WO2001074243A1 - Aimant supraconducteur et appareil d'imagerie par resonance magnetique qui comprend ledit aimant - Google Patents

Aimant supraconducteur et appareil d'imagerie par resonance magnetique qui comprend ledit aimant Download PDF

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Publication number
WO2001074243A1
WO2001074243A1 PCT/JP2001/002879 JP0102879W WO0174243A1 WO 2001074243 A1 WO2001074243 A1 WO 2001074243A1 JP 0102879 W JP0102879 W JP 0102879W WO 0174243 A1 WO0174243 A1 WO 0174243A1
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WIPO (PCT)
Prior art keywords
magnetic field
static magnetic
axis
straight line
superconducting magnet
Prior art date
Application number
PCT/JP2001/002879
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English (en)
Japanese (ja)
Inventor
Yoshihide Wadayama
Shigeru Kakugawa
Katsunori Azuma
Hirotaka Takeshima
Kenji Sakakibara
Takao Honmei
Original Assignee
Hitachi Medical Corporation
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Application filed by Hitachi Medical Corporation filed Critical Hitachi Medical Corporation
Priority to JP2001571991A priority Critical patent/JPWO2001074243A1/ja
Publication of WO2001074243A1 publication Critical patent/WO2001074243A1/fr

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Classifications

    • 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
    • G01R33/3806—Open magnet assemblies for improved access to the sample, e.g. C-type or U-type magnets
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F6/00—Superconducting magnets; Superconducting coils
    • H01F6/06—Coils, e.g. winding, insulating, terminating or casing arrangements therefor

Definitions

  • the present invention relates to a superconducting magnet apparatus suitable for an open-type magnetic resonance imaging apparatus (hereinafter, referred to as an MRI apparatus), and more particularly to a superconducting magnet apparatus having a stronger support structure for an electromagnetic force acting between superconducting coils.
  • an MRI apparatus open-type magnetic resonance imaging apparatus
  • MRI apparatuses using open magnets that do not give a feeling of obstruction to the subject have become mainstream.
  • An open magnet has a pair of static magnetic field sources facing each other across a magnetic resonance imaging region (MRI region). The feeling of pressure during the test is reduced.
  • various magnet structures have been proposed for improving the feeling of opening for the subject and making the structure easy for an operator to access the subject.
  • a first conventional example of the open type superconducting magnet device is disclosed in Japanese Patent Application Laid-Open No. 9-187439.
  • This conventional superconducting magnet device has two sets of static magnetic field sources each having an annular superconducting coil, and these two sets of static magnetic field sources are arranged to face each other across the MRI region. It is configured.
  • These two sets of static magnetic field sources are housed in annular cooling containers. Then, the load of the cooling vessel and the static magnetic field generation source is supported by mechanically connecting the two sets of cooling vessels with four columns. In particular, the four columns support the electromagnetic force acting between the two sets of superconducting coils, thereby preventing the gap between the superconducting coils from changing.
  • the four pillars of the first conventional example are arranged in a room temperature environment, a heat insulating member, a coolant tank and a vacuum tank are provided between the superconducting coil cooled to the coolant (liquid helium) temperature. Etc. are interposed. Therefore, the electromagnetic force of the superconducting coil is transmitted to the support via the heat insulating members and the like.
  • a second conventional example of an open superconducting magnet device is disclosed in USP No. 5,883,558.
  • the superconducting magnet device of this example also has two sets of static magnetic field sources each including an annular superconducting coil, and these two sets of static magnetic field sources are connected to the MRI region. Are arranged opposite to each other.
  • Each of these two sets of static magnetic field sources is housed in an annular cooling container.
  • two sets of cooling containers are connected and supported by one supporting member arranged at one position on the ring of the cooling container.
  • the cross-sectional shape of the entire device is formed in a C-shape, so that the open feeling is excellent.
  • the support member since the support member is disposed in the surrounding air as in the first conventional example, the electromagnetic force of the superconducting coil is transmitted to the support member via a heat insulating member or the like. .
  • the superconducting magnet device of this example has two sets of static magnetic field sources each having an annular superconducting coil, and these two sets of static magnetic field sources are arranged to face each other across the MRI region. It is configured.
  • Each of these two sets of static magnetic field sources is housed in an annular cooling container, and each of these cooling containers is a winding frame of a superconducting coil. Then, the two sets of cooling vessels are connected by two connecting pipes through which the refrigerant flows, thereby supporting the electromagnetic force acting between the two sets of magnetic field generating sources.
  • the two connecting pipes are disposed at asymmetric positions with respect to the center axis of the annular shape of the cooling vessel.
  • a part of the vessel wall on which the electromagnetic force acts is formed thick and reinforced. That is, in the third conventional example, since the side wall of the refrigerant container facing the MRI region also serves as the winding frame of the superconducting coil, when the side wall of the refrigerant container is deformed by the electromagnetic force, the superconducting coil is also deformed. become. Therefore, by increasing the thickness of the side wall of the refrigerant container that receives the electromagnetic force, the deformation of the superconducting coil is prevented, and the quenching resistance is improved so that superconducting destruction does not occur.
  • two pillars are arranged one by one at circumferentially symmetric positions of the annular cooling vessel.
  • the struts arranged two by two Is an obstacle.
  • the feeling of openness is not always excellent because there are two struts near both sides of the test site.
  • the accessibility of the operator and the open feeling of the subject are good.
