JP2016179026A - Biomagnetic field measurement apparatus and biomagnetic field measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biomagnetic field measurement apparatus capable of accurately detecting distribution of magnetic vector of a subject without being affected by a distance sensor.SOLUTION: A biomagnetic field measurement apparatus includes a magnetic sensor 4 for detecting a first direction 4a component of magnetic vector from a measurement surface of a subject 6, a position measurement device 5 for measuring a position in the first direction 4a of the measurement surface with respect to the magnetic sensor 4, a table 3 on which the subject 6 is placed and which moves the subject 6 in the first direction 4a, and a control part 18 for controlling the table 3 so that the distance between the measurement surface and the magnetic sensor 4 falls within a predetermined distance.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a biomagnetic field measurement apparatus and a biomagnetic field measurement method.

  Biomagnetic field measurement devices for measuring the magnetic field of the heart, the magnetic field of the brain, etc., which are smaller than the geomagnetism, have been studied. The biomagnetic field measurement apparatus is non-invasive and can measure the state of an organ without applying a load to the subject. A biomagnetic field measuring apparatus that measures the magnetic field of a fetal heart using a magnetic field detection sensor is disclosed in Patent Document 1. According to this, this apparatus is equipped with a magnetic field detection sensor, and the magnetic field detection sensor is installed toward the person who is the subject. A superconducting quantum interference element is used as the magnetic field detection sensor.

  The magnetic field detection sensor is installed in a container called a cryostat, and the cryostat is supported by a support body called a gantry. The gantry can adjust the magnetic field detection sensor to a predetermined posture. Then, the posture of the cryostat is adjusted according to the posture of the person. When the distance between the magnetic field detection sensor and the subject increases, the sensitivity of the magnetic field detection sensor decreases. Therefore, the magnetic field detection sensor needs to be close to the subject. On the other hand, when the magnetic field detection sensor comes into contact with the subject, the magnetic field detection sensor vibrates and noise increases. Therefore, it is necessary to bring the magnetic field detection sensor close enough not to contact the subject. In the cryostat, it has been proposed to arrange a distance sensor that detects the distance between the cryostat and the person at a location facing the person.

JP 2008-92978 A

  In the biomagnetic field measurement apparatus of Patent Document 1, a distance sensor is installed near the magnetic field detection sensor. Since the distance sensor is driven using electricity, it generates a magnetic field. When a magnetic field is generated, a residual magnetic field is formed and affects the distance sensor. For this reason, detection accuracy falls. Therefore, a biomagnetic field measurement apparatus that can accurately detect the magnetic vector distribution of the subject without being affected by the distance sensor has been desired.

  The present invention has been made to solve the above-described problems, and can be realized as the following forms or application examples.

[Application Example 1]
A biomagnetic field measurement apparatus according to this application example, comprising: a magnetic detection unit that detects a magnetic field emitted from a measurement surface of a subject; and a position measurement unit that measures a position in the first direction of the measurement surface with respect to the magnetic detection unit; A table on which the subject is installed and moves the subject, and a control unit that controls the table so that a distance in the first direction between the measurement surface and the magnetic detection unit becomes a predetermined distance. It is characterized by providing.

  According to this application example, the biomagnetic field measurement apparatus includes a magnetic detection unit, a position measurement unit, a table, and a control unit. The magnetic detection unit detects a magnetic vector emitted from the measurement surface of the subject. Then, the position measurement unit measures the position of the first direction component on the measurement surface. A subject is placed on the table, and the table moves the subject. The control unit controls the position of the table. A control part controls the distance which moves a table from the data of the position of the measurement surface with respect to the magnetic detection part which the position measurement part measured. The control unit controls the distance between the measurement surface and the magnetic detection unit in the first direction to be a predetermined distance. When the distance between the measurement surface and the magnetic detection unit increases, the magnetic intensity detected by the magnetic detection unit is inversely proportional to the square of the distance from the measurement surface. Accordingly, the detection power of the magnetic detection unit decreases as the magnetic detection unit moves away from the measurement surface. Further, since the magnetic detection unit vibrates when the measurement surface comes into contact with the magnetic detection unit, the measurement accuracy decreases. In this application example, the magnetic detection unit can be approached in a range where it does not contact the measurement surface. Then, after the position measurement unit measures the position of the measurement surface with respect to the magnetic detection unit, the table brings the subject closer to the magnetic detection unit. Therefore, even if the position measurement unit is separated from the magnetic detection unit, the subject can be brought close to the magnetic detection unit. As a result, the biomagnetic field measurement apparatus can accurately detect the magnetic field on the measurement surface.

[Application Example 2]
In the biomagnetic field measurement apparatus according to the application example, the table moves the subject in a second direction and a third direction, the second direction and the third direction are orthogonal to the first direction, and the first Two directions and the third direction intersect with each other.

  According to this application example, the table moves the subject in the second direction and the third direction. The second direction and the third direction are directions orthogonal to the first direction. The second direction and the third direction are directions that intersect each other. Therefore, the table can move the subject in a direction along a plane orthogonal to the first direction. As a result, the table can easily perform alignment in a planar direction orthogonal to the first direction of the subject.

[Application Example 3]
In the biomagnetic field measurement apparatus according to the application example, the second direction and the third direction are orthogonal to each other.

  According to this application example, the second direction and the third direction are orthogonal to each other. Then, the table moves the subject in the second direction and the third direction orthogonal to each other. Therefore, since the table can be moved along the orthogonal coordinate system, the moving position of the table can be easily controlled.

[Application Example 4]
In the biomagnetic field measurement apparatus according to the application example, the magnetic detection unit includes a magnetic shield unit that includes the magnetic detection unit and that has a first opening portion that enters and exits in the second direction, and that attenuates magnetic field lines that enter. To do.

  According to this application example, the biomagnetic field measurement apparatus includes the magnetic shield unit. The magnetic shield part attenuates the magnetic field lines that enter. A magnetic detection unit is installed inside the magnetic shield unit, and magnetic field measurement is performed. The magnetic shield part has a first opening to attenuate the magnetic lines of force that enter. As a result, the magnetic detection unit can perform measurement with less noise.

[Application Example 5]
In the biomagnetic field measurement apparatus according to the application example, the position measurement unit measures one place having a high height from the table on the measurement surface.

  According to this application example, the position measurement unit measures one place where the height from the table is high on the measurement surface. Therefore, it is possible to detect the position of the most protruding place on the measurement surface. As a result, the most protruding location on the measurement surface can be approached as long as it does not contact the magnetic detection unit.

[Application Example 6]
In the biomagnetic field measurement apparatus according to the application example, the position measurement unit measures a three-dimensional shape of the measurement surface.

  According to this application example, the position measurement unit measures the three-dimensional shape of the measurement surface. Therefore, it is possible to detect the position of the most protruding place on the measurement surface. As a result, the most protruding location on the measurement surface can be approached as long as it does not contact the magnetic detection unit.

[Application Example 7]
In the biomagnetic field measurement apparatus according to the application example, the position measurement unit scans a light beam on the measurement surface, and measures a place irradiated with the light.

  According to this application example, the position measurement unit scans the light beam on the measurement surface. And the place irradiated with light is measured. Therefore, the position measuring unit can detect the position of the most protruding place within the scanned range of the light beam.

[Application Example 8]
In the biomagnetic field measurement apparatus according to the application example described above, the biomagnetic field measurement apparatus includes a guide light irradiation unit that irradiates a light beam that guides a position where the subject is set, and the position measurement unit measures the measurement by irradiating the subject with a light beam, The position measuring unit also serves as the guide light irradiating unit, and the position measuring unit irradiates a light beam that guides a position where the subject is installed.

  According to this application example, the biomagnetic field measurement apparatus includes a function of a guide light irradiation unit and a function of a position measurement unit. The function of the guide light irradiating unit is a function of irradiating a light beam that guides the position where the subject is placed. The function of the position measurement unit is a function of measuring the shape of the subject by irradiating the subject with light. The position measuring unit also functions as a guide light irradiating unit, and the position measuring unit irradiates a light beam that guides the position where the subject is installed. Therefore, compared with the case where the biomagnetic field measurement apparatus includes a guide light irradiation unit and a position measurement unit separately, the number of components can be reduced. As a result, the biomagnetic field measurement apparatus can be manufactured with high productivity.

[Application Example 9]
In the biomagnetic field measurement apparatus according to the application example, the position measurement unit is installed in the first opening.

  According to this application example, the position measurement unit is installed in the first opening. A subject placed on the table passes through the first opening. Therefore, since the subject passes near the position measuring unit, the position measuring unit can easily irradiate the subject with light.

[Application Example 10]
In the biomagnetic field measurement apparatus according to the application example, a portion of the table that moves to the inside of the magnetic shield portion is nonmagnetic.

  According to this application example, the portion of the table that can move inside the magnetic shield portion is non-magnetic. Accordingly, it is possible to suppress the table from being magnetized and affecting the magnetic field measurement.

[Application Example 11]
In the biomagnetic field measurement apparatus according to the application example, the control unit is located at a location away from the first opening.

  According to this application example, the biomagnetic field measurement apparatus includes the magnetic shield unit. The magnetic shield part attenuates the magnetic field lines that enter. A magnetic detection unit and a table are installed inside the magnetic shield unit, and magnetic field measurement is performed. The magnetic shield part includes a first opening, and allows the subject to enter and exit from the first opening.

  A control unit for controlling the table is located at a location away from the first opening. The control unit controls the table by causing the electric signal to flow. Noise is generated when a magnetic field or residual magnetic field due to this electrical signal is detected by the magnetic detection unit. In this application example, since the control unit is located away from the first opening, the magnetic field and residual magnetic field generated from the control unit are difficult to reach the magnetic detection unit. As a result, the magnetic detection unit can perform measurement with less noise.

[Application Example 12]
In the biomagnetic field measurement apparatus according to the application example, the magnetic shield unit includes a pipe that communicates the inside and the outside, and the pipe extends in a direction orthogonal to the first direction.

  According to this application example, a pipe is installed in the magnetic shield part, and the pipe extends in a direction orthogonal to the first direction and communicates the inside and the outside. The direction of the magnetic vector passing through the pipe is orthogonal to the first direction. Therefore, the magnetic vector passing through the pipe is unlikely to affect the magnetic detection unit. As a result, the magnetic detection unit can perform measurement with less noise.

[Application Example 13]
The biomagnetic field measurement apparatus according to the application example further includes a drive source that moves the table in the third direction, and the drive source is located outside the magnetic shield part, and the table, the drive source, It is characterized by including a detachable part for detaching.

  According to this application example, the drive source moves the table in the third direction. The drive source is provided outside the magnetic shield part and has a detachable part for detaching the table and the drive source. Therefore, the detachable part can connect the table and the drive source and move the table in the third direction using the drive source. Then, when the table is not moved in the third direction, the detachable part can separate the drive source and the table. Then, the drive source can be positioned outside the magnetic shield part, and the table can be moved inside the magnetic shield part. Therefore, it is possible to make it difficult for the magnetic field of the drive source to affect the inside of the magnetic shield part. As a result, the magnetic detection unit can perform measurement with less noise.

