JP2985491B2 - Method of measuring position and direction of film-shaped detection coil of SQUID sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a SQUID for measuring a minute magnetic field such as that formed by a biological activity current source.
The present invention relates to a method for measuring a position and a direction of a film detection coil of a sensor.

[0002]

2. Description of the Related Art When an external stimulus such as light or sound is applied to a living body, a signal (active current) is generated in a sensory nerve.
The magnetic field formed by this biological activity current is referred to as SQUI
The measurement is performed by a sensor using D (Superconducting Quantum Interference Dvice), and the position, size, and direction of the biological activity current source are estimated from the measurement data. The estimated life activity current source (hereinafter simply abbreviated as a current source) is displayed on a tomographic image of the body taken by an X-ray CT apparatus, an MRI apparatus, or the like, and is used to specify a physical position of an affected part or the like. You.

Therefore, it is extremely important to accurately determine the positional relationship between the measurement point of the SQUID sensor and the living body. The SQUID sensor is configured by housing a SQUID, a detection coil and a compensation coil in a container called a dewar, and the inside of the dewar is filled with liquid helium to maintain the superconducting state of the SQUID.

In order to determine the positional relationship between the position and direction of the detection coil, which is the measurement point of the SQUID sensor, and the living body, first, the position and direction of the detection coil with respect to a three-dimensional coordinate system based on Dewar should be designed. Refer to and understand. Next, a light projector is attached to the dewar to irradiate the living body with a light beam, or a small coil is attached to a plurality of locations of the living body, and a magnetic field generated from the small coil is detected by a SQUID sensor, and the coordinates of the dewar are used. Understand the position of the living body with respect to the system. The positional relationship between the position and direction of the detection coil and the living body is obtained from these pieces of information, that is, the relationship between the position and direction of the dewar and the detecting coil and the positional relationship between the dewar and the living body.

However, since the detection coil is immersed in the liquid helium injected into the Dewar and is in a very low temperature state, the detection coil contracts, and the position and direction as practically designed are maintained. Therefore, the relationship between the dewar and the position and direction of the detection coil cannot be accurately grasped. A similar problem occurs due to a manufacturing error of the detection coil, an error in attaching the detection coil to the dewar, or the like.

In view of such circumstances, the present applicant has proposed a method for measuring the position and direction of a detection coil of a SQUID sensor in Japanese Patent Application No. 3-280797. This is a method of taking X-ray images of a detection coil housed in a dewar from a plurality of directions, and measuring the position and direction of the detection coil from an X-ray image of the detection coil. The above problem is solved by obtaining the position and the direction of the detection coil in the state where the detection coil is housed in the dewar.

[0007]

The conventional detection coil is:
It is manufactured by winding an Nb (niobium) superconducting wire having a diameter of about 0.1 mm around a cylindrical bobbin. Such a detection coil can perform X-ray imaging as described above. However, this type of detection coil has drawbacks such as inaccuracy in the winding position around the bobbin and difficulty in making the parallelism between the detection coil and the compensation coil completely identical. Not for mass production.

Therefore, in recent years, a film-shaped detection coil has been used. Extremely low temperature properties such as polyimide film,
It is manufactured by patterning a Nb superconducting thin film on a flexible film and winding it around a cylindrical bobbin. Since the coil pattern is formed on the plane of the film, the accuracy of the coil position is high and suitable for mass production. However, since the coil pattern is a thin film having a thickness of about 10 ^-1 μm or less and a width of about several mm, it is almost impossible to perform X-ray photography. Measurement method cannot be applied.

The present invention has been made in view of such circumstances, and it is possible to measure the position and orientation of a film-shaped detection coil in a state where the detection coil is housed in a dewar.
It is an object of the present invention to provide a method for measuring the position and direction of a film detection coil of a QUID sensor.

