CN105208929A - Magnet device and magnetic resonance imaging device - Google Patents
Magnet device and magnetic resonance imaging device Download PDFInfo
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- CN105208929A CN105208929A CN201480027004.7A CN201480027004A CN105208929A CN 105208929 A CN105208929 A CN 105208929A CN 201480027004 A CN201480027004 A CN 201480027004A CN 105208929 A CN105208929 A CN 105208929A
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- 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
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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
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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
- G01R33/381—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
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Abstract
This magnet device (2) is provided with a pair of generally disk-shaped magnetic poles (4U) situated in opposition, and a yoke (3) which is C-shaped or U-shaped in side view and which is situated with either end of the C-shape or U-shape situated in proximity to the magnetic poles (4U). The yoke (3) has a yoke-side opposing portion (15U) in proximity to and opposing the magnetic poles (4U), the yoke-side opposing portion (15U) having a center strip area (15b) that includes part of a vertical symmetric plane (alpha) of the yoke (3), and side strip areas (15c) situated to either side of the center strip area (15b), further away from the vertical symmetric plane (alpha). At a height (W3) of the yoke-side opposing portion (15U) with respect to a yoke-side opposing surface (15a) which is situated in proximity and opposing the magnetic poles (4U), the center strip area (15c, W3b) is taller than the side strip areas (15c, W3c). The height (W3) of the yoke-side opposing portion (15U) with respect to the yoke-side opposing surface (15a) decreases in weakly monotonic fashion further away from the vertical symmetric plane (alpha), and the maximum value and minimum value thereof differ.
Description
Technical field
The present invention relates to magnet arrangement and the MR imaging apparatus (hereinafter referred to as MRI (MagneticResonanceImaging: nuclear magnetic resonance) device) possessing this magnet arrangement.
Background technology
Subject is placed in the shooting space being formed with uniform magnetostatic field by MRI device, utilizes the nmr phenomena produced when this subject irradiates high-frequency impulse, obtains the image of the Wuli-Shili-Renli system approach characterizing subject.Further, this image is mainly used in medical treatment.MRI device is roughly divided into the horizontal type of this direction towards horizontal direction and the vertical-type towards vertical from its magnetostatic field direction.In the former i.e. horizontal type MRI device, shooting space is in tunnel through in the horizontal direction, and examinee enters in this tunnel and is checked.Therefore, examinee has constriction sometimes.And the latter and vertical-type MRI device form shooting space and examinee to enter structure between this magnetic pole between upper and lower opposed a pair magnetic pole configured, therefore examinee can obtain and open wide 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 opened wide largely, the shape of the yoke be connected with a pair magnetic pole adopts C word or U-shaped (such as with reference to patent documentation 1 etc.).In this description, C word or U-shaped refer to the shape of a part for roughly toroidal excision being opened wide.But when adopting the yoke of C word or U-shaped, can be partial to from the distribution comprising the magnetic of yoke viewed from shooting space, therefore the magnetostatic field of making a video recording in space easily forms non-axis symmetry, and the magnetic field intensity of the magnetostatic field in shooting space easily becomes uneven.For this reason, in patent documentation 1, adopt the extended in the horizontal direction thickness structure that side is thinning gradually forward of horizontal part of a pair up and down making the yoke of C word or U-shaped, thus the C word on camera watch region or the open side of U-shaped and the magnetic field intensity of post side are regulated.
Prior art document
Patent documentation
Patent documentation 1: Japanese Unexamined Patent Publication 2005-168772 publication
Summary of the invention
Invent problem to be solved
Vertical-type MRI device possesses magnet arrangement, in order to produce uniform magnetostatic field in shooting space.Further, in this magnet arrangement, permanent magnet or superconducting coil is adopted.Usually, magnetic field intensity needed in shooting space is less than 0.5T and then adopts permanent magnet, and more than 0.5T then adopts superconducting coil.
