JP2006271520A - Position detection system of capsule medical device, guidance system of capsule medical device, and position detection method of capsule medical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position detection system, a guidance system, and a position detection method which allow a capsule medical device to be free from adjustment of an alternating magnetic field frequency for position detection and to be made more compact and less expensive. <P>SOLUTION: The position detection system is characterized by having a frequency determining section 50B for obtaining a position calculating frequency used for calculating the position and the orientation of a capsule medical device 20 based on the resonance frequency of a magnetic induction coil of the capsule medical device 20, and a position analyzing means 50A for calculating the position and the orientation of the capsule medical device 20 based on the difference between outputs from magnetic sensors 52 when only an AC magnetic field is applied and those from the magnetic sensors 52 when the AC magnetic field and the induced magnetization are applied; and by limiting a frequency range of the AC magnetic field and/or an output frequency range of the magnetic field sensors used for analysis by the position analyzing means 50A based on the position calculating frequency. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a capsule medical device position detection system, a capsule medical device guidance system, and a capsule medical device position detection method.

  2. Description of the Related Art In recent years, a capsule type represented by a swallowable capsule endoscope that can be swallowed by a subject such as a subject to pass through a body cavity duct and acquire an image in the body cavity duct at a target position Medical devices are being researched and developed for practical use. The capsule endoscope is configured to include an imaging element such as a CCD (Charge Coupled Device) that can perform the above medical action, for example, and can acquire an image at a target site in a body cavity duct. Is.

For the capsule medical device to reach the target site in the body cavity channel, or to place it in the target site for performing a detailed examination that requires time, etc., regardless of the peristalsis of the body channel, It is necessary to guide and control the capsule medical device. In order to guide the capsule medical device, it is necessary to detect where the capsule medical device is located in the body cavity conduit, and therefore, the capsule medical device is guided to a place where the position cannot be visually confirmed (such as in the body cavity conduit). A technique for detecting the position of a capsule medical device has been proposed (see, for example, Patent Document 1).
International Publication No. 2004/014225 Pamphlet

In Patent Document 1, the position of a capsule medical device is detected by detecting electromagnetic waves generated from a capsule medical device including a magnetic field generation circuit having an AC power source connected to an LC resonance circuit by a plurality of external detection devices. The technology to detect is public.
However, the frequency characteristics of the coils used in the LC resonance circuit vary within a predetermined range due to factors such as variations during coil manufacture. Further, the frequency characteristic of the LC resonance circuit is also affected by variations in the characteristics of the coil and the capacitor, and there is a problem that the variation occurs within a predetermined range.

As means for solving the above-described problem, a technique using a capacitor whose variable capacity can be adjusted (variable capacitor), a coil whose frequency characteristic can be adjusted (a coil whose position of the core of the coil can be adjusted), or the like is known.
However, since elements such as adjustable capacitors and coils are provided with an adjustment mechanism, there is a problem that it is difficult to reduce the size of the capsule medical device.

There is also known a technique for suppressing variation in frequency characteristics of the LC resonance circuit by selecting capacitors having different capacities in accordance with the characteristics of the coil.
However, when the capacitance of the capacitor is selected for each LC resonance circuit, the manufacturing process of the LC resonance circuit is increased, which increases the production cost of the capsule medical device.
Moreover, since it is necessary to use the power supply inside the capsule and the power supply capacity needs to be increased, it is difficult to reduce the size of the capsule. Or there existed a problem that the drive time of a capsule became short.

  The present invention has been made to solve the above-described problems, and eliminates the need for adjusting the AC magnetic field frequency used for position detection of the capsule medical device, and reduces the size and cost of the capsule medical device. It is an object of the present invention to provide a capsule medical device position detection system, a capsule medical device guidance system, and a capsule medical device position detection method capable of achieving the above.

In order to achieve the above object, the present invention provides the following means.
The present invention relates to a position detection system for a capsule medical device to be inserted into the body of a subject, the magnetic induction coil mounted on the capsule medical device, and disposed outside the operating range of the capsule medical device A drive coil that generates an alternating magnetic field that acts on the magnetic induction coil, and a plurality of magnetic sensors that are disposed outside the operating range of the capsule medical device and detect the induced magnetism generated by the magnetic induction coil; A frequency determination unit that calculates a calculation frequency used for calculating the position and orientation of the capsule medical device based on the resonance frequency of the magnetic induction coil; and only the alternating magnetic field is applied to the magnetic sensor using the calculation frequency. The output of the magnetic sensor when acting, and the output of the magnetic sensor when the alternating magnetic field and the induction magnet act on the magnetic sensor Position analysis means for calculating the position and orientation of the capsule medical device based on the difference between the frequency of the alternating magnetic field and / or the analysis of the position analysis means based on the calculation frequency A position detection system for a capsule medical device that limits an output frequency band of a magnetic sensor is provided.

According to the present invention, the frequency characteristics of the magnetic induction coil can be obtained by detecting the induction magnetism (note that there is a resonance frequency as one of the frequency characteristics). Even if there is a variation, the frequency determination unit can obtain a calculation frequency based on the varied frequency characteristics. Therefore, the capsule medical device position detection system of the present invention can always calculate the position and orientation of the capsule medical device based on the calculation frequency even if the frequency characteristics of the magnetic induction coil vary.
As a result, it is not necessary to mount an element for adjusting the frequency characteristics of the magnetic induction coil, and the capsule medical device can be downsized. Alternatively, in order to adjust the resonance frequency, it is not necessary to select or adjust an element such as a capacitor that constitutes a resonance circuit together with the magnetic induction coil, thereby preventing an increase in production cost of the capsule medical device.

  Since only the alternating magnetic field of the frequency for calculation is used for calculating the position and orientation of the capsule medical device, for example, the time required for calculating the position and orientation is compared with the method of sweeping the frequency of the alternating magnetic field in a predetermined band. Can be shortened.

In addition, when the resonance frequency of the magnetic induction coil changes, for example, a magnet is mounted in a capsule medical device, and movement of the capsule medical device is controlled by controlling the movement of the mounted magnet by applying a magnetic field from the outside. In the structure to control, the case where the resonant frequency of a magnetic induction coil etc. changes under the influence of the mounted magnet can be mentioned.
Even in this case, since the frequency determination unit can obtain the calculation frequency based on the resonance frequency influenced by the mounted magnet, the capsule medical device can be used without using an element for adjusting the resonance frequency. The position and orientation can be calculated.

Moreover, in the said invention, it is desirable for the said frequency determination part to obtain | require the said frequency for calculation based on the output of the said magnetic sensor when the said induction magnet acts on the said magnetic sensor.
According to the present invention, the resonance frequency of the magnetic induction coil is obtained based on the output of the magnetic sensor by induction magnetism, and the calculation frequency is obtained based on the resonance frequency. Therefore, it is possible to use a calculation frequency that is optimal for calculating the position and orientation of each capsule medical device. As a result, it is possible to prevent a decrease in calculation accuracy of the position and orientation of the capsule medical device and to prevent an increase in time required for calculation.

Furthermore, in the said invention, it has a magnetic field frequency variable part which changes the frequency of the said alternating magnetic field temporally, and the said frequency determination part is the induction | guidance | derivation generate | occur | produced from the said magnetic induction coil by the alternating magnetic field which frequency changes temporally. When the magnetism acts on the magnetic sensor, it is desirable to obtain the calculation frequency based on the frequency characteristic of the output of the magnetic sensor.
According to the present invention, since the resonance frequency of the magnetic induction coil is obtained using an alternating magnetic field that changes in frequency with time, the resonance frequency can be obtained even when the variation in the resonance frequency of the magnetic coil increases. Therefore, it is possible to use the optimum calculation frequency for calculating the position and orientation of each capsule medical device, to prevent the calculation accuracy of the position and orientation of the capsule medical device from being lowered, and to increase the time required for calculation. Can be prevented.

  In the above invention, an impulse magnetic field generating unit that generates an impulse-like magnetic field by applying an impulse-like drive voltage to the drive coil, and the frequency determining unit uses the impulse-like magnetic field to generate the magnetic induction coil. It is desirable to obtain the calculation frequency based on the output of the magnetic sensor when the induced magnetism generated from the magnetic field acts.

  According to the present invention, since the impulse-like magnetic field has many frequency components, the frequency characteristic of the magnetic induction coil can be obtained in a shorter time compared to, for example, the method of sweeping the frequency of the magnetic field, and further, The resonance frequency can be obtained in a wide frequency band. As a result, it is possible to use the optimum calculation frequency for calculating the position and orientation of each capsule medical device, to prevent a decrease in calculation accuracy of the position and orientation of the capsule medical device, and to increase the time required for the calculation. Can be prevented.

  In the above invention, it has a mixed magnetic field generator for generating the alternating magnetic field mixed with a plurality of different frequencies, and a variable band limiter that limits the output frequency band of the magnetic sensor and can change the limit range. The frequency determination unit is an output of the magnetic sensor when the induction magnetism generated from the magnetic induction coil is acted on by the AC magnetic field in which a plurality of different frequencies are mixed, through the variable band limiting unit It is desirable to obtain the calculation frequency based on the obtained frequency at which the output of the magnetic sensor changes.

According to the present invention, since the resonance frequency of the magnetic induction coil is obtained using an alternating magnetic field in which a plurality of different frequencies are mixed, even if the variation of the resonance frequency of the magnetic induction coil becomes large, the predetermined frequency change in time The resonance frequency can be easily obtained as compared with the case where an alternating magnetic field having a frequency is used.
Further, by using the variable band limiting unit, the calculation frequency can be obtained based on the output of a predetermined frequency band among the outputs of the magnetic sensor to which the induced magnetism generated by the AC magnetic field is applied.