  • the electromagnetic force acting between the two sets of static magnetic field sources is supported by one support member that is separated from the center axis of the electromagnetic force, two sets of support members are used as fulcrums.
  • the support structure of the static magnetic field source causes flexural deformation, which causes a problem that the uniformity of the static magnetic field is reduced.
  • the cooling container itself due to the electromagnetic force is prevented.
  • the connecting pipe supporting the refrigerant container is arranged symmetrically with respect to the central axis of the superconducting coil, the deformation of the connecting pipe due to the electromagnetic force is considered to be small.
  • the connecting tube is asymmetrically arranged with respect to the center axis of the superconducting coil, it is necessary to prevent the entire device from being deformed by the electromagnetic force as in the second conventional example.
  • a member for adiabatically supporting the superconducting coil cooled to the refrigerant temperature and a cooling member for accommodating the superconducting coil are provided between the opposing superconducting coils as static magnetic field generating sources. Mechanically connected via a container. As a result, heat shrinkage occurs during the process of cooling the superconducting coil structure assembled at room temperature to the refrigerant temperature. Therefore, the relative distance between the superconducting coils changes. Since the change is complicated, it is difficult to control the position between the superconducting coils.
  • a superconducting magnet device of the present invention includes two sets of superconducting coils, two sets of coil supports for supporting and fixing the superconducting coils, respectively, and magnetic resonance imaging of the two sets of superconducting coils. It comprises two sets of support structures that are supported so as to face each other across the region, and two cooling vessels that respectively house the superconducting coils, wherein the two sets of support structures have two columns, It is configured to have two beams that couple each of the columns and each of the coil supports,
  • the two struts are arranged in parallel to the direction of the static magnetic field in the magnetic resonance imaging region, and an inner dividing point of a straight line connecting the two struts in a plane perpendicular to the direction of the static magnetic field is a static magnetic field. Is located away from the central axis of
  • the two beams are arranged so that their extended lines intersect with each other, and an axis (hereinafter, referred to as an S-axis) passing through the intersection and parallel to the direction of the static magnetic field is greater than the inner dividing point. It is characterized by being located on the central axis side of the static magnetic field.
  • two supports in which coil supports for fixing and supporting the superconducting coil are arranged on both sides of a magnetic resonance imaging region (hereinafter referred to as an MRI region), are connected via two beams connected to the two columns. Since the coil supports the coil support, the superconducting coil is firmly supported and the openness of the magnet and the accessibility of the subject are maintained.
  • the axis (S-axis) where the ends of the two beams are in contact with each other or where their extensions intersect is near the center point of the load such as electromagnetic force applied to the magnet.
  • the supporting strength of the superconducting coil is improved. As a result, the distance between the pair of static magnetic field sources is maintained with almost no change, so that the uniformity of the static magnetic field in the MRI region can be improved.
  • the other ends of the beams are connected to each other at the S axis.
  • the ends of the two beams are connected to each other on the S-axis, which is in the vicinity of the center point where the load of the magnet acts, the support strength for supporting the coil support is further improved.
  • the S-axis is located on a straight line connecting the internally dividing point and the central axis of the static magnetic field, and the central axis of the static magnetic field and the internal dividing point with respect to the central axis. It is located between the outermost superconducting coil located on the opposite side.
  • the S-axis where the ends of the two beams are in contact with each other, or the extension of the two beams intersect is closer to the central point of the load, such as the electromagnetic force applied to the magnet. Is further improved.
  • the cross-sectional shape of the column is such that the moment of inertia in the direction toward or near the S-axis is larger than the moment of inertia in the direction orthogonal thereto.
  • the bending stiffness of the support in the direction of the S-axis or in the vicinity of the S-axis located near the center of action of the load such as electromagnetic force applied to the magnet is increased, so that the deformation due to the load applied to the magnet is significantly reduced.
  • the distance between the static magnetic field sources supported thereby is kept almost constant.
  • the cross-sectional shape of the column is an ellipse or a rectangle whose longitudinal direction is the direction toward the S axis or the vicinity thereof.
  • the second moment of area in the direction of the S-axis of the column or in the vicinity thereof increases, the support strength of the column in the direction of or near the S-axis increases.
  • the cross-sectional shape of the column is oval or rectangular, the column can be easily processed.
  • the two columns have a first column and a second column, and the first and second columns are arranged in the longitudinal direction of the beam or in a direction near the beam. They are offset from each other.
  • two columns are offset from each other in the longitudinal direction of the beam or in the vicinity of the beam, so that The second moment of area in the lateral direction is increased, and the support strength of the column in the longitudinal direction or in the vicinity of the beam is improved. Further, by setting the cross-sectional shape of each support to a circle or a rectangle, the support can be easily processed.
  • the support structure including the columns and the beams is housed in the cooling container.
  • the distance between the pair of static magnetic field sources is kept constant regardless of the change in the outside air temperature, so that the static magnetic field uniformity in the MRI region is maintained.
  • the present invention provides the above-described superconducting magnet apparatus in a magnetic resonance imaging apparatus.
  • the present invention provides a pair of static magnetic field generating means for forming a magnetic resonance imaging region, and a pair of the static magnetic field S generating means arranged in parallel with a static magnetic field direction formed by the static magnetic field generating means.
  • a first straight line that is parallel to the static magnetic field direction and that passes through a midpoint of a straight line connecting the pillars is parallel to the static magnetic field direction, and that the magnetic resonance imaging is performed.