Further, as the important parameter of MRI device magnet arrangement, except above-mentioned magnetic field intensity and above-mentioned uniformity of magnetic field, the size of stray field diffusion zone is also had.The large small scale of stray field diffusion zone generally adopts magnetic field intensity to decay to space size needed for 0.5mT.Stray field is needed to suppress for making the degree that this space size is less than the room arranging MRI device.Further, if the magnetic field intensity in shooting space is below 1.0T, then can be undertaken by the magnetic only configuring ferrum etc. in the suppression of the stray field of this degree.And when magnetic field intensity is more than 1T, then only configuring magnetic to the magnetic suppressing to need during stray field tens of tons, configuration magnetic suppresses stray field and impracticable.In this situation, the superconducting coil being called as shielded coil can be adopted to suppress stray field.
Summing up foregoing, is in the vertical-type MRI device in below 0.5T scope in the magnetic field intensity in shooting space, adopts permanent magnet to generate magnetostatic field, and adopt magnetic to suppress stray field to magnetic pole.As magnetic, specifically, yoke made of iron can be adopted.Further, in the vertical-type MRI device in the scope of more than 0.5T below 1.0T, adopt the superconducting coil different from magnetic magnetic pole to generate magnetostatic field, and adopt the magnetic different from magnetic poles gonosome to suppress stray field.
Further, in patent documentation 1, the few iron yoke of continuous print of superconducting coil and magnetic and space is adopted, therefore, it is possible to suppress stray field and generate the magnetostatic field of high magnetic field intensity.In addition, side is thinning gradually forward to make the thickness of the horizontal part of the yoke of C word or U-shaped, thus alleviates the nonaxisymmetry in magnetic field.
But, in the method for thickness regulating the horizontal part front of yoke, there is the nonaxisymmetry that cannot correct.Namely, about the circumferential angle of the vertical axis by camera watch region center, be 0 degree in the post side setting C word or U-shaped, the open side of C word or U-shaped is when being 180 degree, make 0 degree of mechanism consistent on the thickness of the horizontal part front of yoke with the intensity in the magnetic field in 180 degree of directions even if possess, also cannot utilize this mechanism make 0 degree consistent with the intensity in the magnetic field in 90 degree and 270 degree directions.
Further, in patent documentation 1, when making the thinner thickness of horizontal part front of yoke, then such as upside horizontal part with shape from the outer surface of this horizontal part to lower convexity, namely seen from above shape concavely for basic configuration.The shape of this projection of lower face is laterally compared with the shape raised up, can make to flow to the magnetic flux above vertical to bend sharp to the post side of C word or U-shaped, therefore the Distance Shortened that circulates upward to vertical of the magnetic field of the open side of C word or U-shaped, therefore causes needing the camera watch region of uniform magnetic field to diminish.
For this reason, problem to be solved by this invention is to provide a kind of magnet arrangement, and it can make the nonaxisymmetry of magnetostatic field alleviate and improve uniformity.And the MRI device being equipped with this magnet arrangement is provided.
For solving the method for problem
In order to solve above-mentioned problem, the present invention is a kind of magnet arrangement, it is characterized in that, possesses:
A pair that configures roughly discoid magnetic pole opposedly; And
Side-looking is C word or U-shaped and the yoke that closely configures of the both ends of this C word or U-shaped and 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:
Comprise the central zone region of a part for the vertical plane of symmetry roughly dividing above-mentioned yoke equally; And
Leave from the above-mentioned plane of symmetry and be positioned at the region, both sides of both sides, above-mentioned central zone region,
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 region, above-mentioned both sides.
Further, the present invention is a kind of MRI device, it is characterized in that, has:
This magnet arrangement; And
Examinee is transported to the table between a pair magnetic pole,
Above-mentioned magnet arrangement produces uniform magnetostatic field and forms shooting space between a pair above-mentioned magnetic pole.
The effect of invention
According to the present invention, a kind of magnet arrangement can be provided and be equipped with the MRI device of this magnet arrangement, because the magnetic flux being flowed to yoke side opposed portion by magnetic pole is had towards the direction composition of the vertical plane of symmetry, therefore, it is possible to suppress stray field and make the nonaxisymmetry of magnetostatic field alleviate and improve uniformity.Further, problem other than the above, structure and effect can be understood by the following explanation to embodiment.
Accompanying drawing explanation
Fig. 1 is the axonometric chart of the MR imaging apparatus (MRI device) of first embodiment of the invention.
Fig. 2 is the longitudinal section cut off along the vertical plane of symmetry by the magnet arrangement of first embodiment of the invention.