In the above invention, the capsule medical device includes a transmission unit that transmits a frequency value related to a resonance frequency of the magnetic induction coil stored in advance to the frequency determination unit, and the frequency determination unit includes the frequency determination unit, It is preferable that a frequency value related to the resonance frequency is received from a transmission unit, and the calculation frequency is determined based on the received frequency related to the resonance frequency.
According to the present invention, a method for obtaining a calculation frequency by measuring a resonance frequency each time position detection of a capsule medical device is performed by obtaining a calculation frequency based on a frequency related to a resonance frequency stored in advance. In comparison, the time required to calculate the position and orientation of the capsule medical device can be shortened.

In the said invention, it is desirable to have a drive coil control part which controls the said drive coil based on the said frequency for calculation.
According to the present invention, since the drive coil can be controlled based on the calculation frequency, the frequency of the alternating magnetic field generated by the drive coil can be controlled.

In the said invention, it is desirable to have a zone | band limiting part which limits the zone | band of the output frequency of the said magnetic sensor based on the said frequency for calculation.
According to the present invention, it is possible to limit the output frequency band such as induced magnetism detected by the magnetic sensor based on the calculation frequency. Therefore, it is possible to obtain the magnetic sensor output in the frequency band related to the calculation frequency with low noise, and based on this, the position and orientation of the capsule medical device can be calculated.

In the above invention, it is desirable that the plurality of magnetic sensors be arranged in a plurality of directions so as to oppose the operating range of the capsule medical device.
According to the present invention, regardless of the arrangement position of the capsule medical device, the induction magnetism having a detectable intensity acts on the magnetic sensor arranged in at least one direction of the magnetic sensors arranged in the plurality of directions. .
The strength of induced magnetism acting on the magnetic sensor is affected by the distance between the capsule medical device and the magnetic sensor and the distance between the capsule medical device and the drive coil. Therefore, even if the position of the capsule medical device is a position where the induced magnetism acting on the magnetic sensor arranged in one direction is weakened, in the magnetic sensor arranged in the other direction, the guidance acting there This is the position where the magnetism does not become weak.
As a result, the magnetic sensor can always detect the induced magnetism regardless of the position of the capsule medical device.

Further, since the same number of magnetic field information as the number of magnetic sensors arranged at different positions can be obtained, the position information of the capsule medical device according to the number of magnetic field information can be obtained.
Examples of information obtained about the capsule medical device include, for example, rotational phases φ, θ, and two axes around the X, Y, Z coordinates of the capsule medical device and the central axis of the built-in coil and orthogonal to each other. A total of six pieces of information on the intensity of induced magnetism can be listed. Therefore, if six or more pieces of magnetic field information are obtained, the above-described six pieces of position information can be obtained, and the position and direction of the capsule medical device and the strength of the induced magnetism can be obtained.

In the above-mentioned invention, it is desirable to have magnetic sensor selection means for selectively using an output signal having a strong signal output among the output signals of the plurality of magnetic sensors.
According to the present invention, by selectively using an output signal having a strong signal output, a signal output having a small noise component with respect to the signal intensity can be obtained, so that the amount of information to be processed can be reduced. , It is possible to reduce the load on calculation. In addition, since the amount of calculation processing can be reduced at the same time, the time required for calculation can also be shortened.

In the above invention, it is desirable that the drive coil and the magnetic sensor are disposed at positions facing each other across the operating range of the capsule medical device.
According to the present invention, since the drive coil and the magnetic sensor are arranged at positions facing each other across the operating range, the drive coil and the magnetic sensor can be arranged so as not to interfere structurally.

  In the above invention, the relative position changing means for changing the relative position between the drive coil and the magnetic sensor, the relative position measuring means for measuring the relative position, and the magnetic sensor when only the AC magnetic field is applied in advance. As a reference value, a storage unit for storing the position and relative position of the magnetic sensor in association with the reference value, a current position of the magnetic sensor, the drive coil, and the magnetic sensor Current reference value for generating, as a current reference value, the output value of the magnetic sensor when only the current AC magnetic field is applied based on the current relative position of the current and the reference value stored in the storage unit And a generation unit.

According to the present invention, the position and orientation of the capsule medical device can be obtained even if the relative position of the drive coil and the magnetic sensor can be changed.
Since the reference value and the position and relative position of the drive coil are stored in advance, the reference value is measured again even when the relative position of the drive coil and the magnetic sensor at the time of detecting the position of the capsule medical device is different. There is no need to do.

In the above invention, it is preferable that the current reference value generation unit generates the reference value associated with the relative position closest to the current relative position as the current reference value.
According to the present invention, since the reference value associated with the relative position closest to the current relative position is the current reference value, the time required to generate the current reference value can be shortened.

In the above invention, the current reference value generation unit obtains a predetermined approximate expression that associates the relative position with the reference value, and generates the current reference value based on the predetermined approximate expression and the current relative position. It is desirable to do.
According to the present invention, since the current reference value is generated based on a predetermined approximate expression, a more accurate current reference value can be generated as compared with, for example, a method in which the reference value is used as it is.

  Further, in the present invention, the position detection system of the present invention, a permanent magnet mounted on the capsule medical device, and an outside of the operating range of the capsule medical device are arranged and act on the permanent magnet. There is provided a capsule medical device guidance system comprising: a magnetic field generating means for generating a magnetic field to be generated; and a magnetic field direction control means for controlling the direction of the magnetic field applied to the permanent magnet by the magnetic field generating means.

According to the present invention, the direction of the force acting on the magnet can be controlled by controlling the direction of the magnetic field applied to the magnet mounted on the capsule medical device, and the moving direction of the capsule medical device can be controlled. Can be controlled.
At the same time, the position of the capsule medical device can be detected, and the capsule medical device can be guided to a predetermined position.

  In the above invention, the magnetic field generating means includes three pairs of frame-shaped electromagnets arranged to face each other in a direction orthogonal to each other, and a space in which the subject can be placed is provided inside the electromagnet. It is desirable that the drive coil and the magnetic sensor are disposed around a space in which the subject can be disposed.

According to the present invention, the direction of the parallel magnetic field generated on the inner side of the electromagnet is controlled by controlling the strength of the magnetic field generated from the three pairs of frame-shaped electromagnets arranged opposite to each other in a direction orthogonal to each other. Can be controlled in the direction. Therefore, a magnetic field in a predetermined direction can be applied to the capsule medical device, and the capsule medical device can be moved in a predetermined direction.
Further, the space inside the electromagnet is a space where the subject can be placed, and the drive coil and the magnetic sensor are placed around the space. It can be guided to a predetermined position.

In the above invention, it is desirable that a helical mechanism for converting a rotational force around the longitudinal axis of the capsule medical device into a propulsive force in the longitudinal axis direction is provided on the outer surface of the capsule medical device.
According to the present invention, when a rotational force around the longitudinal axis is applied to the capsule medical device, a force for propelling the capsule medical device in the longitudinal axis direction is generated by the operation of the spiral mechanism. Since the spiral mechanism generates a propulsive force, the direction of the propulsive force acting on the capsule medical device can be controlled by controlling the rotation direction around the longitudinal axis.

  In the above invention, the capsule medical device includes an imaging unit having an optical axis along a longitudinal axis of the capsule medical device, and further includes a display unit that displays an image captured by the imaging unit. It is desirable to provide an image control means for rotating the image picked up by the image pickup means in the reverse direction and displaying the image on the display means based on rotation information about the longitudinal axis of the capsule medical device by the direction control means.

According to the present invention, since the photographed image is rotated in the direction opposite to the rotation direction of the capsule medical device based on the rotation information (rotation phase information about the longitudinal axis), the capsule Regardless of the rotation phase of the medical device, the image can always be displayed on the display means as an image taken at a predetermined rotation phase.
For example, when the operator guides the capsule medical device while visually observing the image displayed on the display unit, as compared with the case where the displayed image is an image that rotates with the rotation of the capsule medical device, as described above. In addition, it is easier to guide the capsule medical device to a predetermined position when the displayed image is converted into an image having a predetermined rotational phase.

  In the present invention, a capsule-type medical device mounted with a position-inducing magnetic induction coil and inserted into the body of a subject, a drive coil that generates an alternating magnetic field that acts on the magnetic induction coil, and the magnetic A position detection system having a plurality of magnetic sensors for detecting induction magnetism generated by an induction coil, and a position detection method for a capsule medical device using the magnetic sensor when only the AC magnetic field acts A preliminary measurement step for measuring the frequency characteristic of the magnetic sensor, a measurement step for measuring the frequency characteristic of the magnetic sensor when the AC magnetic field and the induction magnetism act, and the frequency characteristic measured in the preliminary measurement step and the measurement step. Frequency determination for determining a calculation frequency used to calculate the position and orientation of the capsule medical device based on A step of measuring the output of the magnetic sensor when the AC magnetic field and the induction magnetism act on the frequency for calculation, and the position of the capsule medical device based on the detected output of the magnetic sensor And a position calculating step for calculating an orientation, and a position detection method for a capsule medical device.

According to the present invention, since the resonance frequency of the magnetic induction coil can be obtained by detecting the induction magnetism, even if the resonance frequency of the magnetic induction coil varies, the calculation frequency based on the varied resonance frequency is obtained. be able to. Therefore, even if the resonance frequency of the magnetic induction coil varies, the position and orientation of the capsule medical device can always be calculated based on the calculation frequency.
As a result, it is not necessary to mount an element for adjusting the resonance frequency of the magnetic induction coil, and the capsule medical device can be downsized. Alternatively, in order to adjust the resonance frequency, it is not necessary to select or adjust an element such as a capacitor that constitutes a resonance circuit together with the magnetic induction coil, thereby preventing an increase in production cost of the capsule medical device.
Since only the alternating magnetic field of the frequency for calculation is used for calculating the position and orientation of the capsule medical device, for example, it is compared with the method of sweeping the frequency of the alternating magnetic field in a predetermined band every time the position of the capsule medical device is detected. Thus, the time required for calculating the position and orientation can be shortened.

