| 摘要 |
A method for designing an electromagnetic gradient coil for magnetic resonance imaging systems. The method includes the steps of: choosing a set of objectives Li, whereby the objectives Li are combined to one weighted-sum objective function; choosing a design variable ψ for modifying the value of the objectives L; making an initial guess of the value of the design variable ψ; simulating the magnetic field in a computational domain with respect to the distribution of the surface current density; carrying out a sensitivity analysis by calculating a sensitivity vector G=∂L/∂ψ; updating the design variable ψ, whereby the value of the design variable ψ is changed in order to decrease the value of the objective L; determining whether convergency is achieved by either determining whether the value of the objective function does not decrease or the whether the Euclidian norm of the sensitivity vector G approximate to zero; and reconstruction of a discretized coil. The simulation of the magnetic field in a computational domain is effected using a least square finite element analysis. The steps are repeated prior to reconstruction of a discretized coil until convergency is achieved. An effective and improved design for irregular surfaces is thereby created.
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