CN206573704U - A kind of asymmetric gradient coils for magnetic resonance imaging - Google Patents
A kind of asymmetric gradient coils for magnetic resonance imaging Download PDFInfo
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- CN206573704U CN206573704U CN201720233376.6U CN201720233376U CN206573704U CN 206573704 U CN206573704 U CN 206573704U CN 201720233376 U CN201720233376 U CN 201720233376U CN 206573704 U CN206573704 U CN 206573704U
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Abstract
The utility model discloses a kind of asymmetric gradient coils for magnetic resonance imaging, it belongs to magnetic resonance imaging arts, including main coil, vertical winding and shielded coil, wherein, the main coil is used to generate gradient magnetic, the outside that the vertical winding is located at one end of the imaging region of the main coil causes the gradient magnetic linear distribution, and the shielded coil is located at the eddy current magnetism antisymmetry distribution that the outside of the main coil causes the main coil to produce；The utility model can greatly improve the linearity of one end gradient magnetic field distribution of the imaging region of main coil by vertical winding, expand the range of linearity；The utility model causes the eddy current magnetism antisymmetry that the gradient magnetic that blind zone is present is produced by shielded coil, later stage is accurately corrected when carrying out eddy current compensation, so that gradient coil in the gradient magnetic produced by blind zone on zero plane both sides antisymmetry, reach preferable compensation effect.
Description
Technical field
The utility model is related to magnetic resonance imaging arts, and in particular to a kind of asymmetric gradient line for magnetic resonance imaging
Circle.
Background technology
Magnetic resonance imaging gradient coil is used for producing gradient magnetic, and gradient magnetic is used to realize level selection, sky
Between coding, diffusion enhancing etc. function.Gradient coil is divided into longitudinal gradient coil and transverse gradients from the point of view of the distribution of gradient magnetic
Coil, wherein, magnetic field produced by longitudinal gradient coil is along the linear graded in main field direction.
In general, in the main magnet of horizontal magnetic field, longitudinal gradient coil is made up of the winding of multiple concentric circles, this
The diameter of a little windings is identical, along main field direction ordered arrangement, and produced gradient magnetic is in some middle perpendicular to main magnetic
The plane of field direction is zero, and the plane is called zero plane, and the gradient magnetic that gradient coil is produced is to oppose in the both sides of zero plane
Claim linear distribution.And the imaging center of magnet is all overlapped with gradient coil magnetic field zero plane, and gradient magnetic zero plane is general
It is that the geometrically symmetric center being distributed with gradient coil winding is overlapped again.Because gradient coil is general all longer, in order to make one
Body can enter imaging center, and the size of gradient coil diameter allows for accommodating human body entrance.
Still further aspect, for magnetic resonance imaging system, because gradient coil is inserted into main magnet, in gradient coil
Outside be magnet metal structure, the magnetic field, in general produced by gradient coil is pulsed magnetic field, and this pulsed magnetic field will be
Induce vortex in the metal structure of magnet, the magnetic field produced by vortex by the magnetic field produced by being superimposed upon gradient coil, from
And gradient magnetic produced by destroying gradient coil is pure, there is negative impact to imaging, therefore, constituting gradient coil
When, typically there are inside and outside two layers of winding, the sense of current passed through on the contrary, the coil of outer layer is outside shielded coil, shielded coil
Region claim blind zone, inner coil is the gradient magnetic of both sides certain area in main coil, main coil centered on zero plane
It is linear change, referred to as imaging area.
With advances in technology and application demand, modern gradient coil requires gradient magnetic field strength more and more higher, very
In the case of many, its gradient magnetic field strength of the gradient coil of major diameter can not meet requirement, then need to reduce the diameter of gradient coil,
Human body is caused not fully enter, human body can only enter part in gradient coil, cause the zero plane of gradient coil inclined
From to close to one end of gradient coil geometry, in this case, the geometry distribution of gradient coil winding is general no longer
It is, in symmetrical distribution, to constitute so-called asymmetric coils with gradient magnetic zero plane.