[Application Example 14]
The biomagnetic field measurement apparatus according to the application example further includes a drive source that moves the table in the second direction, and the drive source is located outside the magnetic shield part.

  According to this application example, the drive source moves the table in the second direction. The drive source is located outside the magnetic shield part. Therefore, it is possible to make it difficult for the magnetic field of the drive source to affect the inside of the magnetic shield part. As a result, the magnetic detection unit can perform measurement with less noise.

[Application Example 15]
In the biomagnetic field measurement method according to this application example, the subject is placed on a table, the position measurement unit measures the three-dimensional shape of the measurement surface of the subject, and calculates the most protruding portion of the three-dimensional shape Then, the table is moved so that the most protruding place and the magnetic detection unit are brought close to each other with a predetermined interval, and the magnetic detection unit detects the distribution of magnetic vectors in the subject.

  According to this application example, the subject is placed on the table, and the three-dimensional shape of the measurement surface of the subject is measured. And the place which protrudes most among solid shapes is calculated. Next, the table is moved so that the most protruding location and the magnetic detection unit are brought close to each other with a predetermined interval. Subsequently, the distribution of magnetic vectors in the subject is detected. Therefore, the measurement is performed by bringing the magnetism detection unit closer to the measurement surface without touching it. Then, after the position measurement unit measures the position of the measurement surface with respect to the magnetic detection unit, the table brings the subject close to the magnetic detection unit. Therefore, even if the position measurement unit is separated from the magnetic detection unit, the subject can be brought close to the magnetic detection unit. As a result, the biomagnetic field measurement apparatus can accurately detect the magnetic field on the measurement surface.

[Application Example 16]
In the biomagnetic field measurement method according to the application example described above, the position of the subject in a direction orthogonal to the longitudinal direction of the subject is set when measuring the three-dimensional shape, and the table is moved when the table is moved. It is characterized by moving in the longitudinal direction.

  According to this application example, when measuring a three-dimensional shape, first, the position of the subject in a direction orthogonal to the longitudinal direction of the subject is set. Thereby, a measurement range can be measured reliably. Next, the table is moved in the longitudinal direction of the subject. Thereby, a two-dimensional measurement range can be measured.

[Application Example 17]
In the biomagnetic field measurement apparatus according to the application example, the magnetic shield portion extends in the second direction and has a cylindrical shape, and the pipe extends in the second direction along the magnetic shield portion. And

  According to this application example, the pipe extends in the second direction, and the second direction is orthogonal to the first direction. Therefore, the magnetic vector passing through the pipe is unlikely to affect the magnetic detection unit. As a result, the magnetic detection unit can perform measurement with less noise. And since piping is installed along the magnetic shield part, piping is easy to fix to a magnetic shield part. Therefore, piping can be easily installed.

The schematic perspective view which shows the structure of a biomagnetic field measuring apparatus. (A) And (b) is a schematic sectional side view for demonstrating the structure of a position measuring apparatus. (A) is a perspective view of a three-dimensional image measured by the position measurement device, (b) is a schematic side view of a stereoscopic image for explaining the measurement of the position measurement device. (A) And (b) is a schematic sectional side view which shows the structure of a table. (A) is a schematic side view showing the structure of the detachable part, (b) is a side view of the grooved rod, (c) is a side view of the grooved cylinder, and (d) is a schematic side view showing the structure of the detachable part. (A) is a plane sectional view for explaining the composition of piping, and (b) is a side sectional view for explaining the composition of piping. (A) is a schematic side view which shows the structure of a magnetic sensor, (b) is a schematic top view which shows the structure of a magnetic sensor. The electric control block diagram of a control part. The flowchart of the biomagnetic field measuring method. The schematic diagram for demonstrating the biomagnetic field measuring method. The schematic diagram for demonstrating the biomagnetic field measuring method.

Hereinafter, embodiments will be described with reference to the drawings.
In addition, each member in each drawing is illustrated with a different scale for each member in order to make the size recognizable on each drawing.

(Embodiment)
In this embodiment, a characteristic example of a biomagnetic field measurement device and a biomagnetic field measurement method for measuring a cardiac magnetic field emitted from the heart using the biomagnetic field measurement device will be described with reference to the drawings. The structure of the biomagnetic field measurement apparatus according to this embodiment will be described with reference to FIGS. FIG. 1 is a schematic perspective view showing the configuration of the biomagnetic field measurement apparatus. As shown in FIG. 1, the biomagnetic field measurement apparatus 1 mainly includes an electromagnetic shield device 2 as a magnetic shield unit, a table 3, a magnetic sensor 4 as a magnetic detection unit, a position measurement unit, and a position measurement device as a guide light irradiation unit. It is composed of five.

  The electromagnetic shield device 2 includes a rectangular tube-shaped main body 2a. The longitudinal direction of the main body 2a is taken as the Y direction. The direction of gravity is the Z direction, and the direction perpendicular to the Y direction and the Z direction is the X direction. The electromagnetic shielding device 2 suppresses a situation in which an external magnetic field such as geomagnetism flows into the space where the magnetic sensor 4 is disposed. In other words, the influence of the external magnetic field on the magnetic sensor 4 is suppressed by the electromagnetic shield device 2, and the magnetic sensor 4 has a significantly lower magnetic field than the external magnetic field. The main body 2a extends in the Y direction and functions as a passive magnetic shield by itself. The inside of the main body 2a is hollow, and the cross-sectional shape of a plane passing through the X direction and the Z direction (a plane perpendicular to the Y direction in the XZ cross section) is approximately a quadrangle. In the present embodiment, the main body 2a has a square cross-sectional shape. The electromagnetic shield device 2 is provided with a first opening 2b on the −Y direction side, and the table 3 projects from the first opening 2b. Although the size of the electromagnetic shield device 2 is not particularly limited, in this embodiment, for example, the length in the Y direction is about 200 cm, and one side of the first opening 2b is about 90 cm. Then, the subject 6 installed on the table 3 can go in and out with the table 3 from the first opening 2 b of the electromagnetic shield device 2.

  The main body 2a is formed of a ferromagnetic material having a relative permeability of, for example, several thousand or more, or a high conductivity conductor. As the ferromagnetic material, permalloy, ferrite, iron, chromium, or cobalt-based amorphous material can be used. As the high conductivity conductor, for example, aluminum or the like having a magnetic field reducing effect by an eddy current effect can be used. The main body 2a can be formed by alternately laminating ferromagnetic materials and high conductivity conductors. In the present embodiment, for example, the main body 2a is formed by alternately laminating aluminum plates and permalloy plates by two layers, and the total thickness is about 20 to 30 mm.

  A first correction coil (first Helmholtz coil 2c) as a magnetic shield part is installed at the ends of the main body 2a on the + Y direction side and the −Y direction side. The first Helmholtz coil 2c is a coil for correcting an inflow magnetic field flowing into the internal space of the main body 2a. The inflow magnetic field is a magnetic field in which an external magnetic field passes through the first opening 2b and enters the internal space. The inflow magnetic field is strongest in the Y direction with respect to the first opening 2b. The first Helmholtz coil 2c generates a magnetic field so that the inflow magnetic field is canceled by the current.

  The table 3 has a base 7. The base 7 is disposed on the bottom surface inside the main body 2a, and extends in the Y direction (the direction in which the subject 6 can move) from the inside of the main body 2a through the first opening 2b to the outside of the first opening 2b. Extending along. On the base 7, a pair of Y direction rails 8 extending in the Y direction are installed. On the Y direction rail 8, the Y direction table 9 which moves along the Y direction rail 8 in the Y direction which is the second direction 9a is installed. Between the two Y-direction rails 8, a Y-direction linear movement mechanism 10 that moves the Y-direction table 9 is installed.

  A Z-direction table 11 is installed on the Y-direction table 9, and a lifting device (not shown) is installed between the Y-direction table 9 and the Z-direction table 11. The lifting device lifts and lowers the Z-direction table 11. Six X direction rails 12 extending in the X direction are installed on the surface on the + Z direction side of the Z direction table 11. An X-direction table 13 that moves in the X direction along the X-direction rail 12 is installed on the X-direction rail 12.

  An X-direction linear movement mechanism 14 that moves the X-direction table 13 in the X direction that is the third direction 13d is installed on the −Y direction side on the Z-direction table 11. The X-direction linear motion mechanism 14 has a pair of bearing portions 14 a, and the bearing portions 14 a are installed upright on the Z-direction table 11. The X direction table 13 is located between the two bearing portions 14a. And the two bearing parts 14a are supporting the 1st threaded rod 14b rotatably. A first through hole (not shown) that penetrates in the X direction is installed in the X direction table 13, and the first screw rod 14 b is installed through the first through hole of the X direction table 13. A female screw (not shown) is formed in the first through hole, and the first screw rod 14b is engaged with the female screw.

  A detachable portion 15 is installed at one end of the first screw rod 14b on the −X direction side, and the detachable portion 15 is fixed to the first screw rod 14b. And if the removal | desorption part 15 is rotated, the 1st screw rod 14b will rotate. Since the first screw rod 14b is engaged with the female screw of the X-direction table 13, when the first screw rod 14b rotates, the X-direction table 13 moves in the X direction. The detachable part 15 is connected to a rotating shaft of an X-direction table motor 16 as a drive source. Therefore, the X-direction table motor 16 can move the X-direction table 13 in the X direction by rotating the detachable portion 15. The X-direction table motor 16 is connected to a motor moving unit 17 that moves the X-direction table motor 16 in the X direction. The X-direction linear motion mechanism 14 includes a bearing portion 14a, a first screw rod 14b, a detachable portion 15, an X-direction table motor 16, a motor moving portion 17, and the like. The base 7, the Y direction rail 8, the Y direction table 9, the Y direction linear motion mechanism 10, the Z direction table 11, the X direction rail 12, the X direction table 13, etc. that constitute the table 3 are made of wood, resin, ceramic, etc. It is made of a nonmagnetic material such as a nonmagnetic metal.

  The electromagnetic shielding device 2 is provided with a position measuring device 5 on the + Z direction side of the first opening 2b. The position measuring device 5 is a device that measures the positioning and surface shape of the subject 6. The subject 6 installed on the table 3 passes through the first opening 2b. Since the subject 6 passes near the position measuring device 5, the position measuring device 5 can easily irradiate the subject 6 with light.

  A magnetic sensor 4 is installed inside the electromagnetic shield device 2. The magnetic sensor 4 is a sensor that detects a magnetic field emitted from the heart of the subject 6. The magnetic sensor 4 is fixed to the electromagnetic shield device 2. The place where the biomagnetic field measurement device 1 is located is adjusted by the electromagnetic shield device 2 so that there is almost no magnetic field. Therefore, the magnetic sensor 4 can measure the magnetic field emitted from the heart without being affected by noise. The magnetic sensor 4 detects the intensity component of the magnetic field in the first direction 4a, which is the same direction as the Z direction.