  • a magnetic resonance imaging apparatus arranged at a position different from the second straight line passing through the center point of the static magnetic field in the region,
  • a connecting member for connecting the static magnetic field generating means and the supporting column is provided at one end of each of the supporting columns, and each of the connecting members is disposed such that a leading end or an extension line of the extending direction intersects each other.
  • a third straight line passing through the intersection and parallel to the static magnetic field direction is arranged on a plane including the first straight line and the second straight line.
  • the third straight line is disposed at a position opposite to the first straight line with respect to the second straight line, and the third straight line is disposed between the third straight line and the second straight line.
  • the distance may be shorter than the distance between the first straight line and the second straight line.
  • a magnetic resonance imaging apparatus comprises: a pair of static magnetic field generating means for generating a static magnetic field; and a support structure for supporting the pair of static magnetic field generating means so as to face each other.
  • a pair of static magnetic field generating means for generating a static magnetic field
  • a support structure for supporting the pair of static magnetic field generating means so as to face each other.
  • the beam member has a long axis portion of the beam member.
  • the moments generated by the force acting between the static magnetic field generating means may be arranged at positions where the moments cancel each other.
  • the two pillars are arranged such that a line connecting the two pillars is shifted from a center axis of a static magnetic field formed by the pair of static magnetic field generating means, and the beam member is The midpoint of the beam member is arranged on a plane including the midpoint of the line connecting the two columns and the central axis of the static magnetic field.
  • FIG. 1 is an overall perspective view of a first embodiment of a superconducting magnet device according to the present invention
  • FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1
  • FIG. 3 is a cross-sectional view taken along line III-III of FIG. Is an example of the structure of the coil support
  • FIG. 5 is an example of the structure of the connection between the coil support and the beam
  • FIG. 6 is an example of the structure of the connection between the column and the beam
  • FIG. 7 is the second example of the superconducting magnet device according to the present invention
  • FIG. 8 is a cross-sectional view taken along the line VIII-VIII of FIG. 7,
  • FIG. 9 is an overall configuration diagram of a magnetic resonance imaging apparatus according to an embodiment of the present invention.
  • FIG. 1 is an overall perspective view of the device
  • FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1
  • FIG. 3 is a cross-sectional view taken along line III-III of FIG.
  • Fig. 1 describes the overall configuration of the superconducting magnet device
  • Figs. 2 and 3 describe the static magnetic field source and the supporting structure that supports it.
  • FIG. 1 first, a three-dimensional orthogonal coordinate system having the origin at the magnetic field center 0 of the magnetic resonance imaging region (MRI region) 2 is defined.
  • MRI region magnetic resonance imaging region
  • the vertical direction is the Z axis 8
  • the horizontal direction is the X axis 6
  • the direction perpendicular to the paper is the Y axis 7.
  • the two sets of magnetostatic field sources 1A and IB are housed in cooling vessels 3A and 3B, respectively, and these cooling vessels 3A and 3B are vertically (Z-axis 8 directions).
  • the upper and lower cooling vessels 3A, 3B are connected and supported by columns 4 ⁇ , 4 ⁇ constituting a support structure arranged symmetrically with respect to the YZ plane. Up and down direction in MRI area 2
  • the central axis of the MRI region 2 in the direction of the static magnetic field (hereinafter referred to as the magnetic field central axis) is equivalent to the ⁇ axis 8 passing through the magnetic field center 0, so the magnetic field central axis and the ⁇ axis 8 will be treated as the same hereinafter.
  • FIG. 2 is a cross-sectional view taken along line II-II of the cooling vessel 3 in FIG. 1 taken along a plane perpendicular to the axis 8.
  • Figure 2 shows the arrangement of the static magnetic field source 1A inside the cooling vessel 3 ⁇ and the arrangement of the columns 4 ⁇ and 4 ⁇ that support the cooling vessel 3 ⁇ .
  • the cooling vessel 3 ⁇ and the static magnetic field source 1B are also shown.
  • the static magnetic field sources 1A (1B) are arranged with the ⁇ axis 8 as the center axis.
  • each of the static magnetic field sources 1A and IB is constituted by a plurality of superconducting coils 9 formed in an annular shape with the Z axis 8 as the central axis.
  • the superconducting coils 9 are firmly fixed and supported by a coil support 10.
  • the superconducting coils 9 constituting the static magnetic field generating sources 1A and IB are not limited to two, but may be one or a combination of three or more.
  • the static magnetic field generation sources 1A and IB may include a ring-shaped magnetic pole made of a magnetic material in addition to the superconducting coil 9.
  • FIG. 4 shows a structural example of the coil support 10.
  • FIG. 4 (A) is a perspective external view of the assembled product
  • FIG. 4 (B) is an external view of a component before the assembly.
  • the coil support 10 has, for example, eight support plates 31 distributed along the annular direction of the superconducting coil 9 and a fan-shaped, for example, sixteen connection plate for connecting these support plates 31. Consists of 32.
  • the support plate 31 is a rectangular plate having a coil support hole 33 for supporting the superconducting coil 9, and is usually made of nonmagnetic stainless steel or aluminum.
  • the support plates 31 are arranged at intervals of, for example, 45 degrees so that the longitudinal direction of the rectangle faces the central axis of the coil support 10.
  • connection plate 32 is a fan-shaped plate having an opening angle of 45 degrees and is made of the same material as the support plate 31. As shown in the figure, the length of the long side of the support plate 31 and the length of the straight side of the connection plate 32 are the same, and both are welded to the long side of the support plate 31 and the straight side of the connection plate 32. Or, it is assembled by joining by brazing or the like.
