JPH09253065A - Living body magnetic measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more accurately specify the relative pisitional relation of a testee body to a flux meter. SOLUTION: A current supply unit 11 simultaneously supplies the AC currents of different frequencies to respective plural oscillation coils C1-Cn stuck to the testee body M at a prescribed flow rate so as to make magnetic field strength generated for the respective oscillation coils C1-Cn measured by the flux meters S1-Sm be almost same. Magnetic fields simultaneously generated from the respective oscillation coils by the supplied current are detected by the flux meters S1-Sm, passed through a data gathering unit 2 and frequency- analyzed in a magnetic field discrimination part 3 and the magnetic field strength due to the respective oscillation coils C1-Cn is discriminated for the respective flux meters S1-Sm. Based on magnetic field data discriminated for the respective oscillation coils C1-Cn, in a magnetic field analysis part 4, the relative positions of the respective oscillation coils C1-Cn to the flux meters S1-Sm are calculated. Based on the position information, information for indicating a separately measured living body activity current source is displayed at a current source generation position on MRI images.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biomagnetic measurement for measuring a minute magnetic field generated with a living body current source in a subject and obtaining the living body current source in the subject based on the measurement data. Related to the device.

[0002]

2. Description of the Related Art With the development of superconducting device technology in recent years, SQUIDs (Superconducting Quantum Interferen
A biomagnetic measurement device using a high-sensitivity magnetometer called ce Device) is being put to practical use as one of medical diagnostic devices, and is expected to be useful for elucidating brain functions and diagnosing cardiovascular diseases. .

[0003] In this biomagnetism measuring apparatus, the position, direction, size, etc., of a biological activity current source in a coordinate system based on a magnetometer are determined based on measured magnetic field data by, for example, a least square method or a minimum norm method. Is estimated (Ju
kka Sarvas "Basic mathemtical and electromagneti
c concepts of the biomagnetic inverse problem ", Ph
ys. Med. Biol., 1987, vol.32, No.1, 11-22, Printed
by the UK).

On the other hand, an in-vivo magnetoencephalogram obtained from the estimated biological activity current source and a magnetic resonance tomography apparatus (MRI)
Apparatus) and a medical image such as an X-ray tomographic image obtained by an X-ray CT apparatus, it is possible to specify the physical position of a diseased part in the living body. It is important to accurately grasp the positional relationship between the position information of the biological activity current source and the medical image in the coordinate system with reference to. For this reason, a magnetic field generator called PROBE POSITION INDICATOR is placed at a clear position on the head surface, such as the root of the nose or under both ears, and the positional relationship between the biological activity current source and the subject is determined by the following. Method (1) S.Ahlfors, et al, "MAGNETOMETER POSITION IND
ICATOR FOR MULTI CHANNL MEG ", Advances in Biomagne
tism, Edited by SJWilliamson et al, PlenumPress,
New York 693-696, 1989 (2) Neuromag-122 Preliminary Technical Data, August
1991 (3) "Apparatus and method for performing biomagnetic measurement" (Japanese Patent Laid-Open No. 1-503603) (4) "Position detecting device for biomagnetic field measuring apparatus" (Japanese Patent Publication No. 5-55)
No. 126) has been proposed.

In these methods, a DC current is first applied to the first oscillation coil of the three or more oscillation coils attached to the body surface of the subject, and the magnetic field generated from the oscillation coil is applied. Based on the strength of the current applied to the oscillating coil, the strength of the magnetic field detected by each magnetometer, and the positional relationship between the magnetometers, the above-mentioned 1 By obtaining the position of the first oscillation coil and applying this operation to the second and subsequent oscillation coils in sequence, the positions of all the oscillation coils are obtained and the position of the subject with respect to the magnetometer group is determined. . In addition, the magnetic field generated by simultaneously flowing sinusoidal currents of different frequencies in each oscillation coil is detected by each magnetometer, and the magnetic field generated by each oscillation coil is individually calculated by frequency analysis of the detected magnetic field, A method for specifying the position of the subject with respect to the magnetometer group has also been proposed (Japanese Patent Application No. 7-2238).
No. 5).

