JP6865969B2 - Coil structure, 3D magnetic field generator, and directional / position measuring device - Google Patents

Description

The present invention relates to a three-dimensional magnetic field generator composed of a six-axis coil, and more particularly to a three-dimensional magnetic field generator provided with a space for accommodating a patient in a lying state.

In recent years, in medical practice, large-scale surgery has been performed by inserting medical devices such as endoscopes and catheters into the patient's body and performing treatment while checking the image of the affected area and the orientation (orientation) and position of the device. Treatment methods that avoid surgery and ease the burden on the patient are widely adopted.

At the tip of the medical device, a camera that captures an image of the affected area and a sensor for measuring the orientation and position of the device are mounted. As the sensor, a magnetic field sensor can be preferably adopted. By embedding a magnetic field sensor in a medical device, forming a magnetic field space around the patient, and measuring the magnetic field with the magnetic field sensor, the orientation and position of the device can be calculated.

Here, the measurement accuracy by the magnetic field sensor is improved as the sensitivity of the magnetic field sensor is increased and the difference in magnetic field strength within the measurement range is increased. However, when the sensitivity of the magnetic field sensor is increased, the size of the magnetic field sensor becomes large, and in order to increase the difference in magnetic field strength within the measurement range, it is necessary to bring the magnetic field generation source closer or strengthen the generated magnetic field. When the magnetic field source is brought closer, the space inside the device becomes smaller, and when the magnetic field is strengthened, heat generation due to an increase in current and the influence of the strong magnetic field on the surroundings become problems. When putting a directional / position measuring device into practical use, it is desirable that the smaller the sensor mounted on the medical device, the more sensitive the magnetic field sensor is, and the space inside the device is large enough to contain the patient. Need to be provided.

In this regard, in Patent Document 1, a GSR sensor is adopted as a magnetic field sensor, and a three-dimensional magnetic field space composed of a three-dimensional uniform magnetic field and a three-dimensional gradient magnetic field is formed by using a predetermined three-dimensional magnetic field generator. A technique that can reduce the size of a sensor and form a magnetic field space that can contain a patient while maintaining sufficient measurement accuracy is described.

Japanese Patent No. 6256962

However, according to the three-dimensional magnetic field generator of Patent Document 1, as shown in FIG. 6, the surface of the coil structure 1 is blocked by any of the coil pairs 14, 15 and 16 that generate the three-dimensional gradient magnetic field. There is a problem that it is not possible to secure a carry-in entrance for bringing the patient into the measurement space. In addition, since each coil is large and the structure of the device is complicated, the weight of the entire device becomes extremely heavy and enormous in the general method of making the coil sturdy to give it strength and assembling it on a surface plate. It is also difficult to maintain the assembly accuracy due to the various assembly work procedures, and it is also difficult to assemble the device.

Therefore, an object of the present invention is to provide an easily assembling coil structure, a three-dimensional magnetic field generator, and an orientation / position measuring device, which are provided with a carry-in entrance for carrying a patient and can accommodate the patient inside. There is.

In order to solve the above problems, the coil structure of the present invention is used.
(1) A coil structure provided in a three-dimensional space defined by xyz axes that are orthogonal to each other, a uniform magnetic field generating coil that generates a uniform magnetic field along the xyz axis, and a gradient magnetic field along the xyz axis. A gradient magnetic field generating coil that generates a magnetic field and a space that can be carried in with the human body lying down parallel to the x-axis. The space is a region surrounded by a coil that generates a uniform magnetic field along the x-axis. The gradient magnetic field generating coil is provided so as to penetrate the space, and is characterized in that the coil is arranged so as to face the y-axis direction or the z-axis direction via the space.

(2) The uniform magnetic field generation coil is composed of a Helmholtz coil, and the gradient magnetic field generation coil is composed of a parallel 4-wire coil having excellent linearity of the generated magnetic field so that the position calculation accuracy is good.

Further, the three-dimensional magnetic field generator of the present invention is
(3) The coil structure according to the above (1) or (2) is included, and a support column for supporting the coil structure is provided. Each coil has the minimum required strength, and the strength and accuracy at the time of assembly are guaranteed by the support columns.

(4) At this time, in the three-dimensional magnetic field generator of (3) above, in the state before energization, the coil structure cancels the magnetic field from the outside and maintains the magnetic field inside the coil structure at zero. preferable.

Further, the directional / position measuring device of the present invention is
(5) The three-dimensional magnetic field generator according to (3) or (4) above, a magnetic field sensor having one or more axes, and an arithmetic unit that calculates the orientation and position of the magnetic field sensor based on the measurement information of the magnetic field sensor. It is characterized by being prepared.

According to the three-dimensional magnetic field generator of the present invention, a space for accommodating an inspection object is provided in a region surrounded by a coil that generates a uniform magnetic field along the x-axis of the coil structure, and a gradient magnetic field is avoided by avoiding the space. Since the coil pair to be generated is arranged, the coil pair for the gradient magnetic field carries in the patient from the carry-in inlet opened on the surface of the coil structure, and the patient is inside the coil structure, the three-dimensional magnetic field generator, and the orientation / position measuring device. Has the excellent effect of being able to accommodate. In addition, by installing the coils like floor or wall panels by erecting support columns like building a house, it is not necessary to give strength to each coil, so the weight of the entire device can be reduced and it is easy. Can be assembled.

