JP2005323783A - Biomagnetism measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology which simplifies the constitution of a device for positioning a subject for measuring and for measuring the position of the subject as well as measuring procedure in a biomagnetism measuring device. <P>SOLUTION: The positioning of the subject and the position measurement of the subject can be simultaneously carried out by arranging a reflecting mirror secured to the predetermined position of the bottom portion of a cryostat and a displacement gauge measuring the distance between the bottom portion of the cryostat and the subject by irradiating the subject with laser light via the reflecting mirror and using the laser beam irradiated to the subject in the biomagnetism measuring device. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention is a SQUID for measuring a weak magnetic signal generated from a subject's heart or brain.
(Superconducting Quantum Interference Device) The present invention relates to a biomagnetic measuring device including a magnetometer, and more particularly to a biomagnetic measuring device including means for measuring the positional relationship between a subject and a magnetic sensor.

The biomagnetic measuring device uses SQUID (Superconducting) to use the measurement results for diagnosis.
(Quantum Interference Device: Superconducting quantum interference device) It is necessary to correspond the measurement result with the magnetometer and the position of the subject.

  In Patent Document 1, a biomagnetism measuring apparatus provided with means for measuring the measurement and positioning of a subject using three laser beams and an ultrasonic displacement sensor and measuring the distance between the bottom of a cryostat (magnetic sensor cooling means) and the subject. It is disclosed.

JP 2001-299714 A

  In the technology described in Patent Document 1, since three laser beams and an ultrasonic displacement sensor are used, the apparatus configuration is large, and the subject is positioned by the three laser beams and the subject is indirect by the ultrasonic displacement sensor. And measuring the distance between the cryostat and the bottom of the cryostat, there is a problem that preparation for measurement, ie, positioning of the subject and measurement of the distance between the subject and the cryostat is complicated.

  An object of the present invention is to provide a biomagnetic measurement apparatus that has a simple apparatus configuration for measuring and positioning a subject and measuring a distance between the subject and a cryostat bottom and that has a simple measurement procedure.

  The configuration of the present invention for solving the above-described problems is as follows.

  Subject support means for supporting the subject, a magnetic sensor having a superconducting quantum interference element for detecting a magnetic field generated from the subject, and a superconducting quantum for holding the superconducting quantum interference element of the magnetic sensor at a low temperature A biomagnetism measuring apparatus comprising: an interference element cooling means; and a light irradiation means for irradiating the subject with light provided on a bottom surface of the superconducting quantum interference element cooling means on the subject side.

The subject support means is generally a bed, but may be anything as long as the subject can be held in a fixed position. The magnetic sensor can be a normal conducting magnetic sensor other than the superconducting quantum interference device (SQUID), but is preferably a SQUID for measuring a minute magnetic field of a living body. The superconducting quantum interference element cooling means may be any means capable of cooling the magnetic sensor, but is generally referred to as a container-like means for holding a refrigerant such as liquid helium or liquid nitrogen, that is, dewar. Such a cryostat is preferable. Of course, a means for cooling the magnetic sensor by forcibly circulating the refrigerant may be used. The cryostat often has a substantially flat bottom surface so that a plurality of magnetic sensors can be arranged side by side on the bottom surface on the subject side. It is preferable to provide means for irradiating the subject with light on the bottom surface of such a cryostat. As the light irradiation means, a light emitting element such as a light bulb or LED may be provided, or a light source may be provided separately, and light may be guided to the bottom of the cryostat through an optical fiber or the like. Also, a mirror or prism that reflects light is provided at the bottom of the superconducting quantum interference device cold insulation means, and the non-diffused light such as laser light is irradiated from the outside to the mirror, and the light is directed almost perpendicularly on the bottom surface. It is also possible to irradiate the subject after bending it. When such mirrors and prisms are used, it is easy to measure the distance between the bottom of the superconducting quantum interference device cooling means and the subject by measuring the incident angle of light and the reflected angle of light reflected from the subject. Can be.

  According to the present invention described above, in biomagnetism measurement, the measurement position of the subject and the distance measurement between the subject and the magnetic sensor can be easily performed at the same time, so the restraint time for examining the subject is shortened. In addition, troublesome operator operations can be easily performed.