  The present invention also includes a capsule-type medical device that has a magnetic induction coil for position detection and a transmission unit that transmits a frequency value related to a resonance frequency of the magnetic induction coil to the outside, and is inserted into the body of a subject And a position detection system comprising: a drive coil that generates an alternating magnetic field that acts on the magnetic induction coil; and a plurality of magnetic sensors that detect induction magnetism generated by the magnetic induction coil. A position detection method for acquiring a frequency related to the resonance frequency transmitted by the transmitter and calculating a position and orientation of the capsule medical device based on the acquired frequency related to the resonance frequency A frequency determining step for determining a calculation frequency, and a measurement for measuring frequency characteristics of the magnetic sensor when only an alternating magnetic field of the calculation frequency is applied. A detection step of detecting an output of the magnetic sensor when the induction magnetism generated by the step, an AC magnetic field of the calculation frequency, and the induction magnetism generated by the AC magnetic field of the calculation frequency, and the detected output of the magnetic sensor And a position calculating step for calculating the position of the capsule medical device based on the method.

According to the present invention, the calculation frequency can be obtained based on the frequency related to the resonance frequency of the magnetic induction coil stored in advance in the capsule medical device. Therefore, the time required for calculating the position and orientation of the capsule medical device can be shortened as compared with the method of measuring the resonance frequency each time the position of the capsule medical device is detected and obtaining the calculation frequency.
Further, it is not necessary to mount an element for adjusting the resonance frequency of the magnetic induction coil, and the capsule medical device can be downsized. Alternatively, in order to adjust the resonance frequency, it is not necessary to select or adjust an element such as a capacitor that constitutes a resonance circuit together with the magnetic induction coil, and an increase in production cost of the capsule medical device can be prevented.
Since only the alternating magnetic field of the frequency for calculation is used for calculating the position and orientation of the capsule medical device, for example, it is compared with the method of sweeping the frequency of the alternating magnetic field in a predetermined band every time the position of the capsule medical device is detected. Thus, the time required for calculating the position and orientation can be shortened.

According to the capsule medical device position detection system, the capsule medical device guidance system, and the capsule medical device position detection method of the present invention, the frequency determination unit obtains and calculates a calculation frequency based on the varied resonance frequency. Since the position and orientation of the capsule medical device can be calculated based on the frequency for use, there is an effect that adjustment work such as an alternating magnetic field frequency used for detecting the position of the capsule medical device can be eliminated.
Therefore, it is not necessary to mount an element for adjusting the resonance frequency of the magnetic induction coil, and the capsule medical device can be reduced in size. Alternatively, it is not necessary to select or adjust an element such as a capacitor that constitutes a resonance circuit together with the magnetic induction coil in order to adjust the resonance frequency, and the production cost of the capsule medical device can be reduced. .

(Capsule type endoscope guidance system)
[First Embodiment]
Hereinafter, a first embodiment of a capsule endoscope guidance system according to the present invention will be described with reference to FIGS.
FIG. 1 is a diagram showing an outline of a capsule endoscope guidance system in the present embodiment. FIG. 2 is a perspective view of the capsule endoscope guidance system.
A capsule endoscope guidance system (capsule medical device guidance system) 10 is inserted into a body cavity from the mouth or anus of a subject 1 as shown in FIGS. A capsule endoscope (capsule medical device) 20 that optically images a wall surface and wirelessly transmits an image signal; a position detection unit (position detection system) 50 that detects the position of the capsule endoscope 20; A magnetic guidance device 70 for guiding the capsule endoscope 20 based on the detected position of the capsule endoscope 20 and an instruction from the operator, and an image display for displaying an image signal transmitted from the capsule endoscope 20 The apparatus 80 is schematically configured.

As shown in FIG. 1, the magnetic guidance device 70 supplies a triaxial Helmholtz coil unit (magnetic field generating means, electromagnet) 71 that generates a parallel magnetic field that drives the capsule endoscope 20 and a triaxial Helmholtz coil unit 71. A Helmholtz coil driver 72 that amplifies and controls the current to flow, a rotating magnetic field control circuit (magnetic field direction control means) 73 that controls the direction of the parallel magnetic field that drives the capsule endoscope 20, and a capsule endoscope that is input by the practitioner And an input device 74 that outputs the traveling direction of the mirror 20 to the rotating magnetic field control circuit 73.
In the present embodiment, the three-axis Helmholtz coil unit 71 is described, but the condition of the Helmholtz coil may not be strictly satisfied. For example, the coils may not be circular, but may have a substantially square shape as shown in FIG. 1, and the interval between the opposing coils may be outside the conditions of the Helmholtz coil as long as the functions of this embodiment are satisfied. Absent.

As shown in FIGS. 1 and 2, the triaxial Helmholtz coil unit 71 is formed in a substantially rectangular shape. The three-axis Helmholtz coil unit 71 includes three pairs of Helmholtz coils (electromagnets) 71X, 71Y, 71Z facing each other, and each pair of Helmholtz coils 71X, 71Y, 71Z is represented by X, Y, Z in FIG. It arrange | positions so that it may become substantially perpendicular | vertical with respect to an axis | shaft. Helmholtz coils arranged substantially perpendicular to the X, Y, and Z axes will be referred to as Helmholtz coils 71X, 71Y, and 71Z, respectively.
Further, the Helmholtz coils 71X, 71Y, 71Z are arranged so as to form a substantially rectangular space S therein. The space S is a working space for the capsule endoscope 20 as shown in FIG. 1, and is also a space in which the subject 1 is placed as shown in FIG.

The Helmholtz coil driver 72 includes Helmholtz coil drivers 72X, 72Y, and 72Z that control the Helmholtz coils 71X, 71Y, and 71Z, respectively.
The rotating magnetic field control circuit 73 receives data (direction of the rotation axis (longitudinal axis) R of the capsule endoscope 20) in which the capsule endoscope 20 is currently directed from a position detection device described later. The advancing direction instruction of the capsule endoscope 20 input from the input device 74 by the practitioner is input. The rotating magnetic field control circuit 73 outputs signals for controlling the Helmholtz coil drivers 72X, 72Y, and 72Z, and the rotational phase data of the capsule endoscope 20 is output to the image display device 80. ing.
In addition, as the input device 74, an input device that indicates the traveling direction of the capsule endoscope 20 by tilting the joystick is used.
The input device 74 may be a joystick type as described above, or may be another type of input device such as an input device that indicates the direction of travel by pressing a button in the direction of travel. .

As shown in FIG. 1, the position detection unit 50 includes a drive coil (drive coil) 51 that generates induction magnetism in a magnetic induction coil (to be described later) in the capsule endoscope 20, and induction magnetism generated by the magnetic induction coil. A sense coil (magnetic sensor) 52 to be detected, and a position detection device that calculates the position of the capsule endoscope 20 based on the induced magnetism detected by the sense coil 52 and controls the alternating magnetic field formed by the drive coil 51 ( Position analysis means, magnetic field frequency variable unit, drive coil control unit) 50A.
The position detection device 50A is provided with a calculation frequency determination unit (frequency determination unit) 50B, and is configured to receive a signal from a sense coil receiving circuit described later.

Between the position detection device 50A and the drive coil 51, a signal generation circuit 53 for generating an alternating current based on an output from the position detection device 50A and a signal generation circuit 53 based on an output from the position detection device 50A are input. A drive coil driver 54 that amplifies the alternating current and a drive coil selector 55 that supplies an alternating current to the drive coil 51 selected based on the output from the position detection device 50A are disposed.
Between the sense coil 52 and the position detection device 50A, a sense coil selector (selecting an alternating current including position information of the capsule endoscope 20 from the sense coil 52 based on an output from the position detection device 50A) (Magnetic sensor selection means) 56 and a sense coil receiving circuit 57 that extracts an amplitude value from the alternating current that has passed through the sense coil selector 56 and outputs it to the position detection device 50A.

FIG. 3 is a schematic view showing a cross section of the capsule endoscope guidance system.
Here, as shown in FIGS. 1 and 3, the drive coil 51 is obliquely formed at four corners above the substantially rectangular parallelepiped working space formed by the Helmholtz coils 71 </ b> X, 71 </ b> Y, 71 </ b> Z (on the positive side of the Z axis). Has been placed. The drive coil 51 is formed as a substantially triangular coil that connects the corners of rectangular Helmholtz coils 71X, 71Y, 71Z. Thus, by arranging the drive coil 51 upward, interference between the drive coil 51 and the subject 1 can be prevented.
The drive coil 51 may be a substantially triangular coil as described above, or may be a coil having various shapes such as a circular shape.

In addition, the sense coil 52 is formed as an air-core coil, and is located on the inner side of the Helmholtz coils 71X, 71Y, 71Z and facing the drive coil 51 via the working space of the capsule endoscope 20. It is supported by three planar coil support portions 58 arranged at positions facing each other in the Y-axis direction. Nine sense coils 52 are arranged in a matrix on one coil support 58, and the entire position detection unit 50 is provided with 27 sense coils 52.
The position of the sense coil 52 may be on the same plane as the Helmholtz coils 71X, 71Y, 71Z, may be on the outside, or may be freely arranged.

FIG. 4 is a schematic diagram showing a circuit configuration of the sense coil receiving circuit 57.
As shown in FIG. 4, the sense coil receiving circuit 57 amplifies the AC voltage, and a high-pass filter (HPF) 59 that removes a low-frequency component of the AC voltage that includes the input position information of the capsule endoscope 20. A preamplifier 60; a bandpass filter (BPF, band limiting unit) 61 that removes the high frequency included in the amplified AC voltage; an amplifier (AMP) 62 that amplifies the AC voltage from which the high frequency has been removed; An effective value detection circuit (True RMS converter) 63 that detects the amplitude and extracts and outputs the amplitude value, an A / D converter 64 that converts the amplitude value into a digital signal, and the digitized amplitude value temporarily And a memory 65 stored in the memory.
Here, the high-pass filter (HPF) 59 is also induced by a rotating magnetic field generated by the Helmholtz coils 71X, 71Y, 71Z, and also serves to remove a low-frequency signal detected by the sense coil 52. Thus, the position detection unit 50 can be normally operated while the magnetic guidance device 70 is operated.

