Abstract: Provided is an RF shield that achieves a balance between an improved irradiation efficiency and suppression of eddy current-induced heat by a gradient magnetic field coil, while avoiding complexity of conductor pattern design for suppressing an eddy current by the gradient magnetic field coil. A cylindrical RF shield, which is one of elements constituting a high-frequency coil unit, is formed by rolling patterned conductive thin films formed on both front and back surfaces of an insulating sheet, front and back patterns of the patterned conductive thin film are mirror-symmetrical in a central axis direction of a cylinder, the front pattern is divided into two in the central axis direction, one side of two divided patterns is further divided into two in a circumferential direction, each of three independent pattern islands has slits such that strips are formed along to the cylinder axis direction, and each of the strips has a portion connected in an up-down direction at one location.

Abstract: To suppress eddy current generation by a gradient magnetic field while an RF shield has a function of reducing magnetic coupling of an RF coil with a gradient magnetic coil, the RF shield must be formed of a conductive material of a tiled or slitted strip-shaped thin plate. On the other hand, cooling must be performed to suppress temperature rise due to heat generation by the eddy current. Furthermore, to enlarge an opening through which a patient is inserted, the gradient magnetic coil, the RF coil, and the RF shield, which are located in a static field magnet and have roughly concentrically cylindrical shapes, are required to be reduced in thickness.

Abstract: An MRI apparatus equipped with a magnetic shield structure to reduce flux leakage. The MRI apparatus includes: a pair of static magnetic magnets that are disposed on opposite sides of an imaging space; and a pair of gradient coils that are disposed on opposite sides of the imaging space. Each static magnetic magnet has a disk-shaped magnetic material pole 201 and a ring-shaped magnetic material pole 202. Each gradient coil has a first coil 204 that applies a magnetic field gradient in a Z axis direction in an imaging region, and a laminate 301 that shields the disk-shaped magnetic material pole from magnetic flux produced in the first coil. The laminate has a smaller thickness in the Z axis direction on the ring-shaped magnetic material pole side than that in a center portion of the imaging space.

Abstract: An open-type MRI apparatus includes a pair of static magnetic field magnets and a pair of gradient magnetic field coils. Each static magnetic field magnet includes a discoid magnetic pole configured to generate a static magnetic field in a Z axis direction in which the pair of static magnetic field magnets are opposed each other, and an annular magnetic pole configured to generate a static magnetic field on an X-Y plane perpendicular to the Z axis direction. Each gradient magnetic field coil includes a Z coil configured to provide a magnetic field being gradient in the Z axis direction in the imaging region, a magnetic material block configured to shield the discoid magnetic pole from a magnetic flux generated from the Z coil, and a correction coil configured to shield the annular magnetic pole from the magnetic flux generated from the Z coil.

Abstract: An open-type MRI apparatus includes a pair of static magnetic field magnets and a pair of gradient magnetic field coils. Each static magnetic field magnet includes a discoid magnetic pole configured to generate a static magnetic field in a Z axis direction in which the pair of static magnetic field magnets are opposed each other, and an annular magnetic pole configured to generate a static magnetic field on an X-Y plane perpendicular to the Z axis direction. Each gradient magnetic field coil includes a Z coil configured to provide a magnetic field being gradient in the Z axis direction in the imaging region, a magnetic material block configured to shield the discoid magnetic pole from a magnetic flux generated from the Z coil, and a correction coil configured to shield the annular magnetic pole from the magnetic flux generated from the Z coil.

Abstract: Provided are a magnetic resonance imaging device and a superconducting magnet capable of preventing generation of eddy currents accompanying vibration of a radiation shield and of reducing image quality deterioration. The superconducting magnet for a magnetic resonance imaging device includes a substantially cylindrical vacuum vessel, a substantially cylindrical radiation shield that is provided inside the vacuum vessel, and a superconducting coil that is provided inside the radiation shield. The radiation shield has an inner cylinder located radially inward of the superconducting coil. The inner cylinder of the radiation shield is provided with an annular rib formed in a circumferential direction about the central axis of the inner cylinder.