Fig. 3 is the top view of the magnet arrangement of first embodiment of the invention.
Fig. 4 is longitudinal section the first half of the magnet arrangement of first embodiment of the invention cut off along the plane orthogonal with the vertical plane of symmetry and horizontal symmetry face.
Fig. 5 is the top view of the magnet arrangement of first embodiment of the invention, is the figure of the flow direction representing produced magnetic flux.
Fig. 6 is longitudinal section the first half of the magnet arrangement of first embodiment of the invention cut off along the plane orthogonal with the vertical plane of symmetry and horizontal symmetry face, is the figure of the flow direction representing produced magnetic flux.
Fig. 7 is longitudinal section the first half of the magnet arrangement of first embodiment of the invention cut off along the vertical plane of symmetry, is the figure of the flow direction representing produced magnetic flux.
Fig. 8 is longitudinal section the first half of the magnet arrangement of comparative example cut off along the vertical plane of symmetry, is the figure of the flow direction representing produced magnetic flux.
Fig. 9 is the axonometric chart of the first half of the yoke of the magnet arrangement of second embodiment of the invention.
Figure 10 is the top view of the magnet arrangement of second embodiment of the invention.
Figure 11 is longitudinal section the first half of the magnet arrangement of second embodiment of the invention cut off along the plane orthogonal with the vertical plane of symmetry and horizontal symmetry face.
Figure 12 is longitudinal section the first half of the magnet arrangement of second embodiment of the invention cut off along the vertical plane of symmetry.
Figure 13 is the axonometric chart of the first half of the yoke of the magnet arrangement of third embodiment of the invention.
Figure 14 is the longitudinal section cut off along the vertical plane of symmetry by magnet arrangement when adopting permanent magnet.
Detailed description of the invention
Next, suitable reference accompanying drawing is described in detail to embodiments of the present invention.Further, divide mark same symbol to common part in the various figures and omit repeat specification.
(the first embodiment)
Fig. 1 illustrates the axonometric chart of the MR imaging apparatus (MRI device) 1 of first embodiment of the invention.MRI device 1 has: the magnet arrangement 2 generating the uniform magnetostatic field of magnetic field intensity in shooting space 9; By the table 8 that examinee transports to shooting space 9 with flat sleeping state; And MRI device 1 entirety such as magnet arrangement 2, table 8 are controlled, and utilize the nmr phenomena produced when subject irradiates high-frequency impulse, obtain the control part 7 of the image of the Wuli-Shili-Renli system approach characterizing subject.
Control part 7 is connected with magnet arrangement 2, table 8 etc.Control part 7 has: can carry out operating by operator the operating portion 72 adjusting its control content; And the display part 71 of image that display obtains.Operating portion 72 accepts the operation of operator by button or rotary switch etc.Display part 71 shows this operation information and the image that obtains of display.Control part 7 accepts the various operations of operator by operating portion 72, and carrys out controlling magnet device 2 based on this operation and generate magnetostatic field, and control table 8 examinee is transported in the horizontal direction shooting space 9.
Table 8 possesses the drive division 81 being located at bottom and the platen 82 utilizing this drive division 81 to move horizontally on the direction in shooting space 9.Examinee can put down sleeping on platen 82.Drive division 81 makes examinee move together with platen 82 and can the profile image (MRI image) at photographic subjects position.Make platen 82 only move small ormal weight to take profile image at every turn, thus continuous print profile image and 3-D view can be obtained.
Magnet arrangement 2 produces uniform magnetostatic field and forms shooting space 9 in MRI device 1.Magnet arrangement about 2 is configured with one group of discoid magnetic pole 4U and magnetic pole 4L as magnetic field occurring source opposedly.The coil accommodating container 5U of ring (annulus) shape is closely configured with below the magnetic pole 4U of upside.The superconducting coil 6U (with reference to Fig. 2) of coolant and ring (annulus) shape is accommodated with in coil accommodating container 5U.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 coolant and ring (annulus) shape is accommodated with in coil accommodating container 5L.Discoid gradient magnetic field coil 10 is configured with in the inner peripheral surface side of coil accommodating container 5L (5U).Gradient magnetic field coil 10 can produce the leaning magnetic field that magnetic field intensity tilts in shooting space 9.
