JP2020054788A - Biological information measurement system and biological information measurement program - Google Patents

Abstract

To provide a biological information measurement system capable of acquiring an image for position correction of a head with a camera.SOLUTION: A biological information measurement system comprises: a Dewar 2 in which many sensors 1 for biological signal detection are disposed and which covers a head of a subject 10; a measurement part for measuring a neural activity on the basis of biological signals detected by the sensors; an imaging part for acquiring an image containing the Dewar and at least three reference points set in relation to the subject; and a positional relation determination part for determining, using data concerning a positional relation between the plurality of reference points and the Dewar, a positional relation between the reference points of the subject and the sensors, and for re-determining the positional relation between the reference points and the sensors on the basis of images acquired at different times by the imaging part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a biological information measurement system and a biological information measurement program.

  2. Description of the Related Art Conventionally, a magnetoencephalograph that measures a magnetoencephalogram (MEG: Magneto Encephalo Graph) measures and analyzes a weak biomagnetic field generated in association with human brain nerve activity. Such a magnetoencephalograph includes a dewar having a number of magnetic sensors inside. In magnetoencephalography, it is important to determine the positional relationship between the dewar and the head of the subject.

  Therefore, Patent Document 1 discloses a technique for attaching a generator for generating a three-dimensional magnetic field to a Dewar, a receiver for the subject, and obtaining a relationship between the subject coordinate system and the three-dimensional coordinate system based on the magnetic field. It has been disclosed. Further, Patent Document 2 discloses that a Dewar and a frame capable of imaging have a three-dimensional magnetic field generator and a receiver, respectively, and the frame is mounted on the subject's head, so that the positional relationship between the subject and the Dewar can be determined. The prescribed technology is disclosed. Patent Literature 3 discloses a technique in which a light emitting source is attached to a subject and a dewar, and a position sensor determines a relative positional relationship between the subject and the magnetic sensor. Patent Document 4 discloses that a three-dimensional surface shape of a subject and a Dewar is obtained by irradiating a subject and a Dewar with slit light, and projecting a projection line of the slit light with a TV camera. A technique for determining a positional relationship between a human head and a magnetic sensor is disclosed. Patent Document 5 discloses a technique for detecting a relative positional relationship between a living body and a magnetic sensor from a stereo image including index points provided on the Dewar and the living body.

  However, in the technique disclosed in Patent Document 1, the movement of the head causes the magnetic field receiver to come off during the measurement of cranial nerve activity, and the magnetic field generated by the magnetic field generator has an undesirable effect on the measurement of cranial nerve activity. Therefore, it was difficult to simultaneously measure the position and posture of the head during the measurement of cranial nerve activity. In the technique disclosed in Patent Literature 2, the frame is shifted due to the movement of the head. In addition, since the shape of the head is different for each subject, it is not easy to prepare individually. Even if it is a frame that expands and contracts according to the shape of the subject's head, discomfort in which the head is tightened is inevitable, and may be a disturbing signal to cranial nerve activity. In the technology disclosed in Patent Literature 3, the light source can be dislocated due to the movement of the head, similarly to the technology of mounting the magnetic generator and the magnetic receiver. It was difficult to determine the positional relationship between the subjects. The technique disclosed in Patent Literature 4 involves a risk that laser light enters eyes of a subject. Further, since the laser light is scattered on the skin surface, the width of the projection line is widened, and it has been difficult to accurately measure the three-dimensional shape of the subject's head. Patent Literature 5 discloses a technique capable of determining the positional relationship between the dewar and the subject's head even when the subject's head moves during measurement of cranial nerve activity. However, in this patent, the positional relationship between the subject and the Dewar is determined by a stereo camera, and the Dewar moves and scans measurement points one after another, so it was difficult to simultaneously measure cranial nerve activity of the entire head. .

  Here, by making the dewar a helmet type, it is possible to simultaneously measure the cranial nerve activity of the entire head while determining the positional relationship between the subject's head and the dewar in real time, but in this case, In addition, the distance between the stereo cameras must be reduced because the subject's head is hidden behind the Dewar. Then, due to the measurement principle of the stereo camera, a measurement error in the depth direction of the subject's head and the dewar becomes large, and a problem arises that positioning accuracy is reduced.

  The present invention has been made in view of the above, and it is an object of the present invention to enable an image for correcting the position of a head to be acquired by one imaging unit.

  In order to solve the above-described problems and achieve the object, the present invention is based on a dewar covering a plurality of sensors for detecting a biological signal, a dewar covering a head of a subject, and a biological signal detected by the sensor. A measurement unit that measures cranial nerve activity, an imaging unit that acquires at least three or more reference points set in relation to the subject and an image that includes the Dewar, and a plurality of the reference points. By the positional relationship data of the Dewar, determine the positional relationship between the reference point of the subject and the sensor, based on the images acquired at different times by the imaging unit, the reference point and the sensor And a positional relation determining unit for re-determining the positional relation.