  The first direction 4a and the second direction 9a are orthogonal directions. The first direction 4a and the third direction 13d are orthogonal directions. The second direction 9a and the third direction 13d are also orthogonal to each other. The table 3 moves the subject 6 in a second direction 9a and a third direction 13d that are orthogonal to each other. Therefore, since the table 3 can be moved along the orthogonal coordinate system, the moving position of the table 3 can be easily controlled. The direction in which the electromagnetic shield device 2 extends is the second direction 9a.

  A control unit 18 is installed at a location away from the first opening 2b. The control unit 18 controls the biomagnetic field measurement apparatus 1 by flowing an electric signal. Specifically, the control unit 18 controls the electromagnetic shield device 2, the table 3, the magnetic sensor 4, and the position measuring device 5. When a magnetic field or a residual magnetic field is generated by the electric signal of the control unit 18 and is detected by the magnetic sensor 4, it becomes noise. Since the control unit 18 is located away from the first opening 2b, the magnetic field generated from the control unit 18 and the remaining magnetic field are difficult to reach the magnetic sensor 4. As a result, the magnetic sensor 4 can perform measurement with less noise.

  A display device 21 and an input device 22 are installed in the control unit 18. The display device 21 is a display device such as an LCD (Liquid Crystal Display) or an OLED (Organic light-emitting diode). The display device 21 displays the measurement status, measurement results, and the like. The input device 22 includes a keyboard and a rotary knob. The operator operates the input device 22 to input various instructions such as measurement start instructions and measurement conditions of the biomagnetic field measurement apparatus 1.

  FIG. 2A is a schematic side sectional view for explaining the structure of the position measuring device, which is a view cut along the side surface of the electromagnetic shield device 2. FIG. 2B is a schematic side view for explaining the structure of the position measurement device, and is a view of the biomagnetic field measurement device 1 as viewed from the −Y direction. In FIG. 2, the position measuring device 5 includes a laser scanning unit 5a and an imaging device 5b. The laser scanning unit 5a is installed on the ceiling of the main body 2a in the first opening 2b, and emits laser light 5c as light and light in the −Z direction. The laser beam 5c irradiates the front surface 6a of the subject 6. This laser beam 5c is reflected by the front surface 6a. The laser scanning unit 5a has a function of scanning the laser beam 5c in the X direction and a function of irradiating one point without scanning. When the laser scanning unit 5a scans the laser beam 5c, the reflection point 5d where the laser beam 5c is reflected by the front surface 6a becomes linear when viewed from the imaging device 5b. When the laser scanning unit 5a does not scan the laser beam 5c, the reflection point 5d where the laser beam 5c is reflected by the front surface 6a becomes one point.

  When aligning the subject 6, the subject 6 is placed on the table 3 on its back. The laser scanning unit 5a irradiates the chest of the subject 6 without scanning the laser beam 5c. The operator drives the Y direction linear motion mechanism 10 to move the Y direction table 9 in the Y direction. Further, the operator drives the X direction linear motion mechanism 14 and the X direction table motor 16 to move the X direction table 13 in the X direction. Then, the positions of the table 3 in the X direction and the Y direction are adjusted so that the laser beam 5 c irradiates the sword-like projection 6 e of the subject 6.

  The position measuring device 5 has a function of irradiating the laser beam 5c as guide light and a function of position measurement. The function of irradiating the guide light is a function of irradiating a light beam that guides a position where the subject 6 is installed. The function of position measurement is a function of irradiating the subject 6 with light and measuring the shape of the subject. The position measuring device 5 has a function of irradiating guide light, and the position measuring device 5 irradiates a light beam that guides a position where the subject 6 is installed. Therefore, it is possible to reduce the number of components compared to the case where the biomagnetic field measurement apparatus 1 includes a portion where the guide light is irradiated and a portion where the position is measured.

  The imaging device 5b is installed on the main body 2a via the support 5e. The imaging device 5b is installed obliquely with respect to the traveling direction of the laser light 5c. The imaging device 5b captures the reflected light 5f reflected from the front surface 6a of the subject 6. At this time, the laser scanning unit 5a, the reflection point 5d, and the imaging device 5b form a triangle. The distance between the laser scanning unit 5a and the imaging device 5b is a known value. The angle formed by the laser light 5c and the reflected light 5f can be detected from the image captured by the imaging device 5b. Therefore, the position measuring device 5 can measure the distance between the laser scanning unit 5a and the reflection point 5d using the triangulation method.

  A surface that is a predetermined distance away from the surface on the −Z direction side of the magnetic sensor 4 in the −Z direction is defined as a reference surface 23. The reference plane 23 is a plane where a plane for measuring the magnetic field of the subject 6 is arranged. The distance between the surface on the −Z direction side of the magnetic sensor 4 and the reference surface 23 is preferably 2 mm or more and 10 mm or less, and more preferably 5 mm. At this distance, the subject 6 can be approached without contacting the magnetic sensor 4. In this embodiment, for example, the distance between the surface on the −Z direction side of the magnetic sensor 4 and the reference surface 23 is 5 mm. The reference surface 23 is a surface in contact with the surface when the subject 6 inhales air and inflates the chest 6c. The distance between the laser scanning unit 5a and the reference surface 23 is a known value. The control unit 18 calculates a distance 24 between the reference surface 23 and the front surface 6a of the subject 6.

  FIG. 3A is a perspective view of a three-dimensional image measured by the position measuring device. As shown in FIG. 3A, the three-dimensional image 25 measured by the position measuring device 5 is a stereoscopic image of the chest of the subject 6. The position measuring device 5 measures the shape of the front surface 6a of the subject 6 while moving the Y direction table 9 in the Y direction. The position measuring device 5 measures a stereoscopic image of the chest of the subject 6. The three-dimensional image 25 shows the unevenness of the chest. FIG. 3B is a schematic side view of a stereoscopic image for explaining measurement by the position measurement apparatus. As shown in FIG. 3B, the three-dimensional image 25 has a place near the reference plane 23 and a place away from the reference plane 23. A range that the magnetic sensor 4 measures in the three-dimensional image 25 is a magnetic field measurement range 26. In the drawing, the X direction range of the magnetic field measurement range 26 is shown. Similarly, the magnetic field measurement range 26 is set in the Y direction. The control unit 18 calculates the shortest distance 24 a that is the distance 24 of the place closest to the reference plane 23 in the magnetic field measurement range 26 of the three-dimensional image 25.

  FIG. 4 is a schematic sectional side view showing the structure of the table. 4A shows a state in which the table 3 is moving in the −Y direction, and FIG. 4B shows the state in which the table 3 moves into the biomagnetic field measuring apparatus 1 to measure the cardiac magnetic field of the subject 6. It shows the state. As shown in FIG. 4A, the base 7 is provided with a pair of first Helmholtz coils 2c. The first Helmholtz coil 2c has a frame shape and is disposed so as to surround the main body 2a.

  The Y direction linear motion mechanism 10 includes a motor 10a as a drive source. A first pulley 10b is installed on the rotation shaft of the motor 10a, and a second pulley 10c is rotatably installed at the Y-direction end of the Y-direction linear motion mechanism 10. A timing belt 10d is hung on the first pulley 10b and the second pulley 10c. A connecting portion 10e is installed in the timing belt 10d, and the connecting portion 10e connects the timing belt 10d and the Y direction table 9. When the motor 10a rotates the first pulley 10b, the connecting portion 10e moves in the Y direction by the torque of the motor 10a. The Y-direction table 9 is moved by the movement of the connecting portion 10e. Therefore, the motor 10a can move the Y direction table 9 in the Y direction. The motor 10a can move the movement direction of the Y-direction table 9 in both the + Y direction and the -Y direction by changing the rotation direction of the first pulley 10b.

  The materials of the Y-direction rail 8, the second pulley 10c, the timing belt 10d, and the connecting portion 10e are nonmagnetic materials. The timing belt 10d is made of rubber and resin. The Y-direction rail 8, the second pulley 10c, and the connecting portion 10e are made of ceramic. Therefore, the portion of the Y-direction linear motion mechanism 10 that enters the electromagnetic shield device 2 is non-magnetic.

  Four elevating devices 27 are arranged on the Y direction table 9 side by side in the Y direction. Each lifting device 27 has a structure in which three air cylinders are arranged in the X direction. The elevating device 27 can elevate and lower the Z-direction table 11 in the first direction 4a by expanding and contracting the air cylinder. Each air cylinder is provided with a length measuring device (not shown), and the lifting device 27 can detect the amount of movement of the Z-direction table 11. Then, each air cylinder moves the Z-direction table 11 by the same distance, so that the lifting device 27 can move the Z-direction table 11 in parallel. Pneumatic devices such as a compressor and a solenoid valve (not shown) are installed inside the control unit 18. The elevating device 27 is controlled by the control unit 18. The Y direction table 9, the lifting device 27, and the Z direction table 11 are made of aluminum. Therefore, the Y direction table 9, the lifting device 27, and the Z direction table 11 are non-magnetic.

  The X-direction table 13 is in contact with the X-direction rail 12 and wheels 28 are installed. As the wheel 28 rotates, the X-direction table 13 can be easily moved in the X direction. The X-direction table 13, the X-direction rail 12 and the wheels 28 are non-magnetic materials and are made of ceramic. Therefore, the X direction table 13, the X direction rail 12, and the wheel 28 are non-magnetic. And the part which moves to the inside of the electromagnetic shielding apparatus 2 among the tables 3 is nonmagnetic. Therefore, it is possible to suppress the table 3 from being magnetized and affecting the magnetic field measurement.

  The magnetic sensor 4 is installed on the ceiling of the main body 2a via a support member 29. The position of the center of the magnetic sensor 4 in the Z direction is the center position between the ceiling of the main body 2a and the bottom surface of the main body 2a. The position in the X direction at the center of the magnetic sensor 4 is the center position of the wall on the + X direction side and the wall on the −X direction side of the main body 2a. The distance between the center of the magnetic sensor 4 and the −Y direction side end of the main body 2a in the Y direction is twice the distance between the center of the magnetic sensor 4 and the + Y direction side wall of the main body 2a. When the center position of the magnetic sensor 4 is at this position, the magnetic sensor 4 can be made less susceptible to the influence of the magnetic field that enters from the outside of the electromagnetic shield device 2.

