MRI device having magnet with extremely narrow leakage magnetic field

A magnetic field and magnet technology, applied in the field of horizontal magnetic field type MRI devices, can solve the problems of difficult to achieve uniformity, poor accuracy, difficult shielding effect, etc., achieve good uniform magnetic field performance, reduce installation constraints, and reduce the effect of area

Active Publication Date: 2017-02-22
HITACHI HEALTHCARE MFG LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, there is controversy about the fluctuation of the magnetic field due to the magnitude of the deformation, and the distribution of the reference of the magnetic field has not been determined, so it is difficult to achieve the best uniformity as a result.
[0015] In Patent Document 4, the number of SC-CBs is much arranged, but this arrangement is concentrated at a relatively short position in the axial direction, so it is difficult to achieve a sufficient shielding effect
In addition, for the generation of a uniform magnetic field in the imaging area, there is also controversy over the spherical harmonic function, so the calculation of the function of the current distribution becomes complicated, and the accuracy tends to deteriorate due to the superposition of multiple functions

Method used

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  • MRI device having magnet with extremely narrow leakage magnetic field
  • MRI device having magnet with extremely narrow leakage magnetic field
  • MRI device having magnet with extremely narrow leakage magnetic field

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Embodiment Construction

[0039] Hereinafter, the method of constituting a uniform magnetic field in such a manner as to simultaneously satisfy the good uniformity and good leakage magnetic field proposed by the present inventors and the arrangement of the coils that can obtain good uniformity by applying this method to the design of a uniform magnetic field will be described. illustrate.

[0040] In addition, by applying this method to design a uniform magnetic field, there is no need to worry about the uniformity of the imaging region 6 being deteriorated, and the SC-CB can be arranged to effectively suppress the leakage magnetic field to the surroundings. In addition, although the term "coil block (CB)" is used below to properly describe this embodiment, if figure 1 As shown, the coil area schematically shows each coil by reflecting the arrangement and size of the main coil and the shield coil on the horizontal cross section of the magnet. In addition, the coil area corresponding to the main coil ...

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Abstract

In the present invention, an electromagnet, which is configured by a main coil group (positive current) and a shield coil group (negative current) that constitute a magnetic resonance tomography imaging device (MRI) used for medical diagnosis, contains three or more negative current shield coil blocks, and at least one or more of the shield coil blocks is positioned beyond a main coil block and has a radius that is smaller than the other shield coil blocks.

Description

technical field [0001] The present invention relates to a horizontal magnetic field type MRI apparatus. Background technique [0002] In the diagnosis using nuclear magnetic resonance tomography (MRI) for medical diagnosis, since the magnetic field intensity corresponds to the diagnostic site, the magnetic field is the most important in terms of the accuracy required for the magnetic field intensity generated by the magnet system. Variations of one part per million in intensity can be problematic. Here, there are roughly three types of magnetic fields used by the MRI apparatus. [0003] (1) It is stable in time and fixed in space, and usually has an intensity from 0.1 to several tesla, and is in the imaging space (usually the space of a sphere or ellipsoid with a diameter of 30-40 cm) , the magnetic field that falls within the fluctuation range of several ppm [0004] (2) A magnetic field that changes with a time constant of about one second or less and that is spatially ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): A61B5/055
CPCA61B5/055
Inventor 阿部充志竹内博幸
Owner HITACHI HEALTHCARE MFG LTD
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