Existing asymmetric longitudinal gradient coil, because its main coil is along horizontal direction distribution, produced master
Wanting problem is, in this one end entered close to human body, because wiring space is extremely limited, causes the arrangement of gradient coil winding non-
It is often close so as to enter in magnetic field zero plane in human body in the gradient magnetic field distribution of this side, its range of linearity is smaller, and
It also is difficult to expand the range of linearity, the anamorphose of this side is larger when causing to be imaged, and influences some senior scan modes
Realization；On the other hand, currently existing scheme does not all account for the symmetry of vortex, and the symmetry of so-called vortex refers in blind zone
The gradient magnetic of presence, its fractions distribution is antisymmetric on zero plane, and its eddy current magnetism produced is also antisymmetry distribution
, can accurately it be corrected when carrying out eddy current compensation.For traditional symmetrical expression gradient coil, the symmetry of vortex and coil
Design and the distribution of winding are unrelated, it is only necessary to ensure each subcoil being symmetrically installed on geometric position in engineering, so that it may
The automatic symmetry for ensureing eddy current magnetism.In asymmetric coils, the symmetry of the eddy current magnetism of zero plane both sides and coil
Install no longer relevant, but it is related to the winding distribution of coil, the winding distribution of asymmetric longitudinal gradient coil, is no longer zero
Plane both sides are symmetrical.The symmetry of eddy current magnetism is extremely important, asymmetric eddy current magnetism distribution, can cause the vortex in the later stage
When preemphasis is compensated, it is impossible to obtain preferable compensation result, that is to say, that the eddy current compensation of magnetic field zero plane side to preferable shape
Then opposite side can deviate perfect condition to state, and vice versa.
Utility model content
For the problems of in the prior art, it is a kind of for the asymmetric of magnetic resonance imaging that the utility model is provided
Gradient coil, can optimize gradient magnetic linear distribution, extend the gradient magnetic range of linearity, and cause the distribution of eddy current magnetism
It is even more ideal, it is easier to reach preferable eddy current compensation effect.
To achieve these goals, the technical solution adopted in the utility model is as follows：
A kind of asymmetric gradient coils for magnetic resonance imaging, including main coil, vertical winding and shielded coil, its
In, the main coil is used to generate gradient magnetic；It is described vertical around being mounted on one end that the main coil enters close to human body
Outside is to optimize the gradient magnetic linear distribution, and vertical winding causes gradient magnetic to have more preferable linear distribution；The shielding
Coil is located at the eddy current magnetism antisymmetry distribution that the outside of the main coil causes the main coil to produce.
As a kind of perferred technical scheme, the main coil is by the coaxial Circular Winding structure of multiturn diameter phase concentric
Into the Circular Winding is in asymmetric distribution relative to zero plane, for generating gradient magnetic.
As a kind of perferred technical scheme, the asymmetric gradient coils include one or more groups of vertical windings,
Vertical winding described in each group is constituted by a circle or multiturn Circular Winding, and vertical winding is used to improve the imaging region of main coil
Gradient magnetic field distribution the linearity.
As a kind of perferred technical scheme, when the vertical winding includes multigroup, vertical winding edge described in each group
The coaxial of the center of circle of all vertical windings is sequentially distributed, and this kind of mode is optimal distribution mode.
As a kind of perferred technical scheme, when vertical winding described in one group includes multiturn Circular Winding, the multiturn
Circular Winding is distributed in concentric circles in the same plane, and this kind of distribution mode is for improving one end of the imaging region of main coil
The linearity of Distribution of Magnetic Field has optimal effect.
As a kind of perferred technical scheme, the asymmetric gradient coils include multigroup shielded coil, each group
The shielded coil is constituted by a circle or multiturn Circular Winding, and the Circular Winding for constituting shielded coil is that vortex is balanced compensated
Winding, shielded coil be used for make the blind zone in exist gradient magnetic generation eddy current magnetism in imaging area relative to zero plane
Antisymmetry.
As a kind of perferred technical scheme, the center of circle of the shielded coil described in each group along all shielded coils
Coaxial to be sequentially distributed, when shielded coil described in one group includes multiturn Circular Winding, the multiturn Circular Winding is identical with diameter
The parallel distribution of the coaxial mode in the center of circle, this kind of mode is optimal distribution mode.
As a kind of perferred technical scheme, the sense of current of the shielded coil of different groups is identical or opposite；When one
When the group shielded coil is made up of multiturn Circular Winding, the sense of current of the multiturn Circular Winding in same group is identical.
As a kind of perferred technical scheme, the center of circle of all Circular Windings is coaxial.
As a kind of perferred technical scheme, it is provided with gap, the gap and uses between the main coil and the vertical winding
In the winding of insertion horizontal gradient loop, so as on the premise of the distribution of horizontal gradient loop is not influenceed, improve transverse gradients
The level of linearity in magnetic field.