Abstract: According to one embodiment, a magnetic resonance imaging apparatus includes: a cylindrical magnetic pole for generating a static magnetic field in an imaging region; a cylindrical gradient magnetic field coil arranged on a radially inner side of the magnetic pole, coaxially with the magnetic pole to generate a dynamic magnetic field having a linear magnetic field strength in the imaging region; a cylindrical high frequency coil arranged on a radially inner side of the gradient magnetic field coil, coaxially with the magnetic pole and the gradient magnetic field coil to generate a high frequency magnetic field in the imaging region; and a computer system for processing signals to obtain images. The magnetic resonance imaging apparatus further includes at least two loop-shaped additional coils arranged on the radially outer side of the gradient magnetic field coil and having different electric current circulating direction.

Abstract: Provided are a magnetic resonance imaging device and a superconducting magnet capable of preventing generation of eddy currents accompanying vibration of a radiation shield and of reducing image quality deterioration. The superconducting magnet for a magnetic resonance imaging device includes a substantially cylindrical vacuum vessel, a substantially cylindrical radiation shield that is provided inside the vacuum vessel, and a superconducting coil that is provided inside the radiation shield. The radiation shield has an inner cylinder located radially inward of the superconducting coil. The inner cylinder of the radiation shield is provided with an annular rib formed in a circumferential direction about the central axis of the inner cylinder.

Abstract: A superconducting magnet in which efficiency of conduction cooling is improved is described as well as a magnetic resonance imaging apparatus that includes the superconducting magnet and requires no liquid helium. The magnet resonance imaging apparatus includes: a coil portion including a winding core, a winding portion formed by winding a wire around the winding core, a first flange provided on one side of the winding core, and a second flange provided on the other side of the winding core; a cooling device for cooling the coil portion; and a heat conducting member for thermally connecting the coil portion and the cooling device, in which at least one of the first flange, the second flange, and the winding core has a region made of a material whose thermal contraction rate is larger than a thermal contraction rate of the winding portion.

Abstract: According to one embodiment, a magnetic resonance imaging apparatus includes: a cylindrical magnetic pole for generating a static magnetic field in an imaging region; a cylindrical gradient magnetic field coil arranged on a radially inner side of the magnetic pole, coaxially with the magnetic pole to generate a dynamic magnetic field having a linear magnetic field strength in the imaging region; a cylindrical high frequency coil arranged on a radially inner side of the gradient magnetic field coil, coaxially with the magnetic pole and the gradient magnetic field coil to generate a high frequency magnetic field in the imaging region; and a computer system for processing signals to obtain images. The magnetic resonance imaging apparatus further includes at least two loop-shaped additional coils arranged on the radially outer side of the gradient magnetic field coil and having different electric current circulating direction.

Abstract: The present invention addresses a challenge of providing a superconducting magnet device that enables it to realize an operation of opening and closing a permanent current switch of the superconducting magnet device at high speed with small electric heater capacity, avoiding an increase in the amount of heat incursion into the superconducting coil by not providing a driving mechanism from outside while enabling it to reduce refrigerant consumption or electric power consumed by a refrigerator, or an MRI apparatus using it having means for obtaining good image quality.

Abstract: A gradient magnetic field coil device is provided in which an eddy current magnetic field of an even-ordered component can be reduced. The gradient magnetic field coil device includes a forward coil and a reverse coil which faces the forward coil so as to sandwich a middle surface and through which flows an electric current directed opposite to the forward coil. The forward coil and the reverse coil have a middle region approaching the middle surface and an outside-the-middle region where the distance from the middle surface is greater than the middle region. A line width of coil lines in the middle region is narrower than a line width of coil lines in the outside-the-middle region.

Abstract: An alternating current loss measuring apparatus for superconductors includes a superconductor specimen, a magnetic field applying coil, a radiation shield, a vacuum vessel, first cooling means, and second cooling means. The first cooling means or the second cooling means is provided with a temperature regulating mechanism. The magnetic field applying means and the radiation shield are set to be a first cooling part, whereas the superconductor specimen is set to be a second cooling part, and the first cooling part and the second cooling part are cooled by first and second cooling means, respectively. A high thermal resistance member is disposed between the superconductor specimen and the second cooling means, and temperature measuring means are disposed at at least two positions on the high thermal resistance member. The alternating current loss of a superconductor under an external magnetic field can be measured at each of different temperatures.