  ADVANTAGE OF THE INVENTION According to this invention, there exists an effect that the image for head position correction can be acquired by one imaging part.

FIG. 1 is a diagram illustrating an example of a system configuration of the biological information measurement system according to the first embodiment. FIG. 2 is a diagram illustrating an example of a hardware configuration of the information processing apparatus. FIG. 3 is a diagram exemplarily showing a subject's head. FIG. 4 is a diagram exemplarily showing the setting position of the head reference point. FIG. 5 is a diagram illustrating an example in which a seal is attached to the head reference point. FIG. 6 is a diagram illustrating a method for measuring the distance in the depth direction using a stereo camera. FIG. 7 is a diagram illustrating a method of measuring the distance in the depth direction using one camera. FIG. 8 is a diagram illustrating the function of the information processing device. FIG. 9 is a diagram schematically showing processing in the information processing device. FIG. 10 is a diagram schematically illustrating processing in the information processing apparatus according to the second embodiment. FIG. 11 is a diagram schematically illustrating processing in the information processing apparatus according to the third embodiment.

  Hereinafter, embodiments of a biological information measurement system and a biological information measurement program will be described in detail with reference to the accompanying drawings.

(First Embodiment)
FIG. 1 is a diagram illustrating an example of a system configuration of the biological information measurement system 100 according to the first embodiment. As shown in FIG. 1, the biological information measurement system 100 includes a biological information measurement device 4 and an MRI device 7 that captures an MRI (Magnetic Resonance Imaging) image. The biological information measuring device 4 includes a brain function measuring device 3, an image acquiring device 5, and an information processing device 6.

  The brain function measurement device 3 is a magnetoencephalograph that measures a magneto-encephalography (MEG) signal and an electro-encephalography (EEG) signal. The subject 10 to be measured puts his / her head in the dewar 2 of the brain function measurement device 3 with an electrode (or sensor) for brain wave measurement attached to the head. The dewar 2 is a helmet-type sensor storage type dewar that surrounds substantially the entire area of the head of the subject 10. The dewar 2 is a container for holding a cryogenic environment using liquid helium. Inside the dewar 2, a number of magnetic sensors 1 for measuring brain magnetism are arranged. The brain function measurement device 3 collects an electroencephalogram signal from the electrode and a magnetoencephalogram signal from the magnetic sensor 1. The brain function measurement device 3 outputs the collected biological signal to the information processing device 6.

  Although the dewar 2 containing the magnetic sensor 1 is generally arranged in a magnetically shielded room, the magnetically shielded room is omitted for convenience of illustration.

  The information processing device 6 displays the waveform of the brain magnetic signal from the plurality of magnetic sensors 1 and the waveform of the brain wave signal from the plurality of electrodes in synchronization on the same time axis. The electroencephalogram signal represents the electrical activity of a nerve cell (the flow of ionic charges generated in a dendrite of a neuron during synaptic transmission) as a potential difference between electrodes. Magnetoencephalographic signals represent minute magnetic field fluctuations caused by brain electrical activity. The brain magnetic field is detected by a highly sensitive superconducting quantum interferometer (SQUID) sensor.

  Further, the information processing device 6 inputs a tomographic image (MRI image) of the head of the subject 10 captured by the MRI device 7. The imaging by the MRI apparatus 7 may be performed before or after the magnetic measurement by the brain function measurement apparatus 3, and the obtained image data is sent to the information processing apparatus 6 online or offline.

  The tomographic image capturing apparatus that captures a tomographic image of the subject's head is not limited to the MRI apparatus 7, but may be an X-ray CT (Computed Tomography) apparatus or the like.

  Hereinafter, the information processing device 6 will be further described. FIG. 2 is a diagram illustrating an example of a hardware configuration of the information processing device 6.

  The information processing device 6 includes an input device 21, an output device 22, a drive device 23, an auxiliary storage device 24 for storing a biological information measurement program, a memory device 25, an arithmetic processing device 26, and an interface, which are interconnected by a bus 29. A device 27 is provided.

  The input device 21 is a device for inputting various information, and is realized by, for example, a keyboard, a pointing device, or the like. The output device 22 is for outputting various types of information, and is realized by, for example, a display or the like. The interface device 27 includes a LAN card and the like, and is used for connecting to a network.

  The biological information measurement program is at least a part of various programs that control the information processing device 6. The biological information measurement program is provided by, for example, distribution of the storage medium 28 or download from a network. The storage medium 28 storing the biological information measurement program is a storage medium for recording information optically, electrically or magnetically, such as a CD-ROM, a flexible disk, or a magneto-optical disk, or a ROM, a flash memory, or the like. Various types of storage media such as a semiconductor memory for electrically recording information can be used.

