JPS5925726A - Diagnostic observation apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] This invention uses a SQUID magnetometer to
The present invention relates to a diagnostic observation device that detects a weak magnetic field generated from a living body.

In general, it is already well known that an electric current flows through tissues near the heart in synchronization with the movement of the heart, and that this electric current generates a magnetic field. However, this is difficult to determine, and at present it can be measured using a skid magnetometer.

When measuring biomagnetic fields using a skid magnetometer, the pickup coil of the skid magnetometer is brought close to the heart of the living body. However, a problem when measuring minute magnetic fields such as biomagnetic fields is the presence of geomagnetic noise. Earth's magnetic noise is as high as 80 dB in urban areas, and it is necessary to improve this S/N ratio. Therefore, conventionally, a differential pickup coil as shown in FIG. 1 or a second-order differential pickup coil as shown in FIG. 2 has been used.

The case shown in Figure 1 is a so-called gradiometer (Gradiometer).
diometer) and measures the gradient of the magnetic field. That is, the strength H1 of the magnetic field at the center position P1 of the pickup coil C1 and the center position P2 of the pickup coil C2
, H2 is calculated and divided by the distance X between both pickup coils to obtain (H1-H2)/X.

In the case shown in FIG. 2, positional changes in the gradient of the magnetic field are measured. In this case, pickup coils C1 and C2
・The strength of the magnetic field at each center position P1, P2, and P3 of C3 is H
1・H2・H3, find the gradient of the magnetic field at positions P1 and P2 and P2 and P3, and calculate the difference (H1-H2)/X1-(H
2-H3)/X2.

Originally, a first-order differential type pickup coil was used to measure biomagnetic signals, but geomagnetic damage prevention could not be avoided. As a countermeasure to this problem, we adopted a large magnetically shielded case made of permalloy, a material with high magnetic permeability. This magnetic shield was large enough to accommodate not only a skid magnetometer but also a human being, and was made of three or more layers of permalloy plates. However, it still could not completely eliminate noise, and a second-order differential type was used as a pickup coil. started to be used. However, since the strength of the magnetic field is generally inversely proportional to the cube of the distance, the detection output ΔH of the first-order differential type attenuates as the fourth power of the distance, whereas the detection output d( ΔH) will be attenuated by the fifth power of the distance, so if a second-order differential type pickup coil is used, the magnetic moment or the magnetic field due to the current cannot be received as a signal unless it is very close to the pickup coil of the skid magnetometer. The problem remained that it was not possible to confirm whether magnetic signals from deep inside existed.

Therefore, an object of the present invention is to provide a diagnostic device that can detect magnetic signals generated from deep within a living body without being affected by geomagnetic noise.

To summarize, the diagnostic observation device of the present invention detects biomagnetism using a differential coil wound around the pickup coil bobbin of a skid magnetometer, and detects the output of a compensation coil wound around the pickup coil bobbin of the skid magnetometer. This is designed to return and cancel out fluctuations in distant magnetic fields such as the earth's magnetism.

The present invention will be explained in more detail below with reference to the drawings.

FIG. 3 is a block diagram of a diagnostic observation device showing a basic embodiment of the present invention. In the figure, reference numeral 1 denotes a pickup coil bobbin of a skid magnetometer that is brought close to the test subject 2 in order to measure the weak magnetic field Hn generated by the test subject 2. A compensation coil Cx and a differential coil Cxd are wound around this pickup coil bobbin 1. The differential coil Cxd is connected to the electronic device 3. The differential coil Cxd derives an output signal corresponding to the biomagnetic field, and the output signal is amplified by the electronic device 3 and displayed. The circuit system including the differential coil Cxd and the electronic device 3 is configured to be highly sensitive.