The high-pass filter 59 has a resistance 67 disposed on each of the pair of wirings 66A extending from the sense coil 52, a wiring 66B that connects between the pair of wirings 66A and is grounded at the approximate center thereof, and a ground point on the wiring 66B. And a pair of capacitors 68 disposed opposite to each other. The preamplifier 60 is disposed on each of the pair of wirings 66 </ b> A, and the AC voltage output from the preamplifier 60 is input to one band-pass filter 61. The memory 65 temporarily stores the amplitude values obtained from the nine sense coils 52, and outputs the stored amplitude values to the position detection device 50A.
In addition, a common mode filter that can remove common mode noise may be provided.
As described above, the effective value detection circuit 63 may be used for extracting the amplitude value of the AC voltage, or the amplitude value is obtained by detecting the voltage by smoothing the magnetic information using a rectifier circuit. The amplitude value may be detected using a peak detection circuit that detects the peak of the AC voltage.
Further, the detected AC voltage waveform changes in phase with respect to the waveform added to the drive coil 51 depending on the presence / absence and position of the magnetic induction coil 42. This phase change may be detected by a lock-in amplifier or the like.

  As shown in FIG. 1, the image display device 80 is based on an image receiving circuit 81 that receives an image transmitted from the capsule endoscope 20, a received image signal, and a signal from the rotating magnetic field control circuit 73. A display unit (display means, image control means) 82 for displaying an image is included.

FIG. 5 is a schematic diagram showing the configuration of the capsule endoscope.
As shown in FIG. 5, the capsule endoscope 20 includes an exterior 21 that houses various devices therein, an imaging unit (imaging unit) 30 that images an inner wall surface of a body cavity line of a subject, and the like. The battery 39 that drives the imaging unit 30, the induction magnetism generation unit 40 that generates induction magnetism by the drive coil 51, and the drive that drives the capsule endoscope 20 by receiving the magnetism generated by the magnetic induction device 70. And a general magnet (permanent magnet) 45.

The exterior 21 is a cylindrical capsule main body (hereinafter simply referred to as a main body) 22 that transmits infrared rays with the rotation axis (longitudinal axis) R of the capsule endoscope 20 as a central axis, and a transparent covering the front end of the main body 22. The hemispherical tip 23 and the hemispherical rear end 24 covering the rear end of the main body form a capsule container sealed with a watertight structure.
Further, the outer peripheral surface of the main body of the exterior 21 is provided with a spiral portion (spiral mechanism) 25 in which a wire having a circular cross section around the rotation axis R is spirally wound.
When the driving magnet rotates in response to the rotating magnetism generated by the magnetic guiding device 70, the spiral portion also rotates, and the capsule endoscope 20 can be guided in the direction of the rotation axis R in the lumen.

  The imaging unit 30 includes a substrate 36A disposed substantially perpendicular to the rotation axis R, an image sensor 31 disposed on the surface of the substrate 36A on the distal end portion 23 side, and an inner wall surface of the body cavity passage of the subject. A lens group 32 for forming an image of the image sensor 31 on the image sensor 31, an LED (Light Emitting Diode) 33 for illuminating the inner wall surface of the body cavity conduit, and signal processing disposed on the surface on the rear end 24 side of the substrate 36A The unit 34 and a wireless element 35 that transmits an image signal to the image display device 80 are schematically configured.

  The signal processing unit 34 is electrically connected to the battery 39 via the substrates 36A, 36B, 36C, and 36D and the flexible substrates 37A, 37B, and 37C, and is electrically connected to the image sensor 31 via the substrate 36A. The LED 33 is electrically connected via the substrate 36A, the flexible substrate 37A, and the support member 38. Further, the signal processing unit 34 compresses and temporarily stores (memory) the image signal acquired by the image sensor 31, transmits the compressed image signal to the outside from the wireless element 35, and from a switch unit 46 described later. On / off of the image sensor 31 and the LED 33 is controlled based on the above signal.

The image sensor 31 converts an image formed through the distal end portion 23 and the lens group 32 into an electrical signal (image signal) and outputs it to the signal processing unit 34. For example, a CMOS (Complementary Metal Oxide Semiconductor) or a CCD can be used as the image sensor 31.
A plurality of LEDs 33 are arranged at intervals in the circumferential direction around the rotation axis R on the support member 38 arranged on the distal end portion 23 side from the substrate 36A.

The driving magnet 45 is disposed on the rear end portion 24 side of the signal processing unit 34. The drive magnet 45 is arranged or magnetized so as to have a magnetization direction in a direction orthogonal to the rotation axis R (for example, the vertical direction in FIG. 5).
On the rear end portion 24 side of the drive magnet 45, a switch portion 46 disposed on the substrate 36B is provided. The switch unit 46 includes an infrared sensor 47 and is electrically connected to the signal processing unit 34 via the substrate 36B and the flexible substrate 37A, and the battery via the substrates 36B, 36C and 36D and the flexible substrates 37B and 37C. 39 is electrically connected.
A plurality of switch portions 46 are arranged at equal intervals in the circumferential direction around the rotation axis R, and the infrared sensor 47 is arranged so as to face the outside in the diameter direction. In the present embodiment, an example in which four switch units 46 are arranged will be described, but the number of switch units 46 is not limited to four, and any number may be used.

On the rear end portion 24 side of the switch portion 46, a battery 39 is disposed between the substrates 36C and 36D.
A wireless element 35 is disposed on the surface on the rear end 24 side of the substrate 36D. The wireless element 35 is electrically connected to the signal processing unit 34 via the substrates 36A, 36B, 36C, 36D and the flexible substrates 37A, 37B, 37C.

  An induction magnetism generator 40 is disposed on the rear end 24 side of the wireless element 35. The induction magnetism generation unit 40 includes a core member 41 made of ferrite formed in a cylindrical shape whose central axis substantially coincides with the rotation axis R, a magnetic induction coil 42 disposed on the outer peripheral portion of the core member 41, and a magnetic induction coil 42 and a capacitor (not shown) that is electrically connected to 42 and forms a resonance circuit 43.

Note that the capacitance of the capacitor is determined in accordance with the inductance of the magnetic induction coil 42 so that the resonance frequency of the resonance circuit 43 is close to the frequency of the AC magnetic field generated by the drive coil 51 of the position detection unit 50. Further, the frequency of the alternating magnetic field generated by the drive coil 51 may be determined in accordance with the resonance frequency of the resonance circuit 43.
In addition to ferrite, a magnetic material is suitable for the core member, and iron, nickel, permalloy, cobalt, or the like can also be used.

Next, the operation of the capsule endoscope guidance system 10 having the above configuration will be described.
First, an outline of the operation of the capsule endoscope guidance system 10 will be described.
As shown in FIGS. 1 and 2, the capsule endoscope 20 is inserted into the body cavity from the mouth or anus of the subject 1 lying in the position detection unit 50 and the magnetic guidance device 70. The position of the inserted capsule endoscope 20 is detected by the position detection unit 50, and the magnetic guidance device 70 guides the inside of the body cavity of the subject 1 to the vicinity of the affected part. The capsule endoscope 20 captures an image of the inner wall surface of the body cavity duct during guidance to the affected area and in the vicinity of the affected area. Then, the imaged data on the inner wall surface of the body cavity conduit and the data near the affected area are transmitted to the image display device 80. The image display device 80 displays the transmitted image on the display unit 82.

Next, a method for obtaining a calculation frequency used for detecting the position and direction of the capsule endoscope 20 and a method for detecting the position and direction of the capsule endoscope 20 will be described.
6 and 7 are flowcharts for explaining how to obtain the calculation frequency and the procedure for detecting the position and direction of the capsule endoscope 20.

First, as shown in FIG. 6, the position detection unit 50 is calibrated (Step 1; preliminary measurement step). That is, the output of the sense coil 52 that is generated when the capsule endoscope 20 is not disposed in the space S, that is, the AC magnetic field formed by the drive coil 51 acts is measured.
As a specific method of forming the AC magnetic field, as shown in FIG. 1, the signal generation circuit 53 generates an AC signal, and the AC signal is output to the drive coil driver 54. The drive coil driver 54 amplifies the AC signal and supplies the AC current to the drive coil 51 via the drive coil selector 55. The frequency of the generated alternating current is a frequency within a range from several kHz to 100 kHz, and the frequency changes (sweeps) within the above range according to time so as to include a resonance frequency described later. The resonance frequency at this stage may be estimated from characteristic values of the magnetic induction coil 42 and the capacitor. As will be described later, this frequency can be fixed to an arbitrary value.
In addition, the range to be swept is not limited to the above-described range, and may be a narrower range or a wider range, and is not particularly limited.

  The AC signal is amplified by the drive coil driver 54 based on an instruction from the position detection device 50A, and is output to the drive coil selector 55 as an AC current. The amplified alternating current is supplied to the drive coil 51 selected by the position detecting device 50A in the drive coil selector 55. The alternating current supplied to the drive coil 51 forms an alternating magnetic field in the working space S of the capsule endoscope 20.

As shown in FIG. 4, the formed AC magnetic field generates an induced electromotive force in the sense coil 52, and an AC voltage is generated in the sense coil 52. This AC voltage is input to the sense coil receiving circuit 57 via the sense coil selector 56, and the amplitude value of the AC voltage is extracted.
As shown in FIG. 4, the AC voltage input to the sense coil receiving circuit 57 is first amplified by the preamplifier 60 after the low-frequency component included in the AC voltage is removed by the high-pass filter 59. Thereafter, the high frequency is removed by the band pass filter 61 and amplified by the amplifier 62. From the AC voltage from which unnecessary components are removed in this way, the amplitude value of the AC voltage is extracted by the effective value detection circuit 63. The extracted amplitude value is converted into a digital signal by the A / D converter 64 and stored in the memory 65. At this time, the transmission frequency of the bandpass filter 61 is adjusted each time so as to be the frequency of the alternating magnetic field.