  • the support plate 31 is used to support the superconducting coil 9.
  • the connecting plates 32 are arranged at substantially equal intervals in the circumferential direction, and are joined to the supporting plate 31 to secure the interval between the supporting plates 31 and to reinforce the supporting plate 31.
  • the eight connecting plates 32 as a whole form two disk-shaped members.
  • the superconducting coil 9 is supported by the coil support 10 by inserting the superconducting coil 9 into the coil support hole 33 of the support plate 31 and fixing it.
  • the coil support hole 33 may be provided with an inlet for introducing the superconducting coil 9.
  • the width of the inlet can be increased to be equal to the width of the coil support hole 33, and the coil support hole 33 can be used as a winding frame of the superconducting coil 9.
  • FIG. 4 shows an example of the structure of the coil support 10, and the structure is not limited to this. Any structure can be used as long as it can strongly support the superconducting coil 9 and can be connected to a beam 11 described later. .
  • the superconducting coil 9 is cooled by a low-temperature refrigerant such as liquid helium stored inside the cooling containers 3A and 3B so as to have a superconducting transition temperature or lower.
  • a low-temperature refrigerant such as liquid helium stored inside the cooling containers 3A and 3B so as to have a superconducting transition temperature or lower.
  • the cooling containers 3A and 3B are configured by a refrigerant container for storing a low-temperature refrigerant, a heat insulation shield enclosing the refrigerant container, a vacuum container enclosing the heat insulating shield, and the like.
  • the columns 4A and 4B which constitute the two support structures that support the cooling vessels 3A and 3B, are not on the X axis 6 passing through the magnetic field center 0, but in the (+) direction from the X axis 6 to the Y axis 7. They are offset by a certain amount. That is, they are arranged at positions that are asymmetric with respect to the Z axis 8. Therefore, when viewed from the outside of the MRI area 2, the vertical view is blocked by the cooling vessels 3A and 3B, but the horizontal view is forward (Y-axis (one) direction) and left-right direction (X-axis (+ ), (1) direction).
  • the distance between the columns 4A and 4B on the Y-axis (+) side is set so that a bed that allows the subject to lie supine can be inserted, so that the surgeon can access from both the X-axis and Y-axis directions. It is easy to use.
  • FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2, and shows a support structure of the static magnetic field generating sources 1A and IB by the columns 4B.
  • the support of the static magnetic field source 1A and IB The same applies to the holding structure.
  • the structure of the columns 4A and 4B and the details of the support structure of the static magnetic field sources 1A and IB in this embodiment will be described with reference to FIGS.
  • the two columns 4A and 4B are located behind the X axis 6 (Y (+) side) and are equidistant from the Y axis 7 in order to improve the openness of the subject. Is located in the position.
  • the columns 4A and 4B are housed in support cooling vessels 5A and 5B, and are cooled in the same manner as the static magnetic field sources 1A and IB.
  • the support cooling vessels 5A and 5B are connected to the cooling vessels 3A and 3B, and also play a role of thermally and mechanically connecting the upper and lower cooling vessels 3A and 3B.
  • the superconducting coil 9 constituting the static magnetic field generation sources 1A and IB is supported by a coil support.
  • the coil support 10 is supported on the column 4B (4A) via the beam 11B (11A) and the auxiliary beam 12. That is, the beam 11B (11A) is fixed to the outer surface of the upper and lower coil supports 10, the auxiliary beam 12 is fixed to the outer peripheral surface of the upper and lower coil supports 10, and the beam 11B (11A) and the auxiliary beam 12 are Connected to 4B (4A).
  • the static magnetic field sources 1A and IB are supported by the columns 4A and 4B by the connecting members including the beams 11A and 11B coupled to the coil support 10. Further, the combined body of the coil support 10 and the columns 4A and 4B is supported and fixed as a whole by a plurality of supports 13 in the lower cooling vessel 3B.
  • an electromagnetic attraction force acts between the upper and lower static magnetic field generating sources 1A and IB.
  • the weight of the entire upper cooling container 3A is applied, and a load acts on the left and right columns 4A and 4B.
  • the columns 4A and 4B are located behind (the Y (+) side) the Z axis 8, which is the central axis of the magnetic field, in order to improve the openness of the front side (the Y (—) side) of the superconducting magnet device. It is arranged. Therefore, a bending load such as an electromagnetic force is applied to the left and right columns 4A and 4B, and bending deformation occurs.
  • the cross-sectional shape of the columns 4A and 4B is improved, and two beams 11A and 11B are arranged between the two columns 4A and 4B. I have. These two beams 11A and 1IB are similarly arranged for the upper and lower static magnetic field sources 1A and IB.
  • the positional relationship between the two beams 11A and 11B in this embodiment will be described in detail.
  • the line connecting the geometric centers of the cross sections of the left and right columns 4A and 4B (hereinafter referred to as the center of the support structure) 20A and 20B is the internal branch line 21, and the middle point between the center of the support structure 20A and 20B is the internal line.
  • the bending displacement caused by the bending deformation is based on the internal dividing line 21. Then, it increases in the forward direction ( ⁇ (-) side) in the ⁇ axis 7 direction, and decreases in the rear side ( ⁇ (+) side) in the ⁇ axis 7 direction.