[0006]

However, according to the conventional method, the amount of current supplied to each oscillation coil is not particularly specified when the position of the subject is specified, and is usually supplied to each oscillation coil. Since the amount of current is constant, the magnetic field strength detected becomes smaller as the oscillation coil is arranged farther from the magnetometer, and the detection signal with a good S / N ratio (measured magnetic field strength / noise magnetic field strength) is obtained. Was not obtained. In such a case, the position estimation error is different for each oscillation coil, which is a factor that deteriorates the position specifying accuracy of the subject.

The present invention was devised to solve the above problems, and an object of the present invention is to provide a biomagnetism measuring device capable of more accurately specifying the relative positional relationship of the subject with respect to the magnetometer.

[0008]

In order to achieve the above-mentioned object, the present invention measures a minute magnetic field generated with a living body current source in a subject, and based on the measurement data, measures the inside of the subject based on the measurement data. A biomagnetism measurement device for obtaining a biological activity current source, a plurality of oscillation coils attached to the subject,
Current supply means for supplying a current to each of the plurality of oscillation coils, a magnetic flux meter for detecting a magnetic field generated from the plurality of oscillation coils by the supplied current, and a magnetic field detected by the magnetic flux meter for each oscillation coil. Magnetic field discriminating means for discriminating into the magnetic field of, and magnetic field analyzing means for calculating the relative position of each oscillating coil with respect to the magnetometer based on the magnetic field discriminated for each oscillating coil, the current supply means, the magnetic flux A predetermined current is supplied to each oscillating coil so that the position estimation error for each oscillating coil calculated by the magnetic field analyzing means becomes substantially the same based on the magnetic field detected by the total.

Further, the current supply means is an oscillating coil C1.
~ Is the total amount of current supplied to Cn, each oscillation coil Ci (i =
1,2, ... n) Average value of magnetic field data detected by magnetometers S1 to Sm for each oscillation coil Ci (i = 1,2, ... n) when the same current I / n is supplied to each Is Bi (i = 1,2, ... n), the position estimation error is substantially the same by supplying a lower predetermined current Ii to each oscillation coil Ci (i = 1,2, ... n). It is characterized by

Ii = {1 / √Bi ³ } / {Σj = 1, n (1
/ √Bj ³ )} × Is Further, the current supply means outputs the alternating currents of the predetermined intensities different in frequency to the plurality of oscillation coils, and the magnetic field discriminating means detects the magnetic flux by the magnetic flux meter. It is characterized in that it is configured to discriminate the magnetic field of each oscillation coil by frequency analysis of the magnetic field.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is shown in FIGS.
It will be described based on. FIG. 1 is a schematic configuration diagram of a biomagnetism measuring device according to an embodiment of the present invention. In the figure,
The sensor unit 1 includes a pickup coil and a SQUID.
A plurality of high-sensitivity magnetometers S1 to Sm composed of are housed in a duer together with a refrigerant, and are placed close to the head of the subject M when detecting a biological activity current source.

The oscillating coils C1 to Cn are used for the root of the nose, under the ears, etc.
The coil portion is attached to a portion that is characteristic for identifying the subject M. For example, as illustrated in FIG. 2A, a metal is printed on a substrate 31 formed of an insulator such as a ceramic plate to form a coil portion. A coil C formed with 32 or a coil C'formed by winding a metal wire 34 around a bobbin 33 as shown in FIG. 2 (b).
Is used.

The current supply unit 11 supplies alternating currents having different frequencies to the oscillation coils C1 to Cn, respectively.
The magnetic field intensity generated in each of the oscillation coils C1 to Cn measured by Sm is supplied at a predetermined amount and at the same time so that the magnetic field intensities are substantially the same. As shown in FIG. 3, the current supply unit 11 includes n AC current sources AC1 to ACn and amplification amplifiers AMP1 to AMP connected to the AC current sources AC1 to ACn.
n, and current output terminals out of the amplification amplifiers AMP1 to AMPn
-1 to out-n, and this current output terminal out-1
~ Out-n are connected corresponding to the oscillation coils C1 to Cn, respectively.