  The memory 65 stores, for example, an amplitude value corresponding to one period obtained by sweeping the signal generated by the signal generation circuit 53 in the vicinity of the resonance frequency of the resonance circuit 43, and collectively collects the amplitude values for one period. This is output to the 50A frequency determination unit 50B. The output value at this time is Vc (f, N). Here, Vc indicates that f is a function of the frequency of the alternating magnetic field and N: the number of the sense coil.

Next, the capsule endoscope 20 is placed in the space S (Step 2). The arrangement method of the capsule endoscope 20 is not particularly limited. For example, if a holder for holding the capsule endoscope is installed in the space S, the capsule endoscope 20 may be arranged on the holder. Good.
Further, this holder may directly hold the capsule endoscope 20, or may be configured to hold the capsule endoscope in a package (not shown). This configuration is hygienic.

Then, the frequency characteristic of the magnetic induction coil 42 mounted on the capsule endoscope 20 is measured (Step 3; measurement step). Specifically, in the same manner as in Step 1, an alternating magnetic field whose frequency changes in a predetermined band is generated from the drive coil 51, and the sense coil 52 is generated by this alternating magnetic field and induced magnetism induced in the magnetic induction coil 42. Measure the output while changing the frequency (sweep). The output at this time is V ₀ (f, N). f is the frequency of the alternating magnetic field, and N is the number of the sense coil 52.
Since the magnetic induction coil 42 forms the resonance circuit 43 together with the capacitor, if the period of the alternating magnetic field coincides with the resonance frequency of the resonance circuit 43, the induced current flowing through the resonance circuit 43 (magnetic induction coil 42) increases. Inductive magnetism is also strengthened. Further, since the core member 41 made of dielectric ferrite is disposed at the center of the magnetic induction coil 42, the induced magnetic field is easily collected on the core member 41, and the formed induction magnetism is further strengthened.

  Thereafter, the frequency determination unit 50B calculates a difference between the output of the sense coil 52 measured in Step 1 and the output of the sense coil 52 measured in Step 3, and based on the calculated difference, the capsule endoscope 20 The frequency for calculation used for the detection of the position and orientation is obtained (Step 4; frequency determination step).

FIG. 8 is a diagram illustrating the frequency characteristics of the magnetic induction coil 42, and is a diagram illustrating a gain change and a phase change of a certain sense coil 52 output when the frequency of the alternating magnetic field changes. The gain V (f, N) in this graph is represented by V (f, N) = V ₀ (f, N) −Vc (f, N). That is, the gain V (f, N) is indicated by the difference in each frequency between the result measured in Step 1 and the result measured in Step 3.
As shown in FIG. 8, the amplitude value of the AC voltage that is the output of the sense coil 52 varies greatly depending on the frequency characteristics of the AC magnetic field generated by the magnetic induction coil 42, that is, the relationship with the resonance frequency of the resonance circuit 43. In FIG. 8, the horizontal axis represents the frequency of the AC magnetic field, and the vertical axis represents the gain change (dBm) and phase change (degree) of the AC voltage flowing through the resonance circuit 43. The gain change is represented by a solid line. FIG. 8 shows that the maximum value is obtained at a frequency lower than the resonance frequency, the gain change is zero at the resonance frequency, and the minimum value is obtained at a frequency higher than the resonance frequency. ing. Further, the phase change is represented by a broken line, which indicates that it is most delayed at the resonance frequency. Here, it is confirmed that the resonance frequency of the resonance circuit 43 coincides with the frequency at which the phase is most delayed and the frequency at which the gain crosses 0 by measuring the impedance characteristics of the resonance circuit with a network analyzer or an impedance analyzer. .
Depending on the measurement conditions, there may be a minimum value at a frequency lower than the resonance frequency, a maximum value at a frequency higher than the resonance frequency, and the phase most advanced at the resonance frequency.

  Specifically, the frequency at which the gain change of the above-described sense coil 52 is maximized and minimized is obtained, and these two frequencies are used as calculation frequencies. The low frequency is the low frequency calculation frequency, and the frequency is high. The frequency for high frequency side calculation is used. In the present embodiment, as shown in FIG. 8, there are extreme values of gain change at about 18 kHz and about 20.5 kHz, the former being the low frequency side calculation frequency and the latter being the high frequency side calculation frequency. .

Thus, by using the difference in the output of the sense coil 52 between Step 1 and Step 2, it is possible to remove the influence of the drift of the output value due to the temperature characteristic of the sense coil receiving circuit 57, etc., and to obtain a highly accurate calculation frequency. Can be sought.
Here, when the low frequency side calculation frequency is f _LOW and the high frequency side calculation frequency is f _HIGH , Vc (f _LOW , N), Vc (f _HIGH , N), (N: 1) in all sense coils. , 2, 3,..., The number of sense coils) is stored as a reference value. After Step 5, the output of the sense coil 52 measured at the low frequency side calculation frequency (f _LOW ) is measured at V (f _LOW , N) (N is the number of the sense coil) and the high frequency side calculation frequency (f _HIGH ). When the output of the sense coil 52 is expressed as V (f _HIGH , N) (N is the number of the sense coil), the value used for position calculation is Vs (f _LOW , N calculated based on the output of the sense coil 52. ), Vs (f _HIGH , N) is obtained by the following calculation formula.
Vs (f _LOW , N) = V (f _LOW , N) −Vc (f _LOW , N)
_{Vs (f HIGH, N) =} V (f HIGH, N) -Vc (f HIGH, N)
Therefore, in the subsequent steps, Vs (f _LOW , N) and Vs (f _HIGH , N) are expressed as “values calculated based on the output of the sense coil 52”.

  In addition, when calculating | requiring the above-mentioned calculation frequency, if there exists an output of at least 1 sense coil 52, the low frequency side calculation frequency and the high frequency side calculation frequency can be calculated | required. That is, in step 1, output frequency characteristics for all the sense coils 52 are measured, but in step 3, only the specific sense coil 52 needs to be measured, and the processing of step 4 is performed to obtain the calculation frequency. You can do it.

First, one sense coil 52 is selected. Thereafter, an AC magnetic field is generated from the drive coil 51 while sweeping. At that time, the center frequency of the bandpass filter 61 connected to the selected sense coil 52 is changed (swept) in accordance with the frequency of the alternating magnetic field generated from the driver coil 51. The output of the sense coil 52 (output after passing through the bandpass filter 61, the amplifier 62, and the True RMS converter 63) while the AC magnetic field generated from the drive coil 51 is swept is measured.
Thereafter, the capsule endoscope 20 is disposed inside the space S. In the same manner as described above, an AC magnetic field is generated while sweeping from the drive coil 51, and at this time, the center frequency of the bandpass filter 61 connected to the selected sense coil 52 is matched with the frequency of the AC magnetic field generated from the drive coil 51. And the output of the sense coil 52 is measured.

Then, from the measurement result when the capsule endoscope 20 is arranged in the space S (the output of the sense coil 52), the measurement result when the capsule endoscope 20 is not arranged in the space S (the sense coil 52). Difference).
Since the result is the same as the result of FIG. 8 described above, the calculation frequency can be obtained.
Calibration for all the sense coils 52 is performed as follows. That is, after determining the calculation frequency, the capsule endoscope 20 is taken out of the space S again, and the center frequency of the bandpass filter 61 is adjusted to the low frequency side calculation frequency. Then, the frequency of the AC magnetic field formed by the drive coil 51 is adjusted to the low frequency side calculation frequency. Then, an AC magnetic field having a low frequency side calculation frequency is generated from the drive coil 51, and the outputs of all the sense coils 52 are measured. This measured value is stored as Vc (f _LOW , N).

As the next step, the center frequency of the bandpass filter 61 is adjusted to the high frequency side calculation frequency. Then, the frequency of the alternating magnetic field formed by the drive coil 51 is matched with the high frequency side calculation frequency, and an alternating magnetic field of the high frequency side calculation frequency is generated from the drive coil 51. Then, the outputs of all the sense coils 52 are measured. This value is stored as Vc (f _HIGH , N).

When these calculation frequencies are obtained, the position and direction of the capsule endoscope 20 are detected next.
First, the center frequency of the bandpass filter 61 is matched with the low frequency side calculation frequency (Step 5). Further, the transmission frequency band of the band pass filter 61 is set to a band that can extract the extreme value of the gain change of the sense coil 52.
Then, the frequency of the AC magnetic field formed by the drive coil 51 is matched with the low frequency side calculation frequency (Step 6). Specifically, the frequency of the alternating magnetic field formed by the drive coil 51 is controlled by controlling the frequency of the alternating current generated by the signal generating circuit 53 to the low frequency side calculation frequency.

Then, an alternating magnetic field having a low frequency side calculation frequency is generated from the drive coil 51, and the induction magnetism induced in the magnetic induction coil 42 is detected by the sense coil 52 (Step 7; detection step). That is, the output of the sense coil 52 is measured, and a value calculated based on the output of the sense coil 52, Vs (f _LOW , N), is obtained. Here, N indicates the number of the selected sense coil 52.

Next, the center frequency of the bandpass filter 61 is matched with the high frequency side calculation frequency (Step 8).
Then, the frequency of the alternating magnetic field formed by the drive coil 51 is matched with the frequency for high frequency side calculation (Step 9).
Then, an AC magnetic field having a high frequency side calculation frequency is generated from the drive coil 51, and the induction magnetism induced in the magnetic induction coil 42 is detected by the sense coil 52 (Step 10; detection step). That is, the output of the sense coil 52 is measured, and a value calculated based on the output of the sense coil 52, Vs (f _HIGH , N), is obtained. Here, N indicates the number of the sense coil 52.
As described above, detection by the low frequency side calculation frequency may be performed first, and then detection by the high frequency side calculation frequency may be performed later. You may detect by the frequency for low frequency side calculation.

