Purpose: Advantages of magnetic resonance imaging (MRI) in medicine is well known and crucial, but developing a portable MRI device is challenging. A magnet system used to create a static magnetic field (B₀) in a portable MRI scanner should be simple, and lightweight. A lightweight Halbach magnet system might be used to yield suitable B₀ for portable MRI scanners. In this study, a lightweight Halbach magnet system was designed and its performance was evaluated for portable MRI scanners.
Methods: In this study, B₀ was formed with multiple layer dipole Halbach rings that consist of octagon shape NdFeB (neodymium-iron-boron) permanent magnets. Two Halbach rings were placed facing each other with the same magnetization direction. Aluminum was chosen as the holder material. Investigation of the obtained magnetic field was made with Comsol Multiphysics simulations. Homogeneity of the magnetic field was also calculated.
Results: As a result of the simulations, 0.37 T magnetic field was obtained and its stability was achieved along 60 mm on the x-axis, 38 mm on the y-axis, and 32 mm on the z-axis. Gradient results were also obtained from the permanent magnets system.
Conclusion: Nested Halbach rings were used for the magnet system of portable MRI scanners. We present the light and inexpensive magnet design, but more studies should be done for a better understanding of the system. Homogeneity of the system and also the field of view (FOV) should be improved with further studies.
Funding Support, Disclosures, and Conflict of Interest: This work was supported by the Technological Research Council of Turkey through TUBITAK Grants (115E776 & 115E777). No conflict of interest.