The beneficial effects of the utility model are shown：
1st, the utility model is particularly when one group of vertical winding includes concentric circles in multiturn same plane by vertical winding
During the Circular Winding of distribution, it can greatly improve the linearity of the gradient magnetic field distribution of the imaging region of main coil, expand
The winding of horizontal gradient loop is inserted in the range of linearity, and the gap of vertical winding and main coil, from without influenceing laterally ladder
The distribution of coil is spent, the level of linearity in transverse gradients magnetic field is improved.
2nd, the utility model causes the eddy current magnetism that the gradient magnetic that blind zone is present is produced in imaging by shielded coil
Region is relative to zero plane antisymmetry so that the later stage can accurately be corrected during eddy current compensation, it is easier to reach preferable benefit
Repay effect.
Brief description of the drawings
Fig. 1 is a kind of sectional view of asymmetric gradient coils for magnetic resonance imaging of the utility model；
Fig. 2 shows for a kind of overall structure of asymmetric gradient coils embodiment one for magnetic resonance imaging of the utility model
It is intended to；
Fig. 3 shows for a kind of overall structure of asymmetric gradient coils embodiment two for magnetic resonance imaging of the utility model
It is intended to；
In figure：The vertical winding of 1- shielded coils, 2-, 3- main coils, 4- imaging regions, 5- zero planes.
Embodiment
For the ease of it will be appreciated by those skilled in the art that being further described below in conjunction with the accompanying drawings to the utility model.
Fig. 1 is sectional view of the present utility model, including main coil 3, vertical winding 2 and shielded coil 1, wherein, main coil 3
For generating gradient magnetic so that imaging region 4 is located at the side of main coil 3, gradient magnetic is symmetrical on zero plane 5；Vertically
Winding 2 is located at the linear distribution of the outside optimization gradient magnetic of one end of the imaging region 4 of main coil 3；Shielded coil 1 is located at master
The outside of coil 3 make it that the eddy current magnetism that main coil 3 is produced is symmetrical on zero plane 5.
Wherein, main coil 3 is made up of the coaxial Circular Winding of multiturn diameter phase concentric, and Circular Winding is in asymmetric point
Cloth, so as to generate gradient magnetic；The utility model includes one or more groups of vertical windings 2, and each group of vertical winding 2 is by a circle
Or multiturn Circular Winding is constituted, when vertical winding 2 includes multigroup, circle of each group of vertical winding 2 along all vertical windings 2
The coaxial of the heart is sequentially distributed, and when one group of vertical winding 2 includes multiturn Circular Winding, the multiturn Circular Winding is in same plane
It is interior to be distributed in concentric circles；The utility model includes many set of shield coil 1, and each set of shield coil 1 is by a circle or multiturn ring
Shape winding is constituted, and the Circular Winding for constituting shielded coil 1 is the balanced compensated winding of vortex, and each set of shield coil 1 is along all
The coaxial of the center of circle of shielded coil be sequentially distributed, when a set of shield coil 1 includes multiturn Circular Winding, multiturn Circular Winding
With the parallel distribution of the coaxial mode of diameter phase concentric, meanwhile, difference group shielded coils 1 the sense of current it is identical or on the contrary,
When a set of shield coil 1 is made up of multiturn Circular Winding, the sense of current of the multiturn Circular Winding in same set of shield coil 1
It is identical；The center of circle for constituting all Circular Windings of main coil 3, vertical winding 2 and shielded coil 1 is coaxial；Main coil 3 is with hanging down
Gap is provided between straight winding 2, the gap is used for the winding for inserting horizontal gradient loop, so as to not influence horizontal gradient loop
On the premise of distribution, the level of linearity in transverse gradients magnetic field is improved.
Embodiment one
Fig. 2 is the overall structure diagram of the utility model embodiment one, and the internal diameter of main coil 3 is 400mm, shielded coil
1 radius is 280mm.One group of vertical winding 2 is provided with the end of the close imaging region 4 of main coil 3, vertical winding 2 is total to
Three circle Circular Windings are constituted；Shielded coil 1 includes four groups altogether, wherein, according to the direction in Fig. 2 from left to right, successively including 3
Circle, 4 circles, 2 circles and 3 circle Circular Windings, the Circular Winding for constituting shielded coil 1 are the balanced compensated winding of vortex.The coil knot
The linearity for the gradient magnetic that structure is produced in radius 11cm imaging region 4 is+3.6%/- 2.5%.Hung down in imaging region 4
At straight line of symmetry both sides 8cm, vortex produced by 10kHz electric currents is asymmetric to be less than 5.3%.