Coil Cx is connected to amplifier 4, and amplifier 4 is connected to doll coils (Helmholtz coil or rectangular coil) 5a and 5b.
It is connected to the. The magnetic signal detected by the coil Cx is amplified to a predetermined power by the amplifier 4, and then the large coil 5
a and 5b, causing current to flow through the large coils 5a and 5b. The large coils 5a and 5b are negative feedback coils, and the XX direction component of geomagnetic fluctuation is canceled by the magnetic field generated by the flowing current. Therefore, the magnetic field H from the living body 2 to be examined
Only the signal h is received by the differential coil Cxd, amplified by the electronic device 3, and displayed and observed. Here, if coil Cx, amplifier 4
, if there is no feedback system for the coils 5a and 5b, the circuit system of the differential coil Cxd electronic device 3 is highly sensitive, and therefore it is not possible to accurately measure the biomagnetic field due to the influence of geomagnetic fluctuations.

A constant current source 6 is connected to coils 7a and 7b arranged in parallel with the large coils 5a and 5b.

There are cases where it is desired to set a constant magnetic field in the space around the living body 2 to be inspected, the differential coil Cxd, the coil Cx, etc. For example, if you want to set the magnetic field to zero magnetic field or twice the magnitude of earth's magnetism, or if you want to measure the relationship between a living body and a strong magnetic field, you can apply a predetermined current to the coils 7a and 7b from the constant current source 6, and Set the magnetic field. Note that the constant current from the constant current source 6 is configured so that its current value can be set to an arbitrary value.

FIG. 4 is a connection diagram of a diagnostic observation device showing an embodiment of the present invention.

If the axes X-X' of the differential coil Cxd, coil Cx, and large coils 5a and 5b as return coils of the diagnostic observation device shown in Fig. 3 are oriented in the geomagnetic direction, variations in the geomagnetism can be canceled out. A single-axis system such as the XX'-axis coil group shown in FIG. 3 is sufficient.

However, the table (not shown) on which the test subject 2 is placed is often horizontal, and in order to prevent the test subject from getting in the way of coils, etc., the earth's magnetic field is divided into three components, and each component is It is necessary to cancel out the fluctuations in Fourth
The diagnostic observation device shown in the figure is designed to divide geomagnetism into three components and cancel them out. In the figure, a rectangular pickup coil bobbin 1 includes a differential coil Cxd in the X-axis direction, a compensation coil Cx, a differential coil Cdy in the Y-axis direction, and a coil C.
Differential coils Cdz and Cz in the y and Z axis directions are wound orthogonally, respectively. Coil Cx passes through amplifier 4x to feedback coils 5ax and 5bx, and coil Cy passes through amplifier 4y to feedback coils 5ay and 5by. The coil Cz is connected to feedback coils 5az and 5bz via an amplifier 4z. Although not shown, the differential coil Cdx,
Cdy and Cdz are each connected to an electronic device for amplifying and displaying the detected three-axis components of biomagnetism.

The three components of the earth's magnetism applied to the pickup coil bobbin 1 are detected by coils Cx, Cy, and Cz, respectively, and sent to feedback coils 5ax, 5bx, and 5bx via amplifiers 4x, 4y, and 4z, respectively.
Since it is returned to 5ay, 5by, 5az, and 5bz, it cancels out the fluctuations in the earth's magnetic field. Therefore, the magnetic field in the space surrounded by each feedback coil is kept constant and quiet. Differential coil Cd
x, Cdy, and Cdz each measure the gradient of the magnetic field, and detect the three components of the magnetic field generated from the living body, including the one from deep inside, by dividing it into the X axis, Y axis, and Z axis. Once these three components are known, an electronic device calculates the magnitude and direction of the magnetic moment, etc. in the living body.