Thereafter, the position detection device 50A obtains an output difference (amplitude difference) Vs (f _LOW , N) −Vs (f _HIGH , N) at the low frequency side calculation frequency and the high frequency side calculation frequency in each sense coil 52. Then, which sense coil 52 output difference is used to estimate the position of the capsule endoscope 20 is selected (Step 11).
The method of selecting the sense coil 52 is not particularly limited as long as the sense coil 52 having a large output difference can be selected. For example, as shown in FIG. 9, a sense coil 52 that faces the drive coil 51 via the capsule endoscope 20 may be selected, or the drive coil 51 is arranged as shown in FIG. You may select the sense coil 52 which adjoins a surface and is arrange | positioned on the surface which mutually opposes.
The position detection device 50A selects the sense coil 52 by outputting an instruction to the sense coil selector 56 to input the alternating current from the selected sense coil 52 to the sense coil receiving circuit 57.

Then, the position detection device 50A calculates the position and orientation of the capsule endoscope 20 based on the output difference of the selected sense coil 52 (Step 12; position calculation step), and determines the position and orientation (Step 13). .
Specifically, the position detection device 50A solves the simultaneous equations relating to the position, direction, and magnetic field strength of the capsule endoscope 20 based on the amplitude difference obtained from the selected sense coil 52. The position of the capsule endoscope 20 is obtained.
As described above, based on the output difference of the sense coil 52, the change in the characteristics of the sense coil receiving circuit due to environmental conditions (for example, temperature) can be canceled, and stable accuracy is not affected by the environmental conditions. Thus, the position of the capsule endoscope 20 can be obtained.

Examples of the information such as the position of the capsule endoscope 20 include position coordinates of X, Y, and Z, directions φ and θ of the longitudinal axis (rotation axis) of the capsule endoscope 20, and the magnetic induction coil 42. There are six types of information: the strength of the induced magnetism formed by
In order to estimate these six pieces of information by calculation, outputs from at least six sense coils 52 are required. Therefore, in selecting the sense coil 52 in Step 11, it is desirable to select at least six sense coils 52.

Then, as shown in FIG. 7, the sense coil 52 used for the next control is selected (Step 14).
That is, the position detection device 50A calculates the magnetic field intensity generated from the magnetic induction coils 42 at the positions of all the sense coils 52 based on the position and orientation of the capsule endoscope 20 calculated in Step 13, and calculates the magnetic field intensity. The required number of sense coils 52 in the strong position is selected. When the position and orientation of the capsule endoscope are repeatedly obtained, the sense coil 52 is selected based on the position and orientation of the capsule endoscope 20 calculated in Step 22 described later.

  In this embodiment, the number of sense coils 52 to be selected may be six or more. However, when the number of sense coils 52 is about 10 to 15, the position calculation error can be suppressed small. In addition, the selection method of the sense coils 52 is based on the position and orientation of the capsule endoscope 20 obtained in Step 13 (or Step 22 described later), and all the sense coils 52 by the magnetic field generated from the magnetic induction coil 42 are selected. An output may be obtained by calculation, and a required number of sense coils 52 having a large output may be selected.

Thereafter, the center frequency of the bandpass filter 61 is again matched with the low frequency side calculation frequency (Step 15).
Then, the frequency of the alternating magnetic field formed by the drive coil 51 is adjusted to the low frequency side calculation frequency (Step 16).
Then, an alternating magnetic field having a low frequency side calculation frequency is generated from the drive coil 51, and the induction magnetism induced in the magnetic induction coil 42 is detected by the sense coil 52 selected in Step 14 (Step 17; detection step). Then, similarly to Step 7, a value calculated based on the output of the sense coil 52, Vs (f _LOW , N), is obtained.

Next, the center frequency of the bandpass filter 61 is matched with the high frequency side calculation frequency (Step 18).
Then, the frequency of the alternating magnetic field formed by the drive coil 51 is matched with the frequency for high frequency side calculation (Step 19).
Then, an AC magnetic field having a high frequency side calculation frequency is generated from the drive coil 51, and the induction magnetism induced in the magnetic induction coil 42 is detected by the sense coil 52 selected in Step 13 (Step 20; detection step). Then, similarly to Step 10, a value calculated based on the output of the sense coil 52, Vs (f _HIGH , N), is obtained.

Then, the position detection device 50A calculates the position and orientation of the capsule endoscope 20 based on the output difference of the sense coil 52 selected in Step 14 (Step 21; position calculation step), and determines the position and orientation ( Step 22).
In step 22, the calculated position and orientation data of the capsule endoscope apparatus 20 may be output to another apparatus or the display unit 82.
Thereafter, when the detection of the position and orientation of the capsule endoscope apparatus 20 is continued, the process returns to the above Step 14 to detect the position and orientation.

In parallel with the above-described control, the position detection device 50A selects the drive coil 51 that forms a magnetic field, and outputs an instruction to the drive coil selector 55 to supply an alternating current to the selected drive coil 51. To do. As shown in FIG. 11, the selection method of the drive coil 51 includes a straight line connecting the drive coil 51 and the magnetic induction coil 42 (direction of the drive coil 51) and the central axis of the magnetic induction coil 42 (of the capsule endoscope 20). As shown in FIG. 12, the three drive coils 51 are arranged so that the direction of the magnetic field acting on the magnetic induction coil 42 is primarily independent. Is selected to supply alternating current.
As a more preferable method, a method of excluding the drive coil 51 in which the direction of the magnetic force line formed by the drive coil 51 and the central axis of the magnetic induction coil 42 are substantially orthogonal is effective.

As described above, the drive coil selector 55 may be used to limit the number of drive coils 51 that form an alternating magnetic field, or the drive coil selector 55 may be used without changing the number of drive coils 51 from the beginning. Three may be used.
As described above, three drive coils 51 may be selected to form an alternating magnetic field, or all the drive coils 51 may generate an alternating magnetic field as shown in FIG.

Here, the operation | movement which switches the drive coil 51 is demonstrated more concretely.
The operation of switching the drive coil is an induction generated from the magnetic induction coil 42 when the direction of the magnetic field generated by the drive coil 51 and the direction of the magnetic induction coil 42 become perpendicular to each other at the position of the capsule endoscope 20. This is done as a countermeasure against the possibility of problems such as a decrease in the accuracy of position detection due to a decrease in the magnetic field.

The direction of the magnetic induction coil 42, that is, the direction of the capsule endoscope 20, can be known from the output of the position detection device 50A. Further, the direction of the magnetic field created by the drive coil 51 at the position of the capsule endoscope 20 can be obtained by calculation.
Therefore, the angle between the direction of the capsule endoscope 20 and the direction of the magnetic field generated by the drive coil 51 at the position of the capsule endoscope 20 can be obtained by calculation.
Similarly, the direction of the magnetic field at the position of the capsule endoscope 20 of the magnetic field generated by each of the drive coils 51 arranged at different positions and orientations can also be obtained by calculation. Similarly, the capsule endoscope 20 And the angle formed by the direction of the magnetic field created by each drive coil 51 at the position of the capsule endoscope 20 can be obtained by calculation.
As a result, by selecting the drive coil 51 in which the angle formed between the direction of the capsule endoscope 20 and the direction of the magnetic field created by the drive coil 51 at the position of the capsule endoscope 20 is acute, The induction magnetic field generated from the induction coil 42 can be kept large, and a good state can be maintained for position detection.

In order to perform the switching operation of the drive coil 51, the following operation is performed in the calibration of Step 1 described above.
First, one drive coil 51 is selected, and an alternating magnetic field is generated from the drive coil 51 while changing the frequency (sweep). At this time, the outputs of all the sense coils 52 are measured while matching the center frequency of the band-pass filter 61 disposed at the subsequent stage of the sense coil 52 with the frequency of the AC magnetic field generated from the drive coil 51. The frequency characteristic of the sense coil 52 associated with is obtained.
Then, the frequency characteristics of all sense coils are stored in association with the selected drive coil 51.

Next, another drive coil 51 is newly selected, and an alternating magnetic field is generated from the drive coil 51 while changing the frequency (sweep). At this time, the outputs of all the sense coils 52 are measured while matching the center frequency of the band-pass filter 61 arranged at the subsequent stage of the sense coil 52 with the frequency of the alternating magnetic field generated from the drive coil 51, and the drive coils. The frequency characteristic of the sense coil 52 associated with 51 is obtained.
Then, the frequency characteristics of all the sense coils are stored in association with the newly selected drive coil 51.
By repeating this operation for all the drive coils, the frequency characteristics of the sense coils 52 in all combinations of the drive coils 51 and the sense coils 52 can be stored.

Next, as described above, the capsule endoscope 20 is placed in the space S (STEP 2), and the frequency characteristics when the capsule endoscope 20 is placed in the space S are measured. In this measurement, an arbitrary drive coil 51 is selected, an arbitrary sense coil 52 is selected, and an output frequency characteristic of the sense coil 52 in the combination is calculated. (STEP3)
Based on the result obtained in STEP 3, the frequency characteristic of the sense coil 52 stored in STEP 1 in the combination of the drive coil 51 and the sense coil 52 selected in STEP 3 is determined for each frequency component. The result is as shown in FIG. Then, the calculation frequency is selected as described above.

Then, based on the frequency characteristics of the sense coil 52 in the combination of all the drive coils 51 and the sense coil 52 obtained in STEP 1, the capsule endoscope 20 in the combination of all the drive coils 51 and the sense coil 52 at the calculation frequency. The output of the sense coil when no exists in the space S is extracted. This corresponds to the above-described Vc (f _LOW , N) and Vc (f _HIGH , N), but here, since there is a relationship with all the drive coils, Vc (f _LOW , N, M), Vc (f _HIGH , N, M). N is the number of the sense coil, and M is the number of the drive coil.
STEP 5 is the same as described above, and will be omitted.