Abstract: In a gradient magnetic field coil device including: a plurality of main coils generating in an imaging region of a magnetic field resonance imaging device a magnetic field distribution in which an intensity linearly inclines; and a plurality of shield coils, arranged on an opposite side of the imaging region across the main coils, suppressing residual magnetic field generated by the main coils on the opposite side. The plurality of main coils and the plurality of shield coils are connected in series. The device further includes a plurality of current adjusting devices, connected to the shield coils in parallel, independently adjusting currents flowing through the shield coils, respectively, to enhance symmetry of the residual magnetic field. The gradient magnetic field coil device is provided which can suppress generation of eddy current magnetic field even if there is a relative position deviation between the main coils and shield coils.

Abstract: A device includes: a static magnetic field generating device including static magnetic field generating sources generating a homogeneous magnetic field in a space; gradient magnetic field generating sources superimposing a gradient magnetic field on the homogeneous magnetic field, and conductor rings arranged between the static magnetic field generating sources and the gradient magnetic field generating sources in a pair of arranging regions on both sides in a direction of the homogeneous magnetic field in a region where the homogeneous magnetic field is generated (imaging region), respectively, the conductor rings being separated from each other and making a pair. The conductor rings are mechanically connected to the gradient magnetic field generating device or the static magnetic field generating device. This provides an MRI device 1 capable of reduction in vibration with suppression of the image quality deterioration of the tomographic images.

Abstract: The present invention addresses a challenge of providing a superconducting magnet device that enables it to realize an operation of opening and closing a permanent current switch of the superconducting magnet device at high speed with small electric heater capacity, avoiding an increase in the amount of heat incursion into the superconducting coil by not providing a driving mechanism from outside while enabling it to reduce refrigerant consumption or electric power consumed by a refrigerator, or an MRI apparatus using it having means for obtaining good image quality.

Abstract: A gradient coil device includes a major axis gradient coil, having an ellipse in a cross section generating a gradient magnetic field inclined in a major axis direction of the ellipse at a magnetic field space; and a minor axis gradient coil, having an ellipse in a cross section generating a gradient magnetic field inclined in a minor axis direction of the ellipse at the magnetic field space. A length of the minor axis field coil in the center axis direction is shorter than a length of the major axis gradient coil in the center axis direction. A maximum value of a residual magnetic field generated by the minor axis gradient coil at a space outside the magnetic field space is equal to or smaller than a maximum value of a residual magnetic field generated by the major axis gradient coil at a space outside the magnetic field space.

Abstract: An alternating current loss measuring apparatus for superconductors includes a superconductor specimen, a magnetic field applying coil, a radiation shield, a vacuum vessel, first cooling means, and second cooling means. The first cooling means or the second cooling means is provided with a temperature regulating mechanism. The magnetic field applying means and the radiation shield are set to be a first cooling part, whereas the superconductor specimen is set to be a second cooling part, and the first cooling part and the second cooling part are cooled by first and second cooling means, respectively. A high thermal resistance member is disposed between the superconductor specimen and the second cooling means, and temperature measuring means are disposed at at least two positions on the high thermal resistance member. The alternating current loss of a superconductor under an external magnetic field can be measured at each of different temperatures.

Abstract: A superconducting magnet in which efficiency of conduction cooling is improved is described as well as a magnetic resonance imaging apparatus that includes the superconducting magnet and requires no liquid helium. The magnet resonance imaging apparatus includes: a coil portion including a winding core, a winding portion formed by winding a wire around the winding core, a first flange provided on one side of the winding core, and a second flange provided on the other side of the winding core; a cooling device for cooling the coil portion; and a heat conducting member for thermally connecting the coil portion and the cooling device, in which at least one of the first flange, the second flange, and the winding core has a region made of a material whose thermal contraction rate is larger than a thermal contraction rate of the winding portion.

Abstract: In the magnetic resonance imaging device, the distance between the first and second coils is different in the circumferential direction and has a first region (A1) (?=0, ?) and a second region (A2) (?=?/2) narrower than the first region (A1). In the first coil, wiring patterns (17a, 17b) on the side of a zero-plane (F0) passing through the center of the first coil and perpendicular to the axis direction (z-axis direction) meander in the circumferential direction such that the wiring patterns (17a, 17b) depart from the zero-plane (F0) in the first region (A1) and approach the zero-plane (F0) in the second region (A2). This provides a gradient magnetic field coil capable of configuring wiring patterns without using a loop coil that does not pass through the z-axis.