[0010]

The present invention employs the following method to achieve the above object. That is, in the measuring method of the present invention, the position and direction of the film-shaped detection coil on the three-dimensional coordinates of the probe around which the film-shaped detection coil is wound are measured in advance, and the three-dimensional coordinates representing the three-dimensional coordinates are displayed on the probe. A magnetic index point is attached and housed in a dewar, the dewar is X-ray imaged from a plurality of directions, an X-ray image of the index point is collected, and three-dimensional coordinates of the X-ray imaging surface with respect to the three-dimensional coordinate system of the dewar The positional relationship of the system is obtained, and the index point images X-ray imaged from the plurality of directions and each X
The position of the intersection of the straight line connecting the X-ray focal point at the time of X-ray imaging is determined on the three-dimensional coordinates of the X-ray imaging surface, and from this information, the position of the intersection on the three-dimensional coordinates of the Dewar is determined. The positional relationship between the three-dimensional coordinate system and the three-dimensional coordinate system of the probe is obtained, and the position and direction of the film-shaped detection coil on the three-dimensional coordinate of the probe, which has been measured, are used to determine the three-dimensional coordinate of the Dewar. The position and direction of the film-shaped detection coil are determined.

[0011]

The operation of the present invention is as follows. When an index point image obtained by X-ray imaging of the index point of the probe stored in the Dewar from a plurality of directions and the X-ray focal point at the time of each X-ray imaging are connected by a straight line, the intersection of the plurality of straight lines is obtained. From the position, the position of the index point on the three-dimensional coordinates of the X-ray imaging plane is determined. This information and Dewar's three-dimensional coordinate system
From the positional relationship between the X-ray imaging surface and the three-dimensional coordinate system, the position of the index point on the three-dimensional Dewar coordinates is obtained. The position information of the index point indicates the three-dimensional coordinates of the probe, and therefore, the positional relationship between the three-dimensional coordinate system of the Dewar and the three-dimensional coordinate system of the probe can be determined.

If the position and direction of the film-shaped detection coil on the three-dimensional coordinates of the probe are measured, the position and direction of the film-shaped detection coil on the three-dimensional Dewar coordinates can be determined from the above positional relationship. . As described above, if the film-shaped detection coil cannot perform X-ray imaging, an index point is attached to the probe that winds and supports the film-shaped coil, and
Since the line imaging is performed and the position and direction of the film detection coil in the Dewar coordinate system are obtained using the index point image, the position and direction can be measured with the film detection coil stored in the dewar. Since the index point is non-magnetic, it does not disturb the minute magnetic field picked up by the film-shaped detection coil, and does not affect the detection accuracy.

[0013]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1A is a front view of a detection probe of the SQUID sensor according to the present embodiment, and FIG. 1B is a plan view of a detection coil. The detection probe 1 is configured by attaching a film-shaped detection coil 2 (hereinafter, a film coil 2) to an outer periphery of a cylindrical bobbin 3 formed of a nonmagnetic material such as plastic. The film coil 2 is formed by patterning a Nb (niobium) superconductor thin film 2a on a low-temperature resistant flexible material such as a polyimide film. Code 2b
Is a signal extraction pad for connecting the SQUID and the film coil 2. Such a detection probe 1 is immersed in liquid helium together with the SQUID and attached to the dewar.

In order to measure the position and orientation of the film coil 2 in the Dewar three-dimensional coordinate system, first, the position and orientation of the film coil 2 in the three-dimensional coordinate system of the detection probe 1 are measured. The positional relationship between the three-dimensional coordinate system of the detection probe 1 and the Dewar three-dimensional coordinate system is grasped, and the position and orientation of the film coil 2 in the Dewar three-dimensional coordinate system are obtained from these data.

[1] Before attaching the detection probe 1 to the dewar, the transmitter 4 is attached to the end face of the cylindrical bobbin 3 of the detection probe 1 (see FIG. 2). The transmitter 4 forms a magnetic field in three orthogonal axes. A plurality of points on the coil pattern formed on the film coil 2 are designated by the tip of a stylus-type receiver 5 having a built-in coil for receiving the magnitude of each magnetic field from the transmitter 4.

The stylus-type receiver 5 has a coil oriented in three orthogonal directions at the center thereof, obtains reception signals corresponding to the magnitudes of the respective magnetic fields emitted from the transmitter 4, and receives the reception signals. The three-dimensional distance between the transmitter 4 and the coil, that is, the position of the transmitter 4 in the three-dimensional coordinate system, from the size of
The value is converted to the position of the specified point at the tip. This allows
3-dimensional coordinate system position and orientation of the film coil 2 in (= 3-dimensional coordinate system X _P -Y _P -Z _P of detecting probe 1) of the transmitter 4 is obtained.

