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Design of actively shielded main magnets: an improved functional method

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Abstract

An improved functional approach for designing MRI (magnetic resonance imaging) main magnets with active shielding is presented. By nulling one or two external moments as well as a certain series of internal moments of the magnetic field, new designs with improved shielding in combination with or without shorter magnet lengths are obtained. The improved method can be employed to design short and practical superconducting magnets at any given field strength. The resulting designs yield the desired field homogeneity inside the region of interest without using superconducting shim coils. This approach requires only a modest amount of computing power. One of the design steps, a contour plot of the continuous current solutions, can be utilized to study stretch goals for favorable design parameters.

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Acknowledgements

We thank the following people who have provided many useful discussions in the design of main magnets: Roger Efferson and Roger Wheatley at American Magnetics, Gordon DeMeester and Vishnu Srivastava at Philips Medical Systems, Stuart Crozier at University of Queensland, Australia, and Nick Shaw at University of Cambridge, England. This research is supported by NIH R21 RR15211–01.

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Authors and Affiliations

  1. Department of Physics, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106-7079, USA

    Yu-Chung N. Cheng, Timothy P. Eagan, Robert W. Brown, Shmaryu M. Shvartsman & Michael R. Thompson

  2. Philips Medical Systems (Cleveland) Inc., 595 Miner Road, OH 44143, Highland Heights, USA

    Shmaryu M. Shvartsman & Michael R. Thompson

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  1. Yu-Chung N. Cheng
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  2. Timothy P. Eagan
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  3. Robert W. Brown
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  4. Shmaryu M. Shvartsman
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  5. Michael R. Thompson
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Correspondence to Yu-Chung N. Cheng.

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Cheng, YC.N., Eagan, T.P., Brown, R.W. et al. Design of actively shielded main magnets: an improved functional method. Magn Reson Mater Phy 16, 57–67 (2003). https://doi.org/10.1007/s10334-003-0012-x

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  • DOI: https://doi.org/10.1007/s10334-003-0012-x

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