Self-shielded split gradient coil

Abstract

Gradient coil assemblies for horizontal magnetic resonance imaging systems (MRIs) and methods of their manufacture. Some embodiments may be used with open MRIs and can be used with an instrument placed in the gap of the MRI. In general, concentrations of conductors or radially oriented conductors may be moved away from the gap of the MRI so as to reduce eddy currents that may be induced in any instrument placed within the gap. Systems for directly cooling primary gradient and shield coils may be utilized and various coil supporting structures may be used to assist in coil alignment or to facilitate use of an instrument in the MRI gap.

1 - 20 . (canceled) 
     
     
         21 . A gradient coil assembly for a horizontal open magnetic resonance imaging system (MRI), the open MRI having a longitudinal axis and a first magnet and a second magnet separated by a gap, the gradient coil assembly comprising:
 a first plurality of shielding coils located between the first magnet and the longitudinal axis;   a second plurality of shielding coils located between the second magnet and the longitudinal axis;   a first plurality of primary gradient coils located between the first plurality of shielding coils and the longitudinal axis;   a second plurality of primary gradient coils located between the second plurality of shielding coils and the longitudinal axis; and   a supporting structure containing the first and second plurality of shield coils and the first and second plurality of primary gradient coils,   wherein the supporting structure includes a portion traversing the gap for facilitating alignment of the first and second pluralities of coils.   
     
     
         22 . The gradient coil assembly of  claim 21 , wherein the gradient coil assembly is of a singular construction. 
     
     
         23 . The gradient coil assembly of  claim 21 , wherein the portion of the supporting structure traversing the gap is a portion of a continuous former. 
     
     
         24 . The gradient coil assembly of  claim 21 , wherein the portion of the supporting structure traversing the gap has a radiation attenuation value that is uniform across the structure. 
     
     
         25 . The gradient coil assembly of  claim 21 , wherein the portion that traverses the gap comprises an epoxy-fiberglass or epoxy-carbon fiber structure. 
     
     
         26 . The gradient coil assembly of  claim 21 , wherein the portion that traverses the gap has a thickness of approximately 5 mm. 
     
     
         27 . The gradient coil assembly of  claim 21 , wherein the portion that traverses the gap has a density of less than or equal to 2 g/cm 3 .