FIG. 5 is a connection diagram of a diagnostic observation device showing another embodiment of the present invention. This embodiment device is provided with two rectangular pickup coils 1a and 1b, and one pickup coil bobbin 1a has differential coils Cdx and Cd for biomagnetic field detection.
y・Cdz is wound, and a detection coil Cx・Cy・Cy・Cdz for compensating for variations in the earth's magnetic field is wound around the other pickup coil bobbin 1b.
Cz is wound. Around the pickup coil bobbin 1a, larger coils 5ax, 5bx, 5ay, and
5by, 5az and 5bz are provided, and coils 5ax' and 5bx' are provided around the pickup coil bobbin 1b.
, 5ay', 5by', 5az' and 5bz' are provided. Coil Cx is connected to coils 5ax and 5bx through amplifier 4ax and resistor Rx, coil Cy is connected to coils 5ay and 5by through amplifier 4ay and resistor Rx, and coil Cz is connected to amplifier 4az and 5az and 5bz through resistor Rx. There is. In addition, the voltages across the resistors Rx, Ry, and Rz are applied to large coils 5ax, 5bx, 5ay, 5by, and 5az, 5b through amplifiers 4Ax, 4Ay, and 4Az, respectively.
It can be added to z. Note that the differential coil Cd
x, Cdy, and Cdz are electronic devices 3x, 3y, and 3, respectively.
connected to z.

In the embodiment shown in FIG. 5, when a minute magnetic field such as terrestrial magnetism is detected in the coils Cx, Cy, and Cz, the outputs are amplified by amplifiers 4ax, 4ay, and 4az, and are applied to resistors Rx and R.
Coils 5ax', 5bx', 5ay' via y and Rz
・Current flows through 5by', 5az' and 5bz' for negative feedback. Also, the current flowing through these coils is resistors Rx and Ry.
・Taken out as the voltage across Rz, and further connected to the amplifier 4A
x・4Ay・4Az, differential coil Cdx・C
Large coil 5ax installed around dy/Cdz
- It is added to 5bx, 5ay, 5by, 5az, and 5bz, and a current corresponding to the output of coil Cx and CyCz flows through each of these coils. Therefore, pickup coil bobbin 1
The magnetic environment around a is the same as that of the coils Cx, Cy, and Cz, and a uniform and quiet magnetic field is obtained. Therefore, the differential coils Cdx, cdy, and Cdz detect only the weak biomagnetic field, and the output is transmitted to the electronic devices 3x, 3b, and 3.
Derived from z.

The compensation coils Cx, Cy, and Cz are placed apart from the large coil in order to truly detect fluctuations in distant magnetic fields such as terrestrial magnetism without being influenced by other magnetic fields within the large coil. It's for a reason.

FIG. 6 shows a diagnostic observation device showing still another embodiment of the present invention. This embodiment device is also provided with two rectangular pickup coil bobbins 1a and 1b of the skid magnetometer, and one pickup coil bobbin 1a is equipped with differential coils Cdx, Cdy, and Cdz for biomagnetic field detection, and coils Cx and C.
Wind the other pickup coil bobbin 1.
Detection coils Cx' and Cy' for compensating for variations in geomagnetism are shown in b.
・Cx' is wound. With these detection coils, Cx'
-Cy' and Cz' are connected to amplifiers 4x, 4y, and 4z, respectively, and the outputs of the amplifiers 4x, 4y, and 4z are connected to a converter 8 composed of a computing machine. Also, the converter 8 is 3
Transmitting shaft output Xa, Ya, Za to transformer Tx, Ty, T
It is configured to be applied to the coils Cx, Cy, and Cz wound around the pickup coil bobbin 1a through the coil z. Also, the differential coils Cdx, Cdy, and Cz are each electronic device 3x.
・Connected to 3y and 3z.