  Further, when the storage medium 28 storing the biological information measurement program is set in the drive device 23, the biological information measurement program is installed in the auxiliary storage device 24 from the storage medium 28 via the drive device 23. The biological information measurement program downloaded from the network is installed in the auxiliary storage device 24 via the interface device 27.

  The auxiliary storage device 24 stores the installed biological information measurement program and also stores necessary files, data, and the like. The memory device 25 reads and stores the biological information measurement program from the auxiliary storage device 24 when the information processing device 6 is activated. Then, the arithmetic processing device 26 realizes various processes as described below in accordance with the biological information measurement program stored in the memory device 25.

  Here, FIG. 3 is a diagram exemplarily showing the head of the subject 10. As shown in FIG. 3, at least three or more marker coils (magnetic generators) are attached to the head of the subject 10 to be measured. In the present embodiment, marker coils (magnetic generators) M1, M2, M3 are attached.

  In addition, at least three or more head reference points are set on the head of the subject 10. FIG. 4 is a diagram exemplarily showing the setting position of the head reference point. As shown in FIG. 4, the head reference point is desirably provided on any of the skin in contact with the maxilla, frontal bone, nasal bone, cheekbone, or temporal bone. These positions are on the scalp that can be photographed by the image acquisition device 5 described later, are not easily affected by movement of the head such as mastication, and stably extract the head reference point from the image. It is a position that can be.

  The head reference point may be a feature point of the head of the subject 10. As an example, the corners of the eyes, eyebrows, the root of the nose, the contours of the cheeks and the chin, and the ears can be considered. In this case, the present invention can be performed without physically attaching the head indicating the head reference point to the head of the subject 10, so that the load on the subject 10 and the number of mounting steps can be reduced.

  A characteristic point of the head of the subject 10 may be marked with an oil pen or the like and used as a head reference point. In this case, the extraction accuracy of the feature points of the head of the subject 10 in the image is improved.

  Further, a seal having a known size may be attached as a mark to the head reference point. Here, FIG. 5 is a diagram showing an example in which a seal is attached to the head reference point. As shown in FIG. 5, when the seal S is attached to the head reference point, not only is it easy to extract the head reference point of the head of the subject 10 in the image, but also the target is determined based on the aspect ratio in the image. The curvature of the head of the examiner 10 and the information in the image depth direction can be acquired in more detail, and the accuracy of the positional relationship between the magnetic sensor 1 of the dewar 2 and the head of the subject 10 is improved. By these measures, the accuracy of estimating the brain site where the cranial nerve activity has occurred is improved.

  In the present embodiment, as shown in FIG. 3, seals S1, S2, and S3 are attached as head reference points under the nose and both cheeks of the subject 10's head.

  Note that the above-described marker coils M1, M2, and M3 may also serve as head reference points.

  The information processing device 6 calculates the position of the marker coil in the three-dimensional space of the Dewar 2 based on the magnetic field generated from the marker coil detected by the magnetic sensor 1 at the time of measurement by the brain function measuring device 3. Then, the information processing apparatus 6 uses the three-dimensional arrangement data of the magnetic sensor 1 (data indicating the position where the magnetic sensor 1 is arranged) in advance, and the head of the subject 10 in the three-dimensional space. And the magnetic sensor 1 are determined. The three-dimensional arrangement data of the magnetic sensor 1 is dewar structure data (positional relation data) related to the position and orientation of the magnetic sensor 1. Thereby, since the position of the head reference point can be obtained in each coordinate system, a conversion matrix between coordinate systems can be obtained.

  In addition, the information processing device 6 uses the image acquisition device 5 to correctly measure the positional relationship between the brain of the subject 10 and the magnetic sensor 1.

  In the biological information measurement system 100, the signal generated from the neural activity of the brain of the subject 10 is detected by the magnetic sensor 1, but may be an OPAM (optical popping atomic magnetic sensor) or the like. Further, in the biological information measurement system 100, the signal emitted from the nerve activity of the brain of the subject 10 is detected by the magnetic sensor 1, but the present invention is not limited to this. The biological information measurement system 100 only needs to have a sensor for detecting a signal emitted from the nervous activity of the brain, and in order to accurately measure the biological function of the subject 10, it is minimally invasive. And more preferably non-invasive. Examples of such a sensor include an electroencephalogram measurement sensor (potential sensor) and an optical topography (near-infrared light sensor) in addition to the magnetic sensor.

  Further, the magnetic sensor 1 of the present embodiment may include a plurality of these sensors. However, in that case, it is necessary that the operation of one sensor does not affect the measurement by another sensor. In particular, when a magnetic sensor is used as one of the sensors, a signal emitted from the living body can be obtained even when the living body and the magnetic sensor are not in contact with each other, so that the mounting state of the sensor does not affect the measurement result. . Therefore, the magnetic sensor 1 is suitable as an embodiment of the present invention.

