Hitachi, Ltd.

Hitachi-high-technologies Corporation

Hitoshi Sasabuchi

Akihiko Kandori

Keiji Tsukada

Hiroyuki Suzuki

Shoji Kondo

Tsuyoshi Miyashita

Yasuaki Komiyama

Kenichi Okajima

Norihide Saho

Kenji Teshigawara

Hiroyuki Tanaka

Ryuichi Shinomura

Kazuhisa Machida

Masahiro Murakami

A biomagnetic field measuring apparatus has a plurality of fluxmeters disposed externally of a living body and each including a superconducting quantum interference device (SQUID) for detecting a biomagnetic field generated from the living body, the plurality of fluxmeters being operative to detect a temporal change of a component of the biomagnetic field in a first direction which is vertical to the surface of the living body, an operation processor for performing computation for determining a temporal change of a value proportional to a root of square sum of differential value of the first-direction magnetic field component in second and third directions which cross the first direction and computation for integrating the temporal change of the value over a predetermined interval to determine an integral value, and a display for displaying the determined integral value. Distribution of magnetic fields generated from the heart is determined with a small number of fluxmeters.

Biomagnetic field measuring method and apparatus

A biomagnetic measurement apparatus having functions to detect the release of a magnetic field lock in a SQUID fluxmeter operation circuit due to the influence of a much greater noise level than that of a biomagnetic signal, to notify an operator of the release of the magnetic field lock, and to automatically or manually revert to a state for allowing magnetic measurement. The release of the magnetic field lock occurs when an integrator of the fluxmeter operation circuit is saturated. Thus, a high pass filter is provided at a subsequent stage of the integrator, and a function is provided to judge that the integrator is in a saturated state when the noise level of the output after passing through the high pass filter is lower than a pre-set threshold. The biomagnetic measurement apparatus can detect a saturated state of the integrator, which is a cause for the release of the magnetic field lock of the SQUID fluxmeter operation circuit, and thereby when the loading of measured data is conducted in an appropriate operation range of a magnetic sensor, or even when a part of the loaded measured data is data outside an operation range of the magnetic sensor, it is possible to deal with the data so as to properly analyze it.

Biomagnetic measurement apparatus

A magnetic field measurement apparatus includes a plurality of magnetometers each having SQUID's and three detection coils, one of which detects each of three orthogonal directional magnetic field components (B, B, B) of a magnetic field generated from a subject to be inspected, a display which displays time variation of waveforms of the magnitude (&#x221a;(B+B+B)) of magnetic field synthesized by square sum of each of the three orthogonal directional magnetic field components of the magnetic field generated from the subject to be inspected, a holder for holding a Dewar's vessel for arranging magnetometers therein, and a controller for controlling a positional relationship between the subject to be inspected and the Dewar's vessel. Accurate time variation of the magnetic field generated from the subject to be inspected can be detected without influence of positional change of the subject to be inspected, by simultaneously measuring each of the three orthogonal directional magnetic field components (B, B, B) of the magnetic field generated from current sources in the subject to be inspected.

Magnetic field measurement apparatus

In the present invention, when measuring magnetism of a measuring portion of a patient by making use of a dewar incorporating magnetism sensors each including a super conducting quantum interference device, a bed is at first positioned outside a position immediately below the dewar. At this position outside the position immediately below the dewar the patient is laid on the bed in an inspection posture. Marks are attached on the body of the patient at three points for setting X and Y axis coordinate on the measurement portion, at the position outside the position immediately below the dewar cross shaped beam patterns are projected and the position of the bed is adjusted so that the marks at the three points locate on the cross shaped beam patterns, thereafter, bed is transferred by a constant amount to the position immediately below the dewar. Thereby, in the biomagnetism measurement the correlated position between the dewar (magnetism sensors) and the measurement portion of the patient can be ascertained easily and accurately.

Biomagnetism measurement device and method of biomagnetism measurement using the device

The present invention, in the physiological magnetic field measuring instrument, recognizes characteristic waveforms (for example, heart beats) repeatedly appearing by physiological activity from measured signal waveforms, registers one of measured heart beats as a reference waveform, evaluates the difference degree of each measured heart beat data from the reference waveform, and executes the averaging process using only waveforms whose difference degrees are less than the allowable value. The present invention registers waveforms whose difference degrees are more than the allowable value as abnormal data and puts them into the display enabled state. Discrimination information is as signed to measurement conditions necessary for measuring the physiological magnetic field and data analysis conditions and when the discrimination information is designated for measurement, the measurement conditions and analysis conditions can be read. By doing this, the physiological magnetic field measuring instrument independently selects good or defective data automatically, and a reliable automatic averaging process can be obtained, and the data processing and operation can be simplified.

