| 摘要 |
An MRI system has a cylindrical superconducting magnet assembly contained in a bore tube of a cylindrical vacuum vessel (OVC), and a gradient coil assembly situated within the OVC bore tube. In an imaging region within a bore of the gradient coil assembly, the magnet assembly produces a magnetic field that is subject to drift during operation of the MRI system. Compensating material is located at a radial position between the imaging region and the magnet in a location that will be heated over a range of temperatures during operation of the MRI system. The compensating material is adjustable between two magnetic phases in response to an applied physical characteristic, which is selectively applied thereto so as to change the compensating material from a first magnetization to a second magnetization, and thereby compensate the drift. |