Magnetic pole 4U and magnetic pole 4L is supported by yoke 3 made of iron.Yoke 3 side-looking is in roughly C word or U-shaped.Yoke 3 has the vertical plane of symmetry (plane of symmetry) α that roughly divides this yoke 3 equally and symmetrical relative to vertical plane of symmetry α face.Further, above-mentioned magnetic pole 4U and 4L is closely configured with at yoke 3 both ends of this C word or U-shaped.The yoke linking part (yoke vertical component effect) 13 that yoke 3 has close with magnetic pole 4U (4L) and opposed yoke side opposed portion (yoke horizontal part) 15U (15L) and yoke horizontal part 15U, 15L of upper and lower a pair linked.Yoke horizontal part 15U (15L) has: the yoke horizontal leading ends portion 14U (14L, reference Fig. 2) of tapered shape; With its link and the horizontal rear portion 12U of yoke in roughly rectangular shape (12L, with reference to Fig. 2).Horizontal rear portion 12U with 12L of yoke is connected by yoke vertical component effect 13.Further, when forming yoke 3 by some parts, be not limited to each part being divided into this structure, yoke 3 also can as integral piece manufacture.
Fig. 2 illustrates the longitudinal section cut off along vertical plane of symmetry α by the magnet arrangement 2 of first embodiment of the invention.Yoke 3 side-looking is in roughly C word or U-shaped.Therefore, yoke 3 has horizontal symmetry face β and symmetrical relative to β face, horizontal symmetry face.Roughly the magnetic pole 4U of disc-shape and magnetic pole 4L clips shooting space about 9 and configures opposedly.Shooting space 9 is in roughly ball shape, and it is centrally located on the central shaft 101 of the magnetic pole 4U of disc-shape and the common of magnetic pole 4L, and is positioned on horizontal symmetry face β and vertical plane of symmetry α.Magnetic pole 4U is combined with coil accommodating container 5U, in coil accommodating container 5U, contains superconducting coil 6U.Similarly, magnetic pole 4L is combined with coil accommodating container 5L, in coil accommodating container 5L, contains superconducting coil 6L.In this superconducting coil 6U, 6L of upper and lower a pair, circulating current produces magnetic field and magnetic pole 4U and magnetic pole 4L is magnetized, thus can produce the uniform magnetostatic field of magnetic field intensity in shooting space 9.In addition, under magnetic field intensity is less than 0.5T situation, then as shown in figure 14, can and between magnetic pole 4L and yoke horizontal leading ends portion 14L, permanent magnet 16U, 16L be set respectively and save superconducting coil 6U, 6L between magnetic pole 4U and yoke horizontal leading ends portion 14U.Like this, magnet arrangement 2 adopts the structure about β face, horizontal symmetry face symmetry, and therefore the following upside to horizontal symmetry face β structure is described and omits the explanation of downside.
As shown in Figure 2, the outer surface 15e of the counter surface 15a opposition side, yoke side be combined with magnetic pole 4U of yoke horizontal leading ends portion 14U is level and smooth curve form and bends laterally protrudingly.The height W1 from the counter surface 15a of yoke side of yoke horizontal leading ends portion 14U, along with near yoke horizontal leading ends portion 14U front end 15d, namely along with from yoke vertical component effect 13 away from and Generalized Monotone reduce and reduce smoothly.In this manual, Generalized Monotone reduces (monotonicdecreasing) and refers to and not increase in this interval.
Fig. 3 shows magnet arrangement 2 top view of first embodiment of the invention.Known yoke 3 particularly yoke vertical component effect 13 is located at a direction partially relative to the magnetic pole 4U of disc-shape.That is, from central shaft 101, in the plane being normal with central shaft 101 such as horizontal symmetry face β (with reference to Fig. 2), view angle theta when observing yoke vertical component effect 13 than 0 degree greatly and below 180 degree.
Further, yoke horizontal leading ends portion 14U is tapered shape.Specifically, the width W 2 of the normal direction of vertical plane of symmetry α, along with near front end 15d (along with away from yoke vertical component effect 13) continuously and reduce smoothly.Strictly say, if width W 2 Generalized Monotone reduce and its maximum is different with minima.
