Open-Type Magnetically Shielded Room Using Only Canceling Coil Without a Ferromagnetic Wall for Magnetic Resonance Imaging

In order to improve amenities for patients in hospitals, a new open type of magnetically shielded room (MSR) for magnetic resonance imaging (MRI), which uses only canceling coils without a ferromagnetic wall, has been developed. The device was designed by three-dimensional magnetic field analysis and experimentally investigated using an actual MRI of 1.5 T. First, a coil and ferromagnetic material were modeled on an actual MRI, so that the distribution of the leakage magnetic flux vectors was in agreement with that measured. Second, the optimal shaped canceling coil, a saddle-shaped coil which can reduce the leakage flux from the edge plane to the side plane of the room, was designed using the modeled MRI, and realized. The effectiveness of this coil for shielding and its influence on MRI imaging were confirmed experimentally using an actual MRI. In addition, an optimal U-shaped enclosure that can sufficiently shield the leakage flux generated by the coil itself was designed; its effectiveness was confirmed experimentally by using an actual canceling coil.