  • the position of the center point of the bending deformation caused by a load such as electromagnetic force that causes this bending displacement is determined by the bending moment acting on the ⁇ axis (+) side and the ⁇ axis (-) side with the internal line 21 as the central axis.
  • the difference between the load acting on the ⁇ -axis (+) side and the load acting on the ⁇ -axis (-) side, with the internal branch line 21 as the center axis, is calculated by dividing the bending moment acting on the -axis.
  • the columns 5 ⁇ and 5 ⁇ and the static magnetic field source 1A (or 1B) are symmetric with respect to the ⁇ axis 7, so that the bending moment due to a load such as an electromagnetic force can be converted to the ⁇ axis. . Since the bending moments are opposite on the ⁇ axis (+) side and ⁇ axis (-) side of the internal branch line 21, the magnitude of the combined bending moment is on the ⁇ axis (+) side and the ⁇ axis (-) side. And the bending moment acting on each.
  • the position of the center point of the action of the resultant bending moment is determined by the electromagnetic force acting on the ⁇ axis (-) side from the load such as the electromagnetic force acting on the ⁇ axis (+) side of the internal dividing line 21.
  • the distance from the interior dividing point 22 can be obtained.
  • the midpoint of the beam (11A, 11B) is set to the midpoint of the line connecting the struts 5 ⁇ and 5 ⁇ ⁇ so that the moments acting on these first and second areas cancel each other. It is located on the plane containing the central axis S of the magnetic field. Thereby, the static magnetic field generating source 1A can be supported by the beams (11A, 11B) in a well-balanced manner.
  • beams 11A and 11B are provided between the S-axis 14 and the columns 4A and 4B, and these beams 11A and 11B are provided.
  • the ends of the two beams 11A and 11B are connected at the S-axis 14.
  • the present invention is not limited to this, and practical effects can be obtained if the S axis 14 is located near the central point of action. From a practical point of view, the effect is effective if the S axis 14 is located in the forward direction of the Y axis 7 direction (Y (-) side) than the internal branch line 21.
  • the S-axis 14 is selected in a range from the Z-axis 8 force to the Y-axis 7-direction front side (Y (-) side) to the outer periphery of the coil support 10, the effect of improving the support strength is increased.
  • the coil support 10 has a disk shape. However, when the coil support 10 is not a disk shape, the outer circumference of the coil support 10 may be the maximum outer circumference of the coil support 10.
  • the cross sections of the columns 4A and 4B are oblong, and the columns 4A and 4B are arranged so that the longitudinal direction of the ellipse is directed to the S-axis 14 or the vicinity thereof.
  • the cross-sectional secondary moment in the direction of or near the S axis 14 of the columns 4A and 4B increases, so the rigidity against the above bending moment is improved, and the bending angles of the columns 4A and 4B are reduced.
  • the displacement between the upper and lower static magnetic field sources 1 A and IB is suppressed.
  • the cross-sectional shape of the columns 4A and 4B is not limited to the above-mentioned oval shape, but may be a rectangle or a polygon.
  • the length of the S-axis 14 or its vicinity is long, and the length in the orthogonal direction is short. If the shape is such that the second moment of area in or near the S-axis 14 is larger than in other directions, it is effective. Therefore, it may be a hollow member having a hole inside.
  • the cross-sectional shape is oval or rectangular, the workability is good and the cost can be reduced.
  • FIG. 5 shows an example of a coupling structure between the coil support 10 and the beams 11A and 1IB.
  • the figure shows an example of the upper coil support 10.
  • the lower surfaces of the two beams 11A and 1IB correspond to the upper surface 34 of the coil support 10, that is, the disk shape formed by the connection plate 32.
  • the surface is V-shaped and is firmly connected by welding.
  • One end of each of the beams 11A and 11B is connected by welding or the like at a position corresponding to the S-axis 14.
  • the other ends of the two beams 11A and 1IB are not shown, but are connected to the ends of the two columns 4A and 4B.
  • As the material of the beams 11A and 1IB a rectangular square member made of non-magnetic stainless steel or the like, a hollow square member thereof, or an H-shaped member is used.
  • the two beams 11A and 11B are joined at a position corresponding to the S-axis 14, so that the two beams 11A and 1IB are integrated, so that the beams 11A and 1IB are coiled.
  • the support strength for supporting the support 10 is improved.
  • the connection between the beams 11A and 11B and the coil support 10 is not limited to the illustrated one.
  • the extension of the two beams 11A and 11B may be arranged so as to pass through the S axis 14 or its vicinity. . Even in this case, the supporting strength of the coil support 10 by the two beams 11A and 11B is sufficiently ensured.
  • the two beams 11A and 11B have been described as components separate from the coil support 10, but the two beams 11A and 11B and the coil support 10 may be integrally formed. Since both are components for supporting the superconducting coil 9, in a state where they are completed as magnets, they are combined and integrated.
  • Fig. 6 shows an example of a connection structure between the columns 4A and 4B and the beams 11A and 1IB.
  • the figure shows the case of the upper beams 11A and 1IB.
  • the ends of the beams 11A and 11B are placed on the upper end surfaces of the columns 4A and 4B, and are joined by welding or the like.
  • the cross sections of the columns 4A and 4B are rectangular or hollow rectangular. The rectangular shape is joined so that the long sides thereof substantially coincide with the length directions of the beams 11A and 11B.
  • an auxiliary beam 12 is used in addition to the beams 11A and 11B in the structure for supporting the coil support 10 on the columns 4A and 4B.