Further, the Breadth Maximum (equal with the width of yoke horizontal rear portion 12U) of width W 2 is less than the diameter of the magnetic pole 4U of disc-shape.The outer peripheral lines of yoke horizontal leading ends portion 14U has the region that radius of curvature is less than the radius of the magnetic pole 4U of disc-shape.Particularly in the outer peripheral lines of the yoke horizontal leading ends portion 14U of front end 15d periphery, radius of curvature is less than the radius of the magnetic pole 4U of disc-shape.Thus, the distance W4 of the periphery 4a from yoke horizontal leading ends portion 14U to magnetic pole 4U, along with near front end 15d (along with away from yoke vertical component effect 13) continuously and reduce smoothly.If yoke horizontal leading ends portion 14U (yoke side opposed portion 15U) is divided into: comprise the central zone region 15b of a part of vertical plane of symmetry α and leave from vertical plane of symmetry α and be positioned at region, the both sides 15c of 15b both sides, central zone region, the distance W4b of the periphery 4a then from central region 15b to magnetic pole 4U, nearer than the distance W4c of the periphery 4a from region, both sides 15c to magnetic pole 4U.
Fig. 4 illustrates longitudinal section the first half of the magnet arrangement 2 of first embodiment of the invention cut off along the plane γ (with reference to Fig. 3) orthogonal with vertical plane of symmetry α and horizontal symmetry face β.The height W3 from the counter surface 15a of yoke side of yoke horizontal leading ends portion 14U (yoke side opposed portion 15U), along with from vertical plane of symmetry α away from and continuously and reduce smoothly.Strictly say, if height W3 along with from vertical plane of symmetry α away from and Generalized Monotone reduce and its maximum is different with minima.On height W3, the height W3b of central zone region 15b is higher than the height W3c of region, both sides 15c.
For the shape utilizing above-mentioned yoke horizontal leading ends portion 14U (yoke side opposed portion 15U), suppress the nonaxisymmetry of the magnetostatic field in shooting space 9 (with reference to Fig. 2) and principle that uniformity is improved will describe later.
Fig. 5 illustrates the top view of the magnet arrangement 2 of first embodiment of the invention.The flow direction of the magnetic flux that magnet arrangement 2 produces is represented in Figure 5 with arrow.The flow direction (arrow) of magnetic flux shows the flow direction at first arriving the horizontal rear portion 12U of yoke near the periphery 4a of magnetic pole 4U via yoke horizontal leading ends portion 14U.Yoke horizontal leading ends portion 14U expands to circular shape (roughly parabolic shape) gradually towards the horizontal rear portion 12U of yoke, therefore, it is possible to make the magnetic resistance consistent (equal) on each magnetic flux (arrow) path.Thus, flowing to the magnetic flux (arrow) of yoke horizontal leading ends portion 14U from magnetic pole 4U balancedly can flow into from the circumferencial direction of magnetic pole 4U.And, from the magnetic flux (arrow) that this circumferencial direction flows into, on yoke horizontal leading ends portion 14U, not straight to yoke horizontal rear portion 12U, but except the direction composition towards the horizontal rear portion 12U of yoke, also have towards the direction composition of vertical plane of symmetry α.
Fig. 6 illustrates longitudinal section the first half of the magnet arrangement 2 of first embodiment of the invention cut off along plane γ (with reference to Fig. 5).The flow direction of the magnetic flux that magnet arrangement 2 produces is represented in figure 6 with arrow.The flow direction of magnetic flux shows the flow direction at first arriving yoke horizontal leading ends portion 14U from the β of horizontal symmetry face via magnetic pole 4U.As shown in Figure 6, yoke horizontal leading ends portion 14U is then higher the closer to vertical plane of symmetry α, and therefore magnetic flux (arrow) has towards the direction composition of vertical plane of symmetry α.
Thus, yoke horizontal leading ends portion 14U is in the shape expanding to circular shape (roughly parabolic shape) towards the horizontal rear portion 12U of yoke gradually, and it is then higher the closer to vertical plane of symmetry α, therefore balancedly distribute in a circumferential direction from the magnetic flux (arrow) of magnetic pole 4U inflow yoke horizontal leading ends portion 14U, and circulate towards vertical plane of symmetry α, thus the nonaxisymmetry of the magnetic flux in camera watch region 9 can be alleviated.Further, due to be do not adopt in yoke leading section, space is set and make magnetic resistance increase structure to alleviate the structure of nonaxisymmetry, therefore also can not affect ferromagnetic yoke and suppress the function of stray field.