Here, the oscillation frequencies of the AC current sources AC1 to ACn and the amplification degrees of the amplification amplifiers AMP1 to AMPn are individually set by the collection control unit 5 in the computer 6, and the AC current sources AC1 to ACn are respectively set. The on / off control of is also performed by the collection control unit 5.

The data collecting unit 2 A / D-converts the AC magnetic field data generated by the oscillating coils C1 to Cn measured by the magnetometers S1 to Sm and outputs the data to the magnetic field discriminating section 3 of the computer 6.

The computer 6 mainly analyzes the measured magnetic field data and controls the operation of the current supply unit 11 and the like, and is mainly composed of a magnetic field discriminating section 3, a magnetic field source analyzing section 4, and a collection control section 5.

The magnetic field discriminating unit 3 analyzes the frequency of the magnetic field data output from the data collecting unit 2 to individually detect the magnetic field strengths caused by the respective oscillating coils C1 to Cn for each magnetometer S1 to Sm. calculate.

The magnetic field source analysis unit 4 calculates the relative position of each of the oscillation coils C1 to Cn with respect to the magnetometers S1 to Sm from the magnetic field strength calculated by the magnetic field discrimination unit 3. Then, the relative positions of the obtained oscillation coils C1 to Cn are determined by the image storage unit 7
The information on the biological activity current sources, which are associated with specific points of the subject M, such as the root of the nose and both ears on the MRI image read from the MRI image, and which are measured later, are based on the positional relationship associated here. The image is displayed on the monitor 9 so as to be superimposed on the MRI image, and is also stored in the external memory 8 such as a MOD (magneto-optical disk) or output to the printer 10 as necessary.

In addition to controlling the current supply to the current supply unit 11, the collection control section 5 applies light, sound, and electrical stimulation to the subject M when measuring the biological activity current source.
The control for instructing the generation of stimulus for 2 is performed.

Next, the operation of this embodiment will be described based on the flowchart of FIG. 4 showing the operation of the computer 6.

First, the relative position of the oscillating coils C1 to Cn arranged at a predetermined characteristic portion of the subject's head with respect to the magnetometers S1 to Sm is obtained (S1).

Specifically, as shown in the flow chart of FIG. 5, the head of the subject is fixed close to the magnetometers S1 to Sm in the sensor unit 1 of FIG. 1 (S11), and the collection controller From 5 to the current supply unit 11, an instruction for simultaneously outputting alternating currents having the same flow rate (effective value or amplitude of alternating current) to n oscillation coils C1 to Cn at different frequencies f1 to fn, that is, , The setting instruction of the oscillation frequency and the amplification degree is given to each of the AC current sources AC1 to ACn and the amplification amplifiers AMP1 to AMPn in FIG. 3, and the current output instruction is given to the AC current sources AC1 to ACn. The magnetic field generated from C1 to Cn is the magnetometer S1.
~ Sm is detected (S12).

Here, each oscillator coil C1 ...
Generally, the total amount of current supplied to Cn is the allowable current value I
Since max cannot be exceeded, each oscillation coil C1 to Cn
The amount of current supplied to each can be Imax / n.

It should be noted that the frequency fi (i = 1 to
For n), the settable range is determined by the sampling frequency at the time of A / D conversion in the data collection unit 11. That is, the settable frequency fmax is fmax = fs / 2 from the sampling theorem, where fs is the sampling frequency at the time of A / D conversion. On the other hand, at the same time, the intervals fpitch of the respective frequencies for supplying the currents to the oscillation coils C1 to Cn must have at least fpitch = fs / Nsamp, where Nsamp is the number of sampling points.

