| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent a quench of a superconducting magnet and reduce a consumption of a cryogen such as liquid helium by reducing the number of demagnetization and excitation of the superconducting magnet, and to achieve a reduction in the number of shimming adjusting processes. <P>SOLUTION: A magnetic resonance imaging apparatus generates a homogeneous static magnetic field in a columnar bore 6 where a subject is placed by the cylindrical superconducting magnet 3 and includes a magnetic field-adjusting means by a shim tray housing a magnetic material shim for adjusting the homogeneity of the static magnetic field in a direction of an axis of the inner circumference of the columnar bore 6. The magnetic field-adjusting means includes: a plurality of first shim trays 1a housing a required amount of the magnetic material shim; and a plurality of second shim trays 1b housing the magnetic material shim less than the amount of the magnetic material shim in the first shim tray 1a. These shim trays are disposed in positions of approximately the same radius from the center of the axis of the columnar bore 6 at an arbitrary angle interval in the circumferential direction of the superconducting magnet 3. Then, the first shim tray 1a is attached, and the coarse adjustment of the static magnetic field is performed by exciting the superconducting magnet 3. While the excited state is kept, the second shim tray 1b is attached, and the fine adjustment of the static magnetic field is performed. <P>COPYRIGHT: (C)2011,JPO&INPIT |
