CN105208929B - Magnet arrangement and MR imaging apparatus - Google Patents
Magnet arrangement and MR imaging apparatus Download PDFInfo
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- CN105208929B CN105208929B CN201480027004.7A CN201480027004A CN105208929B CN 105208929 B CN105208929 B CN 105208929B CN 201480027004 A CN201480027004 A CN 201480027004A CN 105208929 B CN105208929 B CN 105208929B
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- yoke
- magnetic pole
- yoke side
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
- G01R33/3806—Open magnet assemblies for improved access to the sample, e.g. C-type or U-type magnets
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves
- A61B5/055—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
- G01R33/381—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field using electromagnets
- G01R33/3815—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field using electromagnets with superconducting coils, e.g. power supply therefor
Abstract
Magnet arrangement (2) has：It is opposed to the substantially discoid magnetic pole (4U) of a pair of configuration；The yoke (3) that side view is closely configured in C words or U-shaped and the both ends of the C words or U-shaped with magnetic pole (4U), yoke (3) has the yoke side opposed portion (15U) closely opposed with magnetic pole (4U), and yoke side opposed portion (15U) has：The central zone region (15b) of a part for the vertical plane of symmetry (α) comprising yoke (3)；It is left and the both sides region (15c) of centrally located region (15b) both sides from the vertical plane of symmetry (α), in the height (W3) from the yoke side counter surface (15a) closely opposed with magnetic pole (4U) of yoke side opposed portion (15U), central zone region (15b, W3b) is than both sides region (15c, W3c) height.The height (W3) from yoke side counter surface (15a) of yoke side opposed portion (15U) Generalized Monotone reduction and its maximum value and minimum value difference with separate from the vertical plane of symmetry (α).
Description
Technical field
The present invention relates to magnet arrangements and MR imaging apparatus (the hereinafter referred to as MRI for having the magnet arrangement
(Magnetic Resonance Imaging：Magnetic resonance imaging) device).
Background technology
Subject is placed in the camera shooting space for being formed with uniform magnetostatic field by MRI device, high using being irradiated to the subject
The nmr phenomena generated during frequency pulse obtains the image of the Wuli-Shili-Renli system approach of characterization subject.Also, image master
It is used for medical treatment.MRI device is roughly divided into horizontal type and direction of the direction towards horizontal direction from the point of view of its magnetostatic field direction
The vertical-type of vertical direction.In the former i.e. horizontal type MRI device, camera shooting space is in the tunnel penetrated through in the horizontal direction
Interior, examinee, which enters in the tunnel, to be checked.Therefore, examinee has constriction sometimes.And the latter, that is, vertical-type MRI device
It is to form camera shooting space between a pair of of magnetic pole of configuration is opposed to up and down and examinee enters construction between the magnetic pole, therefore quilt
Inspection person can obtain unlimited sense.Therefore, vertical-type MRI device is also referred to as open type MRI device.
In order to play the speciality of vertical-type MRI device, the space around examinee is made largely to open wide, with a pair of of magnetic
The shape of the yoke of pole connection uses C words or U-shaped (referring for example to patent document 1 etc.).In this specification, C words or U-shaped
Shape refers to the part excision of substantially annulus shape and open shape.But when using the yoke of C words or U-shaped,
It can be biased to from the distribution of the magnetic substance comprising yoke in terms of camera shooting space, therefore the magnetostatic field imaged in space is easily formed
Non-axis symmetry, imaging the magnetic field intensity of the magnetostatic field in space easily becomes uneven.For this purpose, use makes C in patent document 1
End side is gradually thinning forward for the thickness of the horizontal part a pair of up and down extended in the horizontal direction of the yoke of word or U-shaped
Construction, so as to which the C words on imaging area or the open side of U-shaped and the magnetic field intensity of column side be adjusted.
Existing technical literature
Patent document
Patent document 1：Japanese Unexamined Patent Publication 2005-168772 bulletins
Invention content
Problems to be solved by the invention
Vertical-type MRI device has magnet arrangement, to generate uniform magnetostatic field in space is imaged.Also, at this
Permanent magnet or superconducting coil are used in magnet arrangement.In general, required magnetic field intensity is then used less than 0.5T in space is imaged
Permanent magnet, and more than 0.5T then uses superconducting coil.
Also, as the important parameter of MRI device magnet arrangement, in addition to above-mentioned magnetic field intensity and above-mentioned uniformity of magnetic field
Except also have stray field diffusion zone size.The size scale of stray field diffusion zone is generally decayed to using magnetic field intensity
Space size needed for 0.5mT.It needs for stray field to be suppressed to the journey for making the space size smaller than setting the room of MRI device
Degree.Also, if camera shooting space magnetic field intensity be 1.0T hereinafter, if can be by only in the inhibition of the stray field of the degree
The magnetic substance of iron etc. is configured to carry out.And when magnetic field intensity is more than 1T, then it is needed when inhibiting stray field in only configuration magnetic substance
Want tens of tons of magnetic substance, configuration magnetic substance inhibits stray field and impracticable.It is referred to as shielding line in this case, can use
The superconducting coil of circle inhibits stray field.