Therefore, the maximum number of oscillation coils that can be used
Nmax is Nmax = fmax / fpitch = Nsamp / 2.

Next, the magnetic field data of different frequencies sent from the n oscillation coils C1 to Cn at the same time are measured by the magnetometers S1 to Sm.
After being respectively detected by the data collecting unit 2 and A / D converted by the data collecting unit 2, magnetic field analysis is performed by the magnetic field discriminating unit 3 by a method such as Fourier transform, and the oscillating coil is set for each of the magnetometers S1 to Sm.
The magnetic field generated from each of C1 to Cn is calculated (S1
3).

That is, the magnetic fields of different frequencies generated simultaneously from the n oscillation coils C1 to Cn are detected as the following magnetic field data Mj by one magnetometer Sj.

Mj = .SIGMA.Bi.multidot.nj where nj is a normal vector of the pickup coil in the magnetometer Sj, and Bi is a magnetic field vector at the pickup coil position in the magnetometer Sj by the oscillation coil Ci. is there.

A procedure for discriminating the detected magnetic field Mj into magnetic fields for the oscillation coils C1 to Cn in the magnetic field discriminating section 3 will be described with reference to the flowchart of FIG.

First, the magnetic field data Mj detected by one magnetometer Sj shown in FIG. 7a is Fourier transformed (S2).
1). The magnetic field data Mj obtained by the magnetometer Sj is a combination of the magnetic fields emitted from the respective oscillating coils by intentionally changing the frequencies individually.
As shown in, the output signal has a predetermined intensity at each of the frequencies f1 to fn of the current supplied to each oscillation coil C1 to Cn.

Next, by obtaining the signal intensities M'j1 to M'jn for each frequency f1 to fn component, each oscillation coil C1
The magnetic field data resulting from each of ~ Cn is obtained (S22).

Then, the operations of S21 to S22 described above are repeated for all the magnetometers S1 to Sm (S2
3) The magnetic field data resulting from each of the oscillation coils C1 to Cn is obtained for the magnetometers S1 to Sm.

When the magnetic field generated from each of the oscillating coils C1 to Cn is calculated, the magnetic field analyzing unit 4 causes each oscillating coil to
The ratio of the distances from the magnetic field calculated for each C1 to Cn to the magnetometers S1 to Sm is obtained (S14).

That is, in S12, when the currents Imax / n of different frequencies are supplied to the oscillation coils C1 to Cn, the magnetic field data detected by the magnetometers S1 to Sm for each oscillation coil C1 to Cn. Assuming the average value of B i (i = 1,2, ... n), the strength of the magnetic field data is inversely proportional to the distance between the oscillating coils C1 to Cn and the magnetometer, so the ratio of the distance from each oscillating coil to the magnetometer is Is (1 / √B1) :( 1 / √B2): ···: (1 / √B
Bn) can be obtained. The distance ratio obtained here is, to be exact, the distance ratio from each oscillation coil to the center of gravity of the magnetometers S1 to Sm.

Next, in the magnetic field analysis section 4, the optimum current value of each oscillation coil is obtained from the obtained ratio of the distance from each oscillation coil to the magnetometer (S15).

Since the position estimation error of the oscillation coil is inversely proportional to the S / N ratio of the measured magnetic field and proportional to the distance to the magnetometer, a current I flows from the magnetometer to the oscillator coil at the distance d. When the magnetic field measured at this time is B and the position estimation error when the position of the oscillation coil is specified using this magnetic field is e, the noise contained in B is considered to be constant, so the position estimation error e is It is inversely proportional to the measured magnetic field B and proportional to the distance d from the magnetometer. And the measurement magnetic field B
Is inversely proportional to the square of the distance d from the magnetometer and proportional to the supplied current I, the position estimation error e
Can be said to be proportional to the cube of the distance d from the magnetometer and inversely proportional to the supplied current I.