  The image acquisition device 5 includes a camera 51 (see FIG. 7) as an image capturing unit. The camera 51 only needs to be able to capture an image in a range including the dewar and the reference point. Further, as for the configuration of the camera 51, for example, at least one monocular camera may be provided. The image acquisition device 5 acquires an image including the head reference points (seal S1, S2, S3) and the Dewar 2 during the measurement of the magnetoencephalogram and the like by the brain function measurement device 3. Although details will be described later, the information processing device 6 determines the positional relationship between the head of the subject 10 and the magnetic sensor 1 from the dewar 2 and the head reference points (seal S1, S2, S3) in the image. Can be. Therefore, even if the head of the subject 10 moves during the measurement of the magnetoencephalogram or the like by the brain function measurement device 3, the information processing device 6 can determine the positional relationship again. According to the present embodiment, it is possible to simultaneously measure the cranial nerve activity of the entire head while determining the positional relationship between the head of the subject 10 and the Dewar 2 in real time.

  Next, a method of measuring the distance in the depth direction by the camera 51 included in the image acquisition device 5 will be described.

  First, prior to description of a method of measuring the distance in the depth direction with one camera, a method of measuring the distance in the depth direction using a stereo camera (two cameras) will be described.

  The stereo camera obtains a target image using two cameras, and measures a distance in a depth direction from a parallax of a feature point appearing between the obtained two images.

  Here, FIG. 6 is a diagram illustrating a method of measuring the distance in the depth direction using a stereo camera. As shown in FIG. 6, the two cameras 101 and 102 are arranged with a base line length b. The distance between the point P to be measured and the cameras 101 and 102 is Z. The focal length of the cameras 101 and 102 is f.

  The three-dimensional coordinates of the distance measurement target point P are (Px1, Py1, Pz1) when the coordinate system of the left camera 101 is the origin, and when the coordinate system of the right camera 102 is the origin. (Pxr, Pyr, Pzr).

Since the coordinate systems of the left and right cameras 101 and 102 are translated in the x-axis direction by the base line length b, they can be expressed by the following equation (1).
Pxr = Px1-b
Pyr = Py1
Pzr = Pz1
・ ・ ・ ・ ・ (1)

The point at which the point P of the distance measurement object is imaged is (X1, Y1) on the coordinates of the image of the left camera 101 and (Xr, Yr) on the coordinates of the image of the right camera 102. The following equations (2) and (3) hold.
X1 = fPx1 / Pz1 (2)
Xr = f · Pxr / Pzr (3)

From the equations (1), (2), and (3), if the parameters related to the three-dimensional coordinates of the point P to be measured are deleted, the distance Z between the point P to be measured and the cameras 101 and 102 is calculated by the following equation ( 4).
Z = f · b / (X1−Xr) (4)

  Therefore, the distance Z in the depth direction from the two cameras 101 and 102 to the distance measurement target point P can be represented by the focal length f, the base line length b, and the parallax (X1−Xr). That is, by detecting the parallax of the point P in the two obtained images, the distance Z between the point P to be measured and the cameras 101 and 102 can be obtained.

  Next, the distance measurement error of the stereo camera will be described.

Assuming that a minute reading error △ dx exists between the true value dx of the parallax on the image and the actually measured value dx ′,
dx = dx '+ △ dx
It is.

If the true value of the distance from the two cameras 101 and 102 to the point P to be measured is Z, and the distance from 101 and 102 calculated from the parallax read from the image to the point P to be measured is Z '. The distance measurement error ΔZ in the depth direction is expressed by the following equation (5) from the equation (4).
ΔZ = Z′−Z
= Fb / dx'-fb / dx
= Fb / dx'-fb / (dx '+ △ dx)
= (F · b / dx ′ (dx ′ + △ dx)) · Δdx
= (F · b / dx ′) · (f · b / (dx ′ + △ dx)) · (△ dx / (f · b))
= Z ・ Z ′ ・ (△ dx / (f ・ b))
= (Z ² / (f · b)) · △ dx (5)

  Therefore, the distance measurement error △ Z in the depth direction obtained from the stereo image is proportional to the square of the distance Z from the two cameras 101 and 102 to the point P to be measured, and is inversely proportional to the base line length b.

  Next, the depth resolution of the stereo camera will be described.

The minimum resolution of an image is one pixel. Assuming that the point P of the distance measurement target has an error of ± 1 pixel in each of the left and right images, the pixel size is (px, py), and
X1 '= X1 + px, Xr' = Xr-px
It is. Therefore, the distance Z ″ between the point P ′ calculated from the parallax including the pixel reading error and the two cameras 101 and 102 is given by Expression (4).
Z ″ = f · b / ((X1 + px) − (Xr−px))
= Fb / (X1-Xr + 2px)
It is. That is, the magnitude of the image reading error | Z ″ −Z |
| Z ″ −Z | = | f · b / (X1−Xr + 2px) −f · b (X1−Xr) |
It is.