Physiological magnetic field measuring instrument for measuring magnetic field at plural positions of living body

A minimal magnetic-field measurement Dewar vessel includes an inner container which contains a superconducting device and cooling medium, a radiation shield which is composed of an electrical insulation substrate and a first and second plurality of thin line stripes provided on opposite surfaces of the electrical insulation substrate so that the first plurality of thin line stripes is electrically insulated from the second plurality of thin line stripes and provided in a high stripe dense state, an outer container, and a cooling apparatus. A width of one portion of at least one of the first and second plurality of thin line stripes arranged in one area of the radiation shield surrounding the superconducting device is smaller than a width of another portion of the at least one of the first and second plurality of thin line stripes arranged in another area of the radiation shield, respectively.

Minimal magnetic field-measurement dewar vessel

First and second markers are disposed respectively on the processus xiphoideus and the incisura jugularis of the subject to be inspected. The chest of the subject is positioned below the cryostat so that a line joining the first and second markers extends in one direction in which sensors are arranged in the interior of the cryostat. Processing includes (1) forming, from magnetic waveform signals, an image representing the activity of the heart of the subject, (2) making the pixel size of a morphological image, including the heart photographed by an image pickup device, coincident with the pixel size of functional information and forming a functional image equal in pixel size to the morphological image, (3) making the position of the first marker in the functional image and the position of the first marker in the morphological image coincident, and (4) combining the functional image and the morphological image.

Biomagnetic field measuring apparatus

A dewar for SQUID is provided. In the dewar for SQUID, an amount of leak gas discharged from absorbent arranged in the upper portion higher than the liquid surface level of liquid helium is small even if the liquid surface level of the liquid helium is lowered. In order to attain the above object, a dewar in accordance with the present invention comprises an inner container for holding a SQUID magnetometer and a coolant, the inner container being made of a non-magnetic and electrically non-conductive material; an outer container for forming a thermal insulating space between the inner container and the outer container, the outer container being made of a non-magnetic and electrically non-conductive material; and a gas absorber provided inside the thermal insulating space, and the dewar further comprises a non-magnetic thermal conductor in contact both with the gas absorber arranged at a level higher than a level of a holding position of the SQUID magnetometer and with a position of the inner container at a level lower than a level of the gas absorber.

Dewar and biological magnetism measurement apparatus using the dewar

A magnetic field measurement apparatus includes a plurality of magnetometers one comprising SQUID's and three detection coils each of which detects each of three orthogonal directional magnetic field components (B , B , B ) of a magnetic field generated from a subject to be inspected, a display which displays time variation of waveforms of the magnitude &lcub;{square root over ( )}(B &plus;B &plus;B )&rcub; of a magnetic field synthesized by square sum of each of the three orthogonal directional magnetic field components of the magnetic field generated from the subject to be inspected, a holding means for holding a Dewar's vessel for arranging magnetometers therein, and a controlling means for controlling a positional relationship between the subject to be inspected and the Dewar's vessel. Accurate time variation of the magnetic field generated from the subject to be inspected can be detected without influence of positional change of the subject to be inspected, by simultaneously measuring each of the three orthogonal directional magnetic field components (B , B , B ) of the magnetic field generated from current sources in the subject to be inspected.

A biomagnetic field measurement apparatus comprises, a plurality of magnetometers each having a SQUID sensor and a detection coil and each detecting a magnetic field generated from a heart of a fetus in a mother; a processor processing magnetic field wave forms detected by the magnetometers; and a display displaying results obtained by the processor. The processor estimates a position of a current dipole from the magnetic field wave forms, and processes projecting the position of the current dipole on a first plane parallel to a plane on which one ends of the magnetometers are disposed on processes projecting the position of the current dipole on a second plane perpendicular to the plane on which the one ends of the magnetometers are disposed. The position of the current dipole projected on the first plane and the position of the current dipole projected on the second plane are displayed on the display.

Biomagnetic field measurement apparatus

A biomagnetic field measurement apparatus includes a bed which holds a subject to be inspected in a shielded room. A cryostat holds a plurality of SQUID magnetometers at low temperature. The cryostat is arranged in the shielded room and the plurality of SQUID magnetometers detect a magnetic field generated from the subject. A driving and detecting circuit drives the plurality of SQUID magnetometers and detects signals therefrom that are processed by a computer. A display that is arranged in the shielded room displays data for viewing by an operator.

A biomagnetic field measuring apparatus has a plurality of fluxmeters disposed externally of a living body and each including a superconducting quantum interference device (SQUID) for detecting a biomagnetic field generated from the living body, the plurality of fluxmeters being operative to detect a temporal change of a component of the biomagnetic field in a first direction which is normal to the surface of the living body, an operation processor for performing computation for determining a temporal change of a value proportional to a root of square sum of differential values of the first-direction magnetic field component in second and third directions which cross the first direction and computation for integrating the temporal change of the value over a predetermined interval to determine an integral value, and a display for displaying the determined integral value. Distribution of magnetic fields generated from the heart is determined with a small number of fluxmeters.

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Mito, Japan

Hitoshi Sasabuchi