Hitachi, Ltd.

Masayuki Otsuka

Norihide Saho

Masashi Wada

Kihachiro Tanaka

Taichi Sato

Yoshiharu Mohri

Etsuji Yamamoto

Katsuaki Kikuchi

Yukiji Iwase

Hidemi Shiono

Hiroshi Inouye

Takeo Nemoto

Shinji Yamamoto

Kenji Takiguchi

Takao Honmei

Shinichi Shimode

Tuyosi Shudo

Shinya Okabe

Takao Hommei

Shin'ichi Shimode

Tohsuke Hirata

An active noise cancellation apparatus of an MRI apparatus, including a detector for detecting vibration of a bobbin or a driving signal of a magnetism generator as a noise source signal, error signal detectors for detecting actual noise near the ears of a patient, a circuit for generating a noise cancellation signal having an opposite phase to a phase of a noise signal generated by an MRI apparatus and having an amplitude proportional to the output of the error signal detectors, from the detected noise source signal and the output of the error signal detectors, and a sound generator for generating a sound wave by the noise cancellation signal.

Active noise cancellation apparatus in MRI apparatus

A magnetic resonance imaging apparatus includes a magnet for generating a static magnetic field, a gradient coil for generating a gradient magnetic field in a measurement space, and a vibration damping means which includes a container and granular material disposed in the container. The vibration damping means is installed with a supporting bolt between the gradient coil and a supporting means. Since the gradient coil is supported at a constant position without any vibration and deformation, the magnetic resonance imaging apparatus generates an accurate image signal without any acoustic noise.

Magnetic resonance imaging apparatus having vibration damping means on

A gradient magnetic field-generating coil assembly of MR imaging apparatus has a cylindrical core member for carrying coil windings that is divided into at least two cores at a central portion of a magnet bore, a gap is set up between the two cores at the central portion of the magnet bore and each core is provided at its opposite ends with parts for fixing it to the magnet, whereby the natural vibration frequency of the core can be deviated from an exciting force frequency and sound prevailing in the outside of the core and sound in the inside can be brought into interference with each other to thereby suppress vibration of the cores at the central portion of the magnet bore and reduce noise.

Gradient magnetic field generating coil assembly of magnetic resonance

A magnetic-resonance imaging apparatus has superconducting magnets for generating a large uniform magnetic field within a predetermined volume. Within that volume, coils for generating magnetic field gradients are supported on a bobbin, enabling an object within the bobbin to be investigated. The coils on the bobbin are subject to forces but are rigidly connected to the bobbin. Therefore, energy is transmitted to the bobbin which can cause the bobbin to vibrate and so generate noise. To dissipate that energy, the coils are attached to tubes, or other hollow members, on the bobbin, which tubes or hollow members contain movable bodies such as particulate material. The energy due to the forces on the coils cause the movable bodies to move and collide, so dissipating the energy and reducing the noise.

Vibration reduction system for magnetic-resonance imaging apparatus

A nuclear magnetic resonance apparatus in accordance with the present invention includes ferro-magnetic field generation means and gradient field generation means and fixes the gradient field generation means at a predetermined position inside a cylindrical space by a support member. An elastic member is interposed between the support member and the gradient field generation means, and means for improving rigidity of the gradient field generation means, such as another support member and a fastening jig of the gradient field generation means, is disposed and fixed to the elastic member described above. In the manner image quality can be improved and noise can be reduced.

Nuclear magnetic resonance apparatus

Growing community of inventors

Katsuta, Japan

Masayuki Otsuka