In STEP 6, the frequency of the signal generation circuit is set to the low frequency side calculation frequency, and the position detection device 50A operates the drive coil selector 55 to select one of the drive coils 55 as an output drive coil.
In STEP 7, the outputs of all the sense coils are determined. The measured value here is the same as V (f _LOW , N) described above.

A value Vs (f _LOW , N) = V (f _LOW , N) −Vc (f _LOW , N, M) calculated based on the output of the sense coil 52
Ask for. Here, M is a number representing the dry coil selected in STEP6. STEP 5 is the same as described above, and will be omitted.
In STEP 9, the drive coil 52 selected in STEP 6 is left as it is, and the same operation as described above is performed.
In STEP 10, the outputs of all sense coils are measured. The fixed value here is the same as V (f _HIGH , N) described above.

A value Vs (f _HIGH , N) = V (f _HIGH , N) −Vc (f _HIGH , N, M) calculated based on the output of the sense coil 52
Ask for. Here, M is a number representing the drive coil selected in STEP6.
STEP11, STEP12, and STEP13 are the same as described above, and a description thereof is omitted.
In STEP14, the sense coil used for the next position calculation is selected and the drive coil used for the next measurement is selected.
Since the selection of the sense coil is the same as described above, it will be omitted, and a method for selecting the drive coil will be described.

First, the direction of the magnetic field created by the drive coil 51 at the position of the capsule endoscope 20 is obtained by calculation. Next, the angle formed by the direction of the capsule endoscope 20 and the direction of the magnetic field created by the drive coil 51 at the position of the capsule endoscope 20 is calculated.
Similarly, the direction of the magnetic field generated by each drive coil 51 arranged at a different position and orientation at the position of the capsule endoscope 20 is calculated. Similarly, the angle formed by the direction of the capsule endoscope 20 and the direction of the magnetic field created by each of the drive coils 51 at the position of the capsule endoscope 20 is calculated.

From these calculation results, the drive coil 51 having the most acute relationship between the direction of the capsule endoscope 20 and the angle between the direction of the magnetic field created by the drive coil 51 at the position of the capsule endoscope 20 is selected. By selecting the drive coil 51 in this way, the induced magnetic field generated from the magnetic induction coil 42 can be kept large, and a good state can be maintained when performing position detection.
STEP15 is the same as described above, and is omitted.

In STEP 16, the frequency of the signal generation circuit is set to the low frequency side calculation frequency, and the position detection device 50A operates the drive coil selector 55 to select one of the drive coils 55 as an output drive coil.
In STEP 17, the outputs of all the sense coils 52 selected in STEP 14 are measured. This corresponds to V (f _LOW , N). Thereafter, the output of the sense coil when the capsule endoscope in the combination of all the drive coils 51 and the sense coil 52 at the calculation frequency and the sense coil 52 is not present in the space S, Vc (f _LOW , N, M ) To calculate the difference from the data representing the combination of the corresponding sense coil and drive coil, and Vs (f _LOW , N)
Vs (f _LOW , N) = V (f _LOW , N) −Vc (f _LOW , N, M)
Ask for.
Since STEP18 is the same as the above, description is abbreviate | omitted.

In STEP 19, the drive coil 55 set in STEP 16 is not changed, and the frequency of the signal generation circuit is set to the high frequency side calculation frequency.
In STEP 20, the outputs of all the sense coils 52 selected in STEP 14 are measured. This corresponds to V (f _HIGH , N). Thereafter, the output of the sense coil when the capsule endoscope in the combination of all the drive coils 51 and the sense coil 52 at the calculation frequency and the sense coil 52 does not exist in the space S, Vc (f _HIGH , N, M ) To calculate the difference from the data representing the combination of the corresponding sense coil and drive coil, and Vs (f _HIGH , N)
_{Vs (f HIGH, N) =} V (f HIGH, N) -Vc (f HIGH, N, M)
Ask for.

In STEP 21, the position detection device 50 </ b> A determines the output difference (amplitude difference) Vs (f _LOW , N) −Vs (f _HIGH , N) is obtained, and the value is used to calculate the position and direction of the capsule endoscope 20, that is, the magnetic induction coil 42.
Since STEPs 22 and 23 are the same as described above, the description thereof is omitted.

  By performing the operation as described above (selection of the drive coil 51 and the sense coil 52), the induction magnetism generated by the magnetic induction coil 42 is efficiently generated under the condition that the induction magnetism is always as large as possible from the magnetic induction coil 42. Since it can be detected by the sense coil 52, the amount of data used for the position calculation of the capsule endoscope 20 (magnetic induction coil 42) can be reduced without impairing accuracy. Therefore, the amount of calculation can be reduced and the system can be configured at low cost. Effects such as speeding up the system occur.

Further, in selecting the drive coil 51, two or more drive coils 51 may be selected. In this case, the magnetic field generated by all the selected drive coils at the position of the capsule endoscope 20 (magnetic induction coil 42) is calculated, and the direction of the combined magnetic field and the capsule endoscope 20 ( The output of each drive coil 51 is adjusted so that the direction of the magnetic induction coil 42) has an acute angle relationship. The values obtained by the calibration of the selected sense coil 52 are the output values of the output drive coils 51, Vc (f _LOW , N, M), Vc (f _HIGH , N, From M), a coefficient based on the output of each drive coil may be multiplied by Vc (f _LOW , N, M) and Vc (f _HIGH , N, M) to obtain a sum. Alternatively, several output patterns in which the output ratio of each drive coil is determined in advance may be created, and calibration may be performed with each output pattern in STEP 1. In this way, the direction of the magnetic field at the position of the capsule endoscope 20 (magnetic induction coil 42) can be set more freely. Therefore, more accurate and more efficient position detection can be realized.

Further, the output of the drive coil 51 may be adjusted so that the magnetic field at the position of the capsule endoscope 20 (magnetic induction coil 42) created by the drive coil 51 is constant or within a certain magnetic field strength range. Also in this case, each output value of the drive coil 51 output in the same manner as described above, and Vc (f _LOW , N, M) and Vc (f _HIGH , N, M) of the previous measurement result, A coefficient based on the output of the drive coil may be multiplied by Vc (f _LOW , N, M) and Vc (f _HIGH , N, M) to obtain a sum.
In this way, the induction magnetism generated from the magnetic induction coil 42 can be output more stably. Therefore, more accurate and more efficient position detection can be realized.

Next, the operation of the magnetic induction device 70 will be described.
In the magnetic guidance device 70, first, as shown in FIG. 1, the practitioner inputs a guidance direction to the capsule endoscope 20 to the rotating magnetic field control circuit 73 via the input device 74. In the rotating magnetic field control circuit 73, the direction of the parallel magnetic field applied to the capsule endoscope 20 based on the input guiding direction and the direction (rotational axis direction) of the capsule endoscope 20 input from the position detection device 50A. And determine the direction of rotation.
Then, the generated magnetic field strength of each Helmholtz coil 71X, 71Y, 71Z necessary for forming the direction of the parallel magnetic field is calculated, and the current value required to generate these magnetic fields is calculated.

The current value data supplied to the Helmholtz coils 71X, 71Y, 71Z is output to the corresponding Helmholtz coil drivers 72X, 72Y, 72Z. The Helmholtz coil drivers 72X, 72Y, 72Z are supplied with currents based on the input data. Are controlled to supply current to the corresponding Helmholtz coils 71X, 71Y, 71Z.
The Helmholtz coils 71X, 71Y, 71Z to which the current is supplied generate magnetic fields corresponding to the current values, and these magnetic fields are combined to form a parallel magnetic field having the magnetic field direction determined by the rotating magnetic field control circuit 73. Is done.

  As will be described later, a driving magnet 45 is mounted on the capsule endoscope 20, and the capsule endoscope 20 is in its posture (by the force and torque acting on the driving magnet 45 and the parallel magnetic field) ( (Rotational axis direction) is controlled. In addition, the rotation period of the parallel magnetic field is controlled to about 0 Hz to several Hz, and the rotation direction of the capsule endoscope 20 is controlled by controlling the rotation direction of the parallel magnetic field. The traveling direction and traveling speed of the mold endoscope 20 are controlled.

Next, the operation of the capsule endoscope 20 will be described.
As shown in FIG. 5, the capsule endoscope 20 first irradiates infrared rays to the infrared sensor 47 of the switch unit 46, and the switch unit 46 outputs a signal to the signal processing unit 34. When the signal processing unit 34 receives a signal from the switch unit 46, the signal processing unit 34 supplies current from the battery 39 to the image sensor 31, the LED 33, the wireless element 35, and the signal processing unit 34 mounted on the capsule endoscope 20. , Turn on.

  The image sensor 31 captures an image of the wall surface in the body cavity duct of the subject 1 illuminated by the LED 33, converts the image into an electrical signal, and outputs the electrical signal to the signal processing unit 34. The signal processing unit 34 compresses and temporarily stores the input image signal, and outputs the compressed image signal to the wireless element 35. The compressed image signal input to the wireless element 35 is transmitted to the image display device 80 as a radio wave.

  Further, the capsule endoscope 20 can be moved to the front end portion 23 side or the rear end portion 24 side by rotating around the rotation axis R by the spiral portion 25 disposed on the outer periphery of the exterior 21. The moving direction is determined by the rotation direction around the rotation axis R and the rotation direction of the spiral portion 25.

Next, the operation of the image display device 80 will be described.
In the image display device 80, as shown in FIG. 1, first, the image receiving circuit 81 receives the compressed image signal transmitted from the capsule endoscope 20, and the image signal is output to the display unit 82. The compressed image signal is restored in the image receiving circuit 81 or the display unit 82 and displayed on the display unit 82.
Further, the display unit 82 rotates the image signal in the direction opposite to the rotation direction of the capsule endoscope 20 based on the rotation phase data of the capsule endoscope 20 input from the rotating magnetic field control circuit 73. It is displayed from.