The above is summarized, it is right in the magnetic field intensity for imaging space is the vertical-type MRI device in below 0.5T ranges
Magnetic pole, to generate magnetostatic field, and inhibits stray field using permanent magnet using magnetic substance.As magnetic substance, specifically, energy
Enough use yoke made of iron.Also, in the vertical-type MRI device in the range of more than 0.5T below 1.0T, using with magnetism
The different superconducting coil of body magnetic pole inhibits stray field to generate magnetostatic field using the magnetic substance different from magnetic pole magnetic body.
Also, in patent document 1, the continuous iron yoke few using superconducting coil and magnetic substance, that is, gap, therefore
It can inhibit stray field and generate the magnetostatic field of high magnetic field intensity.In addition, make the thickness of the horizontal part of the yoke of C words or U-shaped
End side is gradually thinning forward for degree, so as to mitigate the nonaxisymmetry in magnetic field.
But there is the nonaxisymmetry that can not be corrected in the method for adjusting the thickness of horizontal part front end side of yoke.
That is, the circumferential angle about the vertical axis by imaging area center, the column side for setting C words or U-shaped as 0 degree, C words or
When the open side of U-shaped is 180 degree, even if having the intensity in the magnetic field for making 0 degree and 180 degree direction before the horizontal part of yoke
Consistent mechanism on the thickness of end side can not also utilize the mechanism to make the intensity one in magnetic field in 0 degree and 90 degree and 270 degree direction
It causes.
Also, in patent document 1, in the case where making the thinner thickness of horizontal part front end side of yoke, then for example on
The horizontal part of side using the downwardly convex shape of the outer surface of the horizontal part, i.e. seen from above concave shape as fundamental form
Shape.The shape of this protrusion of lower face outward can make to flow to magnetic flux above vertical to C compared with the shape to raise up
The column side of word or U-shaped is sharp bent, therefore the magnetic field of the open side of C words or U-shaped is circulated upward to vertical
Distance Shortened, therefore the imaging area for resulting in the need for uniform magnetic field becomes smaller.
For this purpose, subject to be solved by this invention is to provide a kind of magnet arrangement, the non-axis symmetry of magnetostatic field can be made
Property mitigates and improves uniformity.And provide the MRI device equipped with the magnet arrangement.
The method used for solving the problem
In order to solve the above problems, the present invention is a kind of magnet arrangement, which is characterized in that is had：
It is opposed to the substantially discoid magnetic pole of a pair of configuration；And
The yoke that side view is closely configured in C words or U-shaped and the both ends of the C words or U-shaped with above-mentioned magnetic pole,
Above-mentioned yoke has the yoke side opposed portion closely opposed with above-mentioned magnetic pole,
Above-mentioned yoke side opposed portion has：
The central zone region of a part comprising the vertical plane of symmetry for substantially dividing above-mentioned yoke equally；And
The both sides region of above-mentioned central zone region both sides is left and is located at from the above-mentioned plane of symmetry,
In the height from the yoke side counter surface closely opposed with above-mentioned magnetic pole of above-mentioned yoke side opposed portion,
Above-mentioned central zone region is higher than above-mentioned both sides region.
Also, the present invention is a kind of MRI device, which is characterized in that is had：
The magnet arrangement；And
Examinee is transported to the table between a pair of of magnetic pole,
Above-mentioned magnet arrangement generates uniform magnetostatic field between a pair of above-mentioned magnetic pole and forms camera shooting space.
The effect of invention
In accordance with the invention it is possible to a kind of magnet arrangement and the MRI device equipped with the magnet arrangement are provided, due to passing through magnetic
Pole flows to the magnetic flux of yoke side opposed portion with the direction ingredient towards the vertical plane of symmetry, therefore can inhibit stray field and make quiet
The nonaxisymmetry in magnetic field mitigates and improves uniformity.Also, subject other than the above, structure and effect can be by right below
The explanation of embodiment and understand.
Description of the drawings
Fig. 1 is the stereogram of the MR imaging apparatus (MRI device) of first embodiment of the invention.
Fig. 2 is the longitudinal section view for cutting off the magnet arrangement of first embodiment of the invention along the vertical plane of symmetry.
Fig. 3 is the vertical view of the magnet arrangement of first embodiment of the invention.
Fig. 4 is by the top half edge of the magnet arrangement of first embodiment of the invention and the vertical plane of symmetry and horizontal symmetrical
The longitudinal section view of the orthogonal plane cut-out in face.
Fig. 5 is the vertical view of the magnet arrangement of first embodiment of the invention, is the flow direction for representing generated magnetic flux
Figure.
Fig. 6 is by the top half edge of the magnet arrangement of first embodiment of the invention and the vertical plane of symmetry and horizontal symmetrical
The longitudinal section view of the orthogonal plane cut-out in face is the figure for the flow direction for representing generated magnetic flux.