This is given by equation (5)
dx '= X1-Xr, △ dx = -2px
Therefore, it is expressed by the following equation (6) from the equation (5).
| △ Z | = | (Z ² / (f · b)) · (−2px) | (6)

  Next, a method of measuring the distance in the depth direction with the camera 51 included in the image acquisition device 5 of the present embodiment will be described.

  Here, FIG. 7 is a diagram illustrating a method of measuring the distance in the depth direction using the camera 51 provided in the image acquisition device 5. As shown in FIG. 7, a point Pd of the distance measurement target is provided on the surface of the Dewar 2 and a point Ph of the distance measurement target is provided on the surface of the head of the subject 10. As shown in FIG. 7, the focal length of the camera 51 is f.

When the coordinate system of the camera 51 is set as the origin, the three-dimensional coordinates of the distance measurement target point Pd are (Xd, Yd, Zdc), and the three-dimensional coordinates of the distance measurement target point Ph are (Xh, Yh, Zhc). It is. Points at which the distance measurement target point Pd and the distance measurement target point Ph are imaged are represented by coordinates Pd (xd, yd) and Ph (xh, yh) in the image. Due to the similarity of the triangle, the distance Zdc between the point Pd to be measured and the camera 51 and the distance Zhc between the point Ph to be measured and the camera 51 are expressed by the following equations (7) and (8).
Zdc = (Xd / xd) · f (7)
Zhc = (Xh / xh) · f (8)

  Here, if an angle between the coordinate system of the camera 51 and the coordinate system of the Dewar 2 is obtained, Xd is a known value from the three-dimensional shape data of the Dewar 2. The angle between the coordinate system of the camera 51 and the coordinate system of the Dewar 2 is a value that can be calculated by detecting the positional relationship between at least three points extracted from the three-dimensional shape data of the Dewar 2 in the image.

  Similarly, if the angle between the coordinate system of the camera 51 and the coordinate system of the head of the subject 10 is determined, Xh is a known value based on the three-dimensional shape data of the head of the subject 10. The angle formed between the coordinate system of the camera 51 and the coordinate system of the head of the subject 10 detects at least three positional relationships extracted from the three-dimensional shape data of the head of the subject 10 in the image. It is a value that can be calculated by

  That is, in Expressions (7) and (8), Xd and Xh are known values, and by detecting xd and xh from the image, the distance Zhc between the point Ph of the distance measurement target and the camera 51 is calculated. The distance Zdc between the point Pd to be measured and the camera 51 can be calculated.

  Next, a distance measurement error in the depth direction using the camera 51 included in the image acquisition device 5 will be described.

It is assumed that a small reading error △ xd exists between the true value xd and the actual measurement value xd ′ of the x coordinate of the distance measurement target point Ph on the head surface of the subject 10 on the image. ,
xd = xd '+ Δxd
It is.

If the true value of the distance from the camera 51 to the point Pd on the surface of the Dewar 2 to be measured is Zdc, and the distance from the camera 51 read from the image to the point Pd to be measured is Zdc ′, the depth direction is assumed. From Equation (7), the distance measurement error ΔZdc of
ΔZdc = Zdc′−Zdc
= (Xd / xd '). F- (Xd / xd) .f
= F.Xd / xd'-f.Xd / (xd '+. DELTA.xd)
It is. Since b is Xd, dx 'is xd', and Δdx is Δxd in equation (5), it is expressed by equation (9) below.
ΔZdc ≒ (Zdc ² / (f · Xd)) · Δxd (9)

  Therefore, the depth measurement error ΔZdc in the depth direction obtained by the image acquisition device 5 is proportional to the square of the distance from the camera 51 to the distance measurement target point Pd on the surface of the Dewar 2, and the three-dimensional coordinate system of the Dewar 2 Is inversely proportional to the x coordinate.

  Next, the resolution of the distance in the depth direction of the camera 51 provided in the image acquisition device 5 will be described.

  In the above-described stereo camera, since there are two cameras, even if the reading error per unit is one pixel, a reading error of up to two pixels occurs in two units. On the other hand, the reading error of one camera is an error of one pixel at the maximum.

In the case of the camera 51 provided in the image acquisition device 5, the resolution is obtained by setting Δxd in Expression (9) to the pixel size px. Therefore, from the equation (9), the distance measurement error ΔZdc in the depth direction can be expressed by the following equation (10).
ΔZdc ≒ (Zdc ² / (f · Xd)) · px (10)

  Based on specific numerical values, the distance measurement error ΔZdc and the resolution in the depth direction between the stereo camera and one camera are compared.