  A second correction coil (second Helmholtz coil 20) having a cubic frame-shaped outer shape is installed inside the electromagnetic shield device 2. Specifically, at least three pairs of second correction coils are installed so as to be orthogonal to the X direction, the Y direction, and the Z direction, respectively. The second Helmholtz coil 20 orthogonal to the X direction has a pair of coils sandwiching the measurement space in which the subject 6 is arranged and the magnetic sensor 4 from the X direction (left and right direction). The second Helmholtz coil 20 orthogonal to the X direction generates a magnetic field in the X direction so that the X component of the magnetic field in the measurement space and the space in which the magnetic sensor 4 is arranged is reduced to a level that does not adversely affect the measurement. The external magnetic field in the X direction can be canceled. In the second Helmholtz coil 20 orthogonal to the Y direction, two pairs of coils (that is, four coils) sandwich the measurement space and the magnetic sensor 4 from the Y direction (front-rear direction). The second Helmholtz coil 20 orthogonal to the Y direction generates a magnetic field in the Y direction so that the Y component of the magnetic field in the measurement space and the space in which the magnetic sensor 4 is arranged is reduced to a level that does not adversely affect the measurement. The external magnetic field in the Y direction can be canceled. Since the main body 2a is cylindrical in the front-rear direction and the inflow magnetic field along the Y direction is large, two pairs of second Helmholtz coils 20 are provided in the Y direction. In the second Helmholtz coil 20 orthogonal to the Z direction, a pair of coils sandwich the measurement space and the magnetic sensor 4 from the Z direction (vertical direction). The second Helmholtz coil 20 orthogonal to the Z direction generates a magnetic field in the Z direction so that the Z component of the magnetic field in the measurement space and the space in which the magnetic sensor 4 is disposed is reduced to a level that does not adversely affect the measurement. The external magnetic field in the Z direction can be canceled. The second Helmholtz coil 20 has a square frame shape when viewed from the orthogonal directions, and is arranged such that the center position of the square frame and the center position of the magnetic sensor 4 overlap. Although the length of the side of the square is not particularly limited, in this embodiment, for example, the length of one side is 75 cm or more and 85 cm or less. In the figure, the shape of the second Helmholtz coil 20 is rectangular for easy viewing, but is originally square.

  Four second Helmholtz coils 20 having a square frame shape and orthogonal to the Y direction are arranged at equal intervals in the Y direction. When viewed from the X direction, the outer periphery of the second Helmholtz coil 20 has a square frame shape, and two coils are arranged in the square frame shape. The center position of the square frame and the center position of the magnetic sensor 4 are arranged so as to overlap each other.

  The shape of the second Helmholtz coil 20 viewed from the Z direction is the same as the shape viewed from the X direction. The center position of the square frame and the center position of the magnetic sensor 4 are arranged so as to overlap each other. By making the second Helmholtz coil 20 into this shape, the magnetic field of disturbance in the magnetic sensor 4 can be further reduced. In particular, the influence of magnetism entering from the −Y direction side of the electromagnetic shield device 2 can be reduced.

  When the table 3 is positioned on the −Y direction side, more than half of the table 3 protrudes from the electromagnetic shield device 2. This makes it easier to place the subject 6 on the table 3. When the subject 6 is placed on the table 3, the height from the floor to the nose of the subject 6 is lower than the height of the surface on the −Z direction side of the magnetic sensor 4 from the floor. Therefore, the subject 6 does not interfere with the magnetic sensor 4 when the Y direction table 9 is moved in the Y direction.

  As shown in FIG. 4B, after the Y direction table 9 is moved in the Y direction, the Z direction table 11 is raised. The distance by which the Z-direction table 11 is raised is the shortest distance 24a calculated by the control unit 18. A place where the magnetic sensor 4 measures the surface of the chest 6c of the subject 6 is defined as a measurement surface 6d. At this time, the measurement surface 6 d is located at a location facing the magnetic sensor 4 and approaches the magnetic sensor 4. The distance between the measurement surface 6d and the magnetic sensor 4 is 5 mm. Then, the magnetic sensor 4 measures the measurement surface 6d.

  FIG. 5A is a schematic side view showing the structure of the detachable portion, and shows a state where the detachable portion 15 is separated. As shown in FIG. 5A, a detachable part installation base 30 is installed on the −X direction side of the base 7. The motor moving unit 17 is installed on the end of the −X direction on the detachable unit installation base 30. The motor moving unit 17 includes a motor 17a, a screw rod 17b, a guide rail 17c, and the like. A motor 17a is installed on the −X direction side on the detachable portion installation base 30, and a guide rail 17c is installed on the + X direction side of the motor 17a. The guide rails 17c are a pair and extend in the X direction.

  An X-direction table motor 16 is installed on the guide rail 17c, and the X-direction table motor 16 reciprocates in the X direction along the guide rail 17c. A screw rod 17b extending in the X direction is installed on the rotation shaft of the motor 17a. The X-direction table motor 16 is provided with a through hole 16a extending in the X direction, and a female screw is formed in the through hole 16a. And the internal thread of the through-hole 16a and the screw rod 17b are screwed together. When the motor 17a rotates the screw rod 17b, the X-direction table motor 16 moves in the X direction along the guide rail 17c. A grooved cylinder 15 a is installed on the rotation shaft of the X-direction table motor 16. A grooved rod 15b is installed at the end of the first screw rod 14b on the -X direction side. When the X-direction table motor 16 moves in the X direction, the grooved rod 15b is inserted into the grooved cylinder 15a.

  FIG. 5B is a side view of the grooved rod, and is a view of the grooved rod 15b viewed from the axial direction. As shown in FIG.5 (b), the groove | channel is installed in the axial direction on the outer periphery of the grooved rod 15b. FIG. 5C is a side view of the grooved cylinder, and is a view of the grooved cylinder 15a viewed from the axial direction. As shown in FIG.5 (c), the groove | channel is installed in the internal diameter of the cylinder 15a with a groove | channel in the axial direction. The outer peripheral shape of the grooved rod 15b and the inner peripheral shape of the grooved cylinder 15a are substantially the same. When the grooved rod 15b is inserted into the grooved cylinder 15a, the groove of the grooved cylinder 15a meshes with the groove of the grooved rod 15b. Thereby, the torque applied to the grooved cylinder 15a is transmitted to the grooved rod 15b.

  FIG. 5D is a schematic side view showing the structure of the detachable portion, and shows a state where the detachable portion 15 is coupled. In FIG.5 (d), the motor moving part 17 moves the X direction table motor 16 to + X direction, and the grooved rod 15b is inserted in the grooved cylinder 15a. And when the X direction table motor 16 rotates a rotating shaft, the grooved rod 15b rotates with rotation of the grooved cylinder 15a. Accordingly, when the X-direction table motor 16 rotates the rotation shaft, the first screw rod 14b connected to the grooved rod 15b is rotated. Then, the X direction table motor 16 moves the X direction table 13 in the X direction.

  FIG. 6A is a plan sectional view for explaining the configuration of the piping, and is a diagram in which the biomagnetic field measuring apparatus 1 is cut along an XY plane crossing the support member 29. FIG. 6B is a side cross-sectional view for explaining the configuration of the piping, and is a view in which the biomagnetic field measurement device 1 is cut along a YZ plane along the −X direction side wall of the electromagnetic shield device 2.

  The biomagnetic field measurement apparatus 1 is provided with a first pipe 31 as a pipe and a second pipe 32 as a pipe. The first pipe 31 is provided with a wiring for supplying electricity for driving the magnetic sensor 4. The second pipe 32 is provided with a pipe through which air that drives the lifting device 27 flows.

  A second opening 2d and a third opening 2e are provided on the side surface on the −X direction side of the main body 2a. The first pipe 31 is disposed through the second opening 2d and communicates the inside and the outside of the electromagnetic shield device 2. In the second opening 2d, the first pipe 31 extends in a third direction 13d orthogonal to the first direction 4a. The direction of the magnetic vector passing through the first pipe 31 in the second opening 2d is orthogonal to the first direction 4a. Therefore, the external magnetic field that leaks into the electromagnetic shield device 2 through the second opening 2d, the third opening 2e, and the first pipe 31 hardly affects the magnetic sensor 4.

  Similarly, the 2nd piping 32 is arrange | positioned through the 3rd opening 2e, and connects the inside of the electromagnetic shielding apparatus 2, and the exterior. In the third opening 2e, the second pipe 32 extends in a third direction 13d orthogonal to the first direction 4a. The direction of the magnetic vector entering the electromagnetic shield device 2 through the second pipe 32 in the third opening 2e is orthogonal to the first direction 4a. Therefore, the magnetic vector passing through the second pipe 32 is unlikely to affect the electromagnetic shield device 2. As a result, the biomagnetic field measurement apparatus 1 can perform measurement with less noise.

  The electromagnetic shielding device 2 extends in the second direction 9a. The second direction 9a is a direction orthogonal to the first direction 4a. The 1st piping 31 is extended in the 2nd direction 9a along the main-body part 2a. Therefore, the first pipe 31 can be easily installed. The first piping 31 extends in the second direction 9a, and the second direction 9a is orthogonal to the first direction 4a. Therefore, the magnetic vector passing through the first pipe 31 hardly affects the magnetic sensor 4. As a result, the biomagnetic field measurement apparatus 1 can perform measurement with less noise.

  The second pipe 32 has a structure that is easily bent, and the second pipe 32 is folded in two at the bent portion 32a on the −Y direction side. When the Y direction table 9 moves in the Y direction, the bent portion 32a also moves in the Y direction. Thereby, the piping can be moved with good durability without the second piping 32 being twisted.

  FIG. 7A is a schematic side view showing the structure of the magnetic sensor, and FIG. 7B is a schematic plan view showing the structure of the magnetic sensor. As shown in FIG. 7, a laser beam 34 is supplied from a laser light source 33 to the magnetic sensor 4. The laser light source 33 is installed in the control unit 18 and supplied to the magnetic sensor 4 through the optical fiber 35 installed in the first pipe 31. The magnetic sensor 4 and the optical fiber 35 are connected via an optical connector 36.

  The laser light source 33 outputs a laser beam 34 having a wavelength corresponding to the absorption line of cesium. Although the wavelength of the laser beam 34 is not particularly limited, in the present embodiment, for example, it is set to a wavelength of 894 nm corresponding to the D1 line. The laser light source 33 is a tunable laser, and the laser light 34 output from the laser light source 33 is continuous light having a constant light amount.

  The laser beam 34 supplied via the optical connector 36 travels in the + X direction and irradiates the polarizing plate 37. The laser beam 34 that has passed through the polarizing plate 37 is linearly polarized light. Next, the laser beam 34 sequentially irradiates the first half mirror 38, the second half mirror 41, the third half mirror 42, and the first reflection mirror 43. The first half mirror 38, the second half mirror 41, and the third half mirror 42 reflect a part of the laser beam 34 to travel in the -Y direction. Then, a part of the laser beam 34 is allowed to pass and is advanced in the + X direction. The first reflecting mirror 43 reflects all the incident laser light 34 in the −Y direction. The laser beam 34 is divided into four optical paths by the first half mirror 38, the second half mirror 41, the third half mirror 42, and the first reflection mirror 43. The reflectivity of each mirror is set so that the laser light 34 in each optical path has the same light intensity.

