| 摘要 |
<p>A magnetic structure generating a substantially uniform magnetic field within a region of interest using permanently magnetized wedge-shaped blocks (10, 12) of magnetic material. In a preferred embodiment, the permanently magnetized wedge-shaped blocks are provided in pairs, positioned on opposite sides of the xz plane of an arbitrary x, y, z, coordinate system, and each of the blocks are magnetized in certain directions. The uniform field is created in the vicinity (30) of the z axis. In another embodiment, the parts of the structure below the x-axis are replaced by a high-permeability, soft magnetic plate to form a so-called mirror system. In still another embodiment, permanently magnetized blocks positioned outside of the wedge-shaped blocks are employed as the main compensation means for field distortions arising from the practical need to truncate the wedge-shaped blocks to a practical size. An important application for the magnetic structure of the invention is MRI, as it can be configured as an open structure accessible to medical intervention during the MRI.</p> |
