Multi-Channel, Actively Shielded, Power Efficient MRI Z-Gradient Cylindrical Coil Design Using Target-Field Method

Gradient coils are essential for MRI where fast and large electrical current pulses are typically applied to conventional, single-channel gradient coils, particularly for high-performance gradient applications. However, these pulses result in significant power losses and heating of the coil. We inve...

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Bibliographic Details
Published in:IEEE access 2022, Vol.10, p.103840-103851
Main Authors: Kassahun, Haile Baye, Alsharafi, Sadeq S, Badawi, Ahmed M, El-Sharkawy, Abdel-Monem M
Format: Article
Language:English
Subjects:
and target-field method
Coils
Coils (windings)
Current density
Current pulses
Design optimization
Design parameters
Energy dissipation
Fourier series
Gradient coil array
Linear equations
Magnetic noise
Magnetic resonance imaging
Magnetic shielding
Mathematical models
MRI
power dissipation
Power efficiency
Series expansion
stream function
Windings
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Summary:Gradient coils are essential for MRI where fast and large electrical current pulses are typically applied to conventional, single-channel gradient coils, particularly for high-performance gradient applications. However, these pulses result in significant power losses and heating of the coil. We investigate the design of power-efficient multi-channel Z-gradient coils operating in the conventional mode comparing them to conventional single-channel coils designed using similar dimensions and alike DC performance characteristics. The power-efficiencies of thirteen different two-channel configurations having various section lengths for two different dimensions are analyzed. The current density of each section is approximated by Fourier series expansion where a linear equation relating the desired target field and current density is formulated and then solved. A stream function is derived from the obtained current density and then used to extract the final winding patterns of each section using a particular track width and a specific number of turns. The design process involves optimizing the current driving each channel, the distribution of coil windings, and the section size. Similarly, the performance of three-channel coils is also investigated. Results show that a power dissipation reduction of 17-28% and ~23% can be achieved using two- and three-channel coils, respectively. Moreover, we showed that multi-channel coils may have a slightly better shielding efficiency compared to conventional coils. A new methodology for designing two- and three-channel coils is presented where an advantage in terms of power efficiency can be gained depending on design parameters, coil's dimensions, number of turns, and other metrics.
ISSN:2169-3536
2169-3536
DOI:10.1109/ACCESS.2022.3210194