  Next, the laser beam 34 sequentially irradiates the fourth half mirror 44, the fifth half mirror 45, the sixth half mirror 46, and the second reflection mirror 47. The fourth half mirror 44, the fifth half mirror 45, and the sixth half mirror 46 reflect a part of the laser beam 34 and advance it in the + Z direction. Then, a part of the laser light 34 is allowed to pass and travel in the −Y direction. The second reflecting mirror 47 reflects all the incident laser light 34 in the + Z direction. The fourth half mirror 44, the fifth half mirror 45, the sixth half mirror 46, and the second reflection mirror 47 divide the laser light 34 of one optical path into four optical paths. The reflectivity of each mirror is set so that the laser light 34 in each optical path has the same light intensity. Therefore, the laser beam 34 is separated into 16 optical paths. The reflectance of each mirror is set so that the light intensity of the laser beam 34 in each optical path is the same.

  On the + Z direction side of the fourth half mirror 44, the fifth half mirror 45, the sixth half mirror 46, and the second reflection mirror 47, a gas cell 48 is installed in each optical path of the laser beam 34. The number of gas cells 48 is 16 in 4 rows and 4 columns. Then, the laser beam 34 reflected by the fourth half mirror 44, the fifth half mirror 45, the sixth half mirror 46, and the second reflection mirror 47 passes through the gas cell 48. The gas cell 48 is a box having a gap inside, and an alkali metal gas is sealed in the gap. The alkali metal is not particularly limited, and potassium, rubidium or cesium can be used. In this embodiment, for example, cesium is used as the alkali metal.

  A polarization separator 49 is provided on the + Z direction side of each gas cell 48. The polarization separator 49 is an element that separates the incident laser beam 34 into two polarized component laser beams 34 that are orthogonal to each other. As the polarization separator 49, for example, a Wollaston prism or a polarization beam splitter can be used.

  A first photodetector 50 is installed on the + Z direction side of the polarization separator 49, and a second photodetector 51 is installed on the −Y direction side of the polarization separator 49. The laser beam 34 having passed through the polarization separator 49 irradiates the first photodetector 50, and the laser beam 34 reflected by the polarization separator 49 irradiates the second photodetector 51. The first photodetector 50 and the second photodetector 51 output a current corresponding to the amount of incident laser light 34 to the control unit 18. Since the measurement may be affected if the first photodetector 50 and the second photodetector 51 generate a magnetic field, the first photodetector 50 and the second photodetector 51 are made of a nonmagnetic material. It is desirable. The magnetic sensor 4 is provided with heaters 52 on both sides in the X direction and both sides in the Y direction. The heater 52 preferably has a structure that does not generate a magnetic field. For example, a heater that heats steam or hot air through a flow path can be used. In addition, the gas cell 48 may be dielectrically heated by a high frequency voltage.

  The magnetic sensor 4 is disposed on the + Z side of the subject 6. Then, the magnetic vector 53 generated by the subject 6 is input to the magnetic sensor 4 from the −Z direction side. The magnetic vector 53 passes through the fourth half mirror 44 to the second reflecting mirror 47 and then passes through the gas cell 48. Then, it passes through the polarization separator 49 and exits from the magnetic sensor 4.

  The magnetic sensor 4 is a sensor called an optical pumping magnetometer or an optical pumping atomic magnetic sensor. The cesium in the gas cell 48 is heated and is in a gas state. Then, by irradiating the cesium gas with the laser beam 34 that is linearly polarized, the cesium atoms are excited and the direction of the magnetic moment is aligned. When the magnetic vector 53 passes through the gas cell 48 in this state, the magnetic moment of the cesium atom precesses due to the magnetic field of the magnetic vector 53. This precession is called Larmor precession. The magnitude of the Larmor precession has a positive correlation with the strength of the magnetic vector 53. The Larmor precession rotates the deflection surface of the laser beam 34. The magnitude of the Larmor precession and the amount of change in the rotation angle of the deflection surface of the laser beam 34 have a positive correlation. Therefore, the intensity of the magnetic vector 53 and the amount of change in the rotation angle of the deflection surface of the laser beam 34 have a positive correlation. The magnetic sensor 4 has high sensitivity in the first direction 4a of the magnetic vector 53, and low sensitivity of a component orthogonal to the first direction 4a.

  The polarization separator 49 separates the laser beam 34 into two orthogonal linearly polarized light components. The first photodetector 50 and the second photodetector 51 detect the intensity of two orthogonal linearly polarized light components. Accordingly, the first photodetector 50 and the second photodetector 51 can detect the rotation angle of the deflection surface of the laser beam 34. The magnetic sensor 4 can detect the strength of the magnetic vector 53 from the change in the rotation angle of the deflection surface of the laser beam 34. An element including the gas cell 48, the polarization separator 49, the first photodetector 50, and the second photodetector 51 is referred to as a sensor element 4d. The magnetic sensor 4 has 16 sensor elements 4d arranged in 4 rows and 4 columns. The number and arrangement of the sensor elements 4d in the magnetic sensor 4 are not particularly limited. The sensor element 4d may be 3 rows or less or 5 rows or more. Similarly, the sensor elements 4d may be 3 rows or less or 5 rows or more. The larger the number of sensor elements 4d, the higher the spatial resolution.

  FIG. 8 is an electric control block diagram of the control unit. As shown in FIG. 8, the biomagnetic field measurement apparatus 1 includes a control unit 18 that controls the operation of the biomagnetic field measurement apparatus 1. The control unit 18 includes a CPU 54 (Central Processing Unit) that performs various arithmetic processes as a processor, and a memory 55 that stores various types of information. The shape sensor driving device 56, the table driving device 57, the electromagnetic shield device 2, the magnetic sensor driving device 58, the display device 21 and the input device 22 are connected to the CPU 54 via the input / output interface 61 and the data bus 62.

  The shape sensor driving device 56 is a device that drives the laser scanning unit 5a and the imaging device 5b. The shape sensor driving device 56 drives the laser scanning unit 5 a to emit laser light 5 c toward the subject 6. Then, the shape sensor driving device 56 scans the laser beam 5c in the horizontal direction. Further, the shape sensor driving device 56 drives the imaging device 5b to capture an image of the reflection point 5d. In addition, the shape sensor driving device 56 irradiates one place without scanning the laser beam 5c. The irradiated reflection point 5d becomes a mark when the subject 6 is aligned.

  The table driving device 57 is a device that drives the X direction table 13, the Y direction table 9, the Z direction table 11, and the motor moving unit 17. The table driving device 57 receives an instruction signal for moving the position of the X direction table 13 from the CPU 54. The X direction table 13 can be moved only when the Y direction table 9 is at a predetermined position. For this reason, first, the Y direction table 9 is moved to a predetermined position. The table driving device 57 detects the position of the Y direction table 9. The Y direction table 9 is provided with a length measuring device that detects its own position, and the position of the Y direction table 9 can be detected. Then, the Y-direction table 9 is moved to move the Y-direction table 9 to a place where the grooved rod 15b faces the grooved cylinder 15a.

  Next, the table driving device 57 drives the motor moving unit 17 to couple the grooved cylinder 15a and the grooved rod 15b. Subsequently, the table driving device 57 detects the position of the X direction table 13. The X direction table 13 is provided with a length measuring device for detecting its own position, and the position of the X direction table 13 can be detected. Then, the difference between the position where the X-direction table 13 is to be moved and the current position of the X-direction table 13 is calculated. Then, the table driving device 57 drives the X direction table motor 16 to move to the position where the X direction table 13 is to be moved. As a result, the table driving device 57 can move the X-direction table 13 to the designated location. Subsequently, the table driving device 57 drives the motor moving unit 17 to separate the grooved cylinder 15a and the grooved rod 15b.

  Similarly, the table driving device 57 receives an instruction signal for moving the position of the Y-direction table 9 from the CPU 54. The table driving device 57 detects the position of the Y direction table 9. Then, the difference between the position where the Y direction table 9 is to be moved and the current position of the Y direction table 9 is calculated. Then, the table driving device 57 drives the motor 10a to move to a position where the Y-direction table 9 is to be moved. Accordingly, the table driving device 57 can move the Y-direction table 9 between a position inside the electromagnetic shield device 2 and a position outside the electromagnetic shield device 2. Further, when the position measuring device 5 measures the chest 6c of the subject 6, the Y direction table 9 is moved at a constant speed.

  Similarly, the table driving device 57 receives an instruction signal for moving the position of the Z-direction table 11 from the CPU 54. A length measuring device that detects the position of the Z direction table 11 is installed in each of the lifting devices 27 that lift and lower the Z direction table 11, and the table driving device 57 detects the position of the Z direction table 11. Then, the difference between the position where the Z-direction table 11 is to be moved and the current position of the Z-direction table 11 is calculated. The elevating device 27 is an air cylinder, and the table driving device 57 includes pneumatic devices such as a compressor and an electromagnetic valve that drive the elevating device 27. Then, the table driving device 57 controls the amount of air supplied to the lifting device 27 and moves to the position where the Z-direction table 11 is to be moved.

  The electromagnetic shield device 2 includes a first Helmholtz coil 2c and a sensor that detects an internal magnetic field. And the electromagnetic shielding apparatus 2 receives the instruction | indication of CPU54, drives the 1st Helmholtz coil 2c, and reduces the magnetic field inside the main-body part 2a.

  The magnetic sensor driving device 58 is a device that drives the magnetic sensor 4 and the laser light source 33. The magnetic sensor 4 is provided with a first photodetector 50, a second photodetector 51, and a heater 52. The magnetic sensor driving device 58 drives the laser light source 33, the heater 52, the first photodetector 50 and the second photodetector 51. The magnetic sensor driving device 58 drives the laser light source 33 to supply the laser light 34 to the magnetic sensor 4. Further, the magnetic sensor driving device 58 drives the heater 52 to maintain the magnetic sensor 4 at a predetermined temperature. The magnetic sensor driving device 58 converts the electrical signals output from the first photodetector 50 and the second photodetector 51 into digital signals and outputs them to the CPU 54.

  The display device 21 displays predetermined information according to an instruction from the CPU 54. Based on the display contents, the operator operates the input device 22 to input the instruction contents. Then, this instruction content is transmitted to the CPU 54.

  The memory 55 is a concept including a semiconductor memory such as a RAM and a ROM, and an external storage device such as a hard disk and a DVD-ROM. Functionally, a storage area for storing program software 63 in which a control procedure of the operation of the biomagnetic field measurement apparatus 1 is described, and measurement unit shape data that is data obtained by measuring the three-dimensional shape of the magnetic field measurement range 26 of the subject 6. A storage area for storing 64 is set. In addition, a storage area for storing table movement amount data 65 that is movement amount data of the Y direction table 9 and the Z direction table 11 is set.

  In addition, a storage area for storing magnetic sensor-related data 66 that is data such as parameters used when driving the magnetic sensor 4 is set in the memory 55. In addition, a storage area for storing magnetic measurement data 67 that is data measured by the magnetic sensor 4 is set in the memory 55. In addition, a work area for the CPU 54, a storage area that functions as a temporary file, and other various storage areas are set.

