Speaker
Description
Imaging quality is a critical metric for evaluating the performance of magnetic resonance systems, heavily influenced by the strength and homogeneity of the main magnetic field. While a high degree of homogeneity can theoretically be achieved during the design phase of the main magnet, unavoidable losses in homogeneity occur during manufacturing and assembly processes. The classical target field method for shim coil design constrains current density distribution to a cylindrical surface, expanding it via Fourier series. Magnetic field values derived from Biot-Savart's law and ideal magnetic field values are used to construct a system of equations to solve for the current density distribution. The resulting current density is subsequently discretized using the stream function method. However, discrepancies between the designed and expected outcomes are occasionally observed. This paper presents an improved shim coil design method for a 5T nuclear magnetic resonance (NMR) system, extending the traditional target field method. The proposed method incorporates considerations of wire spacing and coil turns to ensure the final design satisfies the specified requirements.