Therefore, by using the ratio of the distance from each oscillation coil to the magnetometer obtained in S14, each oscillation coil Ci for making all position estimation errors of each oscillation coil C1 to Cn the same
The optimum current value Ii to be supplied to is {1 / √Bi ³ } / {Σj = 1, n (1 / √Bi ³ )} × I
It can be obtained as max.

When the optimum current values I1 to In to be supplied to the respective oscillating coils C1 to Cn are obtained, the collection controller 5
It is the optimum current value, and the frequency is different as in S12.
Instructions for simultaneously outputting the alternating currents f1 to fn, that is, instructions for setting the oscillation frequency and the amplification degree for the respective alternating current sources AC1 to ACn and the amplification amplifiers AMP1 to AMPn in FIG. Current output is instructed to AC1 to ACn, and each oscillation coil C1 to
The magnetic field generated from Cn is measured by the magnetometers S1 to Sm (S1
6).

The measured magnetic field data is A / D converted by the data collecting unit 2 and then subjected to magnetic field analysis in the magnetic field discriminating unit 3 to generate magnetic fields from the oscillating coils C1 to Cn for each magnetometer S1 to Sm. Data is calculated (S17).

Next, the magnetic field source analysis unit 4 causes the magnetometer S1 to
~ Magnetic field data caused by each oscillating coil C1 ~ Cn obtained for each Sm, and based on the known current intensity supplied to each oscillating coil C1 ~ Cn, of the oscillating coil C1 ~ Cn for the magnetometer S1 ~ Sm A relative positional relationship is calculated (S18).

Here, using the detected magnetic field intensity sequences Mj1 to Mjn discriminated for each oscillation coil C1 to Cn, the relative position of each oscillation coil C1 to Cn with respect to the position of the magnetometers S1 to Sm is calculated by the method of least squares. The procedure to be obtained by will be described based on the flowchart of FIG. 8 showing the operation of the magnetic field source analysis unit 4.

First, the position of the oscillating coil C1 is virtually set (S32) using the magnetic field data resulting from the first oscillating coil C1 (S31). Then, when the oscillating coil C1 is located at the virtual position, the virtual magnetic field strength sequence detected by each of the magnetometers S1 to Sm is calculated (S33). This virtual magnetic field strength series and the actually measured detected magnetic field strength series M11 to Mm
The sum of squares of the differences between the terms corresponding to 1 and 1 is obtained and used as the square error (S34). Next, the obtained squared error is compared with a predetermined determination value (S35), and if the squared error is larger than the predetermined determination value, the virtual position of this oscillation coil is set in a direction in which the squared error becomes smaller. Move (S3
6) Then, using this as a new virtual position, the squared error is similarly obtained, and the above operation is repeated until the squared error becomes equal to or less than the determination value (S33 to S36).

If the squared error is smaller than a predetermined judgment value, its virtual position is specified as the position of the oscillating coil C1 and the second oscillating coil C2 is specified (S39). The above-described operation is repeated for the oscillation coils C1 to Cn (S32 to S37).

As described above, when the relative positional relationship of the oscillating coils C1 to Cn with respect to the magnetometers S1 to Sm is determined, then the actual measurement operation of the biological activity current source is performed. That is, first, a stimulus such as light, sound, or electricity is given to the subject M via the stimulator 12 in order to intentionally generate a biological activity current in the subject M (S2).

Next, the minute magnetic field generated by the biological activity current generated by the applied stimulation is detected by the magnetometers S1 to Sm, and the magnetic field source analysis unit 4 is directly connected via the data acquisition unit 2.
And the relative position of the biological activity current source with respect to the magnetometers S1 to Sm is calculated (S3).

Here, various methods such as a minimum norm method and a least square method have been proposed as a method for calculating the relative position of the biological activity current source with respect to the magnetometers S1 to Sm, and any method may be used. , Here, a conventional current source estimation method using the minimum norm method will be described. That is, as shown in FIG. 9, the sensor unit 1 is arranged close to the subject M,
It is assumed that the magnetometers S1 to Sm are housed in the sensor unit 1.