  The CPU 54 performs control for measuring the magnetic field generated by the heart of the subject 6 according to the program software 63 stored in the memory 55. As a specific function realization unit, the CPU 54 has a shape measurement control unit 68 as a position measurement unit. The shape measurement control unit 68 is a part that controls the measurement of the three-dimensional shape of the magnetic field measurement range 26 in the subject 6 by driving the position measurement device 5 and the Y direction table 9. In addition, the CPU 54 has a shortest distance calculation unit 69. The shortest distance calculation unit 69 is a part that calculates the shortest distance 24 a using the measurement result of the three-dimensional shape of the subject 6.

  In addition, the CPU 54 includes a table movement control unit 70. The table movement control unit 70 is a part that controls the movement and stop positions of the X direction table 13, the Y direction table 9, and the Z direction table 11. In addition, the CPU 54 has an electromagnetic shield control unit 71. The electromagnetic shield control unit 71 is a part that controls the electric field around the magnetic sensor 4 by driving the electromagnetic shield device 2.

  In addition, the CPU 54 has a magnetic sensor control unit 72. The magnetic sensor control unit 72 is a part that controls the magnetic sensor driving device 58 to detect the intensity of the magnetic vector 53 by driving the magnetic sensor 4. In addition, the CPU 54 has a laser pointer control unit 73. The laser pointer control unit 73 is a part that performs control to drive the laser scanning unit 5a and irradiate the laser beam 5c only at one predetermined place.

  In the present embodiment, each function of the biomagnetic field measurement apparatus 1 is realized by program software using the CPU 54. However, each function described above is realized by a single electronic circuit (hardware) that does not use the CPU 54. If possible, such an electronic circuit can also be used.

  Next, a biomagnetic field measurement method using the above-described biomagnetic field measurement apparatus 1 will be described with reference to FIGS. FIG. 9 is a flowchart of the biomagnetic field measurement method. In the flowchart of FIG. 9, step S1 is a subject installation step. This step is a step of placing the subject 6 on the X-direction table 13. Next, the process proceeds to step S2. Step S2 is an alignment process. In this step, the laser scanning unit 5a irradiates the chest 6c with the laser beam 5c. Then, the operator moves the X direction table 13 and the Y direction table 9 by operating the input device 22 so that the reflection point 5d irradiates the sword-like projection 6e of the subject 6. Next, the process proceeds to step S3.

  Step S3 corresponds to a measurement surface shape measurement step. This step is a step in which the shape measurement control unit 68 drives the Y direction table 9 and the position measuring device 5 to measure the three-dimensional shape of the measurement surface 6d of the subject 6. Next, the process proceeds to step S4. Step S4 is a shortest distance calculation step. This step is a step of calculating the shortest distance 24a using the three-dimensional shape data measured by the shortest distance calculation unit 69. Next, the process proceeds to step S5.

  Step S5 is a table moving process. In this step, the table movement control unit 70 moves the table 3 and moves the chest 6 c of the subject 6 to a place facing the magnetic sensor 4. This is a step of bringing the measurement surface 6d closer to the magnetic sensor 4. Next, the process proceeds to step S6. Step S6 is a measurement process. In this step, the magnetic sensor control unit 72 causes the magnetic sensor driving device 58 to drive the magnetic sensor 4. The magnetic sensor 4 is a step of detecting magnetism generated from the chest 6 c of the subject 6. The process of measuring the magnetic field of the subject 6 is completed by the above process.

Next, the biomagnetic field measurement method will be described in detail with reference to FIGS. 10 and 11 in association with the steps shown in FIG. 10 and 11 are schematic diagrams for explaining the biomagnetic field measurement method.
FIG. 10A is a diagram corresponding to the subject setting process in step S1. As shown in FIG. 10A, the subject 6 is placed on the X direction table 13 in step S1. More than half of the X direction table 13 protrudes from the electromagnetic shield device 2. Since the Z-direction table 11 is lowered, the subject 6 can easily move on the X-direction table 13.

  FIG. 10A and FIG. 10B are diagrams corresponding to the alignment process in step S2. As shown in FIG. 10A, in step S2, the operator operates the input device 22 to input an instruction to start alignment. Then, the laser pointer controller 73 outputs an instruction signal for irradiating the shape sensor driving device 56 with the laser beam 5c. The shape sensor driving device 56 receives the instruction signal and drives the laser scanning unit 5a. Laser light 5c is emitted from the laser scanning unit 5a in the -Z direction. The laser beam 5c irradiates one point located in the −Z direction from the laser scanning unit 5a.

  As shown in FIG. 10B, the subject 6 has a sword-like projection 6e on the −Y direction side of the chest 6c. The xiphoid process 6e is a procession projecting to the lower end of the sternum, and is in a part called a groove where the left and right radial arches join. Returning to FIG. 10A, the operator operates the input device 22 to input an instruction to move the X direction table 13 in the X direction. Then, the table movement control unit 70 outputs a signal for moving the X direction table 13 to the table driving device 57. The table driving device 57 drives the motor moving unit 17 to move the X direction table motor 16 in the + X direction. Thereby, the grooved cylinder 15a and the grooved rod 15b are connected.

  Next, the table driving device 57 rotates the X direction table motor 16 to move the X direction table 13 in the X direction. The movement of the X direction table 13 follows the instruction input by the operator using the input device 22. Then, the operator causes the laser beam 5c to be irradiated on the Y-direction side of the sword-like projection 6e.

  Subsequently, the operator operates the input device 22 to input an instruction to move the Y direction table 9. Then, the table movement control unit 70 outputs a signal for moving the Y direction table 9 to the table driving device 57. The table driving device 57 drives the motor moving unit 17 to move the X direction table motor 16 in the −X direction. Thereby, the grooved cylinder 15a and the grooved rod 15b are separated.

  Next, the table driving device 57 rotates the motor 10a to move the Y direction table 9 in the Y direction. The movement of the Y direction table 9 follows the instruction input by the operator using the input device 22. Then, the operator causes the sword-like projection 6e to be irradiated with the laser beam 5c. Thereafter, the operator operates the input device 22 to input information indicating that the alignment of the subject 6 has been completed.

  The magnetic sensor 4 has a reference point 4b for confirming the position to be measured. The position of the reference point 4b in the X direction is the same as the position in the X direction of the position irradiated with the laser beam 5c in step S2. The distance in the Y direction between the position of the reference point 4b and the position where the laser beam 5c passes is set to a predetermined reference distance 4c.

  FIG. 10C is a diagram corresponding to the measurement surface shape measurement process in step S3 and the shortest distance calculation process in step S4. In step S3, the operator causes the subject 6 to perform normal breathing. Before taking measurements, you may take a deep breath to adjust your breathing. The operator operates the input device 22 to input an instruction to start measuring the three-dimensional shape of the measurement surface 6d. The shape measurement control unit 68 receives an instruction to start measurement and outputs an instruction signal for scanning the laser beam 5c to the shape sensor driving device 56. As shown in FIG. 10C, the laser scanning unit 5a irradiates the measurement surface 6d with the laser beam 5c, and reciprocates the reflection point 5d in the X direction. Then, the imaging device 5b receives the reflected light 5f. Since the reflection point 5d reciprocates on the measurement surface 6d, the imaging device 5b captures an image in which the reflection point 5d is linear. The shape sensor driving device 56 calculates the distance of the reflection point 5d from the laser scanning unit 5a using the image data and the triangulation method, and outputs it to the memory 55. In the memory 55, data on the distance from the laser scanning unit 5 a to the reflection point 5 d is stored as a part of the measurement unit shape data 64.

  The shape measurement control unit 68 outputs an instruction signal for moving the Y direction table 9 to the table driving device 57 in cooperation with the table movement control unit 70. The movement range of the Y direction table 9 is the same as the magnetic field measurement range 26. The table driving device 57 moves the Y direction table 9 in the −Y direction, and then moves the Y direction table 9 in the + Y direction at a predetermined speed. Then, the table driving device 57 outputs data indicating the position in the Y direction of the Y direction table 9 to the memory 55. Thereby, the data of the distribution of the distance from the laser scanning unit 5a to the reflection point 5d in the magnetic field measurement range 26 is accumulated in the measurement unit shape data 64 of the memory 55. When the position measuring device 5 finishes measuring the magnetic field measurement range 26, the table movement control unit 70 sends an instruction signal for moving the Y-direction table 9 so that the sword-like projection 6e is positioned at a location facing the laser scanning unit 5a. It outputs to the table drive device 57. The table driving device 57 moves the Y direction table 9 in response to the instruction signal. The operator communicates to the subject that he may take a deep breath.

  In step S4, the shortest distance calculation unit 69 calculates the distance 24 between the reference surface 23 and the measurement surface 6d in the magnetic field measurement range 26. The distance 24 is calculated by subtracting a predetermined value from the distance of the reflection point 5d from the laser scanning unit 5a measured by the position measuring device 5. Next, the shortest distance 24a which is the shortest distance among the distances 24 calculated by the shortest distance calculation unit 69 is calculated.

  FIG. 11A is a diagram corresponding to the table moving process in step S5 and the measuring process in step S6. As shown in FIG. 11A, the table movement control unit 70 outputs an instruction signal for moving the Y-direction table 9 to the table driving device 57 in step S5. The table driving device 57 inputs an instruction signal and moves the Y direction table 9 by the reference distance 4c in the + Y direction. Next, the table movement control unit 70 outputs an instruction signal for raising the Z-direction table 11 to the table driving device 57. The table driving device 57 inputs an instruction signal and raises the Z direction table 11 in the + Z direction by the shortest distance 24a. Thereby, the location closest to the magnetic sensor 4 in the measurement surface 6d coincides with the reference surface 23.

  As a result, the reference point 4b and the sword-like protrusion 6e are located at a location facing each other, and the measurement surface 6d is located at a location facing the magnetic sensor 4. The distance between the surface on the −Z direction side of the magnetic sensor 4 and the measurement surface 6d is 5 mm. When the subject 6 is breathing normally, the surface on the −Z direction side of the magnetic sensor 4 and the measurement surface 6d are not in contact with each other. Since the magnetic sensor 4 vibrates when the measurement surface 6d comes into contact with the magnetic sensor 4, the measurement accuracy decreases. In this embodiment, since the measurement surface 6d does not contact the magnetic sensor 4, the biomagnetic field measurement apparatus 1 can detect the magnetic field of the measurement surface 6d with high accuracy.

  When the distance between the measurement surface 6d and the magnetic sensor 4 is increased, the magnetic intensity detected by the magnetic sensor 4 is inversely proportional to the square of the distance from the measurement surface 6d. Therefore, the detection power of the magnetic sensor 4 decreases as the magnetic sensor 4 moves away from the measurement surface 6d. In this embodiment, since the measurement surface 6d approaches to the extent that it does not contact the magnetic sensor 4, the biomagnetic field measurement apparatus 1 can accurately detect the magnetic field of the measurement surface 6d.

