Active acoustic control in gradient coil design for mri

An acoustically quiet coil design for MRI including a magnetic coil system comprising a first outer coil loop carrying a first current and a second inner coil loop carrying a second current at least a first portion of the first outer coil loop and a portion of the second inner coil loop being embedded in or fixed to a first block of first material of generally rectangular or arcuate shape with predetermined acoustic characteristics and at least a second portion of the first outer coil loop and a second portion of the second inner coil loop being embedded in or fixed to a second block of said first material generally of rectangular or arcuate shape with predetermined acoustic characteristics, said first and second blocks of material being separated by a second material which could be air and in which said first and second coils comprise a generally rectangular or arcuate path and in which at least the second portion of said inner coil is positioned to create a force when energized with said first and second currents appropriately phased either to counter or to assist the force generated by said first portion of said outer coil on at least two opposite sides of each of said blocks said forces being transmitted by columns, struts or ties and in which each portion of each coil comprises a corresponding conductor portion and in which the conductor portion forming the first portion of the first outer coil loop and the opposing second portion of the second inner coil loop is formed to be substantially rigid and in which said stiffened conductor portions are rigidly attached by said columns, struts or ties to form a substantially rigid structure.

A method of providing an acoustically quiet coil design for MRI including a magnetic coil system consisting of at least four sectors each sector comprising a first outer coil loop carrying a first current and a second inner coil loop carrying a second current at least a first portion of the first outer coil loop and a first portion of the second inner coil loop being embedded in or fixed to a first block of first material of generally rectangular or arcuate shape with predetermined acoustic characteristics and at least a second portion of the first outer coil loop and a second portion of the second inner coil loop being embedded in or fixed to a second block of said first material generally of rectangular or arcuate shape with predetermined acoustic characteristics, said first and second blocks of material being separated by a second material which could be air and in which said first and second coils comprise a generally rectangular or arcuate path and in which at least the second portion of said inner coil is positioned to create a force when energized with said first and second currents appropriately phased either to counter or assist the force generated by said first portion said outer coil on at least two sides of each of said blocks said forces being transmitted by columns, struts or ties and in which each portion of each coil comprises a corresponding conductor portion and in which the conductor portion forming the first portion of the first outer coil loop and the opposing second portion of the second inner coil loop is formed to be substantially rigid and in which said stiffened conductor portions are rigidly attached by said columns, struts or ties to form a substantially rigid structure.