[2] From the end face of the detection probe 1 to the transmitter 4
Then, as shown in FIG. 3, a plurality of X-ray-capable small balls 6 are mounted on the coil pattern of the film coil 2. The small ball 6 is formed of a material that blocks X-rays, for example, lead. Such a detection probe 1 is housed in a liquid helium container (not shown). Before injecting the liquid helium into the liquid helium container, X-rays are irradiated from the direction of the arrow in the drawing, and an image of the small sphere 6 (hereinafter, referred to as a spherical image 6 ′) is transferred to the X-ray film 7.

After X-ray photography, liquid helium is injected into the liquid helium container. When the temperature of the detection probe 1 in the container reaches the same temperature as the liquid helium, X-ray imaging is performed again.
Two X-ray films taken before and after liquid helium injection 7
Are superimposed, and the displacement of the spherical image 6 ′ is measured. For example, if the spherical image 6 ′ photographed after the injection of liquid helium is at the position shown by hatching in FIG. 3, the displacement Δ from the position of the spherical image 6 ′ photographed before the injection of liquid helium
Measure x and Δz.

Δx indicates the amount of displacement of the cylindrical detection probe 1 in the radial direction, and Δz indicates the amount of displacement in the direction of the cylinder axis. The material of the cylindrical bobbin 3, i.e., if the uniform shrinkage with temperature, also as many displaced [Delta] x in the Y _P direction is a radial (Δy = Δx). From the position of the film coil 2 in a three-dimensional coordinate system X _P -Y _P -Z _P of the detection probe 1 which had been obtained in the above (1), the displacement amount Δx in the three axial directions of measurement, delta
y and Δz are differentiated, and the position of the film coil 2 is updated with the position obtained by the difference.

The updated position is the position of the detection probe 1 in the three-dimensional coordinate system X _P -Y _P -Z _P in the liquid helium, that is, the position of the detection probe 1 in the state of being stored in the dewar. it is equivalent to the position of the film coil 2 in the dimension coordinate system X _P -Y _P -Z _P.

When the cylindrical bobbin 3 is deformed by the contraction in liquid helium, the change in the direction of the film coil 2 is also taken into consideration. For example, the line segment Lz in the Z _P direction and the line segment Lx in the X _P direction connecting the spherical images 6 ′ obtained before the injection of liquid helium by lines, and the spherical image 6 ′ obtained after the injection of liquid helium by lines. line segment of connecting it Z _P direction Lz ', X
_The amount of tilt displacement with respect to the line segment Lx ′ (not shown) in the _P direction is obtained, and the direction of the film coil 2 is corrected in the same manner as described above.

Film coil 2 before and after liquid helium injection
Is unique to the material of the cylindrical bobbin 3 and the film coil 2, and therefore, it is not necessary to measure the displacement of the same material twice or three times. Position and orientation of the film coil 2 in a three-dimensional coordinate system X _P -Y _P -Z _P of the detection probe 1 to be measured in [1] for different depending on the design of the SQUID sensor, should be measured every specification is changed There is. However, for a device equipped with a large number of the same detection probes 1 such as a multi-channel SQUID sensor, the measurement in [1] is also performed by one.
Only the degree is necessary.

Each of the above measurements can also be performed as follows. (A) In [1] above, the detection probe 1
While the dimension coordinate system X _P -Y _P -Z film position and orientation of the coil 2 at _P measured, it may be used a three-dimensional position measuring apparatus using an optical beam. That is, a light beam is applied to any three points of the detection probe 1, the reflected light is detected, and the three-dimensional coordinates of the detection probe 1 are input. Next, a plurality of points on the coil pattern of the film coil 2 are designated by a light beam and their positions are input, and the position and orientation of the film coil 2 on the three-dimensional coordinates of the detection probe 1 previously input are determined. Ask. Since the detection probe 1 is not housed in the dewar, various other measurement methods can be applied.

(B) In the above [2], the amount of displacement of the film coil 2 before and after liquid helium injection was measured using an X-ray image, but the transmitter 4 was attached to the end face of the cylindrical bobbin 3 of the detection probe 1. A method in which the magnetic field from the transmitter 4 is stored in a liquid helium container while being attached, and the magnetic field from the transmitter 4 is detected by a receiver installed outside the container may be considered. That is, before injecting the liquid helium, the three-dimensional magnetic field strength from the transmitter 4 is detected to determine the three-dimensional position of the transmitter 4. Similarly, after the injection of liquid helium, the three-dimensional position of the transmitter 4 is detected, and the displacement of the three-dimensional position of the transmitter 4 before and after the injection of liquid helium is calculated.

