Title :
Passive shimming of the superconducting magnet for MRI
Author :
Belov, A. ; Bushuev, V. ; Emelianov, M. ; Eregin, V. ; Severgin, Yu. ; Sytchevski, S. ; Vasiliev, V.
Author_Institution :
Efremov (D.V.) Sci. Res. Inst. of Electrophys. Apparatu, St. Petersburg, Russia
fDate :
6/1/1995 12:00:00 AM
Abstract :
The method of passive shimming of homogeneous magnets is presented. The simple regular configuration of the thin iron strips is used. Positions of the strips are optimized by computer simulation and independent of the field distribution, i.e. remain the same despite magnet modification. The variable parameter for field correction is the number of strips on each position. Contribution of shims to the field distribution is defined by computer simulation. The number of strips is calculated by a regularized least square method taking into account point field measurements in the working volume. This method was successfully used for correction of the field of the 0.3 T superconducting magnet for MRI with large initial unhomogeneities. The results are presented.<>
Keywords :
NMR imaging; least squares approximations; magnetic fields; simulation; superconducting magnets; 0.3 T; MRI; computer simulation; homogeneous magnets; magnetic field correction; passive shimming; point field measurements; regularized least square method; superconducting magnet; thin iron strips; Azimuth; Coils; Computer simulation; Iron; Magnetic field measurement; Magnetic resonance imaging; Saturation magnetization; Solenoids; Strips; Superconducting magnets;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