Fig. 7 illustrates longitudinal section the first half of the magnet arrangement 2 of first embodiment of the invention cut off along vertical plane of symmetry α, and Fig. 8 illustrates longitudinal section the first half of the magnet arrangement 2 of comparative example cut off along vertical plane of symmetry α.The flow direction of the magnetic flux that magnet arrangement 2 produces is represented in figures 7 and 8 with arrow.The flow direction (arrow) of magnetic flux shows the flow direction at first arriving the horizontal rear portion 12U of yoke from the β of horizontal symmetry face 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 first embodiment of Fig. 7 raises up, and the outer surface 15e of the yoke horizontal leading ends portion 14Ua (yoke horizontal part 15Ua) of comparative example is then to lower convexity.In a comparative example, the flow direction (arrow) of magnetic flux injects yoke horizontal leading ends portion 14Ua obliquely, and incoming position also offsets to yoke vertical component effect 13 (the horizontal rear portion 12U of yoke) side.On the other hand, in the first embodiment compared with comparative example, the flow direction (arrow) of magnetic flux is to inject yoke horizontal leading ends portion 14U closer to the angle of vertical.Thus, the magnetic flux in the space between magnetic pole 4U and 4L, increase towards the direction composition of vertical, the nonaxisymmetry in the magnetic field near camera watch region 9 can be alleviated.As known from the above, according to the present embodiment, yoke horizontal leading ends portion 14U can be utilized to be led in camera watch region 9 by magnetic flux (arrow) vertical axis direction, therefore can not affect stray field suppression efficiency, and the nonaxisymmetry in the magnetic field in camera watch region 9 can be alleviated and expand camera watch region.
(the second embodiment)
Fig. 9 illustrates the axonometric chart of the first half of the yoke 3 of the magnet arrangement of second embodiment of the invention.In the second embodiment and the first embodiment, distinctive points is the shape of yoke 3, is wherein the shape of yoke horizontal leading ends portion 14U.The outer surface 15e of the yoke horizontal leading ends portion 14U of the first embodiment uses flexure plane to form, and multiple inclined planes that the outer surface 15e of the yoke horizontal leading ends portion 14U of the second embodiment then uses angle of inclination different are formed.
Figure 10 illustrates the top view of the magnet arrangement 2 of second embodiment of the invention.Yoke horizontal leading ends portion 14U is tapered shape.Specifically, the width W 2 of the normal direction of vertical plane of symmetry α reduces in 2 grades of stages along with near front end 15d (away from yoke vertical component effect 13).Strictly say, as long as width W 2 is along with to reduce near front end 15d and Generalized Monotone and its maximum is different with minima.The maximum of width W 2 is equal with the width of yoke horizontal rear portion 12U.Width W 2 is with 2 stage constrictions.Further, although in this second embodiment width W 2 was set as 2 stages, is not limited thereto and also can be set as the multistage.
And, if yoke horizontal leading ends portion 14U (yoke side opposed portion 15U) is divided into: comprise the central zone region 15b of a part of vertical plane of symmetry α and leave from vertical plane of symmetry α and be positioned at region, the both sides 15c of 15b both sides, central zone region, the distance W4b of the periphery 4a then from central region 15b to magnetic pole 4U, nearer than the distance W4c of the periphery 4a from region, both sides 15c to magnetic pole 4U.The central zone region 15b of yoke horizontal leading ends portion 14U extends to the direction with yoke vertical component effect 13 opposition side relative to region, both sides 15c.
Figure 11 illustrates longitudinal section the first half of the magnet arrangement 2 of second embodiment of the invention cut off along plane γ (with reference to Figure 10).The height W3 from the counter surface 15a of yoke side of yoke horizontal leading ends portion 14U (yoke side opposed portion 15U) periodically reduces along with leaving from vertical plane of symmetry α.Strictly say, if height W3 along with from vertical plane of symmetry α away from and Generalized Monotone reduce and its maximum is different with minima.Height W3b on the 15b of central zone region is higher than the height W3c on the 15c of region, both sides.Further, although in this second embodiment height W3 was set as 2 stages, is not limited thereto and also can be set as the multistage.
