Abstract: A permanent magnet assembly for an imaging apparatus having a permanent magnet body having a first surface and a stepped second surface which is adapted to face an imaging volume of the imaging apparatus, wherein the stepped second surface contains at least four steps.

Abstract: A method for graphical visualization of a measured magnetic field on an imaging volume of a MRI magnet includes providing data values measured at selected points of the measured magnetic field, converting each of the data values to a visualizable value based on where the data value lies within a predetermined range of data values and thus within a range of visualizable values corresponding to the range of data values, and plotting each visualizable value corresponding to each data value at a position on a grid corresponding to the position of the selected point of the measured magnetic field such that the visualizable values once plotted on the grid provide a graphical visualization of the condition of the measured magnetic field.

Abstract: A method for generating a ferromagnetic shim calibration file includes the steps of performing a computation of an analytical Finite Element solution of an internal magnetic field for each location where a shim is assumed to be present in an imaging volume of a magnet, performing a computation of an equivalent magnetic dipole moment of a shim with a saturated magnetization using the analytical Finite Element solution of the internal magnetic field, making a correction of the computation of the equivalent magnetic dipole moment of the shim to compensate for an aspect ratio for the shape of the shim, making another correction of the corrected computation of the equivalent magnetic dipole moment of the shim to compensate for a magnetic mirror effect in a pole-face of the magnet, and storing all computations and corrections for each shim in a shim calibration file.

Abstract: A method for generating a ferromagnetic shim calibration file includes the steps of performing a computation of an analytical Finite Element solution of an internal magnetic field for each location where a shim is assumed to be present in an imaging volume of a magnet, performing a computation of an equivalent magnetic dipole moment of a shim with a saturated magnetization using the analytical Finite Element solution of the internal magnetic field, making a correction of the computation of the equivalent magnetic dipole moment of the shim to compensate for an aspect ratio for the shape of the shim, making another correction of the corrected computation of the equivalent magnetic dipole moment of the shim to compensate for a magnetic mirror effect in a pole-face of the magnet, and storing all computations and corrections for each shim in a shim calibration file.

Abstract: A method for graphical visualization of a measured magnetic field on an imaging volume of a MRI magnet includes providing data values measured at selected points of the measured magnetic field, converting each of the data values to a visualizable value based on where the data value lies within a predetermined range of data values and thus within a range of visualizable values corresponding to the range of data values, and plotting each visualizable value corresponding to each data value at a position on a grid corresponding to the position of the selected point of the measured magnetic field such that the visualizable values once plotted on the grid provide a graphical visualization of the condition of the measured magnetic field.

Abstract: A shim assembly for a magnet and a method for making a shim assembly. A first spool has a shaft, a first rim attached to a first longitudinal end of the shaft, and a second rim attached to a second longitudinal end of the shaft. A first magnetizable tape has a predetermined length and is wound around the shaft longitudinally between the first and second rims.

Abstract: A magnet having an imaging volume, a pole piece with a laminated portion including a first surface hole, a non-magnetizable first insert with an internally-threaded hole, and a first shim with a shape of an externally-threaded bolt. The first insert is positioned in the first surface hole and is attached to the pole piece. The first shim is threaded into the hole of the first insert. Additional shims for additional inserts for additional surface holes are used to shim the magnet to reduce magnetic field inhomogeneities in the imaging volume.

Abstract: A compression molding apparatus includes a mold of a first material having a first coefficient of thermal expansion and a plug of a second material having a second coefficient of thermal expansion different from the first coefficient of thermal expansion. The mold has a cavity into which the plug is placed such that the mold and plug are disposed relative to one another providing a gap therebetween having a first volume for holding a body that at least partially fills the gap when the mold and plug are at a first temperature and for molding the body into a molded product when the mold and plug are subjected to a second temperature that causes one of the first and second materials of the mold and plug to change in size more than the other and thereby change the gap to a second volume different from the first volume and compress the body.

Abstract: A dehumidifier for an x-ray detector includes a box having an inlet, an outlet, and a drain. A thermo-electrical element includes a cold plate disposed inside the box for cooling air channeled therethrough, and an opposite hot plate disposed outside the box for liberating heat. Air is cooled inside the box for condensing moisture therefrom which is removed by the drain, and the cooled air is heated for reducing relative humidity thereof. The resulting dry air is channeled to a housing protecting the x-ray detector.

Abstract: A shim assembly for a pole face of a magnet. A non-magnetizable shim tray may be positioned proximate, and preferably is attachable to, the pole face. The positioned shim tray has a surface hole having longitudinally adjacent first and second portions. The second portion has a generally circular circumference. The first portion has a perimeter generally identical to the circumference but with, for example, a flat region. A shim holder has a perimeter generally identical to the perimeter of the first portion so that it may be inserted through the first portion and into the second portion of the surface hole. A predetermined shim is removably attachable to the shim holder. The inserted shim holder, with the attached shim, is rotatable, and, when so rotated, the flat regions of the perimeters of the shim holder and the second portion of the surface hole are misaligned.