  • the upper coil support 10 is supported and fixed from above by beams 11A and 11B, and is supported and fixed from below by an auxiliary beam 12.
  • the lower coil support 10 is supported and fixed from below by beams 11A and 11B, and is supported and fixed from above by an auxiliary beam 12.
  • the combined body of the columns 4A and 4B and the coil support 10 is supported by a plurality of supports 13. Have been.
  • the material of the constituent elements such as the coil support 10, the beams 11A and 11B, the auxiliary beams 12, the columns 4A and 4B, and the support 13 that support the superconducting coil 9 constituting the static magnetic field generating sources 1A and IB
  • a metal material such as nonmagnetic stainless steel or a nickel-based alloy, or a fiber-reinforced composite material such as FRP.
  • FRP fiber-reinforced composite material
  • the mechanical strength of these materials tends to increase as the operating temperature decreases, so that, for example, when used at a low temperature such as a liquid helium temperature, a smaller breakage than when used at room temperature. Since a material having an area is sufficient, weight and cost can be reduced, and mechanical safety can be improved.
  • the columns 4A and 4B may have either a hollow pipe structure or a rod structure. In the former case, the weight can be reduced.
  • the upper and lower static magnetic field sources 1A and IB composed of the superconducting coil 9 are strongly and directly restrained by the coil support 10, the beams 11A and 11B, and the columns 4A and 4B.
  • these structural members are immersed in a low-temperature refrigerant such as liquid helium, like the superconducting coil 9.
  • a low-temperature refrigerant such as liquid helium
  • the static magnetic field sources 1A and IB and the structural members supporting them are always maintained at a constant temperature, so that the relative position between the upper and lower static magnetic field sources 1A and IB is constantly and constantly maintained constant. Will be.
  • FIG. 7 and 8 show a second embodiment of the superconducting magnet device according to the present invention.
  • the external view of the apparatus of this embodiment is almost the same as that of FIG.
  • FIG. 7 is a cross-sectional view of the apparatus, in which a portion of the cooling vessel 3 is cut along a plane perpendicular to the Z axis 8 as in FIG.
  • FIG. 8 is a cross-sectional view taken along the line VIII-VI II of FIG. 7, and shows the supporting structure of the static magnetic field sources 1A and IB, similarly to FIG.
  • the structures of the static magnetic field generating sources 1A and IB and the coil support 10 supporting the same are the same as those of the first embodiment, but the structures of the columns 4A and 4B are different.
  • the left and right columns 4A and 4B are two types of parallel columns, namely, the first column 25 and the second column 25B. It consists of a composite of columns 26.
  • the first support 25 is disposed on the side near the magnetic field center 0, and the second support 26 is disposed on the side far from the magnetic field center 0.
  • the first support 25 and the second support 26 are both connected to the beams 11A and 11B, and the two beams 11A and 11B are connected to each other at the S-axis 14.
  • the present invention is not limited to this, and the two beams 11A and 1IB are connected to the coil support 10 so that their extension lines intersect in the S-axis. It may be.
  • the first support 25 and the second support 26 are arranged in the length direction of the beams 11A and 11B, and when the beams 11A and 11B are lever rods,
  • the first strut 25 serves to support the lever
  • the second strut 26 supports one end of the tiller.
  • the first and second columns 25 and 26 are accommodated in the support structure cooling container 5.
  • the strut structure using the principle of leverage as in the present embodiment is a magnet with a large electromagnetic force acting between the upper and lower static magnetic field sources 1A and IB, and the elliptical or rectangular cross-section strut according to the first embodiment. It is effective when the load cannot be supported within the allowable limit of deformation even if is applied.
  • the line connecting the first support 25 and the second support 26 is arranged on the S-axis or a line passing in the vicinity thereof. Therefore, the moment of inertia of the column as a whole in the direction of the S-axis or in the vicinity of it is greatly increased, and the bending stiffness is significantly improved.
  • the cross-sectional shapes of the first support 25 and the second support 26 are both circular in shape as shown in FIG. The cross-sectional shape of both is not limited to this, and may be rectangular or the like. Further, the cross-sectional shapes of both may be different, for example, a circular shape and a rectangular shape.
  • the cross-sectional areas of the two may be different, for example, the cross-sectional area of the first support 25 may be increased and the cross-sectional area of the second support 26 may be reduced.
  • the object to be processed is smaller than in the case of being integrated, so that the workability is often improved.
  • the present invention is not limited to a superconducting magnet of a liquid immersion type such as liquid helium, but also employs a superconducting type in which conduction cooling is performed from a small refrigerator through a heat transfer member without using a low-temperature refrigerant. Also applicable to magnets. In this case, the size of the device can be reduced.
  • the present invention can be applied to a normal conducting magnet or a permanent magnet other than the superconducting magnet.
  • various shapes such as an arc shape, a saw shape, and a wavy shape may be applied instead of the rod shape.
  • the beams 11A and 11B are each independently extended from the column, but can be formed integrally.
  • the shape can be a chevron shape, a bow shape, or an arc shape, and the ends can be joined to the columns.
  • FIG. 9 shows an overall configuration diagram of an embodiment of a magnetic resonance imaging apparatus in which the superconducting electromagnet apparatus of the present invention is applied to a static magnetic field generator.
  • the magnetic resonance imaging apparatus includes a static magnetic field generator 101, a gradient magnetic field generator 102, a transmission system 103, a reception system 104, a signal processing system 105, a sequencer 106, and a central processing unit (CPU) 107. It is comprised including.