Fig. 7 is to regard the vertical profile that the top half of the magnet arrangement of first embodiment of the invention is cut off along the vertical plane of symmetry
Figure is the figure for the flow direction for representing generated magnetic flux.
Fig. 8 is the longitudinal section view for cutting off the top half of the magnet arrangement of comparative example along the vertical plane of symmetry, is to represent institute
The figure of the flow direction of the magnetic flux of generation.
Fig. 9 is the stereogram of the top half of the yoke of the magnet arrangement of second embodiment of the invention.
Figure 10 is the vertical view of the magnet arrangement of second embodiment of the invention.
Figure 11 is that the top half edge of the magnet arrangement of second embodiment of the invention is right with the vertical plane of symmetry and level
The longitudinal section view of the orthogonal plane cut-out in title face.
Figure 12 is the vertical profile for cutting off the top half of the magnet arrangement of second embodiment of the invention along the vertical plane of symmetry
View.
Figure 13 is the stereogram of the top half of the yoke of the magnet arrangement of third embodiment of the invention.
The longitudinal section view that magnet arrangement when Figure 14 is by using permanent magnet is cut off along the vertical plane of symmetry.
Specific embodiment
Next, suitable for reference to attached drawing, detailed description of embodiments of the present invention.Also, in the various figures to common
Part marks same symbol and omits repeated explanation.
(first embodiment)
Fig. 1 shows the stereogram of the MR imaging apparatus (MRI device) 1 of first embodiment of the invention.MRI device 1
Have：The magnet arrangement 2 of the generation uniform magnetostatic field of magnetic field intensity in camera shooting space 9；By examinee to lie down state to taking the photograph
The table 8 that image space 9 transports；And it controls, and utilize to subject the MRI devices such as magnet arrangement 2, table 81 are whole
The nmr phenomena generated during high-frequency impulse is irradiated, obtains the control unit of the image of the Wuli-Shili-Renli system approach of characterization subject
7。
Control unit 7 and magnet arrangement 2, table 8 etc. are connect.Control unit 7 has：It can be operable to adjust by operator
The operation portion 72 of its control content；And the display unit 71 of image that display obtains.Operation portion 72 passes through button or rotary switch
Etc. receiving the operation of operator.Display unit 71 shows the operation information and the image that display obtains.Control unit 7 is by operation portion
72 receive the various operations of operator, and generate magnetostatic field based on the operation to control magnet arrangement 2, and control table 8 will
Examinee is transported to camera shooting space 9 in the horizontal direction.
Table 8 has set on the driving portion 81 of lower part and is moved using the driving portion 81 is horizontal on the direction in camera shooting space 9
Dynamic platen 82.Examinee can lie down on platen 82.Driving portion 81 makes examinee be moved together with platen 82 and can clap
Take the photograph the profile image (MRI image) of target site.Platen 82 is made only to move small specified amount every time to shoot profile image, from
And continuous profile image i.e. 3-D view can be obtained.
Magnet arrangement 2 generates uniform magnetostatic field in MRI device 1 and forms camera shooting space 9.Magnet arrangement is right about 2
It is configured with the magnetic pole 4U discoid as one group of magnetic field source and magnetic pole 4L with putting.Below the magnetic pole 4U of upside closely
It is configured with the coil accommodating container 5U of ring (annulus) shape.The super of refrigerant and ring (annulus) shape is accommodated in coil accommodating container 5U
Loop 6U (with reference to Fig. 2).The coil accommodating container 5L of ring (annulus) shape is closely configured with above the magnetic pole 4L of downside.
The superconducting coil 6L (with reference to Fig. 2) of refrigerant and ring (annulus) shape is accommodated in coil accommodating container 5L.In coil accommodating container 5L
The inner peripheral surface side of (5U) is configured with discoid gradient magnetic field coil 10.Gradient magnetic field coil 10 can produce in camera shooting space 9
The inclined leaning magnetic field of magnetisation field intensity.
Magnetic pole 4U and magnetic pole 4L is supported by yoke 3 made of iron.3 side view of yoke is in substantially C words or U-shaped.Yoke 3 has
Substantially divide the vertical plane of symmetry (plane of symmetry) α of the yoke 3 equally and symmetrical relative to vertical plane of symmetry α faces.Also, in the C words or U
3 both ends of yoke of word shape are closely configured with above-mentioned magnetic pole 4U and 4L.Yoke 3 has close and opposed with magnetic pole 4U (4L)
Yoke side opposed portion (yoke horizontal part) 15U (15L) and the yoke that yoke horizontal part 15U, 15L of upper and lower a pair link is connected
Knot (yoke vertical component effect) 13.Yoke horizontal part 15U (15L) has：Yoke horizontal leading ends portion 14U (14L, the ginseng of tapered shape
According to Fig. 2)；Link and be in the yoke horizontal rear portion 12U (12L, reference Fig. 2) of approximately cuboid shape with it.Yoke horizontal rear portion
12U is connected with 12L by yoke vertical component effect 13.If also, in the case where forming yoke 3 by stem portion, it is not limited to be divided into
Each part of the structure, yoke 3 can also be used as integral piece manufacture.