The displacement of the transmitter 4 indicates the displacement of the cylindrical bobbin 3 of the detection probe 1. Assuming that the film coil 2 is firmly attached to the cylindrical bobbin 3 and contracts integrally with the cylindrical bobbin 3, the displacement of the transmitter 4 is the displacement of the film coil 2.

[3] Next, with the detection probe 1 attached to the dewar, the three-dimensional coordinate system X of the detection probe 1
Obtaining a positional relationship between the 3-dimensional coordinate system _P -Y _P -Z _P and dewar. First, as shown in FIG. 4, index points A1 and X1 of a non-magnetic material capable of X-ray imaging at appropriate three locations of the detection probe 1.
Attach A2 and A3. Position of index points A1, A2, A3 are three-dimensional coordinates X _P of the detection probe 1, Y _P, represents a Z _P. Such a detection probe 1 is installed in a dewar 9 shown in FIG.

A transmitter 4 for forming a magnetic field in each of the three orthogonal axes is mounted at an appropriate position on the outer surface of the dewar 9, and an index point D1 made of, for example, lead is provided at the tip of the dewar 9 in which the detection probe 1 is incorporated. , D2, D3, D4. An X-ray magazine 10 having a built-in X-ray film is arranged directly below the tip of the dewar 9, and similar index points F 1, F 2, and F 3 are attached to appropriate three places of the X-ray magazine 10. The positions of the index points F1, F2, and F3 are three-dimensional coordinates X on the X-ray imaging surface.
_F , Y _F and Z _F are represented.

Index points F1, F attached to the X-ray magazine 6 at the tip of a stylus-type receiver 5 containing a coil for receiving the magnitude of each magnetic field from the transmitter 4 respectively.
2, specify the F3, three-dimensional coordinate system of three points on the X-ray magazine 10 in (three-dimensional coordinate system X _D -Y _D -Z _D Dewar 9) F1, F2, the position of the F3 of the transmitter 4, That is,
Previously obtained positional relationship of the three-dimensional coordinate system X _F -Y _F -Z _F of the imaging surface.

Hereinafter, the three-dimensional coordinate system X _{P of} the detection probe 1 will be described.
Replace -Y _P -Z _P to "probe coordinates X _P -Y _P -Z _P", a 3-dimensional coordinate system X _D -Y _D -Z _D Dewar 9 "dewar coordinates X _D -Y _D -Z _D" the replacement, the three-dimensional coordinate system of the imaging plane X _F -Y _F -Z _F the "imaging plane coordinate X _F -
Described by replacing the Y _F -Z _F ".

Similarly, the index points D1, D2, D3, and D4 attached to the tip of the dewar 9 are designated by the stylus-type receiver 3, and the dewar coordinates X _D -Y _D -Z _D
, The positions of the index points D1, D2, D3, D4 are obtained. And, Dewar coordinates X _D -Y _D, which had been obtained previously
The positional relationship between the -Z _D and the imaging surface coordinates X _F -Y _F -Z _F, determine the position of the imaging surface coordinates X _F -Y _F -Z indicators on Dewar 9 points in _F D1, D2, D3, D4 .

Further, a standard receiver 11 for receiving the magnitude of the magnetic field in three axial directions from the transmitter 4 is attached to an appropriate position of the X-ray magazine 10, and the Dewar 9 when the Dewar 9 moves or rotates. advance to be able to grasp the position of the standard receiver 11 for X _D -Y _D -Z _D. By doing so, the dewar 9 can be obtained from the three-dimensional position information of the standard receiver 11.
Dewar coordinates X _D -Y when moves or rotates
Movement of the _D -Z imaging surface coordinates for _D X _F -Y _F -Z _F,
Rotation can be detected.

