Consideration on Current and Coil Block Placements With Good Homogeneity for MRI Magnets Using Truncated SVD

Abe, Mitsushi; Shibata, Kouichi

doi:10.1109/tmag.2012.2236564

Cited by 10 publications

(9 citation statements)

References 20 publications

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“…Considerations 3) and 4) are not discussed in this paper. The magnetic design is done based on the MRI technologies (they are technologies of magnetic design, persistent operation, structural design, quench protection and zero liquid helium boil-off) and following limitations [7,8,9,10]. The CB current density (Cd) is around 125 A/mm2 and maximum magnetic field on each CB (B MXC ) is less than 5.5 T. These parameters are corresponding to around 65 % load factor and consistent with the NbTi superconducting wire for MRI magnets.…”

Section: Specifications and Design Baselinesmentioning

confidence: 99%

“…Trials of rCB placements were done and placements with small residual FL currents was chosen. The optimizations are done by tuning the eigenmode strengths [9,10]. The magnetic field is divided into two components (Fig.…”

Section: Figure 3 Is Amentioning

confidence: 99%

“…Since the conventional injection scheme is not applicable, we have discussed a three-dimensional (3D) spiral injection scheme and determined that the new injection scheme is suitable for the precise beam control in such a compact ring [5,6]. We expect such homogeneous magnetic field can be realized by a superconducting magnet using MRI technologies [7,8], which are the determination method of magneto-motive force placements (coil blocks (CBs) placements [9,10] and iron pole optimizations [11]) in MRI magnet design, and the shimming calculation method to obtain iron piece placements for magnetic field shimming [12,13], using SVD (singular value decomposition) regularization [14,15], as well as superconducting aspects of MRI magnets including the persistent current operation. Using the compact magnet with these technologies, we expect that residual and error fields are much reduced from those of previous measurements.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Magnetic Design of a Superconducting Magnet for Muon g-2/EDM Precise Measurements in a Cylindrical Volume with Homogeneous Magnetic Field

Abe

Iinuma

Murata

et al. 2019

Proceedings of the 3rd International Symposium of Quantum Beam Science at Ibaraki University "Quantum Beam Science in Biology A

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For g-2/EDM precise measurements, a magnet, with a very homogeneous (±0.1 ppm) 3.0 T magnetic field in cylindrical muon storage volume (MSV: 0.333 m radius with 3.0 cm thickness and 10.0cm height) and without negative radial field B R in the spiral injection region (Z > 0.0 cm), is necessary. A design method of magneto-motive force (coil blocks (CBs) and iron-yoke with poles) placements, developed for MRI magnets, has been applied. Candidate placements are calculated under superconducting limitations. The two-dimensional (2D) placements are determined by tuning SVD (singular value decomposition) eigenmode strengths and the SVD is applied on a response matrix from magneto-motive forces to the magnetic fields in the muon storage region. Magnetic field ripples in the azimuthal direction are minimized. The candidate has five CBs and an iron-yoke with center iron-poles and satisfies the specifications.

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Section: Specifications and Design Baselinesmentioning

confidence: 99%

Section: Figure 3 Is Amentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Magnetic Design of a Superconducting Magnet for Muon g-2/EDM Precise Measurements in a Cylindrical Volume with Homogeneous Magnetic Field

Abe

Iinuma

Murata

et al. 2019

Proceedings of the 3rd International Symposium of Quantum Beam Science at Ibaraki University "Quantum Beam Science in Biology A

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“…MRI Magnets are designed with adequate coil block (CB) placements to have the capabilities to produce sufficient homogeneities. 3 – 5 However, the magnets have some errors in their static magnetic fields due to manufacturing tolerances on CB placements and magnetic site environment. Each just manufactured magnet is subjected to a magnetic field correction procedure called shimming work to ensure they have a designed homogeneous magnetic field at the installation site.…”

Section: Introductionmentioning

confidence: 99%

“…SVD has been applied to CB placements in MRI magnet design, 3 , 4 which are done by tuning the large singular value (low ordered) eigenmodes. Such eigenmodes have significant magnetic field strengths.…”

Section: Introductionmentioning

confidence: 99%

Passive Shimming of MRI Static Magnetic Field Using Regularization of Truncated Singular Value Decomposition

Abe¹

2017

magn reson med sci

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Purpose:To develop a new shimming calculation method, which can calculate iron piece placements rapidly to make the magnetic field homogeneous at intended homogeneity and then to make the shimming working time short.Materials and Methods:The shimming calculation yields magnetic moment (MM) distribution, which is calculated by the truncated singular value decomposition (SVD) from the measured magnetic field. The MM distribution is described by a superposition of eigenmodes obtained by SVD of a response matrix from the moment distributions to magnetic fields at the field of view (FOV). The homogeneity is regulated by a truncation number of the superposed eigenmodes. The magnetic moments are converted into iron volumes with the assumption of saturated magnetization and the iron pieces are placed according to the calculation results. Since the SVD calculation can be done in advance, the computational time at the shimming site is short.Results:Trial applications on a 0.5T magnetic resonance imaging (MRI) magnet were done using the new shimming calculation method, which was proved to work well. However, since the iron piece volumes had tolerances, the work was repeated until enough homogeneity was obtained. As a result, an intended homogeneity of 8.9 ppm (peak-to-peak) on 40 cm diameter spherical surface was successfully obtained from measured homogeneity of 543 ppm with short computational and working time.Conclusion:The test shimming work showed that the developed shimming calculation method with truncated SVD regularization is applicable to the shimming work on the MRI magnets.

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Three-dimensional spiral injection scheme for the g−2/EDM experiment at J-PARC

Iinuma

Nakayama

Oide

et al. 2016

Nuclear Instruments and Methods in Physics Research Section A:

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Consideration on Current and Coil Block Placements With Good Homogeneity for MRI Magnets Using Truncated SVD

Cited by 10 publications

References 20 publications

Magnetic Design of a Superconducting Magnet for Muon g-2/EDM Precise Measurements in a Cylindrical Volume with Homogeneous Magnetic Field

Magnetic Design of a Superconducting Magnet for Muon g-2/EDM Precise Measurements in a Cylindrical Volume with Homogeneous Magnetic Field

Passive Shimming of MRI Static Magnetic Field Using Regularization of Truncated Singular Value Decomposition

Three-dimensional spiral injection scheme for the g−2/EDM experiment at J-PARC

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