provided on the outer periphery thereof to greatly improve the magnetic field uniformity. Further, a flange part 8c extending outward is provided in the outer peripheral part of the surface of the magnetic pole piece facing the gap of the annular projection 8a, by which the diameter of the magnetic pole piece 8 is made substantially larger than the diameter of the other magnetic pole piece 7. The uniform magnetic field space is thus improved without increasing the size of the device.