Hitachi, Ltd.

Hitachi Instrument Engineering Co., Ltd.

Goh Miyajima

Takao Takahashi

Yoshiki Igarashi

Tuyosi Shudo

Kunishige Kuroda

Shohei Suzuki

Takehiko Konno

Apparatus for cancelling magnetic fields for cancelling a leakage magnetic field from a static magnetic field generation assembly are disposed outside the static magnetic field generation assembly. A magnetic shield made of a magnetic substance is disposed between the static magnetic field generating assembly and the cancelling magnetic field apparatus. The cancelling magnetic field generation apparatus is of a cryostatless type.

Magnetic field generator

There is disclosed a gradient magnetic field coil for use in a magnetic resonance imaging system for imaging an imaginary or virtual cross-section of a desired portion of a subject to be inspected, utilizing a magnetic resonance phenomenon. The gradient magnetic field coil includes a coil bobbin and coil windings fixedly mounted on the coil bobbin. The coil bobbin includes a tubular body portion of a honeycomb construction having a number of vacancies formed in a wall of the tubular body portion, a sheet-like outer peripheral portion of a constrained damping structure fixedly secured to an outer peripheral surface of the body portion to reinforce the body portion, and a sheet-like inner peripheral portion fixedly having at least one layer and secured to an inner peripheral surface of the body portion to reinforce the body portion. The generation and continuation of vibrations in the coil bobbin are controlled or suppressed directly by the coil bobbin itself, thereby minimizing the generation of noise.

Gradient magnetic field coil for magnetic resonance imaging system

A silencer for a plurality of magnetic field gradient coils in a magnetic resonance imaging apparatus, comprising a magnet for generating a stationary magnetic field, a bobbin which holds the plurality of inclined magnetic field gradient coils disposed within the magnet for generating in the stationary magnetic field gradients to impart positional information to a magnetic resonance signal, and a silencer provided between an internal space between the magnet and the bobbin and a space outside the magnet for reducing the diffusion of noise occurring due to an electric current flowing through the plurality of magnetic field gradient coils to the external space through the internal space.

Silencer for magnetic field gradient coils in a magnetic resonance

A magnetic field gradient coil system for use in a magnetic resonance imaging apparatus forming a magnetic field gradient in a direction of a Z-axis of an X, Y, Z orthogonal coordinate system having its origin at a selected position in the imaging apparatus comprises one pair of first coils and one pair of second coils having their centers on the Z-axis and having the same radius, the coils of each coil pair disposed symmetrically with respect to an XY plane including the origin, the coils of the second coil pair disposed more distant from the origin than the coils of the first coil pair, the coils of the first and second coil pairs disposed on one side of the origin supplied with current in the same direction, the coils disposed on the other side of the origin supplied with current opposite to the direction of current in the coils on the one side of the origin, each of the coils of the first coil pair disposed where the value of the Z-axis magnetic field component of first order at a selected position on the Z-axis becomes substantially maximum, and the ampere-turn and position of each of the coils of the second coil pair selected so that, at the selected position, the Z-axis magnetic field components of third and fifth orders provided by the second coil pair have values which can substantially cancel the Z-axis magnetic field components of third and fifth orders provided by the first coil pair.

Magnetic field gradient coil system

A superconducting magnetic assembly has a first superconducting coil for generating a magnetic field in an internal magnetic space in the first superconducting coil, a pair of second superconducting coils one provided at each end of the first superconducting coil for generating a cancelling magnetic field counteracting a leakage magnetic field leaking from the magnetic field in the internal space, and a magnetic shield of a superconducting material surrounding the first superconducting coil so as to be open to the internal space.

Superconducting magnet assembly with suppressed leakage magnetic field

In a nuclear magnetic resonance signal detecting system in which a body subject to measurement placed in a static magnetic field is irradiated with a magnetic field of high frequency by means of a high-frequency magnetic field radiating coil and in which a nuclear magnetic resonance signal of the body is detected by means of a nuclear magnetic resonance signal detecting coil, a high-frequency coil system for the nuclear magnetic resonance measurement comprises a plurality of coil groups juxtaposed to one another in a given direction and each implemented in such a structure as to be divisible in the direction orthogonal to the given direction, for detecting a magnetic field in the axial direction coinciding with an axis extending through the coil groups and/or generating a magnetic field in the axial direction.

Divisible coil system for NMR imaging apparatus

In a permanent magnet device, a pair of pole pieces of a ferromagnetic material are disposed opposite to each other, and, in order to generate a homogeneous magnetic field in a gap space between the pole pieces, a pair of members of a permanent magnet material magnetized in a direction substantially orthogonal to the direction of the magnetic field and also magnetized in directions opposite to each other in themselves are disposed adjacent to the pole pieces and symmetrical with each other respectively.

Permanent magnet device

A cylindrical permanent magnet apparatus and electromagnet apparatus used with a nuclear magnetic resonance imaging system are disclosed, in which a magnetic path of ferromagnetic material is arranged around a predetermined Z axis, magnetic field source are arranged at the ends of the magnetic path, a cylindrical magnetic flux conductor is interposed between the magnetic field sources, and an object to be inspected is adapted to be inserted in the cylindrical magnetic flux conductor. A cylindrical magnet apparatus comparatively light in weight which has a homogeneous magnetic field and has magnetic shielding effect and is suitable for routine applications is thus provided.

Growing community of inventors

Katsuta, Japan

Goh Miyajima