  Here, the distance between the camera and the distance measurement target is Z = 900 mm. In addition, a condition in which a horizontal width of the subject of 200 mm is acquired in the image so that the Dewar 2 and the head of the subject 10 are included in the image is considered.

  Also, if the image sensor of the camera is a 1/3 type (4.8 mm in the horizontal direction × 3.6 mm in the vertical direction) and the number of pixels is about 2 million pixels (1920 × 1080), the width of one pixel is 2.5 μm. . Therefore, when an image in the horizontal direction of 200 mm is acquired from a position Z = 900 mm away from the distance measurement target, the focal length f becomes 21.6 mm.

Under the above conditions, assuming that the stereo camera base line length is 50 mm and the parallax reading error is ± 1 pixel, the distance measurement error ΔZ is given by the following equation (5).
ΔZ ≒ (Z2 / (f · b)) · Δdx
≒ 4mm
It is.

In addition, the resolution is obtained from the equation (6).
| ΔZ | ≒ | (Z ² / (f · b)) · (−2px) |
≒ 4mm
It is.

  In the stereo camera, since a matching error occurs in the parallax in the process of searching for the same feature point from two images, the distance measurement error and the resolution further decrease.

On the other hand, the distance measurement error ΔZdc at the camera 51 provided in the image acquisition device 5 is expressed by the following equation (9) at the point Pd of Xd = 50 mm on the surface of the dewar 2.
ΔZdc ≒ (Zdc ² / (f · Xd)) · Δxd
≒ 2mm
It is.

Also, the resolution is given by equation (10).
ΔZdc ≒ (Zdc ² / (f · Xd)) · px
≒ 2mm
It is.

  As described above, even if the camera 51 included in the image acquisition device 5 includes the three-dimensional shape data of the dewar 2 and the subject 10, the distance in the depth direction can be accurately detected.

  Next, among the functions of the information processing device 6 of the present embodiment, characteristic functions will be described. FIG. 8 is a diagram illustrating the function of the information processing device 6.

  The information processing device 6 includes a measuring unit 61 and a positional relationship determining unit 62 that is a positional relationship determining unit.

  The measurement unit 61 and the positional relationship determination unit 62 are realized by the arithmetic processing device 26 reading and executing a biological information measurement program stored in the auxiliary storage device 24, the memory device 25, or the like.

  The measurement unit 61 measures cranial nerve activity based on a biological signal (brain magnetic signal) detected by the magnetic sensor 1 in response to the stimulus.

  The positional relationship determining unit 62 associates the positional relationship between the plurality of head reference points and the Dewar 2 and, based on the Dewar structure data related to the position and orientation of the magnetic sensor 1, the subject 10 in the three-dimensional space. The positional relationship between the head reference point of the head and the magnetic sensor 1 is determined. In the present embodiment, the dewar structure data is three-dimensional arrangement data of the magnetic sensor 1.

  In addition, the positional relationship determination unit 62 detects a change in the position of the head of the subject 10 based on images captured at different times by the camera 51 (imaging unit), and detects a change in the reference point of the subject 10 and the magnetic field. The positional relationship with the sensor 1 is determined again. More specifically, the positional relationship determining unit 62 determines the head of the subject 10 based on the detection value of the magnetic sensor 1 that detects the magnetic field generated by the marker coil and the three-dimensional arrangement data of the magnetic sensor 1. The positional relationship between the section reference point and the magnetic sensor 1 is determined. The position of the reference point is more preferably the head of the subject closer to the Dewar (for example, the face of the subject).

  First, the process of determining the positional relationship between the dewar 2 and the head reference points (seal S1, S2, S3) in the information processing device 6 will be described.

  Here, FIG. 9 is a diagram schematically showing the processing in the information processing device 6. As shown in FIG. 9, the positional relationship determination unit 62 of the information processing device 6 first obtains the image A including the head reference points (seal S1, S2, S3) and the Dewar 2 from the image obtaining device 5, and The positional relationship between the dewar 2 in A and the head reference point (seal S1, S2, S3) is calculated.

  Next, the positional relationship determination unit 62 of the information processing device 6 determines that the relationship between the shape of the dewar 2 and the head reference points (seal S1, S2, S3) in the three-dimensional space becomes the above-described positional relationship. Calculate the appropriate head reference point.

  Then, the positional relationship determination unit 62 of the information processing device 6 determines the head reference point (seal S1, S2, S3) in the three-dimensional space and the magnetic sensor 1 is determined.

  The magnetic measurement on the head of the subject 10 is performed immediately after this.

  Next, the relative position change amount acquisition processing in the information processing device 6 will be described. During the measurement of the magnetoencephalogram or the like by the brain function measurement device 3, the positional relationship determination unit 62 of the information processing device 6 determines the relative position based on the measurement direction and position of the dewar 2 and the head of the subject 10 at the time of measurement. Get the amount of change.

