In a shimming method for an irregular object to be examined by magnetic
resonant equipment magnetic field parameters are measured at measurement
points located on the surface of an irregular object to be examined.
Based on the measured magnetic field parameters, the positions and number
of shims for adjusting magnetic field homogeneity are calculated when a
passive shimming is to be performed, or the current value in a shimming
coil are calculated when an active shimming is to be performed, or at the
same time both the positions and number of shims and current value in the
shimming coil are calculated when active shimming and passive shimming
are to be performed at the same time. Shimming is then performed
according to the calculated results. These above steps are repeated until
achieving required magnetic field homogeneity. Since the homogeneous
region is designed to have an irregular shape, it can provide a better
coverage of the irregular object to be examined, and at the same time it
reduces the shimming constraints to the unnecessary regions outside the
irregular object to be examined, therefore avoiding shimming in those
unnecessary regions.