Resonant inductive coupling network for human-sized magnetic particle imaging

Fabian Mohn; Fynn Förger; Florian Thieben; Martin Möddel; Ingo Schmale; Tobias Knopp; Matthias Graeser

doi:10.1063/5.0192784

Resonant inductive coupling network for human-sized magnetic particle imaging

Rev Sci Instrum. 2024 Apr 1;95(4):044701. doi: 10.1063/5.0192784.

Authors

Fabian Mohn^{1

2}, Fynn Förger^{1

2}, Florian Thieben^{1

2}, Martin Möddel^{1

2}, Ingo Schmale³, Tobias Knopp^{1

2

4}, Matthias Graeser^{4

5}

Affiliations

¹ Institute for Biomedical Imaging, Hamburg University of Technology, 21073 Hamburg, Germany.
² Section for Biomedical Imaging, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany.
³ Philips GmbH Innovative Technologies, Research Laboratories, 22335 Hamburg, Germany.
⁴ Fraunhofer Research Institution for Individualized and Cell-based Medical Engineering, IMTE, 23562 Lübeck, Germany.
⁵ Institute of Medical Engineering, University of Lübeck, 23562 Lübeck, Germany.

PMID: 38557882
DOI: 10.1063/5.0192784

Abstract

In magnetic particle imaging, a field-free region is maneuvered throughout the field of view using a time-varying magnetic field known as the drive-field. Human-sized systems operate the drive-field in the kHz range and generate it by utilizing strong currents that can rise to the kA range within a coil called the drive field generator. Matching and tuning between a power amplifier, a band-pass filter, and the drive-field generator is required. Here, for reasons of safety in future human scanners, a symmetrical topology and a transformer called an inductive coupling network are used. Our primary objectives are to achieve floating potentials to ensure patient safety while attaining high linearity and high gain for the resonant transformer. We present a novel systematic approach to the design of a loss-optimized resonant toroid with a D-shaped cross section, employing segmentation to adjust the inductance-to-resistance ratio while maintaining a constant quality factor. Simultaneously, we derive a specific matching condition for a symmetric transmit-receive circuit for magnetic particle imaging. The chosen setup filters the fundamental frequency and allows simultaneous signal transmission and reception. In addition, the decoupling of multiple drive field channels is discussed, and the primary side of the transformer is evaluated for maximum coupling and minimum stray field. Two prototypes were constructed, measured, decoupled, and compared to the derived theory and method-of-moment based simulations.