  An embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of a biomagnetic measurement apparatus according to an embodiment of the present invention. As shown in FIG. 1, in the magnetic shield room 1, a bed 4 on which a subject 8 lies, a plurality (multiple channels) of SQUID magnetic sensors and a refrigerant (liquid helium) for maintaining a superconducting state. Alternatively, a cryostat 2 that stores liquid nitrogen) and a gantry 3 that mechanically holds the cryostat 2 are disposed. The bed 4 is movable in the X direction, the Y direction, and the Z direction. Outside the magnetic shield room 1, a SQUID magnetometer operating circuit 5, an amplifier circuit and filter circuit unit 6, and a data capture and data analysis computer 7 are arranged.

  A biomagnetic signal detected by the SQUID magnetic sensor is amplified by an amplifier circuit and filter circuit unit 6 and passes a frequency signal lower than a set frequency, a high-pass filter that passes a frequency signal higher than a set frequency, and a commercial power supply After undergoing signal processing such as a notch filter that cuts only the frequency, it is taken into the personal computer (computer) 7 as raw data. Further, the personal computer 7 can store the captured raw data in a raw data file, display the waveform on the screen, or perform waveform signal processing and display the waveform.

  FIG. 2 is a view showing a measurement positioning means for a subject and a means for measuring the distance between the subject and the cryostat bottom in the biomagnetic measurement apparatus according to the embodiment of the present invention.

  Laser light 17 irradiated horizontally from the side of the cryostat 11 from the laser light irradiation unit 14 of the displacement meter 13 using laser light is reflected at a right angle by the reflecting mirror 12 attached to a predetermined position on the bottom of the cryostat 11. The subject 16 is irradiated. The subject is measured and positioned by matching the position of the subject to be measured with the position of the irradiated laser beam. Moreover, the distance between a test subject and a cryostat bottom part can be measured with the displacement meter 13 using a laser beam. The measurement principle of the displacement meter 13 using laser light is not limited in the present invention, but as an example, the laser light emitted from the laser light irradiation unit 14 is applied to the object and reflected. The returned laser beam is captured by the light receiving unit 15. Since the angle of the laser light reflected and returned from the object changes according to the distance of the object, the distance to the object is measured by the angle of the laser light detected by the light receiving unit 15. A CCD light receiving element or the like is used as the light receiving unit 15. Furthermore, the distance between the cryostat bottom and the subject can be measured by setting the distance between the reflecting mirror 12 and the laser beam irradiator to 0 in advance by an offset.

  The light irradiation means may be provided with a light emitting element such as a light bulb or LED instead of the laser light on the bottom surface of the cryostat, or the light source is provided at a location different from the bottom surface of the cryostat and the light is transmitted through the optical fiber or the like at the bottom of the cryostat. You may lead to.

  FIG. 3 is an embodiment in which the shape of the bottom of the cryostat 11 is changed in the embodiment of FIG. In FIG. 3, a groove 23 is cut at the bottom of the cryostat 21 and a reflecting mirror 22 is embedded. Laser light 24 is irradiated from the side of the cryostat along the groove 23, and the laser light 24 is directed vertically downward by the reflecting mirror 22. Reflect. Even when the subject approaches or contacts the bottom of the cryostat, the groove 23 can measure the distance without blocking the optical path of the laser light 24. Further, the groove 23 may be filled with a transparent material that does not refract laser light, glass or acrylic.

  FIG. 4 is a diagram illustrating the principle of distance measurement between the magnetic sensor and the subject according to the embodiment of the present invention. In FIG. 4, a cryostat 41 is provided with a magnetic sensor 42, which is filled with a refrigerant 43 (liquid helium or liquid nitrogen) for operating the magnetic sensor 42 in a superconducting state. The distance 49 between the bottom of the cryostat 41 and the subject 47 is measured by irradiating the subject with the laser beam 45 irradiated from the displacement meter 44 using laser light at a right angle from the bottom of the cryostat by the reflecting mirror 46. To do. The distance 49 measured by the displacement meter 44 is displayed on the monitor 50 as the distance from the subject to the magnetic sensor, taking into account the distance 48 from the designed magnetic sensor to the cryostat bottom.

