Method for measuring linearity of gradient magnetic field generated by gradient coils in MRI (magnetic resonance imaging) system

Abstract

The invention relates to a method for measuring the linearity of a gradient magnetic field generated by gradient coils in an MRI (magnetic resonance imaging) system, which is characterized by comprising the steps 1, setting sampling points in an imaging area; 2, acquiring a z-direction magnetic field value generated by the gradient coils at each sampling point; 3, calculating harmonic coefficients A<n, m> and B<n, m> of a z-direction magnetic field according to the z-direction magnetic field value of the sampling point; and 4, calculating the volume root mean square linearity Vrms of the gradient magnetic field according to an integral formula. According to the invention, the volume root square mean linearity Lvrms of the gradient magnetic field is calculated by adopting harmonic coefficient expansion, and three-dimensional volume integrals can be expanded into an expression of the sum of squares of the harmonic coefficients as for a spherical imaging area, thereby having very high efficiency and precision.

Description

technical field [0001] The invention relates to a method for calculating the linearity of a gradient field in an MRI system, in particular to a method for measuring the linearity of a gradient magnetic field generated by a gradient coil in an MRI system. Background technique [0002] Magnetic resonance imaging (hereinafter referred to as MRI) is a new medical imaging technology that uses the principle of nuclear magnetic resonance to perform imaging. MRI imaging equipment is divided into permanent magnet type and superconducting type. In recent years, superconducting MRI imaging equipment has gradually replaced permanent magnet imaging equipment and become the mainstream of the market. Whether it is a permanent magnet MRI or a superconducting MRI, the core key component is the gradient coil. The most important index to measure the quality of the gradient field produced by the gradient coil is the linearity. At present, in engineering, the common way to measure the lineari...

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Problems solved by technology

[0006] The technical problem to be solved by the present invention is to provide a new and more reasonable method for measuring the linearity of the gradient magnetic field produced by the gradient coil in the MRI system for the above-mentioned prior art, so as to solve the lack of accurate and effective linearity of the gradient magnetic field in the prior art The problem with measurement

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