| 摘要 |
PROBLEM TO BE SOLVED: To produce a gradient magnetic field with extremely small changes in a spatial distribution and field strength. SOLUTION: A magnet 7 of a MRI has a pair of magnetic poles 4A, 4B. The magnetic poles 4A, 4B are made of iron and are placed to have a space 8 formed between them. The magnetic poles 4A, 4B are connected by an iron core 6. A protruded part 5A is provided on the underside of the magnetic pole 4A. A gradient magnetic field coil 1A is placed below the magnetic pole 4A and between the protruded parts 5A. An eddy current suppressing member 2A made of a silicon steel plate and an eddy current suppressing member 3A made of aluminum are placed between the surface of the magnetic pole 4A and the gradient magnetic field coil 1A. The coil 1A is placed on the underside of the eddy current suppressing member 2A. Production of eddy current is extremely suppressed because of the eddy current suppressing members 2A, 3A, and the gradient magnetic field which has temporally, extremely small changes in the spatial distribution and field strength is produced.
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