Room: Exhibit Hall | Forum 8
Purpose: Magnetic gradient field of a newly emerging and developing Magnetic Particle Imaging (MPI) scanner is modeled and simulated in COMSOL Multiphysics software. The magnetic particle imaging scanner uses gradient field to define field of view (FOV) and generate field free point (FFP) which is used to localize the superparamagnetic nanoparticles (SPIONs). Selection field setup of (-3.25, -3.25, 6.5) T/m gradient is simulated in (x,y,z) directions for 3D imaging scanner. Homogeneity is one of the key factors in MPI performance, so it is thoroughly analyzed at point of interest region.
Methods: Gradient fields for 3D MPI scanner was modeled and simulated by using AC/DC module in COMSOL Multiphysics 5.3a. High gradient field increases resolution of the medical imaging; to achieve high homogeneity, Maxwell configuration was preferred for selection field modeling. Two pairs of disc shape NdFeB permanent magnets (PM) distinct diameters and thicknesses were used to design selection field of desired gradient. Opposite pole placement of the magnet pairs produced the FFP at midpoint over the aligned axis. N50 permanent magnets were used which has a remanent flux density of 1.39 T. Outer and inner permanent magnets have radiuses 10 cm and 6.92 cm, respectively. The inner space of this setup is 10 cm along the z-axis which will be used to place three drive, and three receive coils.
Results: The magnetic flux density (T) of 0.72 ÂµT was measured at the midpoint (0, 0, 0) of the selection field setup, due to very weak field strength it was considered as FFP practically. Homogeneity of 96% was measured in the gradient field within 5 cm range around the FFP along the z-axis.
Conclusion: Virtual implementation of selection field helps to design permanent magnets for required specifications; e.g. gradient field strength, homogeneous field range. It is a time-saving and cost-effective method.
Funding Support, Disclosures, and Conflict of Interest: The present work was supported by the TUBITAK (Project number:115E776 & 115E777).
Magnetic Fields, High-resolution Imaging, Modeling
IM- Multi-modality imaging systems: Development (new technology and techniques)