  • the static magnetic field generator 101 generates a uniform static magnetic field in a space where the subject 109 is placed, and employs the above-described superconducting electromagnet apparatus.
  • the direction of the static magnetic field is usually the body axis direction of the subject 109 or a direction orthogonal to the body axis.
  • the gradient magnetic field generator 102 has a gradient magnetic field coil 110 for generating a gradient magnetic field in three orthogonal axes (X, Y, ⁇ ), and a gradient magnetic field power supply 111 for supplying a drive current for the gradient magnetic field coil 110. It is configured.
  • the gradient magnetic field power supply 111 applies gradient magnetic fields G s, G p, and G f in directions of three orthogonal axes ( ⁇ , ⁇ , ⁇ ) to the subject 109 in accordance with an instruction of the sequencer 106.
  • the slice plane of the tomographic image can be set by the manner of applying the gradient magnetic field.
  • the sequencer 106 operates under the control of the CPU 107, sends commands to the gradient magnetic field generator 102, the transmission system 103, the reception system 104, etc. in accordance with an imaging sequence called a pulse sequence, and is necessary to capture a tomographic image. It performs the control.
  • the transmission system 103 irradiates a high-frequency pulse to cause nuclear magnetic resonance in the nucleus constituting the living tissue of the subject 109 by the high-frequency magnetic field pulse.
  • the high-frequency oscillator 112, the modulator 113, the high-frequency amplifier 114 It has a high-frequency irradiation coil 115.
  • the transmission system 103 modulates the amplitude of the high-frequency pulse output from the high-frequency oscillator 112 by the modulator 113 according to the instruction of the sequencer 106, and further modulates the high-frequency pulse.
  • RF pulse high-frequency magnetic field pulse
  • the receiving system 104 detects a magnetic resonance signal such as an echo signal emitted by nuclear magnetic resonance of the nucleus of the living tissue of the subject 109, and includes a high-frequency receiving coil 116, an amplifier 117, and a quadrature phase detector 118 on the receiving side. And an A / D converter 119.
  • the magnetic resonance signal received by the high-frequency receiving coil 116 is amplified by the amplifier 117, detected by the quadrature phase detector 118, and then converted into digital signal measurement data by the AZD converter 119.
  • the two series of measurement data sampled with the phase shifted by 90 ° by the quadrature phase detector 118 at the timing controlled by the sequencer 106 are sent to the signal processing system 105.
  • the signal processing system 105 includes a CPU 107, a ROM 120, a RAM 121, a magneto-optical disk 122, a display 123 such as a CRT, and a magnetic disk 124.
  • the CPU 107 performs an image reconstruction process including a Fourier transform process on the input measurement data, creates a signal intensity distribution of an arbitrary cross section or an image obtained by performing a predetermined process, and displays the tomographic image on the display 123. It is displayed as.
  • the ROM 120 stores a program for performing image analysis processing and measurement over time, an invariable parameter used for the execution, and the like.
  • the RAM 121 temporarily stores the measurement parameters used in the previous measurement, the echo signals detected by the transmission system 104, and the image used to set the region of interest, and also stores the parameters used to set the region of interest.
  • the magneto-optical disk 122 and the magnetic disk 124 record an image reconstructed by the CPU 107.
  • the display 123 visualizes image data stored on the magneto-optical disk 122 and the magnetic disk 124 and displays the image data as a tomographic image.
  • the operation unit 108 is for inputting control information of processing executed in the signal processing system, and includes, for example, a trackball or a mouse 125 and a keyboard 126.
  • the superconducting electromagnet apparatus As the static magnetic field generator 101 of the magnetic resonance imaging apparatus configured as described above, the superconducting electromagnet apparatus according to the above-described first or second embodiment is applied. Then, the diagnostic site of the subject 109 is positioned in the MRI region, and the static magnetic field generator 101 is driven to apply a uniform static magnetic field to the diagnostic site of the subject 109.
  • two sets of opposing static magnetic field sources are supported by two columns, and the line connecting the two columns is positioned outside the MRI region, and Since the narrower columns of the struts are arranged so as to be wider than a certain value, the subject 109 can be given a large open feeling, and the operator can have excellent access to the subject 109.
  • the other end or the intersection of the axes of the two beams fixed to the ends of the two columns is located on the opposite side of the MRI area with respect to the line connecting the two columns, and It features a disk-shaped coil support with a superconducting coil assembled directly to the beam.
  • the two sets of superconducting coils placed opposite to each other are firmly supported and fixed without intervening heat insulating members, etc., so that bending deformation due to the load of electromagnetic force or the like acting between the superconducting coils is reduced. Can be.
  • the uniformity of the static magnetic field in the MRI region can be significantly improved.
  • the struts are housed in the support cooling vessel and the superconducting coils are directly supported by the struts, beams, and coil supports, it is easy to control ambient temperature changes and position control during superconducting coil cooling.
  • a superconducting magnet device can be realized.
  • the supporting structure consisting of the columns, beams, and coil support is cooled by the same refrigerant as the superconducting coil, the strength of the material increases as the temperature decreases (stainless steel, nickel-based material). Alloys, FRP, etc.) can reduce the weight and cost of the support structure.