Fig. 2 shows the longitudinal section views for cutting off the magnet arrangement 2 of first embodiment of the invention along vertical plane of symmetry α.Magnetic
3 side view of yoke is in substantially C words or U-shaped.Therefore, yoke 3 is symmetrical relative to horizontal symmetrical face β faces with horizontal symmetrical face β.
The magnetic pole 4U and magnetic pole 4L of substantially disc-shape clip camera shooting space and are opposed to be configured about 9.Space 9 is imaged in approximately spherical
Shape, center are located on the common central shaft 101 of the magnetic pole 4U and magnetic pole 4L of disc-shape, and positioned at horizontal symmetrical face β
On vertical plane of symmetry α.Coil accommodating container 5U is combined on magnetic pole 4U, superconducting line is contained in coil accommodating container 5U
Enclose 6U.Similarly, coil accommodating container 5L is combined on magnetic pole 4L, superconducting coil is contained in coil accommodating container 5L
6L.Circulating current generates magnetic field and magnetizes magnetic pole 4U and magnetic pole 4L in superconducting coil 6U, 6L of the upper and lower a pair, so as to
It is enough that the uniform magnetostatic field of magnetic field intensity is generated in space 9 is imaged.In addition, it is less than 0.5T in magnetic field intensity, then as schemed
It, can be between magnetic pole 4U and yoke horizontal leading ends portion 14U and between magnetic pole 4L and yoke horizontal leading ends portion 14L shown in 14
Permanent magnet 16U, 16L are set respectively and save superconducting coil 6U, 6L.In this way, magnet arrangement 2 is using about horizontal symmetrical face β
Face symmetrically constructs, therefore illustrates and omit the explanation of downside to the upper side structure of horizontal symmetrical face β below.
As shown in Fig. 2, the yoke side counter surface 15a opposite sides combined with magnetic pole 4U of yoke horizontal leading ends portion 14U
Outer surface 15e is bent raisedly outward in smooth curve form.The slave yoke side of yoke horizontal leading ends portion 14U is opposed
The height W1 that surface 15a rises, with the front end 15d of close yoke horizontal leading ends portion 14U, i.e. with far from yoke vertical component effect 13
And Generalized Monotone reduces and smoothly reduces.In the present specification, Generalized Monotone, which reduces (monotonic decreasing), is
Finger does not increase in the section.
Fig. 3 shows 2 vertical view of magnet arrangement of first embodiment of the invention.It is vertical to understand that yoke 3 is particularly yoke
Portion 13 is set on a direction partially relative to the magnetic pole 4U of disc-shape.It is being method with central shaft 101 that is, from central shaft 101
On the plane of line such as horizontal symmetrical face β (with reference to Fig. 2), view angle theta when observing yoke vertical component effect 13 is than 0 degree greatly and in 180 degree
Below.
Also, yoke horizontal leading ends portion 14U is in tapered shape.Specifically, the width of the normal direction of vertical plane of symmetry α
W2, with continuous by front end 15d (with far from yoke vertical component effect 13) and smoothly reduce.Strictly, width W2
As long as Generalized Monotone reduction and its maximum value and minimum value difference.
Also, the maximum width (equal with the width of yoke horizontal rear portion 12U) of width W2, than the magnetic pole 4U of disc-shape
Diameter it is small.There is the radius of curvature smaller than the radius of the magnetic pole 4U of disc-shape in the outer peripheral lines of yoke horizontal leading ends portion 14U
Region.Particularly in the outer peripheral lines of the yoke horizontal leading ends portion 14U on front end 15d peripheries, radius of curvature is than the magnetic of disc-shape
The radius of pole 4U is small.The distance W4 of periphery 4a from yoke horizontal leading ends portion 14U to magnetic pole 4U as a result, with by front end 15d
(with far from yoke vertical component effect 13) and it is continuous and smoothly reduce.If by yoke horizontal leading ends portion 14U, (yoke side is opposed
Portion 15U) it is divided into：It the central zone region 15b of a part comprising vertical plane of symmetry α and leaves and is located at from vertical plane of symmetry α
The distance W4b of the both sides region 15c, then the periphery 4a from central region 15b to magnetic pole 4U of central zone region 15b both sides,
Distance W4c than the periphery 4a from both sides region 15c to magnetic pole 4U is near.
Fig. 4 is shown the top half edge of the magnet arrangement 2 of first embodiment of the invention and vertical plane of symmetry α and level
The longitudinal section view of plane γ (with reference to Fig. 3) cut-out orthogonal plane of symmetry β.Yoke horizontal leading ends portion 14U (yoke side opposed portion 15U)
The height W3 from the counter surface 15a of yoke side, with separate and continuous from vertical plane of symmetry α and smoothly reduce.Strictly
Ground says, if height W3 with separate from vertical plane of symmetry α and Generalized Monotone reduces and its maximum value and minimum value difference.