On the other hand, a large number of grid points 1 to n are set in the diagnostic target region of the subject M, for example, the brain, and an unknown current source (current dipole) is assumed at each grid point, and each current source is It is represented by a three-dimensional vector VPj (j = 1 to n). Then, the magnetic fields B1 to Bm detected by the magnetometers S1 to Sm are calculated by the following equation (1).
It is represented by

[0048]

[Equation 1] In Expression (1), VPj = (Pjx, Pjy, Pjz) αij =
(Αijx, αijy, αijz) where αij is X,
When a current source of unit size in the Y and Z directions is placed, the magnetometer
It is a known coefficient indicating the strength of the magnetic field detected at each position of S1 to Sm.

[B] = (B1, B2, ... Bm) [P] = (P1x, P1y, P1z, ... Pnx, Pny, P
nz), the equation (1) can be rewritten as a linear relational equation like the equation (2). [B] = A [P] (2) In the equation (2), A is 3n × m represented by the following equation (3).
It is a matrix with elements.

[0050]

[Equation 2] When the inverse matrix of A is represented by A ⁻ , [P] is represented by the following equation (4).

[P] = A ⁻ [B] (4) Here, the minimum norm method is based on the number m of equations (magnetic flux meters S 1 to Sm).
It is assumed that the number of unknowns is 3n (the number of unknowns in consideration of the sizes of the current sources assumed in each lattice point in the X, Y, and Z directions) than the number of unknowns. P]
The solution of the current source [P] is obtained by adding the condition that the norm | [P] | Note that a solution can be uniquely obtained by making the number m of the above equations equal to the number 3n of unknowns. In such a case, however, the solution becomes very unstable, so the minimum norm method is used. Is used.

By adding the condition that the norm | [P] | of the current source [P] is minimized, the above equation (4) is expressed by the following equation (5).

[P] = A ⁺ [B] (5) Here, A ⁺ is a general matrix represented by the following equation (6).

A ⁺ = A ^t (AA ^t ) ⁻¹ (6) where A ^t is the transposed matrix of A.

Solving the above equation (5), the current source VP on each lattice point
Estimate the direction and magnitude of j, and let the one with the largest value be close to the true current source.

Further, in order to improve the position resolution of the minimum norm method, the minimum norm solution can be repeatedly obtained while subdividing the grid point division.

FIG. 10 is an enlarged view of a part of the lattice point group N shown in FIG. 9, and the symbol J in the drawing is a true current source estimated using the above-mentioned minimum norm method. A grid point group M (shown by small black dots in FIG. 10) subdivided around this grid point J is additionally set at a grid point having a current source close to, and newly set to the grid point group initially set. In the form including the grid point group M, the current source closer to the true current source is estimated by using the same method as described above.

As described above, when the relative positional relationship of the oscillating coils C1 to Cn with respect to the magnetometers S1 to Sm and the generation position of the biological activity current source with respect to the magnetometers S1 to Sm are obtained, next, from the image storage unit 7. MRI imaged of the subject M in advance
The image is read and displayed on the monitor 9 in a state in which the information indicating the biological activity current source is superimposed on the MRI image (S
4).

Here, in order to superimpose and display the information indicating the biological activity current source at a predetermined position on the MRI image, first, a marker for MRI imaging is attached to the position where the oscillation coils C1 to Cn should be attached. MR taken by performing MRI
The attached marker is displayed on the I image, and the attached marker is removed and the oscillating coils C1 to Cn are attached to the positions at the time of measurement of the biological activity current source to specify the positions of the oscillating coils C1 to Cn. Accordingly, if the position of the oscillation coil is made to correspond to the position of the marker displayed on the MRI image, the positions of the magnetometers S1 to Sm on the MRI image are specified. The position on the MRI image will be specified.

The accuracy of the above calculation result improves when the coil portion of the oscillation coil is close to a perfect circle and there is no variation in the coil portions of all the oscillation coils.

