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Static magnetic field control method and magnetic resonance imaging device

A technology of magnetic resonance imaging and static magnetic field, applied in magnetic resonance measurement, measurement device, material analysis through resonance, etc., can solve the problems of permanent magnet polarizer Sp1 being easily affected by temperature change and narrowing of adjustment range, etc.

Inactive Publication Date: 2003-02-05
GE MEDICAL SYST GLOBAL TECH CO LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] In the MRI apparatus 500 as described above, there is a primary problem that the permanent magnets 1M1 and 1M2 and the base yoke YB and the deflector Sp1 may be susceptible to temperature changes after adjusting the number of threads of the screw 51
On the contrary, if the magnetic permeability is small enough, the adjustment accuracy will be higher, while on the other hand the adjustment range will be narrow

Method used

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  • Static magnetic field control method and magnetic resonance imaging device
  • Static magnetic field control method and magnetic resonance imaging device
  • Static magnetic field control method and magnetic resonance imaging device

Examples

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no. 1 example

[0060] now refer to figure 1 , which shows a partial sectional view of an MRI apparatus according to a first preferred embodiment of the present invention. Referring also to Figure 2, which shows along the figure 1 The K-K' line sees the past sectional view.

[0061] The MRI apparatus 100 is an open type MRI apparatus that generates a static magnetic field Bo in a vertical direction from permanent magnets, ie, permanent magnets 1M1 and 1M2 installed at opposite positions on the bottom and top.

[0062] On the surfaces of the respective permanent magnets 1M1 and 1M2, deflectors Sp1 and Sp2 are installed, which improve the uniformity of the static magnetic field Bo in the imaging zone KK.

[0063] The permanent magnets 1M1 and 1M2, the deflectors Sp1 and Sp2, the base yoke YB, and the column yoke Yp may constitute a magnetic circuit. Materials for permanent magnets 1M1 and 1M2 may include, for example, neodymium magnetic material (Nd-Fe-B), samarium-cobalt magnetic material...

no. 2 example

[0085] now refer to Figure 6 , which shows a partial cross-sectional view of an MRI apparatus according to a second preferred embodiment of the present invention. Also refer to Figure 7 , which represents along Figure 6 The cross-sectional view seen on the K-K' line.

[0086]In this MRI apparatus 200, the permanent magnet 1M1 and the base yoke YB can be provided with threaded holes at many positions, that is, the static magnetic field adjustment unit installation devices 20-1 to 20-10, which can be freely connected and removed from the Static magnetic field adjustment units 21 - 1 to 21 - 10 selected from a group consisting of a plurality of types of units ( 21α , 21β , 21γ shown in FIG. 8 ).

[0087] Such as Figure 8A As shown, the static magnetic field adjustment unit 21α can be composed of a non-magnetic sleeve 210α and a magnetic core 211α, wherein the sleeve 210α is a hollow cylindrical member, and its shape is a threaded screw, and the magnetic core 211α runs thr...

no. 3 example

[0097] The MRI apparatus according to the third preferred embodiment of the present invention adopts Figure 9 The static magnetic field adjustment unit 31 is shown in place of the static magnetic field adjustment unit 21 (see FIG. 8 ) employed in the second preferred embodiment described above. Specifically, the static magnetic field adjustment unit 31 assembly is adopted, which is screwed into the primary ring 311 of the hollow cylinder form in the center hole of the final ring 310 in the form of a hollow cylinder, and screwed into the solid ring 311 in the center hole of the primary ring 311. A core 312 in the form of a cylinder is assembled.

[0098] As shown in FIGS. 10 ( A1 ) and ( B1 ), either one of the final ring 310A of magnetic material or the final ring 310B of nonmagnetic material will be selected as the final ring 310 .

[0099] As shown in FIGS. 10(A2) and (B2), either one of the primary ring 311A ​​of magnetic material or the primary ring 311B of non-magnetic ...

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Abstract

The temperature of permanent magnet blocks embedded in several positions in permanent magnets and base yokes will be adjusted by device of a heater to improve the static field uniformity.

Description

technical field [0001] The present invention relates to a method of controlling a static magnetic field and to an MRI (Magnetic Resonance Imaging) apparatus. More particularly, the present invention relates to a static magnetic field adjustment method for controlling the uniformity of a static magnetic field and an MRI apparatus that properly implements the static magnetic field adjustment method. technical background [0002] Figure 12 A partial sectional view showing a typical example of a conventional MRI apparatus. [0003] The MRI apparatus 500 is an open type MRI apparatus that generates a static magnetic field Bo in a vertical direction. [0004] The static magnetic field generator magnet is composed of permanent magnets 1M1 and 1M2 arranged oppositely at the top and bottom, a base yoke YB, a cylindrical yoke Yp, and a deflector Sp1. [0005] A screw 51 of magnetic material for static magnetic field adjustment may be inserted into the permanent magnets 1M1 and 1M2 ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R33/387A61B5/055G01R33/383G01R33/389
CPCG01R33/387G01R33/389
Inventor 后藤隆男星野和哉井上勇二佐久间正章
Owner GE MEDICAL SYST GLOBAL TECH CO LLC
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