  FIG. 5 is a diagram showing an example of a subject-magnetic sensor distance monitor screen as an example of the present invention as an example of the display of the monitor 50 in FIG. The subject-magnetic sensor distance monitor screen 51 includes a distance display (measurement value display) 52 from the subject to the cryostat bottom, a distance display (design value) 53 from the cryostat bottom to the magnetic sensor, and the subject. A distance display (calculated value obtained from 52 and 53) 54 to the magnetic sensor is displayed.

It is the figure which showed the structure of the biomagnetic measuring device which is an Example of this invention. It is the figure which showed the means for the measurement positioning of the test subject of the biomagnetic measuring device which is an Example of this invention, and the means to measure the distance between a test subject and a cryostat bottom part. It is the figure which showed the means for the measurement positioning of the test subject of the biomagnetic measuring device which is an Example of this invention, and the means to measure the distance between a test subject and a cryostat bottom part. It is the figure which showed the principle of the distance measurement between the magnetic sensor and test subject in the biomagnetic measurement which is an Example of this invention. It is the figure which showed an example of the test subject-magnetic sensor distance monitor screen in the biomagnetism measurement which is an Example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Magnetic shield room, 2 ... SQUID magnetic sensor and cryostat, 3 ... Gantry, 4 ... Bed, 5 ... SQUID magnetometer operation circuit, 6 ... Amplifier circuit and filter circuit unit, 7 ... Computer, 8, 16, 47 ... Subject DESCRIPTION OF SYMBOLS 11, 21, 41 ... Cryostat, 12, 22, 46 ... Reflector, 13, 44 ... Displacement meter using laser light, 14 ... Laser light irradiation part, 15 ... Light receiving part, 17, 24, 45 ... Laser light , 23 ... groove, 42 ... magnetic sensor, 43 ... refrigerant, 48 ... distance from the magnetic sensor to the cryostat bottom, 49 ... distance from the cryostat bottom to the subject, 50 ... subject-magnetic sensor distance monitor, 51 ... subject -Distance monitor screen between magnetic sensors, 52 ... Distance display from subject to cryostat bottom (measured value) Shown), 53 ... distance display (a design value between the cryostat bottom to the magnetic sensor), 54 ... values calculated from the distance display (52 and 53 between the subject to the magnetic sensor).

Claims (7)

A subject support means for supporting the subject;
A magnetic sensor having a superconducting quantum interference element for detecting a magnetic field generated from a subject;
A superconducting quantum interference device cold-retaining means for keeping the superconducting quantum interference device of the magnetic sensor at a low temperature;
A light irradiating means for irradiating the subject with light, provided on a bottom surface of the superconducting quantum interference device cold insulating means on the subject side;
A biomagnetism measuring device comprising:   The biomagnetism measuring apparatus according to claim 1, wherein the light irradiation means is a light reflector, and reflects light incident from a side of the superconducting quantum interference device cold insulation means toward the subject. The biomagnetism measuring device according to claim 2,
A biomagnetic measurement characterized in that an optical path for allowing light incident from the side of the superconducting quantum interference device cold insulation means to pass is formed on the bottom surface of the superconducting quantum interference device cold insulation means on the subject side. apparatus.   The biomagnetic measuring apparatus according to claim 3, wherein at least a part of the optical path is filled with a transparent material capable of transmitting light. In the biomagnetism measuring device according to any one of claims 1 to 4,
A biomagnetism measuring apparatus comprising: a light receiving means for receiving light irradiated to the subject from the light irradiation means and reflected from the subject. The biomagnetic measurement apparatus according to claim 5,
A calculating means for calculating a distance between the subject and the superconducting quantum interference device cooling means based on information on an angle of light emitted from the light irradiating means to the subject and an angle of light reflected from the subject; A biomagnetism measuring device characterized by comprising. A subject support means for supporting the subject;
A magnetic sensor having a superconducting quantum interference element for detecting a magnetic field generated from a subject;
A superconducting quantum interference device cold-retaining means for keeping the superconducting quantum interference device of the magnetic sensor at a low temperature;
A superconducting quantum interference device cold insulation means of a biomagnetic measurement device comprising:
A superconducting quantum interference element cold insulation means, comprising a light irradiation means for irradiating the subject with light on the bottom surface of the superconducting quantum interference element cold insulation means on the subject side.

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