  The position measuring device 5 is a device that operates by electricity, and forms a magnetic field when the position measuring device 5 operates. A residual magnetic field is also formed when the position measuring device 5 stops operating. The magnetic sensor 4 is installed at a location distant from the position measuring device 5 and installed inside the electromagnetic shield device 2. The table 3 is moved from the place where the position measuring device 5 measures the measurement surface 6d to the place where the magnetic sensor 4 measures. Therefore, even if the position measuring device 5 is separated from the magnetic sensor 4, the measurement surface 6 d can be brought close to the magnetic sensor 4. As a result, the magnetic sensor 4 can accurately detect the magnetic field on the measurement surface 6d without being affected by the position measuring device 5.

  Fig.11 (a)-FIG.11 (c) are figures corresponding to the measurement process of step S6. As shown in FIG. 11A, in step S6, the magnetic sensor 4 detects a magnetic vector 53 traveling in the first direction 4a from the measurement surface 6d of the subject 6. The magnetic sensor control unit 72 outputs an instruction signal for starting measurement to the magnetic sensor driving device 58. The magnetic sensor driving device 58 inputs a measurement start instruction signal and drives the laser light source 33 and the heater 52. The laser light source 33 irradiates a laser beam 34. When the light emission of the laser light source 33 is stabilized and the magnetic sensor 4 is stabilized at a predetermined temperature, the measurement is started. The intensity of the magnetic field detected by the magnetic sensor 4 is output as an electric signal. The magnetic sensor driving device 58 converts the electrical signals output from the first photodetector 50 and the second photodetector 51 into electrical signals indicating the strength of the magnetic field. Further, the magnetic sensor driving device 58 converts an electric signal indicating the strength of the magnetic field into digital data and transmits the digital data to the memory 55 as the magnetic measurement data 67.

  In FIG. 11B, the first region 74a to the sixteenth region 74r indicate regions where each sensor element 4d detects the magnetic vector 53. The first region 74a to the sixteenth region 74r are arranged in a 4 × 4 grid. The position of the sword projection 6e is located in the second region 74b. With this arrangement, it is possible to detect the magnetic vector 53 emitted from the heart of the subject 6 in the first region 74a to the sixteenth region 74r without leakage.

  FIG. 11C is an example of transition data of the magnetic field detected by the magnetic sensor 4. The vertical axis indicates the magnetic field strength, and the upper side in the figure is stronger than the lower side. The horizontal axis shows the change of time, and the time changes from the right side to the left side in the figure. The intensity of the magnetic vector 53 detected by the sensor element 4d is referred to as a magnetic field intensity. The first transition line 75a is the transition of the magnetic field strength in the twelfth region 74m, and shows the transition of the magnetic field strength in the upper left of the heart. The upper left of the heart shows the position in the + X direction and the + Y direction. A second transition line 75b is a transition of the magnetic field strength in the fourth region 74d, and shows a transition of the magnetic field strength in the lower left of the heart. A third transition line 75c is a transition of the magnetic field strength in the second region 74b, and shows a transition of the magnetic field strength in the lower right of the heart. The fourth transition line 75d is the transition of the magnetic field strength in the tenth region 74j, and shows the transition of the magnetic field strength at the upper right of the heart. From the magnetic sensor 4, 16 magnetic field strength transition lines are obtained. In this figure, four transition lines are shown for easy viewing of the figure.

  After the first transition line 75a passes the peak, the second transition line 75b peaks. Next, the third transition line 75c has a peak, and then the fourth transition line 75d has a peak. In this way, it is observed that the peak of the magnetic field strength moves around the heart. When the heart is not operating normally, the waveforms of the first transition line 75a to the fourth transition line 75d are deformed. Therefore, the operator can diagnose the heart of the subject 6 by observing the waveforms of the first transition line 75a to the fourth transition line 75d.

  After the measurement of the magnetic field is completed, the Z direction table 11 is lowered and the Y direction table 9 is moved in the −Y direction. Then, the step of moving the subject 6 from the table 3 and measuring the magnetic field of the heart of the subject 6 ends.

As described above, this embodiment has the following effects.
(1) According to the present embodiment, the biomagnetic field measurement device 1 includes the magnetic sensor 4, the position measurement device 5, the table 3, and the control unit 18. The magnetic sensor 4 detects the first direction 4a component of the magnetic vector 53 coming out of the measurement surface 6d of the subject 6. The position measuring device 5 measures the position of the measurement surface 6d in the first direction 4a. A subject 6 is placed on the table 3, and the table 3 moves the subject 6 in the first direction 4a. The control unit 18 controls the position of the table 3. The control unit 18 controls the distance by which the table 3 is moved from the data of the position in the first direction 4a of the measurement surface 6d with respect to the magnetic sensor 4 measured by the position measuring device 5. Then, the control unit 18 controls the distance between the measurement surface 6d and the magnetic sensor 4 to be 5 mm.

  When the distance between the measurement surface 6d and the magnetic sensor 4 is increased, the magnetic intensity detected by the magnetic sensor 4 is inversely proportional to the square of the distance from the measurement surface 6d. Therefore, the detection power of the magnetic sensor 4 decreases as the magnetic sensor 4 moves away from the measurement surface 6d. Moreover, since the magnetic sensor 4 vibrates when the measurement surface 6d comes into contact with the magnetic sensor 4, the measurement accuracy decreases. In the present embodiment, the magnetic sensor 4 can be approached in a range where it does not contact the measurement surface 6d. After the position measurement device 5 measures the position of the measurement surface 6 d with respect to the magnetic sensor 4, the table 3 brings the subject 6 close to the magnetic sensor 4. Accordingly, the subject 6 can be brought close to the magnetic sensor 4 even if the position measuring device 5 is separated from the magnetic sensor 4. As a result, since the magnetic sensor 4 is not easily affected by the position measurement device 5, the biomagnetic field measurement device 1 can accurately detect the magnetic field on the measurement surface 6d.

  (2) According to this embodiment, the table 3 moves the subject 6 in the second direction 9a and the third direction 13d. The second direction 9a and the third direction 13d are directions orthogonal to the first direction 4a. The second direction 9a and the third direction 13d are directions that intersect each other. Therefore, the table 3 can move the subject 6 in a direction along a plane orthogonal to the first direction 4a. As a result, the table 3 can facilitate the alignment of the subject 6 in the plane direction orthogonal to the first direction 4a.

  (3) According to the present embodiment, the second direction 9a and the third direction 13d are orthogonal to each other. Then, the table 3 moves the subject 6 in the second direction 9a and the third direction 13d that are orthogonal to each other. Therefore, since the table 3 can be moved along the orthogonal coordinate system, the moving position of the table 3 can be easily controlled.

  (4) According to this embodiment, the X-direction table motor 16 moves the table 3 in the third direction 13d. The X-direction table motor 16 includes an attachment / detachment portion 15 that is located outside the electromagnetic shield device 2 and that attaches / detaches the X-direction table 13 and the X-direction table motor 16. After the detachable portion 15 connects the X direction table 13 and the X direction table motor 16, the X direction table 13 is moved in the third direction 13d using the X direction table motor 16.

  When the X-direction table 13 is not moved in the third direction 13d, the detachable portion 15 separates the X-direction table motor 16 and the X-direction table 13. Then, the X direction table motor 16 can be positioned outside the electromagnetic shield device 2, and the X direction table 13 can be moved into the electromagnetic shield device 2. Therefore, the magnetic shield device 2 can be prevented from being affected by the magnetic field of the X-direction table motor 16. As a result, the magnetic sensor 4 can perform measurement with less noise.

  (5) According to this embodiment, the position measuring device 5 measures the three-dimensional shape of the measurement surface 6d. Therefore, it is possible to detect the position of the most protruding place on the measurement surface 6d. As a result, the measurement surface 6d can be brought close to the magnetic sensor 4 in a range where the most protruding location on the measurement surface 6d does not contact the magnetic sensor 4.

  (6) According to the present embodiment, the position measuring device 5 scans the laser beam 5c on the measurement surface 6d. And the place where the laser beam 5c was irradiated is measured using the triangulation method. Therefore, the position measuring device 5 can detect the position of the most protruding place within the range scanned with the laser beam 5c.

  (7) According to the present embodiment, the position measuring device 5 irradiates the laser beam 5c for guiding to align the position of the subject 6. This function is a guide light irradiation function. Further, the position measuring device 5 measures the three-dimensional shape of the measurement surface 6d. This function is a position measurement function. The position measuring device 5 has two functions. Compared with the case where the biomagnetic field measurement apparatus 1 includes a device having a guide light irradiation function and a device having a position measurement function separately, the number of components can be reduced. As a result, the biomagnetic field measurement apparatus 1 can be manufactured with high productivity.

  (8) According to the present embodiment, the position measuring device 5 is installed in the first opening 2b. The subject 6 installed on the table 3 passes through the first opening 2b. Therefore, since the subject 6 passes near the position measuring device 5, the position measuring device 5 can easily irradiate the subject 6 with the laser beam 5c.

  (9) According to this embodiment, the part which moves to the inside of the electromagnetic shielding apparatus 2 among the tables 3 is nonmagnetic. Therefore, it is possible to suppress the table 3 from being magnetized and affecting the magnetic field measurement.

  (10) According to this embodiment, the electromagnetic shielding device 2 attenuates the magnetic force lines that enter. A magnetic sensor 4 and a table 3 are installed inside the electromagnetic shield device 2. The electromagnetic shield device 2 includes a first opening 2b and allows the subject 6 to enter and exit from the first opening 2b. And the control part 18 is located in the place away from the 1st opening part 2b.

  The control unit 18 controls the table 3 by causing the electric signal to flow. When a magnetic field is generated by this electrical signal and is detected by the magnetic sensor 4, it becomes noise. In this embodiment, since the control part 18 is located in the place away from the 1st opening part 2b, the magnetic field generated from the control part 18 cannot reach the magnetic sensor 4 easily. As a result, the magnetic sensor 4 can perform measurement with less noise.

  (11) According to this embodiment, the electromagnetic shielding device 2 is provided with the first pipe 31 and the second pipe 32, and the first pipe 31 and the second pipe 32 extend in a direction orthogonal to the first direction 4a. The inside and the outside are in communication. The direction of the magnetic vector passing through the first pipe 31 and the second pipe 32 is orthogonal to the first direction 4a. Therefore, the magnetic vector passing through the first pipe 31 and the second pipe 32 is unlikely to affect the magnetic sensor 4. As a result, the magnetic sensor 4 can perform measurement with less noise.

  (12) According to the present embodiment, the first pipe 31 and the second pipe 32 extend in the second direction 9a, and the second direction 9a is orthogonal to the first direction 4a. Therefore, the magnetic vector passing through the first pipe 31 and the second pipe 32 is unlikely to affect the magnetic sensor 4. As a result, the magnetic sensor 4 can perform measurement with less noise. And since the 1st piping 31 and the 2nd piping 32 are installed along the electromagnetic shielding apparatus 2, it can be arranged so that the 1st piping 31 and the 2nd piping 32 can be installed easily.