[4] X-rays are emitted from an X-ray tube (not shown) arranged opposite to the X-ray magazine 10 so as to sandwich the tip of the dewar 9 so that the posture shown in FIG. An X-ray fluoroscopic image of the Dewar 9 is captured on an X-ray film built in the X-ray magazine 10. The index points A1, A2, A3 attached to the detection probe 1, the index points D1, D2, D3, D4 attached to the dewar 9 and the index points F1, F2, F3 attached to the X-ray magazine 10 are as described above. Thus, since it is formed of lead, it is projected on an X-ray film as a black point (see FIG. 6).

Since the positional relationship between the X-ray film 12 and the X-ray magazine 10 is fixed and known, the X-ray film 12
The distance between the target point and the X-ray magazine 10 is corrected, and the index point images D1 ', D2', D3 ', D projected on the X-ray film 12 are corrected.
A coordinate position at 4 ′ imaging plane coordinates X _F −Y _F −Z _F is obtained. Then, as shown in FIG. 7, the images D1 ′, D2 ′, D3 ′, D4 ′ of these index points and the index points on the Dewar 9 at the imaging plane coordinates X _F −Y _F −Z _F obtained above. D1, D2, D3, and D4 are connected by straight lines, and the three-dimensional position coordinates of the intersection of each straight line are obtained. This intersection is the X-ray focal point in the coordinate system XYZ of the imaging plane.

[5] The dewar 9 shown in FIG. 5 is rotated by about 90 ° in the direction of the symbol R in the figure, and the magnitude of each magnetic field from the transmitter 4 in the three orthogonal directions is measured by the X-ray magazine 10. The signal is received by the standard receiver 11 attached to the. As aforementioned,
A Dewar coordinates X _D -Y _D -Z _D from the received signal, is obtained positional relationship between the imaging surface coordinates X _F -Y _F -Z _F. Here, based on the dewar coordinates X _D -Y _D -Z _D, regarded as the imaging surface coordinates X _F -Y _F -Z _F is rotated 90 °.

An X-ray fluoroscopic image of the tip of the dewar 9 is taken in the same manner as described in the above [4], and the X-ray focus S2 at the imaging plane coordinates X _F90 -Y _F90 -Z _F90 rotated by 90 °.
Are obtained (see FIG. 8).

[6] Index point images A1 ', A2' of the detection probe 1 on the two X-ray films 12 obtained so far,
Each of the imaging surface coordinates of _{A3 'X F -Y F -Z F} , X
_{Find the} position at _F90- YF90- _ZF90 . As described above, since the positional relationship between the X-ray film 12 and the X-ray magazine 10 is fixed and known, these distances are corrected,
The coordinate position of each point of the index point image of the detection probe 1 projected on the X-ray film 12 in the coordinate system of the imaging surface is obtained.

As shown in FIG. 9, the coordinate systems X _F -Y _F -Z _F and X _F90 -Y _F90 -Z _F90 of these two imaging planes are combined, and the index point image of the detection probe 1 of each coordinate system is used. The X-ray focal points S1 and S2 in each coordinate system obtained in advance are connected to each other by a straight line. The positions of the index points A1, A2, and A3 of the detection probe 1 are obtained as intersections of these corresponding straight lines. The position of each intersection indicates the position of the imaging surface coordinates X _F -Y _F -Z index points in _F A1, A2, A3. The positions of the index points A1, A2, A3 are the probe coordinates _XP ,
Y _P and Z _P are shown. Therefore, the imaging plane coordinates X _F −Y _F −Z
Positional relationship between the _F and the probe coordinate X _P -Y _P -Z _P is obtained.

As described above, the positional relationship between the imaging plane coordinates X _F -Y _F -Z _F and the dewar coordinates X _D -Y _D -Z _D is determined by the index points F 1, F 1 attached to the X-ray magazine 10. F
Since it is obtained from the position of 2, F3,
Dewar coordinates X _D -Y _D -Z _D and probe coordinate X _P -Y
Determine the positional relationship between the _P -Z _P.

[0039] [7] The probe coordinates X _P -Y _P -Z film coil 2 at _P which has been determined in the above [2]
Position and orientation information and Dewar coordinates X _D -Y _D -Z _D
A probe coordinate X _P -Y _P from the positional relationship between the -Z _P, Dewar coordinates X _D -Y _D -Z film in _D coil 2
The position and orientation of.