In this embodiment, the position of the oscillating coil with respect to the magnetometer is obtained from the magnetic field data obtained by one oscillating operation, but the present invention is not limited to this, and compensates for the instability of the alternating current source. Therefore, it may be configured to oscillate a plurality of times and collect magnetic field data, and add and average them.

Further, in this embodiment, the signal intensity corresponding to the frequency emitted from each oscillation coil was obtained based on the magnetic field data after the Fourier transform, but within a certain range including the frequency assigned to each oscillation coil. For example, the maximum value of the signal strength within the frequency range determined by the average value of the frequencies assigned to the adjacent oscillation coils may be used as the detection magnetic field from the corresponding oscillation coil.

In addition, in the above-described embodiment, in order to obtain the optimum current value to be supplied to each oscillating coil, an embodiment is shown in which sinusoidal currents of different frequencies are simultaneously applied to each oscillating coil. A direct current is applied to the first oscillating coil, and the magnetic fields emitted from the oscillating coil are detected by a plurality of magnetometers whose positional relationships are known to each other, and the strength of the current applied to the oscillating coil and each magnetometer are detected. The position of the first oscillating coil with respect to the magnetometer group is obtained from the strength of the magnetic field and the positional relationship between the magnetometers, and this operation is sequentially applied to the second and subsequent oscillating coils to determine all of the oscillating coils. It may be configured to supply a current to each oscillation coil by a method of obtaining a position and determining a position of the subject with respect to the magnetometer group.

[0064]

According to the present invention, a predetermined current is supplied to each oscillation coil so that the position estimation error of each oscillation coil is made uniform according to the relative position of each oscillation coil and the magnetometer. Therefore, it is possible to improve the position specifying accuracy of the specified living body.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a biomagnetism measuring apparatus according to the present invention.

FIG. 2 is a diagram showing an embodiment of an oscillation coil according to the present invention.

FIG. 3 is a diagram showing a configuration of a current supply control unit according to an embodiment of the present invention.

FIG. 4 is a flowchart showing the operation of the present invention.

FIG. 5 is a flowchart showing an operation for obtaining an optimum current value to be supplied to each oscillation coil.

FIG. 6 is a flowchart showing the operation of the magnetic field discriminating means according to the present invention.

FIG. 7 is a diagram showing a signal detected by a magnetometer and a signal obtained by Fourier-transforming the signal.

FIG. 8 is a flowchart showing the operation of the magnetic field analysis means according to the present invention.

FIG. 9 is a diagram for explaining a method for estimating a biological activity current source.

FIG. 10 is a diagram for explaining a conventional biological activity current source estimation method.

[Explanation of symbols]

 M object S1 to Sm magnetometer C1 to Cn oscillation coil 1 sensor unit 2 data acquisition unit 3 magnetic field discriminator 4 magnetic field analysis unit 5 acquisition control unit 6 computer 7 image storage unit 8 external memory 9 monitor 10 printer 11 power supply unit 12 Stimulator

Claims (1)

[Claims] 1. A biomagnetism measuring apparatus for measuring a minute magnetic field generated by a living body activity current source in a subject, and obtaining a living body activity current source in the subject based on the measurement data. A plurality of oscillating coils attached to the oscillating coil, a current supply means for supplying a current to each of the plurality of oscillating coils, a magnetometer for detecting a magnetic field generated from the plurality of oscillating coils by the supplied current, and a magnetic flux A magnetic field discriminating means for discriminating the magnetic field detected by the meter into a magnetic field for each oscillating coil, and a magnetic field analyzing means for calculating the relative position of each oscillating coil with respect to the magnetometer based on the magnetic field discriminated for each oscillating coil, The current supply means includes oscillation coils so that position estimation errors calculated by the magnetic field analysis means for each oscillation coil are substantially the same based on the magnetic field detected by the magnetometer. Biomagnetic measurement apparatus, characterized by supplying a predetermined current against.