On height W3, height W3cs high of the height W3b than both sides region 15c of central zone region 15b.
For the shape using above-mentioned yoke horizontal leading ends portion 14U (yoke side opposed portion 15U), inhibit camera shooting space 9
The nonaxisymmetry of magnetostatic field in (with reference to Fig. 2) and make uniformity improve principle will be described later.
Fig. 5 shows the vertical view of the magnet arrangement 2 of first embodiment of the invention.It is depicted with arrows magnet cartridge in Figure 5
Put the flow direction of magnetic flux caused by 2.The flow direction (arrow) of magnetic flux is shown near the periphery 4a of magnetic pole 4U at first via magnetic
Yoke horizontal leading ends portion 14U reaches the flow direction of yoke horizontal rear portion 12U.Yoke horizontal leading ends portion 14U is towards yoke horizontal rear portion 12U
Circular shape (substantially parabolic shape) is gradually expanded to, therefore the consistent (phase of the magnetic resistance on each magnetic flux (arrow) path can be made
Deng).The magnetic flux (arrow) for flowing to yoke horizontal leading ends portion 14U from magnetic pole 4U as a result, can be from the circumferencial direction of magnetic pole 4U balancedly
It flows into.Also, the magnetic flux (arrow) flowed into from the circumferencial direction, is not after yoke level on yoke horizontal leading ends portion 14U
Portion 12U is straight, but other than the direction ingredient towards yoke horizontal rear portion 12U, the direction also towards vertical plane of symmetry α
Ingredient.
Fig. 6 shows along plane γ to cut off the top half of the magnet arrangement 2 of first embodiment of the invention (with reference to Fig. 5)
Longitudinal section view.It is depicted with arrows the flow direction of magnetic flux caused by magnet arrangement 2 in figure 6.The flow direction of magnetic flux is shown from water
Flat plane of symmetry β plays the flow direction that yoke horizontal leading ends portion 14U is at first reached via magnetic pole 4U.As shown in fig. 6, yoke horizontal leading ends portion
14U is then higher closer to vertical plane of symmetry α, therefore magnetic flux (arrow) has the direction ingredient towards vertical plane of symmetry α.
Yoke horizontal leading ends portion 14U is in and gradually expands to circular shape towards yoke horizontal rear portion 12U (substantially to throw as a result,
Object wire shaped) shape, it is and then higher closer to vertical plane of symmetry α, therefore yoke horizontal leading ends portion 14U is flowed into from magnetic pole 4U
Magnetic flux (arrow) be balancedly distributed in a circumferential direction, and towards vertical plane of symmetry α circulate, so as to mitigate imaging area
The nonaxisymmetry of magnetic flux in 9.Also, due to being not using in the knot that yoke front end, which sets gap, rises magnetic resistance
Structure mitigates the construction of nonaxisymmetry, therefore will not influence the function that ferromagnetic yoke inhibits stray field.
Fig. 7 shows to cut off the top half of the magnet arrangement 2 of first embodiment of the invention along vertical plane of symmetry α vertical
Sectional view, Fig. 8 show the longitudinal section view for cutting off the top half of the magnet arrangement 2 of comparative example along vertical plane of symmetry α.In Fig. 7
With the flow direction that magnetic flux caused by magnet arrangement 2 is depicted with arrows in Fig. 8.The flow direction (arrow) of magnetic flux is shown from horizontal symmetrical
Face β plays the flow direction that yoke horizontal rear portion 12U is at first reached via magnetic pole 4U and yoke horizontal leading ends portion 14U (14Ua).
The outer surface 15e of the yoke horizontal leading ends portion 14U (yoke horizontal part 15U) of the first embodiment of Fig. 7 is upward
Protrusion, and the outer surface 15e of the yoke horizontal leading ends portion 14Ua (yoke horizontal part 15Ua) of comparative example is then downwardly convex.Than
Compared in example, the flow direction (arrow) of magnetic flux obliquely injects yoke horizontal leading ends portion 14Ua, and incoming position is also to yoke vertical component effect 13
(yoke horizontal rear portion 12U) side deviates.On the other hand, in the first embodiment compared with comparative example, the flow direction (arrow of magnetic flux
Head) with the angle injection yoke horizontal leading ends portion 14U of closer vertical.As a result, the space between magnetic pole 4U and 4L it is magnetic flux,
Towards the direction ingredient increase of vertical direction, the nonaxisymmetry in the magnetic field near imaging area 9 can be mitigated.By above may be used
Know, according to the present embodiment, magnetic flux (arrow) can be oriented to vertical in imaging area 9 using yoke horizontal leading ends portion 14U
Axis direction, therefore do not interfere with stray field and inhibit efficiency, and the nonaxisymmetry in magnetic field in imaging area 9 can be mitigated and expanded
Big imaging area.