  Regarding the relative position change amount acquisition, first, the positional relationship determination unit 62 of the information processing device 6 acquires the magnetic fields emitted from the marker coils M1, M2, and M3 detected by the magnetic sensor 1, and at the same time, acquires the head of the subject 10 An image A including the section reference points (seals S1, S2, S3) and marker coils (magnetic generators) M1, M2, M3 is acquired from the image acquisition device 5. When the subject is a child, there is a tendency to dislike wearing a marker coil or the like. In this regard, in the present invention, the marker coil may be removed after measuring the position with the marker coil.

  Next, the positional relationship determination unit 62 of the information processing device 6 acquires the image A including the head reference points (seal S1, S2, S3) at a different time from the above, and compares the image A with the previously acquired image A. A position change with respect to the section reference point (seal S1, S2, S3), that is, a position change of the head of the subject 10 is detected.

  As a result, even if the subject 10 moves, the information processing device 6 detects a change in the position of the head of the subject 1 after the movement, and thus the information processing apparatus 6 detects the position of the dewar 2 in the three-dimensional space. The positional relationship of the head of the examiner 10 can be accurately determined.

  As described above, according to the present embodiment, it is possible to obtain an image for correcting the position of the head with one imaging unit. In addition, the cranial nerve activity of the entire head can be simultaneously measured while determining the positional relationship between the subject's head and the dewar in real time with high precision without causing a decrease in the position definition accuracy in the image depth direction. .

(Second embodiment)
Next, a second embodiment will be described.

  The second embodiment differs from the first embodiment in that the shape of the dewar 2 and the three-dimensional arrangement data of the magnetic sensor 1 are used as the dewar structure data. Hereinafter, in the description of the second embodiment, the description of the same parts as those of the first embodiment will be omitted, and the points different from the first embodiment will be described.

  The information processing apparatus 6 according to the first embodiment uses the three-dimensional arrangement data of the magnetic sensor 1 as the structural data of the Dewar, and determines the subject based on the detection value of the magnetic sensor 1 that detects the magnetic field generated by the marker coil. The positional relationship between the ten heads and the magnetic sensor 1 was determined.

  On the other hand, the information processing apparatus 6 according to the present embodiment uses the shape of the dewar 2 and the three-dimensional arrangement data of the magnetic sensor 1 as the structural data of the dewar, and the head of the subject 10 and the magnetic sensor 1 Determine the positional relationship.

  Here, FIG. 10 is a diagram schematically illustrating a process in the information processing device 6 according to the second embodiment. First, the process of determining the positional relationship between the dewar 2 and the head reference points (seal S1, S2, S3) in the information processing device 6 will be described.

  As shown in FIG. 10, the positional relationship determination unit 62 of the information processing device 6 first obtains the image A including the head reference points (seal S1, S2, S3) and the Dewar 2 from the image obtaining device 5, The positional relationship between the dewar 2 in A and the head reference point (seal S1, S2, S3) is calculated.

  Next, the positional relationship determination unit 62 of the information processing device 6 determines that the relationship between the shape of the dewar 2 and the head reference points (seal S1, S2, S3) in the three-dimensional space becomes the above-described positional relationship. Calculate the appropriate head reference point.

  Then, the positional relationship determination unit 62 of the information processing device 6 determines the head reference point (seal S1, S2, S2) in the three-dimensional space based on the shape of the dewar 2 and the three-dimensional arrangement data of the magnetic sensor 1 which are provided in advance. The positional relationship between S3) and the magnetic sensor 1 is determined.

  Further, the positional relationship determination unit 62 of the information processing device 6 determines that the magnetic sensor 1 and the head reference points (seals S1, S2) are changed by changing the position of the head reference points (seal S1, S2, S3) between two different intervals. , S3) is calculated.

  As described above, according to the present embodiment, by having the relative positional relationship data of the head reference point of the head of the subject 10 in the three-dimensional space and the shape of the Dewar 2 in advance, the cranial nerve activity is obtained. Based on the image acquired during the measurement, the cranial nerves of the entire head are determined in real time with high accuracy without deteriorating the accuracy of position definition in the depth direction of the image. Activity can be measured simultaneously.

(Third embodiment)
Next, a third embodiment will be described.

  The third embodiment is different from the first embodiment and the second embodiment in that the image acquisition device 5 acquires a three-dimensional shape image including the Dewar 2 and the head reference point of the subject 10. Different from form. Hereinafter, in the description of the third embodiment, the description of the same parts as in the first embodiment or the second embodiment will be omitted, and the description will be different from the first embodiment or the second embodiment. The parts will be described.

  The image acquisition device 5 according to the first embodiment captures a two-dimensional image of the head of the subject 10. On the other hand, the image acquisition device 5 of the present embodiment can acquire a three-dimensional shape image including the Dewar 2 and the head reference point of the subject 10.

