US 6,714,109 B1Granted

Method of shimming a magnetic field

AssigneeFonar Corporation

InventorsJoseph F. Rimkunas, William H. Wahl

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Abstract

A process for adjusting an homogeneity of a magnetic field produced by a magnet having a pole includes placing a spherically-shaped magnetic shim element within the magnetic field so as to become magnetized and have a localized effect on the magnetic field. The magnetic field is mapped to provide an original field map, and a sphere action is selected that will adjust the homogeneity of the magnetic field. An effect on the magnetic field caused by the selected sphere action is calculated and combined with the original field map, to provide an adjusted field map, which is compared with the original field map. Based on the comparison, it is determined if the adjusted field map indicates a satisfactory adjustment of the homogeneity of the magnetic field, in which case the selected sphere action is performed.

Claims41

Dependent claims

A process for adjusting an homogeneity of a magnetic field produced by a magnet having a pole, comprising:

mapping the magnetic field to provide an original field map;
selecting a sphere action that will adjust the homogeneity of the magnetic field, wherein the selected sphere action is selected from the group consisting of adding, removing, and replacing a spherically-shaped magnetic shim element within the magnetic field so as to become magnetized and have an effect on the magnetic field;
calculating an effect on the magnetic field caused by the selected sphere action;
combining the calculated effect on the magnetic field of the selected sphere action with the original field map, to provide an adjusted field map;
comparing the adjusted field map with the original field map;
determining, based on the comparison, if the adjusted field map indicates a satisfactory adjustment of the homogeneity of the magnetic field;
and
performing the selected sphere action to adjust the homogeneity of the magnetic field, if it is determined that the adjusted field map indicates a satisfactory adjustment of the homogeneity of the magnetic field.

5 more elements

A process for adjusting an homogeneity of a magnetic field produced by a magnet having a pole, comprising:

placing at least one spherically-shaped magnetic shim element within the magnetic field so as to become magnetized and have an effect on the magnetic field;
mapping the magnetic field to provide an original field map;
selecting a sphere action that will adjust the homogeneity of the magnetic field, wherein the selected sphere action is selected from the group consisting of adding, removing, and replacing at least one of the spherically-shaped magnetic shim elements within the magnetic field so as to become magnetized and have an effect on the magnetic field;
calculating an effect on the magnetic field caused by the selected sphere action;
combining the calculated effect on the magnetic field of the selected sphere action with the original field map, to provide an adjusted field map;
comparing the adjusted field map with the original field map;
determining, based on the comparison, if the adjusted field map indicates a satisfactory adjustment of the homogeneity of the magnetic field;
and
performing the selected sphere action to adjust the homogeneity of the magnetic field, if it is determined that the adjusted field map indicates a satisfactory adjustment of the homogeneity of the magnetic field.

6 more elements

Dependencies are inferred from the claim text.