In this embodiment device, when variations in the earth's magnetic field are detected by coils Cx, Cy, and Cz, the respective three-axis components are transmitted to amplifiers 4x, 4y, and 4z, converter 8, and transfer transformers Tx and Cz.
It is applied to the coils Cx, Cy, and Cz via TyTz, causing currents ixa, iya, and iza to flow. This current ixa・i
The magnetic field generated by ya and iza cancels out noise caused by variations in the earth's magnetic field generated around the pickup coil bobbin 1a. In this case, if the magnetic axes of the pickup coil bobbins 1a and 1b match, the amplifier 4
x, 4y, 4z output voltage and current ixa, iya, i
The three axis values of za match, but if the magnetic axes of pickup coil bobbins 1a and 1b are different, then ixa=kxx
X+kxyY+kxzZiya=kyxX+kyyY+
kyzZiza=kzxX+kzyY+kzzZ, and in order to determine these currents ixa, iya, and iza, the converter 8 calculates a coefficient kij according to the angular difference. In this way, by removing the geomagnetic noise that invades the vicinity of the pickup coil bobbin 1a, only the biomagnetic field is detected in the differential coils Cdx, Cdy, and Cdz, and the output thereof is led out to the electronic devices 9x, 9y, and 9z. .

According to this embodiment, the geomagnetic component output detected by a compensation coil wound on a pickup coil bobbin other than the pickup coil bobbin around which the differential coil is wound is transferred to the pickup coil bobbin around which the differential coil is wound. In addition to the compensation coil wound around it, it also compensates for the variation and eliminates noise, so there is no need for large coils for noise elimination as shown in Figures 3 to 5. The entire device can be downsized.

As described above, since the diagnostic observation device of the present invention detects a biomagnetic field using a so-called first-order differential type differential coil, it is also possible to detect a magnetic field generated from inside a living body. In addition, since the geomagnetic output detected by the coil wound around the pickup coil bobbin of the skid magnetometer is negatively fed back to the feedback coil to compensate for geomagnetic fluctuations, it is not affected by geomagnetic noise and can be used to detect weak geomagnetic noise. Only biomagnetic fields can be measured.

[Brief explanation of the drawing]

Figure 1 is a diagram showing a differential pickup coil for explaining conventional biomagnetic field measurement, Figure 2 is a diagram showing a second-order differential pickup coil, and Figure 3 is a diagram showing a basic implementation of the present invention. 4, 5, and 6 are connection diagrams of a diagnostic observation device showing other embodiments. 1, 1a, 1b: Pickup coil bobbin, 2: Test subject, 3, 3x, 3y, 3z: Electronic device, 4, 4ax,
4ay・4az・・4Ax・4Ay・4Az・4x・4
y・4z: Amplifier, 5a・5b・5ax・5bx・5a
y・5by・5az・5bz・5ax'・5bx'・5
ay', 5by', 5az', 5bz': Doll (return)
Coil, Cdx/Cdy/Cdz: Differential coil, Cx/
Cy・Cz・Cx'・Cy'・Cz': Compensation coil,
8: Converter.

Claims (5)

[Claims] (1) An operating coil for biomagnetism detection wound around the pickup coil bobbin of the skid magnetometer, a compensation coil wound around the pickup coil bobbin of the skid magnetometer, and an output signal from this compensation coil used for compensation. A diagnostic observation device characterized by comprising a period coil that flows a current corresponding to a magnetic field input to the coil to cancel fluctuations in a return magnetic field around the differential coil. (2) The diagnostic observation device according to claim 1, wherein the operating coil and the compensation coil are wound on the same pickup coil bobbin. (3) The diagnostic observation device according to claim 1, wherein the operating coil and the compensation coil are respectively wound on different pickup coil bobbins. (4) A plurality of the differential coils and the compensation coils are provided in different axial directions, and a plurality of pairs of the feedback coils are provided corresponding to the compensation coils. The diagnostic observation device according to item 1, item 2, or item 3. (5) a plurality of actuating coils for biomagnetic detection wound around the pickup coil bobbin of the first skid magnetometer; and a plurality of first working coils wound around the pickup coil bobbin of the first skid magnetometer. A compensating coil and a plurality of second compensating coils wound around the pickup coil bobbin of the second skid magnetometer receive the outputs of these second compensating coils and perform a mixing operation, and the output signal is converted to the above-described output signal. A diagnostic observation device comprising, in addition to a first compensation coil, means for canceling fluctuations in a far-field magnetic field around the operating coil.