(second embodiment)
Fig. 9 shows the stereogram of the top half of the yoke 3 of the magnet arrangement of second embodiment of the invention.It is real second
It applies distinctive points in mode and first embodiment and is the shape of yoke 3, wherein being the shape of yoke horizontal leading ends portion 14U.The
The outer surface 15e of the yoke horizontal leading ends portion 14U of one embodiment is formed using flexure plane, and the yoke of second embodiment
The outer surface 15e of horizontal leading ends portion 14U is then formed using the different multiple inclined surface in angle of inclination.
Figure 10 shows the vertical view of the magnet arrangement 2 of second embodiment of the invention.Yoke horizontal leading ends portion 14U is in tapering
Shape.Specifically, the width W2 of the normal direction of vertical plane of symmetry α is with (remote from yoke vertical component effect 13 by front end 15d
From) and reduce in 2 grades of stages.Strictly, as long as width W2 is with Generalized Monotone reduction and its maximum value by front end 15d
It is different with minimum value.The maximum value of width W2 is equal with the width of yoke horizontal rear portion 12U.Width W2 is with 2 stage constrictions.
Also, although width W2 was set as 2 stages in this second embodiment, but not limited to this and can also be set as multistage
Section.
Also, if yoke horizontal leading ends portion 14U (yoke side opposed portion 15U) is divided into：Include vertical plane of symmetry α's
A part central zone region 15b and left and the both sides region of centrally located region 15b both sides from vertical plane of symmetry α
The distance W4b of 15c, then the periphery 4a from central region 15b to magnetic pole 4U, than outer from both sides region 15c to magnetic pole 4U
The distance W4c of all 4a is near.The central zone region 15b of yoke horizontal leading ends portion 14U hangs down relative to both sides region 15c to yoke
The direction extension of 13 opposite side of straight portion.
Figure 11 shows along plane γ to cut the top half of the magnet arrangement 2 of second embodiment of the invention (with reference to Figure 10)
Disconnected longitudinal section view.The height from the counter surface 15a of yoke side of yoke horizontal leading ends portion 14U (yoke side opposed portion 15U)
W3 periodically reduces with being left from vertical plane of symmetry α.Strictly, height W3 with separate from vertical plane of symmetry α and
As long as Generalized Monotone reduction and its maximum value and minimum value difference.Height W3b on the 15b of central zone region is than both sides zone
Height W3c high on the 15c of domain.Also, although height W3 was set as 2 stages in this second embodiment, but not limited to this
And the multistage can also be set as.
Figure 12 shows cut off the top half of the magnet arrangement 2 of second embodiment of the invention along vertical plane of symmetry α
Longitudinal section view.The outer surface 15e of yoke horizontal leading ends portion 14U is formed using two tilt angle theta 1, θ 2 different inclined surface.
The tilt angle theta 1 of the inclined surface of downside is bigger (1 ＞ θ 2 of θ) than the tilt angle theta 2 of the inclined surface of upside.Outer surface 15e as a result,
Outward (on) protrusion.Also, although tilt angle theta 1, θ 2 were set as 2 stages in this second embodiment, it is not limited to
This and the multistage can also be set as.The height W1 from the counter surface 15a of yoke side of yoke horizontal leading ends portion 14U, with
And Generalized Monotone separate from yoke vertical component effect 13 reduces and smoothly reduces.
In this second embodiment, the shape of yoke horizontal leading ends portion 14U also has common point, profit with first embodiment
It in the same manner as first embodiment, can then inhibit the nonaxisymmetry of magnetostatic field with the common point and improve uniformity.
(third embodiment)
Figure 13 shows the stereogram of the top half of the yoke 3 of the magnet arrangement of third embodiment of the invention.Third is real
The distinctive points for applying mode and second embodiment are the shape of yoke 3, wherein being also the shape of yoke vertical component effect 13.Second
Yoke vertical component effect 13 is 1 column in embodiment, and is in the third embodiment more columns (being 2 in Figure 13 examples).According to
This, can be set between more yoke vertical component effects 13 adjacent to each other the pipeline for connecting coil accommodating container 5U with 5L, with
Wiring, refrigeration machine that superconducting coil 6U is connected with 6L etc..By the region configuring pipes between adjacent yoke vertical component effect or
Wiring etc., can expand table 8 by region and more open ground ensure table 8 move degree of freedom.Also, by adjacent
Yoke vertical component effect between refrigeration machine is set, can refrigeration machine near superconducting coil be set and more effectively cools down superconducting line
Circle.
Also, include various modifications example the present invention is not limited to above-mentioned first to third embodiment.Such as above-mentioned first
It is used to be not limited to the detailed description of the invention in favor of understanding have illustrated entire infrastructure to third embodiment.And
And a part for the structure of some embodiment can be also replaced into the structure of other embodiment, it in addition also can be to certain
The structure of a embodiment adds the structure of other embodiment.It also, also can be to a part for the structure of each embodiment
Carry out addition, deletion, the displacement of other structures.