Figure 12 illustrates longitudinal section the first half of the magnet arrangement 2 of second embodiment of the invention cut off along vertical plane of symmetry α.Two inclined planes that the outer surface 15e of yoke horizontal leading ends portion 14U uses tilt angle theta 1, θ 2 different are formed.The tilt angle theta 1 of the inclined plane of downside is larger than the tilt angle theta 2 of the inclined plane of upside (θ 1 > θ 2).Thus, outer surface 15e laterally (on) protruding.Further, although in this second embodiment tilt angle theta 1, θ 2 were set as 2 stages, are not limited thereto and also can be set as the multistage.The height W1 from the counter surface 15a of yoke side of yoke horizontal leading ends portion 14U, along with from yoke vertical component effect 13 away from and Generalized Monotone reduce and reduce smoothly.
In this second embodiment, the shape of yoke horizontal leading ends portion 14U also has common point with the first embodiment, utilizes this common point then in the same manner as the first embodiment, can suppress the nonaxisymmetry of magnetostatic field and improve uniformity.
(the 3rd embodiment)
Figure 13 illustrates the axonometric chart of the first half of the yoke 3 of the magnet arrangement of third embodiment of the invention.The distinctive points of the 3rd embodiment and the second embodiment is the shape of yoke 3, is also wherein the shape of yoke vertical component effect 13.Yoke vertical component effect 13 is 1 post in this second embodiment, and is many posts (being 2 in Figure 13 example) in the third embodiment.Accordingly, the pipeline that coil accommodating container 5U and 5L can be communicated with, the distribution, refrigeration machine etc. that are connected with superconducting coil 6U and 6L are set between many yoke vertical component effects 13 adjacent one another are.By the area configurations pipeline between adjacent yoke vertical component effect or distribution etc., region that table 8 passes through can be expanded and more the degree of freedom of table 8 movement is guaranteed in open ground.Further, by arranging refrigeration machine between adjacent yoke vertical component effect, can refrigeration machine be set near superconducting coil and more effectively cool superconducting coil.
Further, the invention is not restricted to the above-mentioned first to the 3rd embodiment and comprise various variation.Such as above-mentioned first to the 3rd embodiment is used for being beneficial to understand to the detailed description of the invention and being not limited to possess illustrated entire infrastructure.Further, also a part for the structure of certain embodiment can be replaced into the structure of other embodiment, also can add the structure of other embodiment in addition to the structure of certain embodiment.Further, also can to a part for the structure of each embodiment carry out other structure add, delete, displacement.
Symbol description
1-nuclear magnetic resonance (MRI) device; 2-magnet arrangement; 3-yoke; 4U, 4L-magnetic pole; The periphery of 4a-magnetic pole; 5U, 5L-coil accommodating container; 6U, 6L-superconducting coil; 7-control part; 8-table; 9-shooting space (uniform magnetostatic field); 10-gradient magnetic field coil; The horizontal rear portion of 12U, 12L-yoke; 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 side counter surface of 15a-yoke side opposed portion; The central zone region of 15b-yoke side opposed portion; The region, both sides of 15c-yoke side opposed portion; The front end of 15d-yoke side opposed portion; The outer surface of 15e-yoke side opposed portion; The central shaft of 101-superconducting coil; The height from the counter surface of yoke side of W1-yoke side opposed portion; The width of the normal direction of the vertical plane of symmetry of W2-yoke side opposed portion; The height from the counter surface of yoke side of W3-yoke side opposed portion; Height on W3b-central zone region; Height on W3c-region, both sides; W4-from yoke side opposed portion to the distance of magnetic pole periphery; The distance of W4b-from central region; The distance of W4c-from region, both sides; The vertical plane of symmetry (plane of symmetry) of α-yoke; The horizontal symmetry face of β-yoke; The plane of γ-orthogonal with α and β; Visual angle during θ-observation yoke linking part.
Claims (14)
1. a magnet arrangement, is characterized in that, possesses:
A pair that configures roughly discoid magnetic pole opposedly; And
Side-looking is C word or U-shaped and the yoke that closely configures of the both ends of this C word or U-shaped and 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 comprises a part for the vertical plane of symmetry roughly dividing above-mentioned yoke equally; And
Region, both sides, it leaves from the above-mentioned plane of symmetry and is positioned at both sides, above-mentioned central zone region,
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 region, above-mentioned both sides.
