摘要:
A method for shimming a magnetic resonance imaging magnet requiring higher magnetic field homogneity on a small imaging volume and by magnetic field measurements on a larger volume providing small measurement error and practical field strength measurements and utilizing the spherical harmonic coefficients of the measurements.
摘要:
In the installation of a superconducting magnet for magnetic resonance imaging at a preselected position in a mobile van, preselected curvilinear magnetic segments are applied to preselected locations on the exterior of the magnet to counteract magnet inhomogeneities in the imaging bore which would otherwise occur because of magnetic material in the van structure.
摘要:
A superconducting magnet electrical circuit is provided for quench protection. A superconducting coil assemblage is provided including a plurality of spatially separated main and secondary magnet coil portions. The main magnet coil portions are connected in series to form at least one main coil series circuit. The secondary magnet coil portions are also connected in a series to form at least one secondary coil series circuit. At least one temperature limiting circuit is also provided. The temperature limiting circuit may be a quench heater circuit or a quench resistor circuit. The temperature limiting circuit has a plurality of quench heaters or a plurality of quench resistors connected with the superconducting coil assemblage. A superconductive switch is coupled with the superconducting coil assemblage.
摘要:
An apparatus and method for shimming a magnetic field of a magnet in a volume of interest includes a nonmagnetic holder configured with an array of fluid containing pockets; and a solidified ferromagnetic fluid in each pocket of the array of fluid containing pockets, wherein the solidified ferromagnetic fluid is fabricated from a ferromagnetic fluid, a diluting liquid, a hardener, and an accelerator agent. The ferromagnetic fluid includes a carrier liquid, ferromagnetic particles, and a surfactant.
摘要:
An apparatus and method for shimming a magnetic field of a magnet in a volume of interest includes a nonmagnetic holder configured with an array of fluid containing pockets; and a solidified ferromagnetic fluid in each pocket of the array of fluid containing pockets, wherein the solidified ferromagnetic fluid is fabricated from a ferromagnetic fluid, a diluting liquid, a hardener, and an accelerator agent. The ferromagnetic fluid includes a carrier liquid, ferromagnetic particles, and a surfactant.
摘要:
A multi purpose interconnect assembly between upper and lower helium vessels in a recondensing superconducting magnet to provide isothermal connections to extend the ride-through period, and to provide for helium liquid and gas passage, electrical interconnections, and to accommodate differential thermal contraction and expansion.
摘要:
A system and a method for magnetizing one of a plurality of substantially non-magnetized blocks disposed on a plate of a magnetic assembly used in an MRI device are provided. The system includes first and second arm portions operably coupled together. The system further includes a first electromagnetic coil disposed on a first end of the first arm portion, wherein the first electromagnetic coil is configured to generate a magnetic field that propagates from the first electromagnetic coil through at least one non-magnetized block and the plate and further through the first and second arm portions to magnetize the block.
摘要:
Disclosed herein is a method for assembling a magnetic field generator for a magnetic resonance imaging system. The method comprises: establishing an arrangement for a permanent magnet of a magnet assembly comprising a ferromagnetic yoke plate and a permanent magnet, wherein the arrangement includes a portion of a cavity formed from placement of a portion of a plurality of retainers attached at substantially the perimeter of the yoke plate. The method also includes populating the first portion of the cavity with a set of rails attached to the yoke plate and affixing a plurality of gliders to a plurality of magnet blocks and magnetizing the gliders and magnet blocks to form a plurality of block assemblies. Finally, the method includes sliding each block assembly of the plurality of block assemblies along a rail of the set of rails; initiating with an outermost rail and concluding with an innermost, securing each successively filled rail with a retainer.
摘要:
An open architecture Magnetic Resonance Imaging Magnet with a pair of spaced annular superconducting magnet assemblies utilizing a cantilevered main magnet coil and correction magnet coil within each assembly.
摘要:
Disclosed herein is a magnetic field generator and method for assembling the same for a magnetic resonance imaging system, the method comprising: establishing a layout for a permanent magnet of a magnet assembly comprising a pole piece, a ferromagnetic plate yoke and a permanent magnet. The method also includes populating the layout with a plurality of mock-up sticks and block retainers to form a mock layout for the permanent magnet; and installing a magnet block in place of at least one mock-up stick of the plurality of mock-up sticks. Installing the magnet blocks includes pushing the magnet block along a selected slot formed by the displacement of at least one mock-up stick of the plurality of mock-up sticks.