Symbol description
1-magnetic resonance imaging (MRI) device；2-magnet arrangement；3-yoke；4U, 4L-magnetic pole；Outside 4a-magnetic pole
Week；5U, 5L-coil accommodating container；6U, 6L-superconducting coil；7-control unit；8-table；9-camera shooting space is (uniform quiet
Magnetic field)；10-gradient magnetic field coil；12U, 12L-yoke horizontal rear portion；13-yoke vertical component effect (yoke linking part)；14U、
14L-yoke horizontal leading ends portion；15U, 15L-yoke horizontal part (yoke side opposed portion)；The yoke of 15a-yoke side opposed portion
Side counter surface；The central zone region of 15b-yoke side opposed portion；The both sides region of 15c-yoke side opposed portion；15d—
The front end of yoke side opposed portion；The outer surface of 15e-yoke side opposed portion；The central shaft of 101-superconducting coil；W1-yoke
The height from the counter surface of yoke side of side opposed portion；The width of the normal direction of the vertical plane of symmetry of W2-yoke side opposed portion
Degree；The height from the counter surface of yoke side of W3-yoke side opposed portion；Height on W3b-central zone region；W3c-two
Height on the region of side；W4-from yoke side opposed portion to the distance of magnetic pole periphery；W4b-from central region away from
From；The distance of W4c-from the region of both sides；The vertical plane of symmetry (plane of symmetry) of α-yoke；The horizontal symmetrical face of β-yoke；
The plane of γ-orthogonal with α and β；Visual angle during θ-observation yoke linking part.
Claims (13)
1. a kind of magnet arrangement, which is characterized in that have：
It is opposed to the substantially discoid magnetic pole of a pair of configuration；And
The yoke that side view is closely configured in C words or U-shaped and the both ends of the C words or U-shaped with above-mentioned magnetic pole,
Above-mentioned yoke has the yoke side opposed portion closely opposed with above-mentioned magnetic pole,
Above-mentioned yoke side opposed portion has：
Central zone region, it includes a parts for the vertical plane of symmetry for substantially dividing above-mentioned yoke equally；And
Both sides region is left from the above-mentioned vertical plane of symmetry and is located at above-mentioned central zone region both sides,
It is above-mentioned in the height from the yoke side counter surface closely opposed with above-mentioned magnetic pole of above-mentioned yoke side opposed portion
Central zone region is higher than above-mentioned both sides region,
Above-mentioned central zone region is than above-mentioned both sides region close to the periphery of above-mentioned magnetic pole.
2. a kind of magnet arrangement, which is characterized in that have：
It is opposed to the substantially discoid magnetic pole of a pair of configuration；And
The yoke that side view is closely configured in C words or U-shaped and the both ends of the C words or U-shaped with above-mentioned magnetic pole,
Above-mentioned yoke has the yoke side opposed portion closely opposed with above-mentioned magnetic pole,
Above-mentioned yoke side opposed portion has：
Central zone region, it includes a parts for the vertical plane of symmetry for substantially dividing above-mentioned yoke equally；And
Both sides region is left from the above-mentioned vertical plane of symmetry and is located at above-mentioned central zone region both sides,
It is above-mentioned in the height from the yoke side counter surface closely opposed with above-mentioned magnetic pole of above-mentioned yoke side opposed portion
Central zone region is higher than above-mentioned both sides region,
From above-mentioned yoke side opposed portion to the distance of the periphery of above-mentioned magnetic pole with close to the front end of above-mentioned yoke side opposed portion and
Continuously reduce.
3. magnet arrangement according to claim 1 or 2, which is characterized in that
The width of the normal direction relative to the above-mentioned vertical plane of symmetry of above-mentioned yoke side opposed portion is with close to above-mentioned yoke side
The front end of opposed portion and Generalized Monotone reduces, and the maximum value of the width and minimum value are different.
4. magnet arrangement according to claim 1 or 2, which is characterized in that
The height from the counter surface of above-mentioned yoke side of above-mentioned yoke side opposed portion with separate from the above-mentioned vertical plane of symmetry and
Generalized Monotone reduces, and the maximum value of the height and minimum value difference.
5. magnet arrangement according to claim 1 or 2, which is characterized in that
The height from the counter surface of yoke side of above-mentioned yoke side opposed portion is with close to the front end of above-mentioned yoke side opposed portion
And Generalized Monotone reduces,
And the outer surface opposed with above-mentioned yoke side counter surface of above-mentioned yoke side opposed portion is raised outward.
6. magnet arrangement according to claim 1 or 2, which is characterized in that
Above-mentioned yoke has the yoke linking part of a pair of above-mentioned yoke side opposed portion of connection,
On the central shaft common from a pair of above-mentioned magnetic pole, and using above-mentioned central shaft as the above-mentioned yoke of the plan view of normal
Visual angle during linking part is than 0 degree greatly and below 180 degree.