2. magnet arrangement according to claim 1, is characterized in that,
Above-mentioned central zone region than region, above-mentioned both sides near the periphery of above-mentioned magnetic pole.
3. magnet arrangement according to claim 1, 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 along with near the front end of above-mentioned yoke side opposed portion, Generalized Monotone reduces, and the maximum of this width is different with minima.
4. magnet arrangement according to claim 1, is characterized in that,
The height from the counter surface of above-mentioned yoke side of above-mentioned yoke side opposed portion along with from the above-mentioned vertical plane of symmetry away from and Generalized Monotone reduces, and the maximum of this height is different with minima.
5. magnet arrangement according to claim 1, is characterized in that,
Along with the front end of close above-mentioned yoke side opposed portion, Generalized Monotone reduces the height from the counter surface of yoke side of above-mentioned yoke side opposed portion,
And the outer surface opposed with above-mentioned yoke side counter surface of above-mentioned yoke side opposed portion is protruding laterally.
6. magnet arrangement according to claim 1, is characterized in that,
Above-mentioned yoke has the yoke linking part of link a pair above-mentioned yoke side opposed portion,
From the central shaft that a pair above-mentioned magnetic pole is common, and the visual angle when the above-mentioned yoke linking part of the plan view being normal with above-mentioned central shaft is larger and below 180 degree than 0 degree.
7. magnet arrangement according to claim 1, is characterized in that,
Reduce continuously along with near the front end of above-mentioned yoke side opposed portion from above-mentioned yoke side opposed portion to the distance of the periphery of above-mentioned magnetic pole.
8. magnet arrangement according to claim 1, 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 reduces continuously along with near the front end of above-mentioned yoke side opposed portion.
9. magnet arrangement according to claim 1, 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 along with from the above-mentioned vertical plane of symmetry away from and reduce continuously.
10. magnet arrangement according to claim 1, 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 periodically reduces along with near the front end of above-mentioned yoke side opposed portion.
11. magnet arrangements according to claim 1, 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 along with from the above-mentioned plane of symmetry away from and periodically reduce.
12. magnet arrangements according to claim 1, is characterized in that,
A pair that possesses that above-mentioned magnetic pole closely configures with a pair roughly circular superconducting coil.
13. magnet arrangements according to claim 1, is characterized in that,
Possess a pair roughly discoid permanent magnet that above-mentioned magnetic pole closely configures with a pair.
14. 1 kinds of MR imaging apparatus, is characterized in that having:
Magnet arrangement according to any one of claim 1 to 13; And
Examinee is transported to the table between a pair magnetic pole,
Above-mentioned magnet arrangement produces uniform magnetostatic field and forms shooting space between a pair above-mentioned magnetic pole.
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| 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 true CN105208929A (en) | 2015-12-30 |
| CN105208929B CN105208929B (en) | 2018-06-08 |
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| CN201480027004.7A Active CN105208929B (en) | 2013-06-04 | 2014-05-27 | Magnet arrangement and MR imaging apparatus |
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| Country | Link |
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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 (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07171131A (en) * | 1993-04-08 | 1995-07-11 | Oxford Magnet Technol Ltd | Improvement of mri magnet |
| JPH0845729A (en) * | 1994-07-29 | 1996-02-16 | Sumitomo Special Metals Co Ltd | Magnetic field generating device for mri |
| 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 |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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
-
2014
- 2014-05-27 WO PCT/JP2014/063947 patent/WO2014196411A1/en active Application Filing
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07171131A (en) * | 1993-04-08 | 1995-07-11 | Oxford Magnet Technol Ltd | Improvement of mri magnet |
| JPH0845729A (en) * | 1994-07-29 | 1996-02-16 | Sumitomo Special Metals Co Ltd | Magnetic field generating device for mri |
| 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 |
|---|---|
| CN105208929B (en) | 2018-06-08 |
| WO2014196411A1 (en) | 2014-12-11 |
| JP6046560B2 (en) | 2016-12-14 |
| JP2014233525A (en) | 2014-12-15 |
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