  (13) According to the present embodiment, the subject 6 is placed on the table 3 in the subject placement step of step S1. In the measurement surface shape measurement step of step S3, the three-dimensional shape of the measurement surface 6d of the subject 6 is measured. In the shortest distance calculation step of step S4, the shortest distance 24a of the most protruding portion of the three-dimensional shape is calculated. In the table moving step in step S5, the table 3 is moved to bring the most protruding location close to the magnetic sensor 4 with a predetermined interval. In the measurement process of step S6, the distribution of the magnetic vector 53 in the subject 6 is detected.

  Therefore, the measurement is performed by bringing the magnetic sensor 4 close to the measurement surface 6d so as not to contact the measurement surface 6d. After the position measurement device 5 measures the position of the measurement surface 6 d with respect to the magnetic sensor 4, the table 3 brings the subject 6 close to the magnetic sensor 4. Accordingly, the subject 6 can be brought close to the magnetic sensor 4 even if the position measuring device 5 is separated from the magnetic sensor 4. As a result, since the magnetic sensor 4 is not easily affected by the position measurement device 5, the biomagnetic field measurement device 1 can accurately detect the magnetic field on the measurement surface 6d.

  (14) According to this embodiment, the motor 10 a of the Y-direction linear movement mechanism 10 is located outside the electromagnetic shield device 2. The motor 10a easily generates a residual magnetic field by generating an electromagnetic wave. Since the motor 10 a is located outside the electromagnetic shield device 2, the residual magnetic field of the motor 10 a is less likely to affect the magnetic sensor 4. Therefore, the biomagnetic field measurement apparatus 1 can detect the magnetic field on the measurement surface 6d with high accuracy.

Note that the present embodiment is not limited to the above-described embodiment, and various changes and improvements can be added by those having ordinary knowledge in the art within the technical idea of the present invention. A modification will be described below.
(Modification 1)
In the embodiment, the position measuring device 5 irradiates the subject 6 with the laser beam 5c, and the imaging device 5b images the reflection point 5d. And the three-dimensional shape of the measurement surface 6d was measured from the image | video which the imaging device 5b image | photographed. Another method may be used as a method of measuring the three-dimensional shape of the measurement surface 6d. For example, measurement may be performed using an ultrasonic length measuring device or laser light interference. In addition, a three-dimensional shape may be measured by moving a contact displacement meter up and down and tracing the surface of the subject 6. An easy-to-measure method can be selected.

(Modification 2)
In the embodiment, an air cylinder is used for the lifting device 27. A hydraulic cylinder may be employed for the lifting device 27. Since oil has less elasticity than air, the amount of movement can be controlled with high accuracy. In addition, a manual jack may be used for the lifting device 27. The device can be simplified.

(Modification 3)
In the embodiment, a length measuring device is installed in the lifting device 27 to feed back the movement amount. In addition, the up and down distance may be controlled by controlling the amount of air supplied to the air cylinder. Since the number of parts can be reduced, the biomagnetic field measurement apparatus 1 can be manufactured with high productivity.

(Modification 4)
In the above-described embodiment, the X-direction linear movement mechanism 14 is electrically driven by the X-direction table motor 16. The X-direction linear motion mechanism 14 may be manually operated. Generation of a magnetic field can be reduced. Further, the Y-direction linear movement mechanism 10 of the Y-direction table 9 is electrically operated. The Y-direction linear motion mechanism 10 may be manually operated. Since the generation of electromagnetic waves can be suppressed, the influence of the residual magnetic field can be suppressed.

(Modification 5)
In the embodiment, the magnetic field is measured inside the electromagnetic shield device 2. When the biomagnetic field measurement apparatus 1 is installed in a room that is electromagnetically shielded, the electromagnetic shield apparatus 2 may be omitted. Since the number of parts can be reduced, the biomagnetic field measurement apparatus 1 can be manufactured with high productivity.

(Modification 6)
In the embodiment, the three-dimensional shape of the measurement surface 6d is measured in a state where the subject 6 is normally breathing. The three-dimensional shape of the measurement surface 6d may be measured with the lungs inflated. Then, the most projecting place may be detected, and the position of the most projecting place may be measured with the lungs inflated. Even when the subject 6 inflates the lung, the subject 6 can be prevented from coming into contact with the magnetic sensor 4.

(Modification 7)
In the embodiment, the electromagnetic shield device 2 is open without a wall on the −Y direction side. You may install a door in the place where the electromagnetic shield apparatus 2 is open on the -Y direction side. The door is made of the same material as that of the main body 2a so as to shield the magnetism. When the Y-direction table 9 enters the electromagnetic shield device 2, the door is closed. Thereby, the magnetism which advances toward the magnetic sensor 4 from the -Y direction side of the electromagnetic shielding apparatus 2 can be shielded. As a result, the magnetic sensor 4 can detect the magnetic field of the subject 6 with higher accuracy without being affected by the disturbance of the magnetic field.

  When installing a door on the −Y direction side of the electromagnetic shield device 2, it is preferable to change the positions of the magnetic sensor 4 and the second Helmholtz coil 20. The position of the center of the magnetic sensor 4 in the Y direction is the center position of the wall on the + Y direction side of the main body 2a and the door on the −Y direction side. Then, the center position of the second Helmholtz coil 20 is set to the same position as the center position of the magnetic sensor 4. When the center position of the magnetic sensor 4 is at this position, the magnetic sensor 4 can be made less susceptible to the influence of the magnetic field that enters from the outside of the electromagnetic shield device 2.

(Modification 8)
In the said embodiment, the electromagnetic shielding apparatus 2 was provided with the square-tube-shaped main-body part 2a. Therefore, the electromagnetic shield device 2 has a rectangular frame shape in cross section along a plane orthogonal to the Y direction. The electromagnetic shield device 2 may have a circular, hexagonal, or octagonal frame shape in cross section along a plane orthogonal to the Y direction. The magnetic field in the magnetic sensor 4 can be further reduced.

(Modification 9)
In the embodiment, the imaging device 5b captures the three-dimensional image 25, and the shortest distance calculation unit 69 calculates the shortest distance 24a. The operator may select a location closest to the reference surface 23 among the measurement surfaces 6d and measure one location. In other words, the distance 24 at the place where the height from the table 3 is the highest in the measurement surface 6d may be measured. The measured value may be the shortest distance 24a. The shortest distance 24a can be measured efficiently in a short time.

  DESCRIPTION OF SYMBOLS 1 ... Biomagnetic field measuring apparatus, 2 ... Electromagnetic shield apparatus as a magnetic shield part, 2b ... 1st opening part, 3 ... Table, 4 ... Magnetic sensor as a magnetic detection part, 4a ... 1st direction, 5 ... Position measurement part And a position measuring device as a guide light irradiation unit, 5c... Laser light as light and light, 6... Subject, 6d... Measurement surface, 9a. DESCRIPTION OF SYMBOLS 15 ... Desorption part, 16 ... X direction table motor as a drive source, 18 ... Control part, 31 ... 1st piping as piping, 32 ... 2nd piping as piping, 53 ... Magnetic vector.

Claims (16)

A magnetic detector for detecting the magnetic field emitted from the measurement surface of the subject;
A position measuring unit that measures a position in the first direction of the measurement surface with respect to the magnetic detection unit;
A table on which the subject is installed and moves the subject;
A biomagnetic field measurement apparatus comprising: a control unit that controls the table so that a distance in the first direction between the measurement surface and the magnetic detection unit is a predetermined distance. The biomagnetic field measurement apparatus according to claim 1,
The table moves the subject in a second direction and a third direction;
The biomagnetic field measurement apparatus, wherein the second direction and the third direction are orthogonal to the first direction, and the second direction and the third direction intersect. The biomagnetic field measurement apparatus according to claim 2,
The biomagnetic field measurement apparatus, wherein the second direction and the third direction are orthogonal to each other. The biomagnetic field measurement apparatus according to claim 2 or 3,
A biomagnetic field measurement apparatus comprising a magnetic shield part that includes the magnetic detection part and has a first opening part in which the table enters and exits in the second direction to attenuate magnetic lines of force entering the table. It is a biomagnetic field measuring device according to any one of claims 1 to 4,
The biomagnetic field measuring apparatus according to claim 1, wherein the position measuring unit measures one place having a high height from the table on the measurement surface. It is a biomagnetic field measuring device according to any one of claims 1 to 4,
The biomagnetic field measuring apparatus, wherein the position measuring unit measures a three-dimensional shape of the measurement surface. The biomagnetic field measurement apparatus according to claim 6,
The position measurement unit scans a light beam on the measurement surface, and measures a place irradiated with the light. It is a biomagnetic field measuring device according to any one of claims 1 to 7,
A guide light irradiation unit for irradiating a light beam for guiding a position where the subject is installed;
The position measurement unit irradiates the subject with light and measures,
The position measuring unit also serves as the guide light irradiating unit, and the position measuring unit irradiates a light beam that guides a position where the subject is installed. It is a biomagnetic field measuring device according to any one of claims 4 to 8,
The biomagnetic field measurement apparatus, wherein the position measurement unit is installed in the first opening. It is a biomagnetic field measuring device according to any one of claims 4 to 9,
A part of the table that moves to the inside of the magnetic shield part is nonmagnetic. It is a biomagnetic field measuring device according to any one of claims 4 to 10,
The biomagnetic field measurement apparatus, wherein the control unit is located at a location away from the first opening. It is a biomagnetic field measuring device according to any one of claims 4 to 11,
The magnetic shield part includes a pipe communicating the inside and the outside,
The biomagnetic field measurement apparatus according to claim 1, wherein the pipe extends in a direction orthogonal to the first direction. It is a biomagnetic field measuring device according to any one of claims 4 to 12,
And a drive source that moves the table in the third direction.
The biomagnetic field measuring apparatus according to claim 1, wherein the driving source includes a detaching unit that is located outside the magnetic shield unit and detaches the table and the driving source. It is a biomagnetic field measuring device according to any one of claims 4 to 13,
And a drive source for moving the table in the second direction,
The biomagnetic field measuring apparatus according to claim 1, wherein the driving source is located outside the magnetic shield part. Place the subject on the table,
The position measurement unit measures the three-dimensional shape of the measurement surface of the subject,
Calculate the most prominent place in the three-dimensional shape,
Move the table so that the most protruding place and the magnetic detection part are approached at a predetermined interval,
The biomagnetic field measurement method, wherein the magnetic detection unit detects a magnetic vector distribution in the subject. The biomagnetic field measurement method according to claim 15,
When measuring the three-dimensional shape, set the position of the subject in a direction orthogonal to the longitudinal direction of the subject,
A biomagnetic field measurement method, wherein the table is moved in the longitudinal direction of the subject when the table is moved.

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