MAGNETIC RESONANCE IMAGING DEVICE

摘要

PROBLEM TO BE SOLVED: To relatively suppress the time required for shimming for adjusting the uniformity of the magnetic field and attain high magnetic field uniformity by setting a secondary arrangement position of a shim piece in a position enabling shorter movement than the center distance of two unit shim pieces adjoining on a first pattern. SOLUTION: A magnetic substance shim mounted tray 38 is provided with holes A bored in central parts of squares and holes B separated from the holes A by distance d/21/2. In a first step, unit magnetic substance shims are optimally arranged using only the holes A. In the next step, the rearrangement is performed using the holes B. Those changeable of their positions into the holes B out of the unit magnetic substance shims arranged based on the optimization results in the first step can be moved their central positions to the holes B. Combinations further improving the magnetic field uniformity by moving out of the holes B are found by a computer calculation.