3-D optimal shape design of pole piece in permanent magnet MRI using parameterized nonlinear design sensitivity analysis

Ryu, Jae Seop; Yao, Yingying; Koh, Chang Seop; Shin, Yung Woo

doi:10.1109/tmag.2006.871563

Cited by 19 publications

(2 citation statements)

References 6 publications

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“…The two discs are connected by a ferromagnetic yoke (usual made of steel), which is not magnetically saturated, but which increases the magnetic field strength between the two discs. There is an optimum spacing between the discs, in relation to the radius of each disc, which maximizes the B0 field homogeneity [ 38 , 39 ]. To further improve the homogeneity, smaller permanent magnets can be placed in suitable locations and/or electrical systems for shimming incorporatedfor low-field MRI applications [ 34 , 35 , 40 , 41 ].…”

Section: System Design For Poc Systemsmentioning

confidence: 99%

Tackling SNR at low-field: a review of hardware approaches for point-of-care systems

Webb

O’Reilly

2023

Magn Reson Mater Phy

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Objective To review the major hardware components of low-field point-of-care MRI systems which affect the overall sensitivity. Methods Designs for the following components are reviewed and analyzed: magnet, RF coils, transmit/receive switches, preamplifiers, data acquisition system, and methods for grounding and mitigating electromagnetic interference. Results High homogeneity magnets can be produced in a variety of different designs including C- and H-shaped as well as Halbach arrays. Using Litz wire for RF coil designs enables unloaded Q values of ~ 400 to be reached, with body loss representing about 35% of the total system resistance. There are a number of different schemes to tackle issues arising from the low coil bandwidth with respect to the imaging bandwidth. Finally, the effects of good RF shielding, proper electrical grounding, and effective electromagnetic interference reduction can lead to substantial increases in image signal-to-noise ratio. Discussion There are many different magnet and RF coil designs in the literature, and to enable meaningful comparisons and optimizations to be performed it would be very helpful to determine a standardized set of sensitivity measures, irrespective of design.

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Section: System Design For Poc Systemsmentioning

confidence: 99%

Tackling SNR at low-field: a review of hardware approaches for point-of-care systems

Webb

O’Reilly

2023

Magn Reson Mater Phy

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“…Using splines to define the pole face permits the creation of poles with arbitrary levels of complexity. Splines have been employed in the optimization of axisymmetric MRI magnets [18,19]. The details of this current implementation are discussed in the following section.…”

Section: Splined Polesmentioning

confidence: 99%

Optimization of low aspect ratio, iron dominated dipole magnets

Majernik

Barber

Tilborg

et al. 2019

Phys. Rev. Accel. Beams

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A study of the optimization of iron dominated dipole magnets with pole face widths comparable or less than the gap size, i.e., low aspect ratio (AR), is conducted using both theoretical and computational approaches. This regime of magnet design is particularly relevant in the context of laser plasma accelerators (LPA) due to unique beam parameters and geometric constraints, namely large energy spreads and the requirement for large apertures to accommodate drive laser passage. The breakdown of commonly employed approximations and rules of thumb in typical AR ≫ 1 magnet design is examined. A library of generalized, optimized pole face geometries is provided to expedite optimization of future magnets. Finally, this methodology is used to design an electromagnetic chicane which has been fabricated, validated, and is currently in use in an x-ray free electron laser driven LPA experiment at LBNL.

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