Lightweight asymmetric magnet arrays
First Claim
1. A magnet array for use in a Magnetic Resonance Imaging (MRI) system, the magnet array comprising:
- multiple magnet rings, which are made of a permanent magnet material, and which are positioned along a longitudinal axis and are coaxial with the longitudinal axis, wherein at least one of the magnet rings encircles a predefined imaging volume of the MRI system, wherein the magnet rings are divided into (i) a first assembly characterized by a first minimal inner radius that is smallest among inner radii of the magnet rings of the first assembly, and (ii) a second assembly positioned alongside the first assembly along the longitudinal axis and characterized by a second minimal inner radius that is smallest among the inner radii of the magnet rings of the second assembly, wherein the first minimal inner radius of the first assembly is larger than the second minimal inner radius of the second assembly, wherein a center of the imaging volume is located outside the second assembly, and wherein at least one of the magnet rings in the first assembly has a non-zero inner radius and has a longitudinal magnetization component along the longitudinal axis, the magnet rings configured to jointly generate a magnetic field of at least a given level of uniformity inside the imaging volume; and
a frame, which is configured to fixedly hold the multiple magnet rings in place.
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Accused Products
Abstract
A magnet array includes multiple magnet rings and a frame. The multiple magnet rings are positioned along a longitudinal axis and are coaxial with the longitudinal axis. At least one of the magnet rings encircles a predefined inner volume. A minimal inner radius of the magnet rings positioned on one side of a center of the inner volume along the longitudinal axis is different from the minimal radius of the magnet rings positioned on the other side of the center of inner volume. The magnet rings are configured to jointly generate a magnetic field of at least a given level of uniformity inside the inner volume. The frame is configured to fixedly hold the multiple magnet rings in place.
52 Citations
28 Claims
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1. A magnet array for use in a Magnetic Resonance Imaging (MRI) system, the magnet array comprising:
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multiple magnet rings, which are made of a permanent magnet material, and which are positioned along a longitudinal axis and are coaxial with the longitudinal axis, wherein at least one of the magnet rings encircles a predefined imaging volume of the MRI system, wherein the magnet rings are divided into (i) a first assembly characterized by a first minimal inner radius that is smallest among inner radii of the magnet rings of the first assembly, and (ii) a second assembly positioned alongside the first assembly along the longitudinal axis and characterized by a second minimal inner radius that is smallest among the inner radii of the magnet rings of the second assembly, wherein the first minimal inner radius of the first assembly is larger than the second minimal inner radius of the second assembly, wherein a center of the imaging volume is located outside the second assembly, and wherein at least one of the magnet rings in the first assembly has a non-zero inner radius and has a longitudinal magnetization component along the longitudinal axis, the magnet rings configured to jointly generate a magnetic field of at least a given level of uniformity inside the imaging volume; and a frame, which is configured to fixedly hold the multiple magnet rings in place. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for producing a magnet array for use in a Magnetic Resonance Imaging (MRI) system, the method comprising:
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positioning multiple magnet rings, which are made of a permanent magnet material, along a longitudinal axis, coaxially with the longitudinal axis, wherein at least one of the magnet rings encircles a predefined imaging volume of the MRI system, wherein the magnet rings are divided into (i) a first assembly characterized by a first minimal inner radius that is smallest among inner radii of the magnet rings of the first assembly, and (ii) a second assembly positioned alongside the first assembly along the longitudinal axis and characterized by a second minimal inner radius that is smallest among the inner radii of the magnet rings of the second assembly, wherein the first minimal inner radius of the first assembly is larger than the second minimal inner radius of the second assembly, wherein a center of the imaging volume is located outside the second assembly, and wherein at least one of the magnet rings in the first assembly has a non-zero inner radius and has a longitudinal magnetization component along the longitudinal axis, the magnet rings configured to jointly generate a magnetic field of at least a given level of uniformity inside the imaging volume; and fixedly holding the multiple magnet rings in place using a frame. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A magnet array for use in a Magnetic Resonance Imaging (MRI) system, the magnet array comprising:
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multiple magnet rings, which are made of a permanent magnet material, and which are positioned along a longitudinal axis and are coaxial with the longitudinal axis, wherein at least one of the magnet rings encircles a predefined imaging volume of the MRI system, wherein the magnet rings are arranged with reflectional asymmetry with respect to the longitudinal axis, wherein each magnet ring has a rotational symmetry with respect to an in-plane rotation of the magnet ring around the longitudinal axis, and wherein at least one of the magnet rings has a non-zero inner radius and has a longitudinal magnetization component along the longitudinal axis, the magnet rings configured to jointly generate a magnetic field of at least a given level of uniformity inside the imaging volume; and a frame, which is configured to fixedly hold the multiple magnet rings in place.
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28. A method for producing a magnet array for use in a Magnetic Resonance Imaging (MRI) system, the method comprising:
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positioning multiple magnet rings, which are made of a permanent magnet material, along a longitudinal axis, coaxially with the longitudinal axis, wherein at least one of the magnet rings encircles a predefined imaging volume of the MRI system, wherein the magnet rings are arranged with reflectional asymmetry with respect to the longitudinal axis, and wherein each magnet ring has a rotational symmetry with respect to an in-plane rotation of the magnet ring around the longitudinal axis, and wherein at least one of the magnet rings has a non-zero inner radius and has a longitudinal magnetization component along the longitudinal axis, the magnet rings configured to jointly generate a magnetic field of at least a given level of uniformity inside the imaging volume; and fixedly holding the multiple magnet rings in place using a frame.
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Specification