(A) is a perspective view of a coil structure showing an embodiment of the present invention, and (b) is a schematic view showing a storage position of an inspection object in the coil structure. It is (a) plan view, (b) side view, (c) front view of the coil structure. It is a schematic diagram which shows the coil pair which generates the uniform magnetic field along the (a) x-axis, (c) y-axis, and (c) z-axis directions which form the coil structure of FIG. It is a schematic diagram which shows the coil pair which generates the gradient magnetic field along the (a) x-axis, (c) y-axis, and (c) z-axis directions which form the coil structure of FIG. It is (a) side view and (b) front view of the direction / position measuring apparatus. It is a perspective view which displayed only the parallel 4-wire coil pair among the conventional coil structures.

Hereinafter, an embodiment embodying the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, the coil structure 1 is provided in a three-dimensional space defined by xyz axes orthogonal to each other, and a coil pair that generates a uniform magnetic field along the x, y, z axis directions, respectively. It includes 11, 12, and 13 and coil pairs 14, 15, and 16 that generate gradient magnetic fields along the x, y, and z-axis directions, respectively. At this time, it is preferable that the coil pairs 11, 12, and 13 that generate a uniform magnetic field are Helmholtz coils, and the coil pairs 14, 15, and 16 that generate a gradient magnetic field are parallel 4-wire coils.

The coil structure 1 includes a space S that can be carried in parallel to the x-axis (in the direction of the arrow) with an object to be inspected such as a human body lying down. The space S is formed so as to penetrate a region A (see FIG. 3A) surrounded by a coil pair 11 that generates a uniform magnetic field along the x-axis, and x, so as to sandwich the space S in between. Coil pairs 14, 15 and 16 that generate gradient magnetic fields along the y and z axis directions are arranged. Further, a coil pair 12 that generates a uniform magnetic field along the y-axis and a coil pair 13 that generates a uniform magnetic field along the z-axis are arranged so as to surround the coil pair 11.

FIG. 3 shows a pair of coils that generate a three-dimensional uniform magnetic field decomposed for each dimension. The coil pair 11 is composed of a pair of coils 11a and 11b arranged relative to each other in the y-axis direction, and the coil pair 12 is composed of a pair of coils 12a and 12b arranged relative to each other in the x-axis direction. The coil pair 13 is composed of a pair of coils 13a and 13b arranged so as to face each other in the z-axis direction.

FIG. 4 shows a pair of coils that generate a three-dimensional gradient magnetic field decomposed for each dimension. The coil pair 14 is composed of a pair of coils 14a and 14b arranged relative to each other in the z-axis direction via the space S, and the coil pair 15 is arranged relative to each other through the space S in the z-axis direction. The coil pair 16 is composed of a pair of coils 15a and 15b, and the coil pair 16 is composed of a pair of coils 16a and 16b arranged so as to face each other with respect to the space S in the y-axis direction.

The coils 11a, b to 16a, b are formed in a substantially rectangular frame shape, and a plurality of conducting wires (not shown) are inserted inside the frame body. Further, the plurality of inserted conductors are connected via a connector and circulate inside the frame to form a coil. When manufacturing the coil structure of the present invention, one coil frame is divided, the divided coil frame is inserted into another coil frame, and the internal conducting wire is reconnected at the connector portion to obtain a desired configuration. It is possible to assemble a coil structure.

FIGS. 3 and 4 show a state in which the coil pairs 11 to 16 are disassembled. The size of the coil structure 1 is 0.5 m to 3 m on each side, and by passing a current in the direction of the arrow in FIGS. 3 and 4, the coil pairs 11 to 13 have a uniform magnetic field, and the coil pairs 14 to 16 have a uniform magnetic field. Generates a gradient magnetic field. At this time, the uniform magnetic field is formed in the range of ± 2.5 cm to ± 15 cm with the central portion of the coil structure 1 as the origin. The inclination of the gradient magnetic field at this time is about 0.05 mG / μm to 1 mG / μm. FIG. 3A is a front view and a perspective view of the coil pair 11 that generates a uniform magnetic field along the x-axis direction, and FIG. 3B is a perspective view of the coil pair 12 that generates a uniform magnetic field along the y-axis direction. A side view and a perspective view, FIG. 3C is a plan view of a coil pair 13 that generates a uniform magnetic field along the z-axis direction. Further, FIG. 4A is a plan view and a perspective view of a coil pair 14 that generates a gradient magnetic field along the x-axis direction, and FIG. 4B is a coil pair 15 that generates a uniform magnetic field along the y-axis direction. 4 (c) is a side view and a perspective view of a coil pair 16 that generates a uniform magnetic field along the z-axis direction.