In the above embodiment, the shaft type detection probe 1
In the same manner, the position and the orientation of the flat type detection probe can be measured. Instead of the uniaxial type detection probe as in the embodiment, the angle between them can be measured as shown in FIG. Three pairs of different coils 20a, 20b, 20
The same measurement can be performed for a three-axis type detection probe provided with c.

Further, a plurality of SQUIDs and the detection probe 1
When the present invention is applied to a multi-channel SQUID sensor equipped with the above, the index points A1, A2, and A3 attached to the detection probes 1 are shifted along the cylinder axis direction so that the positions do not overlap. Thereby, it is possible to determine the positional relationship between the coordinate system and the dewar coordinates X _D -Y _D -Z _D of each detection probe 1 from the same two X-ray images as examples.

[0042]

As is apparent from the above description, in the measuring method of the present invention, the position and direction of the film-like detection coil on the three-dimensional coordinates of the probe are measured, and the nonmagnetic index point attached to the probe is measured. X-ray image of the probe 3
The positional relationship between the three-dimensional coordinate system and the Dewar three-dimensional coordinate system is determined, and the position and direction of the film-shaped detection coil on the three-dimensional Dewar coordinates are determined from these information. This allows accurate measurement regardless of the displacement of the film-shaped detection coil due to the contraction action of liquid helium, the mounting error of the film-shaped detection coil, and the like. As a result, the grasp of the estimated positional relationship between the biological activity current source and the living body increases, and the accuracy of diagnosis and the safety of treatment and surgery can be ensured.

[Brief description of the drawings]

FIG. 1 is a front view of a detection probe including a film coil according to an embodiment of the present invention, and a plan view of the film coil.

FIG. 2 is a diagram illustrating an example of a method of measuring a position and a direction of a film coil on three-dimensional coordinates of a detection probe.

FIG. 3 is also a diagram illustrating an example of a method of measuring the position and direction of a film coil on three-dimensional coordinates of a detection probe.

FIG. 4 is a perspective view showing a detection probe to which a nonmagnetic index point is attached.

FIG. 5 is a perspective view illustrating a measurement example of a positional relationship between a three-dimensional coordinate system of a detection probe and a three-dimensional coordinate system of a Dewar.

FIG. 6 is a diagram showing an example of an X-ray fluoroscopic image of a dewar tip.

FIG. 7 is a diagram illustrating a method of obtaining a position of an X-ray focal point.

FIG. 8 is a diagram illustrating a method of obtaining an X-ray focal point when X-ray imaging is performed from another angle.

FIG. 9 is a diagram illustrating a method of obtaining a positional relationship between a coordinate system of an imaging surface and a coordinate system of a detection probe.

FIG. 10 is a front view showing another example of the detection probe.

[Explanation of symbols]

1 ... detection probe 2 ... film coil 9 ... Dewar A1, A2, A3 ... index point X _D -Y _D -Z _D ··· 3-dimensional coordinates of the dewar X _F -Y _F -Z _F 3-dimensional coordinates of ... imaging plane X _P -Y _P -Z 3-dimensional coordinates of _P ... detection probe

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) A61B 5/05 G01R 33/035

Claims (1)

(57) [Claims] 1. A non-magnetic index point representing the three-dimensional coordinates of the probe in which the position and direction of the film-shaped detection coil on the three-dimensional coordinates of the probe around which the film-shaped detection coil is wound are measured in advance. Is attached and stored in a dewar, the dewar is X-ray imaged from a plurality of directions, an X-ray image of the index point is collected, and the positional relationship of the three-dimensional coordinate system of the X-ray imaging surface with respect to the three-dimensional coordinate system of the dewar Is obtained on the three-dimensional coordinates of the X-ray imaging plane, and the position of the intersection of a straight line connecting the index point image obtained by X-ray imaging from the plurality of directions and the X-ray focal point at each X-ray imaging is obtained. The position of the intersection on the Dewar's three-dimensional coordinates is determined to find the Dewar's 3D position.
The positional relationship between the three-dimensional coordinate system and the three-dimensional coordinate system of the probe is obtained, and the position and direction of the film-shaped detection coil on the three-dimensional coordinate of the probe, which has been measured, are used to determine the three-dimensional coordinate of the Dewar. Measuring the position and direction of the film-shaped detection coil of the SQUID sensor, wherein the position and direction of the film-shaped detection coil are determined.