The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 26, 2002
Filed:
Jan. 12, 2000
Michael Westphal, Offenbach, DE;
Bruker Analytik GmbH, Rheinstetten, DE;
Abstract
An iterative method of homogenizing the magnetic field in the working volume ( ) of the main field magnet ( ) of a magnetic resonance apparatus uses ferromagnetic homogenizing elements ( ) which are mounted at predetermined positions ( ) on one or more support bodies ( ), wherein in a first measuring step, the profile of the magnetic field is determined through measurements and in a first calculation step, occupation by homogenizing elements ( ) at the predetermined positions ( ) is calculated such that the calculated overall field, i.e. a superposition of the magnetic field of the main field magnet with all homogenizing elements, is approximately homogeneous, wherein in a first compensation step, the calculated number of homogenizing elements is placed at the predetermined positions and subsequently, in a further measuring step, each respective magnetic field profile in the working volume is determined in iterations and afterwards, in a further calculation step, a change in the positions occupied by homogenizing elements is calculated for further improvement of the homogeneity and carried out in a further compensation step. The method is characterized in that the predetermined positions of the homogenizing elements are subdivided into groups having various distances from the geometric center of the working volume and that, starting from the second calculating step and the second compensating step, occupation of the positions of the group with the shortest distances from the center of the working volume is no longer changed. In this manner, it is possible to obtain a reliable convergence of the iteration steps and thus an improvement of the homogeneity of the main magnetic field when the errors in the contributions of the homogenizing elements to the overall magnetic field approach the order of magnitude of the field inhomogeneities being compensated.