Open type MRI system transverse gradient coil distortion space design method

A technology of gradient coils and deformation spaces, applied in the direction of measuring magnetic variables, measuring devices, instruments, etc., can solve problems such as inability to construct coil patterns

Inactive Publication Date: 2008-09-17
浙江华际天府智能科技有限公司
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Problems solved by technology

This method can naturally set finite size coils, but currently only applies simple shapes, such as straight lines or loops, and cannot construct more complex coil patterns to meet more complex gradient field distribution requirements

Method used

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  • Open type MRI system transverse gradient coil distortion space design method
  • Open type MRI system transverse gradient coil distortion space design method
  • Open type MRI system transverse gradient coil distortion space design method

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Embodiment Construction

[0027] The design requirements of the present invention are that the target gradient field strength is 6.25mT / m, the DSV is 0.38m, the distance between two planes is 0.5m, and the coil size is limited in a circle with a radius of 0.43m.

[0028] The polar coordinate formula of the selected curved line is (1):

[0029] r=a+bcosθ,

[0030] (1)

[0031] θ ∈ [0, 2π]

[0032] In the formula, r represents the radial coordinate of the clam line, θ represents the angular coordinate of the clam line, a and b represent the control parameters of the curve shape of the clam line, different situations of a and b will form different curve shapes, for example, when afigure 1 Shown is the situation when a=1 / 2, b=1; when a=b, a heart-shaped line is formed, such as figure 2 The situation when a=b=1 is shown; when 2b>a>b, the cockle line forms ripples, such as image 3 Shown is the case when a=3 / 2, b=1. Depend on figure 1 , 2 , As shown in 3, it can also be seen that the cl...

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Abstract

The invention discloses a deformation-space design method for the transverse gradient coil in an opening MRI system, used in the design of dual-plane symmetrical transverse gradient coil. The method first adds control parameters to implement the form-deformation to the limacon, and uses a plurality of deformed limacons to represent coil current-carrying wire, and then the parameters defines the arrangement of the whole coil system, and the deformation control of the whole closed curve can be realized by using the parameters; limited object point is selected in an interested spherical space of imaging region; the gradient field arrangement of an initial coil is calculated and error function formula is created by using the Biot-Savart theorem according to the design requirement and the limited object point; the optimal parameter optimized by the least-square method is obtained thereby reaching the design object and obtaining proper uniform gradient field; each deformed limacon can be drawn out according to the obtained optimal parameter assembly, so that the coil form can be obtained. The method is simple and effective, size limit is naturally contained in the optimizing process, so the method can be used for designing the transverse gradient coil with complex form.

Description

technical field [0001] The invention relates to a deformation space design method of a transverse gradient coil in an open MRI system. Background technique [0002] In the field of magnetic resonance imaging, a great deal of work has been done with respect to gradient coils in order to obtain uniform gradient magnetic fields. There are mainly two design methods. One is a design method based on Fourier space, such as the target field method (R.Turner, "A target field approach to optimal coil design," Journal of Physics D: Applied Physics, vol.19, pp.L147-L151, 1986.) ; The other is a method based on real space, such as simulated annealing (S.Crozier and D.M.Doddrell, "Gradient-coil design by simulated annealing," J.Magn.Reson.A, vol.103, pp.354-357, 1993.). Both methods have advantages and disadvantages. [0003] The design method based on Fourier space is to use analytical formula or series expansion to express the current density on the coil plane. Such as the target f...

Claims

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Application Information

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IPC IPC(8): G01R33/385
Inventor 夏灵朱敏华刘锋
Owner 浙江华际天府智能科技有限公司
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