  Here, FIG. 11 is a diagram schematically showing processing in the information processing device 6 according to the third embodiment. As illustrated in FIG. 11, the information processing device 6 first obtains a three-dimensional shape image B including the dewar 2 and the head reference point of the head of the subject 10 from the image obtaining device 5.

  Next, the positional relationship determination unit 62 of the information processing device 6 determines the three-dimensional head shape data of the subject 10 and the image including the three-dimensional Dewar 2 shape data of the subject 10 acquired by the image acquisition device 5. The positional relationship between the plurality of head reference points (seal S1, S2, S3) in the three-dimensional head shape data of the subject 10 and the Dewar 2 is associated.

  Then, the positional relationship determination unit 62 of the information processing device 6 determines the head reference point in the three-dimensional space based on the shape of the dewar 2 previously provided as the dewar structure data and the three-dimensional arrangement data of the magnetic sensor 1. The positional relationship between the (seal S1, S2, S3) and the magnetic sensor 1 is determined.

  Further, the positional relationship determination unit 62 of the information processing device 6 determines whether the magnetic sensor 1 and the head reference point have changed based on a change in the position of the head reference point (seal S1, S2, S3) in the images acquired at different times by the imaging unit. The relative position change amount of the point (seal S1, S2, S3) is calculated.

  Thereby, the positional relationship of the head of the Dewar 2 in the three-dimensional space can be determined.

Reference Signs List 1 sensor 2 dewar 4 biological information measuring device 7 tomographic image capturing device 51 image capturing device 61 measuring unit 62 positional relationship determining unit 100 biological information measuring system M1, M2, M3 magnetic generator

JP-A-3-251226 JP-A-4-303417 JP-A-4-226631 JP-A-4-109930 JP-A-4-10932

Claims (8)

A number of sensors for biological signal detection are arranged, and a dewar covering the head of the subject,
A measurement unit that measures cranial nerve activity based on the biological signal detected by the sensor,
One imaging unit that acquires at least three or more reference points set in relation to the subject and an image including the Dewar,
By the plurality of reference points and the positional relationship data of the Dewar, determine the positional relationship between the reference point of the subject and the sensor, based on the images acquired at different times by the imaging unit, A positional relationship determining unit that redetermines the positional relationship between the reference point and the sensor,
A biological information measurement system, comprising: The test subject is provided with at least three magnetic generators provided,
The dewar positional relationship data is data indicating a position where the sensor is arranged,
The positional relationship determination unit is configured to detect a reference point of the subject and the sensor based on a detection value of the sensor that detects a magnetic field generated by the magnetic generator and data indicating a position where the sensor is disposed. Determine the positional relationship with
The biological information measurement system according to claim 1, wherein: The dewar positional relationship data is data indicating the shape of the dewar and the position where the sensor is arranged,
The positional relationship determining unit associates the positional relationship between the plurality of reference points and the Dewar based on the image, and uses a data indicating a shape of the Dewar and a position where the sensor is arranged in a three-dimensional space. Determine the positional relationship between the reference point of the subject and the sensor at,
The biological information measurement system according to claim 1, wherein: The one imaging unit is capable of acquiring a three-dimensional shape image,
The dewar positional relationship data is data indicating the shape of the dewar and the position where the sensor is arranged,
The positional relationship determination unit is configured to determine the three-dimensional shape of the subject based on an image including the three-dimensional head shape data of the subject and the three-dimensional shape data of the Dewar acquired by the one imaging unit. The positional relationship between the plurality of reference points and the dewar in the head shape data is associated with each other, and the data indicating the shape of the dewar and the position at which the sensor is arranged is used as the subject in a three-dimensional space. Determining the positional relationship between the reference point and the sensor,
The biological information measurement system according to claim 1, wherein: The reference point is a feature point of the subject's head,
The biological information measurement system according to any one of claims 1 to 4, wherein: The reference point includes a mark having a known size that can be captured by the one imaging unit,
The biological information measurement system according to any one of claims 1 to 5, wherein: The reference point is provided on the skin in contact with the maxilla, frontal bone, nasal bone, zygomatic bone, or temporal bone,
The biological information measurement system according to claim 1, wherein: Numerous sensors for detecting biological signals are arranged, a dewar covering the head of the subject, a measuring unit for measuring cranial nerve activity based on the biological signals detected by the sensors, and setting in relation to the measuring unit A computer that controls a biological information measurement system including one imaging unit that acquires at least three or more reference points and an image including the Dewar.
By the plurality of reference points and the positional relationship data of the Dewar, determine the positional relationship between the reference point of the subject and the sensor, based on the images acquired at different times by the imaging unit, A biological information measurement program for functioning as a positional relationship determining means for redetermining the positional relationship between a reference point and the sensor.

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