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Abstract

Des sources (1A, 1B) produisant un champ magnétique et dotées de bobines (9) supraconductrices placées de manière opposée sur deux côtés d'une région (2) de saisie d'image par résonance magnétique sont supportées à demeure par une bobine de support (10) contenue dans des boîtiers de refroidissement (3A, 3B). La bobine de support (10) est soutenue par deux montants (4A, 4B) placés excentriquement par rapport au centre O du champ magnétique statique, deux bras (11A, 11B) possédant chacun une de leurs extrémités couplée à la partie terminale des montants (4A, 4B) et l'autre de leur extrémités couplées ensemble en un point (ci-après appelé S) proche du point d'action centrale de la charge magnétique. Les bras (11A, 11B) sont également couplés à la bobine de support (10) et les montants (4A, 4B) sont contenus dans un boîtier de refroidissement (5). Le fait qu'une section transversale ayant un moment d'inertie géométrique qui augmente vers l'axe S est employée et que l'axe S est placé plus près de l'axe central (8) du champ magnétique qu'un point de division interne (22) permet d'obtenir une rigidité élevée par rapport au moment de charge de l'aimant. En outre, l'ouverture et l'accessibilité de l'échantillon sont améliorées.
PCT/JP2001/002879 2000-04-03 2001-04-03 Aimant supraconducteur et appareil d'imagerie par resonance magnetique qui comprend ledit aimant WO2001074243A1 (fr)

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Cited By (6)

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Publication number Priority date Publication date Assignee Title
EP1530058A2 (fr) * 2003-11-06 2005-05-11 Hitachi, Ltd. Appareil supraconducteur d'imagerie par résonance magnétique avec réduction de vibrations
EP1610143A1 (fr) * 2004-06-23 2005-12-28 Hitachi, Ltd. Appareillage de formation image de résonance magnétique
JP2006305033A (ja) * 2005-04-28 2006-11-09 Hitachi Ltd 磁気共鳴イメージング装置
JP2008124400A (ja) * 2006-11-15 2008-05-29 Hitachi Ltd 超電導磁石装置および磁気共鳴イメージング装置
JP2020035959A (ja) * 2018-08-31 2020-03-05 ジャパンスーパーコンダクタテクノロジー株式会社 超伝導マグネット装置
CN112858971A (zh) * 2019-11-26 2021-05-28 西门子(深圳)磁共振有限公司 磁共振成像装置的超导磁体及磁共振成像装置

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JPH0723927A (ja) * 1993-07-12 1995-01-27 Ge Yokogawa Medical Syst Ltd Ｍｒｉ装置のマグネットアセンブリ
EP0883143A1 (fr) * 1996-10-30 1998-12-09 Hitachi Medical Corporation Dispositif magnetique supraconducteur
JPH11197132A (ja) * 1998-01-13 1999-07-27 Hitachi Medical Corp パッシブシールド型超電導磁石
EP0987558A2 (fr) * 1998-09-02 2000-03-22 Sumitomo Special Metals Company Limited Générateur de champ magnétique pour l'IRM
JP2001070284A (ja) * 1999-09-09 2001-03-21 Hitachi Medical Corp 静磁場発生装置及びそれを用いた磁気共鳴イメージング装置

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Publication number Priority date Publication date Assignee Title
JPH0723927A (ja) * 1993-07-12 1995-01-27 Ge Yokogawa Medical Syst Ltd Ｍｒｉ装置のマグネットアセンブリ
EP0883143A1 (fr) * 1996-10-30 1998-12-09 Hitachi Medical Corporation Dispositif magnetique supraconducteur
JPH11197132A (ja) * 1998-01-13 1999-07-27 Hitachi Medical Corp パッシブシールド型超電導磁石
EP0987558A2 (fr) * 1998-09-02 2000-03-22 Sumitomo Special Metals Company Limited Générateur de champ magnétique pour l'IRM
JP2001070284A (ja) * 1999-09-09 2001-03-21 Hitachi Medical Corp 静磁場発生装置及びそれを用いた磁気共鳴イメージング装置

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1530058A2 (fr) * 2003-11-06 2005-05-11 Hitachi, Ltd. Appareil supraconducteur d'imagerie par résonance magnétique avec réduction de vibrations
EP1530058A3 (fr) * 2003-11-06 2005-09-07 Hitachi, Ltd. Appareil supraconducteur d'imagerie par résonance magnétique avec réduction de vibrations
US7112966B2 (en) 2003-11-06 2006-09-26 Hitachi, Ltd. Magnetic resonance imaging apparatus
EP1610143A1 (fr) * 2004-06-23 2005-12-28 Hitachi, Ltd. Appareillage de formation image de résonance magnétique
US7276908B2 (en) 2004-06-23 2007-10-02 Hitachi, Ltd. Magnetic resonance imaging apparatus with suppressed noise
JP2006305033A (ja) * 2005-04-28 2006-11-09 Hitachi Ltd 磁気共鳴イメージング装置
JP4521311B2 (ja) * 2005-04-28 2010-08-11 株式会社日立製作所 磁気共鳴イメージング装置
JP2008124400A (ja) * 2006-11-15 2008-05-29 Hitachi Ltd 超電導磁石装置および磁気共鳴イメージング装置
JP2020035959A (ja) * 2018-08-31 2020-03-05 ジャパンスーパーコンダクタテクノロジー株式会社 超伝導マグネット装置
JP7039423B2 (ja) 2018-08-31 2022-03-22 ジャパンスーパーコンダクタテクノロジー株式会社 超伝導マグネット装置
CN112858971A (zh) * 2019-11-26 2021-05-28 西门子(深圳)磁共振有限公司 磁共振成像装置的超导磁体及磁共振成像装置

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