Subsequently, the three-dimensional magnetic field generator 2 and the azimuth / position measuring device 3 configured to include the coil structure 1 described above will be described. As shown in FIG. 5, the three-dimensional magnetic field generator 2 of the present invention is composed of a coil structure 1 and a support column 21 that supports the coil structure 1. The orientation / position measuring device 3 is a three-dimensional magnetic field generator 2, a magnetic field sensor 31 mounted on a medical device 33 such as a catheter, and a calculation device that calculates the orientation / position of the magnetic field sensor 31 in the three-dimensional space. It is composed of 32.

The magnetic field sensor 31 moves inside the human body P together with the medical device 33 and measures the magnetic field distribution intensity. Further, the magnetic field sensor 31 digitally converts the measured magnetic field distribution intensity to generate magnetic field distribution intensity data, and transfers the measured magnetic field distribution intensity data to the external arithmetic unit 32. The arithmetic unit 32 that has received the magnetic field distribution intensity data performs a predetermined calculation to calculate the orientation and position of the magnetic field sensor 31 in the three-dimensional space. As the magnetic field sensor 31, a GSR sensor, which is a uniaxial magnetic field sensor, can be preferably adopted. The GSR sensor is a high-precision magnetic field sensor capable of measuring the magnetic field distribution intensity in a three-dimensional space with a resolution of 1 mG or less.

At this time, the three-dimensional magnetic field generator 2 is configured to cancel the magnetic field from the outside and maintain the magnetic field inside the coil structure at zero before the start of energization. By keeping the external magnetic field generated from geomagnetism, iron machinery, reinforced buildings, etc. at zero, the coordinate position of the direction vector measured by the GSR sensor in the xyz coordinate system can be measured accurately.

The support column 21 is provided along the coil pairs 11 to 16 to support the coil structure 1. Since the structure of the coil structure 1 is complicated, if the coil pairs 11 to 16 themselves are reinforced, the weight of the coil pairs 11 to 16 increases, which makes the assembly work difficult. By using the support column 21, the coil pairs 11 to 16 can be supported in a desired arrangement without reinforcing the coil pairs 11 to 16 themselves.

According to the coil structure 1, the three-dimensional magnetic field generator 2, and the orientation / position measuring device 3 configured as described above, all the coil pairs 11 to 16 constituting the coil structure 1 are in the space S. Since it does not invade, it is possible to carry out various measurements and tests by carrying an inspection object such as a human body lying down toward the inside of the coil structure 1 in parallel with the x-axis. Further, since the coil structure 1 is supported by using the support columns 21, the weight of each coil pair 11 to 16 can be suppressed, and the transportation and assembly work can be saved.

In addition, the present invention is not limited to the above-described embodiment, and the configuration of each part can be arbitrarily changed and implemented without departing from the spirit of the invention. For example, a coil that generates a uniform magnetic field / gradient magnetic field along the x and y axes can be used as a coil that generates a uniform magnetic field / gradient magnetic field along the y and x axes, respectively.

1 Coil structure 2 Three-dimensional magnetic field generator 3 Direction / position measuring device 11 Coil pair that generates a uniform magnetic field along the x-axis 12 Coil pair that generates a uniform magnetic field along the y-axis 13 Uniform magnetic field along the z-axis Coil pair 14 Generates a gradient magnetic field along the x-axis Coil pair 15 Generates a gradient magnetic field along the y-axis Coil pair 16 Generates a gradient magnetic field along the z-axis Coil pair 17 Space 21 Support column 31 Magnetic field sensor 32 Computing device 33 Medical device S Space P Human body

Claims (5)

A coil structure provided in a three-dimensional space defined by xyz axes that are orthogonal to each other.
a uniform magnetic field generating coil for generating each a uniform magnetic field along the xyz axes, the gradient magnetic field generating coil for generating respective magnetic gradient fields along the xyz axes space available carried while being recumbent human body parallel to the x-axis And with
The space is provided so as to penetrate a region surrounded by a uniform magnetic field generation coil that generates a uniform magnetic field along the x-axis.
The gradient magnetic field generation coil that generates the gradient magnetic field along the x-axis is arranged so as to face the z-axis direction via the space.
The gradient magnetic field generation coil that generates the gradient magnetic field along the y-axis is arranged so as to face the z-axis direction via the space.
A coil structure characterized in that the gradient magnetic field generation coil for generating a gradient magnetic field along the z-axis is arranged so as to face each other in the y-axis direction via the space. The coil structure according to claim 1, wherein the uniform magnetic field generating coil is composed of a Helmholtz coil, and the gradient magnetic field generating coil is composed of a parallel 4-wire coil. The coil structure according to claim 1 or 2 is included.
A three-dimensional magnetic field generator comprising a support column for supporting the coil structure. The three-dimensional magnetic field generator according to claim 3, wherein the coil structure cancels the magnetic field from the outside and maintains the magnetic field inside the coil structure at zero in the state before energization. The three-dimensional magnetic field generator according to claim 3 or 4, the magnetic field sensor arranged in the three-dimensional space, and a calculation device that calculates the orientation and position of the magnetic field sensor based on the measurement information of the magnetic field sensor. An orientation / position measuring device characterized by being equipped.

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