Embodiment two
Fig. 3 is the overall structure diagram of the utility model embodiment two, and the internal diameter of main coil 3 is 640mm, shielded coil
1 radius is 390mm.Two groups of vertical windings 2 are provided with the end of the close imaging region 4 of main coil 3, wherein, one group hangs down
Straight winding is made up of 4 circle Circular Windings, and another group of vertical winding is made up of 2 circle Circular Windings；Shielded coil 1 includes seven groups altogether,
Wherein, according to the direction in Fig. 3 from left to right, successively including 4 circles, 3 circles, 4 circles, 5 circles, 2 circles, 3 circles and 3 circle Circular Windings, structure
Circular Winding into shielded coil 1 is the balanced compensated winding of vortex.The loop construction is produced in radius 20cm imaging region 4
The linearity of raw gradient magnetic is+5.6%/- 2.0%.At the vertical symmetrical line both sides 11cm of imaging region 4,10kHz electric currents
Produced vortex is asymmetric to be less than 3%.
Above content is only to structure example of the present utility model and explanation, the technology of affiliated the art
Personnel are made various modifications or supplement to described specific embodiment or substituted using similar mode, without departing from
The structure of utility model surmounts scope defined in the claims, all should belong to protection domain of the present utility model.
Claims (10)
1. a kind of asymmetric gradient coils for magnetic resonance imaging, it is characterized in that, including main coil, vertical winding and shielding line
Circle, wherein,
The main coil is used to generate gradient magnetic；
It is described vertical linear to optimize the gradient magnetic around the outside of one end that the main coil enters close to human body is mounted on
Distribution；
The shielded coil is located at the eddy current magnetism antisymmetry distribution that the outside of the main coil causes the main coil to produce.
2. a kind of asymmetric gradient coils for magnetic resonance imaging according to claim 1, it is characterized in that, the main line
Circle is made up of the coaxial Circular Winding of multiturn diameter phase concentric, and the Circular Winding is in asymmetric distribution.
3. a kind of asymmetric gradient coils for magnetic resonance imaging according to claim 1, it is characterized in that, it is described non-right
Gradient coil is claimed to include one or more groups of vertical windings, vertical winding is by a circle or multiturn Circular Winding described in each group
Constitute.
4. a kind of asymmetric gradient coils for magnetic resonance imaging according to claim 3, it is characterized in that, hung down when described
When straight winding includes multigroup, the center of circle coaxial of the vertical winding along all vertical windings is sequentially distributed described in each group.
5. a kind of asymmetric gradient coils for magnetic resonance imaging according to claim 3, it is characterized in that, when one group of institute
When stating vertical winding comprising multiturn Circular Winding, the multiturn Circular Winding is distributed in concentric circles in the same plane.
6. a kind of asymmetric gradient coils for magnetic resonance imaging according to claim 1, it is characterized in that, it is described non-right
Gradient coil is claimed to include multigroup shielded coil, shielded coil described in each group is constituted by a circle or multiturn Circular Winding.
7. a kind of asymmetric gradient coils for magnetic resonance imaging according to claim 6, it is characterized in that, each group of institute
State the center of circle coaxial of the shielded coil along all shielded coils to be sequentially distributed, when shielded coil described in one group includes multiturn
During Circular Winding, the multiturn Circular Winding is with the parallel distribution of the coaxial mode of diameter phase concentric.
8. a kind of asymmetric gradient coils for magnetic resonance imaging according to claim 6, it is characterized in that, difference group
The sense of current of the shielded coil is identical or opposite；It is same when shielded coil described in one group is made up of multiturn Circular Winding
The sense of current of the multiturn Circular Winding in group is identical.
9. a kind of asymmetric gradient coils for magnetic resonance imaging according to Claims 2 or 3 or 6, it is characterized in that, institute
The center of circle for the Circular Winding having is coaxial.
10. a kind of asymmetric gradient coils for magnetic resonance imaging according to claim 1, it is characterized in that, the master
Gap is provided between coil and the vertical winding.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720233376.6U CN206573704U (en) | 2017-03-11 | 2017-03-11 | A kind of asymmetric gradient coils for magnetic resonance imaging |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720233376.6U CN206573704U (en) | 2017-03-11 | 2017-03-11 | A kind of asymmetric gradient coils for magnetic resonance imaging |
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| Publication Number | Publication Date |
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| CN206573704U true CN206573704U (en) | 2017-10-20 |
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| CN201720233376.6U Active CN206573704U (en) | 2017-03-11 | 2017-03-11 | A kind of asymmetric gradient coils for magnetic resonance imaging |
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- 2017-03-11 CN CN201720233376.6U patent/CN206573704U/en active Active
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