7. magnet arrangement according to claim 1 or 2, which is characterized in that
The width of the normal direction relative to the above-mentioned vertical plane of symmetry of above-mentioned yoke side opposed portion is with close to above-mentioned yoke side
The front end of opposed portion and continuously reduce.
8. magnet arrangement according to claim 1 or 2, which is characterized in that
The height from the counter surface of yoke side of the above-mentioned yoke side opposed portion closely opposed with above-mentioned magnetic pole is with from upper
It is separate and continuously reduce to state the vertical plane of symmetry.
9. magnet arrangement according to claim 1 or 2, which is characterized in that
The width of the normal direction relative to the above-mentioned vertical plane of symmetry of above-mentioned yoke side opposed portion is with close to above-mentioned yoke side
The front end of opposed portion and periodically reduce.
10. magnet arrangement according to claim 1 or 2, which is characterized in that
The height from the counter surface of yoke side of the above-mentioned yoke side opposed portion closely opposed with above-mentioned magnetic pole is with from upper
It is separate and periodically reduce to state the vertical plane of symmetry.
11. magnet arrangement according to claim 1 or 2, which is characterized in that
Has a pair of substantially circular superconducting coil being closely configured with a pair of above-mentioned magnetic pole.
12. magnet arrangement according to claim 1 or 2, which is characterized in that
Has the substantially discoid permanent magnet of a pair being closely configured with a pair of above-mentioned magnetic pole.
13. a kind of MR imaging apparatus, which is characterized in that have：
Magnet arrangement described in any one of claim 1 to 12；And
Examinee is transported to the table between a pair of of magnetic pole,
Above-mentioned magnet arrangement generates uniform magnetostatic field between a pair of above-mentioned magnetic pole and forms camera shooting space.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2013117757A JP6046560B2 (en) | 2013-06-04 | 2013-06-04 | Magnet apparatus and magnetic resonance imaging apparatus |
| JP2013-117757 | 2013-06-04 | ||
| PCT/JP2014/063947 WO2014196411A1 (en) | 2013-06-04 | 2014-05-27 | Magnet device and magnetic resonance imaging device |
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| CN105208929A CN105208929A (en) | 2015-12-30 |
| CN105208929B true CN105208929B (en) | 2018-06-08 |
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| JP (1) | JP6046560B2 (en) |
| CN (1) | CN105208929B (en) |
| WO (1) | WO2014196411A1 (en) |
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| JP6046560B2 (en) * | 2013-06-04 | 2016-12-14 | 株式会社日立製作所 | Magnet apparatus and magnetic resonance imaging apparatus |
| CN111741590A (en) * | 2020-07-21 | 2020-10-02 | 中国原子能科学研究院 | Deflection magnet and deflection device with same |
| JP2022165843A (en) * | 2021-04-20 | 2022-11-01 | テラル株式会社 | Magnetic field generating device |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6150911A (en) * | 1996-07-24 | 2000-11-21 | Odin Technologies Ltd. | Yoked permanent magnet assemblies for use in medical applications |
| CN101825692A (en) * | 2009-03-02 | 2010-09-08 | 绵阳西磁磁电有限公司 | High-field-intensity focusing nuclear magnetic resonance magnetic field and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2276946B (en) * | 1993-04-08 | 1997-04-02 | Oxford Magnet Tech | Improvements in or relating to MRI magnets |
| JP3113513B2 (en) * | 1994-07-29 | 2000-12-04 | 住友特殊金属株式会社 | Magnetic field generator for MRI |
| JP2005168772A (en) * | 2003-12-11 | 2005-06-30 | Hitachi Ltd | Magnetic generator and magnetic resonance imaging apparatus using the same |
| CN100434038C (en) * | 2004-03-05 | 2008-11-19 | 西门子（中国）有限公司 | Device for regulating magnet field of MRI device |
| JP6046560B2 (en) * | 2013-06-04 | 2016-12-14 | 株式会社日立製作所 | Magnet apparatus and magnetic resonance imaging apparatus |
-
2013
- 2013-06-04 JP JP2013117757A patent/JP6046560B2/en active Active
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2014
- 2014-05-27 CN CN201480027004.7A patent/CN105208929B/en active Active
- 2014-05-27 WO PCT/JP2014/063947 patent/WO2014196411A1/en active Application Filing
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6150911A (en) * | 1996-07-24 | 2000-11-21 | Odin Technologies Ltd. | Yoked permanent magnet assemblies for use in medical applications |
| CN101825692A (en) * | 2009-03-02 | 2010-09-08 | 绵阳西磁磁电有限公司 | High-field-intensity focusing nuclear magnetic resonance magnetic field and preparation method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2014196411A1 (en) | 2014-12-11 |
| JP2014233525A (en) | 2014-12-15 |
| CN105208929A (en) | 2015-12-30 |
| JP6046560B2 (en) | 2016-12-14 |
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