According to the above configuration, since the resonance frequency of the magnetic induction coil 42 is obtained using an alternating magnetic field that changes in frequency with time, the resonance frequency can be obtained even if the resonance frequency of the magnetic induction coil 42 varies greatly. The calculation frequency can be obtained based on the resonance frequency. Therefore, even if the resonance frequency of the magnetic induction coil 42 varies, the position and orientation of the capsule medical device 20 can always be calculated based on the calculation frequency.
As a result, it is not necessary to mount an element for adjusting the resonance frequency of the magnetic induction coil 42, and the capsule medical device 20 can be downsized. Alternatively, it is not necessary to select or adjust an element such as a capacitor constituting the resonance circuit 43 together with the magnetic induction coil 42 in order to adjust the resonance frequency, and an increase in production cost of the capsule medical device 20 can be prevented.

  Since only the alternating magnetic field of the low frequency side calculation frequency and the high frequency side calculation frequency is used for calculating the position and orientation of the capsule medical device 20, for example, compared with a method of sweeping the frequency of the alternating magnetic field in a predetermined band, The time required for calculating the position and orientation can be shortened.

  Since the band-pass filter 61 can limit the band of the output frequency of the sense coil 52 based on the low frequency side calculation frequency and the high frequency side calculation frequency, the frequency close to the low frequency side calculation frequency and the high frequency side calculation frequency. Based on the sense coil output of the band, the position and orientation of the capsule medical device 20 can be calculated, and the time required to calculate the position and orientation can be shortened.

An alternating magnetic field is applied to the magnetic induction coil 42 of the capsule endoscope 20 from three or more directions that are linearly independent. Therefore, induction magnetism can be generated in the magnetic induction coil 42 by an alternating magnetic field from at least one direction regardless of the direction of the magnetic induction coil 42.
As a result, regardless of the direction of the capsule endoscope 20 (the axial direction of the rotation axis R), it is possible to always generate induced magnetism in the magnetic induction coil 42, so that the sense coil 52 always detects the induced magnetism. And the position can always be accurately detected.

Further, since the sense coil 52 is arranged in three different directions with respect to the capsule endoscope 20, at least one of the sense coils 52 arranged in the three directions regardless of the arrangement position of the capsule endoscope 20. Inductive magnetism having a detectable intensity acts on the sense coil 52 arranged in the direction, so that the sense coil 52 can always detect the induced magnetism.
Further, since the number of the sense coils 52 arranged in one direction is nine, the X, Y, Z coordinates of the capsule endoscope 20 and the rotation axis R of the capsule endoscope 20 are orthogonal to each other. In addition, it is possible to obtain an input sufficient to obtain a total of six pieces of information including rotational phases φ and θ around two axes orthogonal to each other and the intensity of induced magnetism.

By setting the frequency of the AC magnetic field in the vicinity of the frequency at which the resonance circuit 43 resonates (resonance frequency), it is possible to generate induced magnetism having a larger amplitude than in the case of other frequencies. Since the amplitude of the induced magnetism increases, the sense coil 52 can easily detect the induced magnetism, and the position of the capsule endoscope 20 can be easily detected.
Further, since the frequency of AC magnetism is swept over a frequency band near the resonance frequency, for example, the resonance frequency of the resonance circuit 43 changes due to a change in environmental conditions (for example, temperature conditions), or resonance due to individual differences in the resonance circuit 43. Even if there is a variation in frequency, the resonance circuit 43 can be caused to resonate if the changed resonance frequency or the varied resonance frequency is included in the frequency band.

  Since the position detection device 50A selects the sense coil 52 that detects the strong induced magnetism by the sense coil selector 56, the accuracy is impaired even if the amount of information processed by the position detection device 50A is reduced. And the load on the calculation can be reduced. Further, since the amount of calculation processing can be reduced at the same time, the time required for calculation can also be shortened.

  Since the drive coil 51 and the sense coil 52 are disposed at positions facing each other across the operating range of the capsule endoscope 20, the drive coil 51 and the sense coil 52 may be disposed so as not to interfere structurally. it can.

  By controlling the direction of the parallel magnetic field applied to the drive magnet 45 mounted on the capsule endoscope 20, the direction of the force applied to the drive magnet 45 can be controlled, and the capsule endoscope The moving direction of the mirror 20 can be controlled. At the same time, since the position of the capsule endoscope 20 can be detected, the capsule endoscope 20 can be guided to a predetermined position, and therefore based on the detected position of the capsule endoscope 20. The capsule endoscope 20 can be accurately guided.

By controlling the strengths of the magnetic fields generated from the three pairs of Helmholtz coils 71X, 71Y, 71Z arranged opposite to each other in a direction orthogonal to each other, the direction of the parallel magnetic field generated inside the Helmholtz coils 71X, 71Y, 71Z is changed. It can be controlled in a predetermined direction. Therefore, a parallel magnetic field in a predetermined direction can be applied to the capsule endoscope 20, and the capsule endoscope 20 can be moved in a predetermined direction.
Further, the space inside the Helmholtz coils 71X, 71Y, 71Z is a space in which the subject 1 can be arranged, and the drive coil 51 and the sense coil 52 are arranged around the space. The endoscope 20 can be guided to a predetermined position in the body of the subject 1.

  As the capsule endoscope 20 rotates about the rotation axis R, the spiral portion 25 generates a force for propelling the capsule endoscope 20 in the axial direction of the rotation axis. Since the spiral portion 25 generates a propulsive force, the direction of the propulsive force acting on the capsule endoscope 20 can be controlled by controlling the rotation direction around the rotation axis R of the capsule endoscope 20. .

The image display device 80 performs a process of rotating the displayed image in the direction opposite to the rotation direction of the capsule endoscope 20 based on the rotation phase information about the rotation axis R of the capsule endoscope 20. Therefore, regardless of the rotational phase of the capsule endoscope 20, the image is always stationary at a predetermined rotational phase, that is, as if the capsule endoscope 20 does not rotate around the rotational axis R. An image that is traveling in the direction along the direction can be displayed on the display unit 82.
Therefore, when the operator visually guides the capsule endoscope 20 while viewing the image displayed on the display unit 82, the displayed image is compared with a case where the displayed image is an image that rotates with the rotation of the capsule endoscope 20. Then, when the image displayed as described above is displayed as an image having a predetermined rotation phase, it is easier for the practitioner to see and the capsule endoscope 20 is easily guided to a predetermined position.

Note that, as described above, the frequency of the AC magnetic field used for calculating the calculated frequency (Step 1, Step 3) may be swept, or the position detecting device 50A may generate an impulse magnetic field from the drive coil 51. And an impulse-like magnetic field may be used when calculating the calculation frequency.
As shown in FIG. 13A, the impulse-like magnetic field generated by applying the impulse-like drive voltage to the drive coil 51 has many frequency components as shown in FIG. Compared with the method of sweeping the frequency of the magnetic field, the resonance frequency of the magnetic induction coil 42 can be obtained in a short time, and the resonance frequency can be obtained in a wider frequency band. In this case, a spectrum analyzer (not shown) capable of analyzing frequency components is connected to the sense coil receiving circuit 57 connected to the sense coil 52, so that an impulse drive voltage is applied to the drive coil 51. The frequency component of the signal output from the sense coil 52 can be detected.

In addition, when the position detection device 50A is used as a mixed magnetic field generation unit that generates an alternating magnetic field in which a plurality of different frequencies are mixed from the drive coil 51, an alternating magnetic field in which a plurality of different frequencies are mixed is used when obtaining a calculation frequency. The frequency band input to the frequency determination unit 50B may be controlled using the variable band limiting unit that can change the frequency band transmitted through the band-pass filter 61.
By adopting such a configuration, even when the variation in the resonance frequency of the magnetic induction coil 42 increases, the resonance frequency can be easily obtained as compared with the case where an alternating magnetic field having a predetermined frequency is used.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS.
The basic configuration of the capsule endoscope guidance system of the present embodiment is the same as that of the first embodiment. However, the first embodiment is different from the first embodiment in the calculation frequency determination method and the configuration related to the determination. Is different. Therefore, in the present embodiment, only the calculation frequency determination method and the configuration related to the determination will be described using FIG. 14 and FIG. 15, and description of the magnetic induction device and the like will be omitted.
FIG. 14 is a diagram showing an outline of a capsule endoscope guidance system in the present embodiment.
In addition, the same code | symbol is attached | subjected to the component same as 1st Embodiment, and the description is abbreviate | omitted.

  As shown in FIG. 14, a capsule endoscope guidance system (capsule medical device guidance system) 110 optically images an inner wall surface of a body cavity conduit and wirelessly transmits an image signal. (Capsule medical device) 120, position detection unit (position detection system) 150 for detecting the position of the capsule endoscope 120, and capsules based on the detected position of the capsule endoscope 120 and instructions of the operator The magnetic guidance device 70 that guides the mold endoscope 120 and the image display device 180 that displays the image signal transmitted from the capsule endoscope 120 are schematically configured.

As shown in FIG. 14, the position detection unit 150 includes a drive coil 51 that generates induction magnetism in a magnetic induction coil (to be described later) in the capsule endoscope 120, and a sense coil that detects induction magnetism generated by the magnetic induction coil. 52 and a position detection device (position analysis means, magnetic field frequency variable unit) that calculates the position of the capsule endoscope 120 based on the induced magnetism detected by the sense coil 52 and controls the alternating magnetic field formed by the drive coil 51 , Drive coil control unit) 150A.
The position detection device 150A is provided with a calculation frequency determination unit (frequency determination unit) 150B, and is configured to receive a signal from a sense coil reception circuit and a signal from a capsule information reception circuit, which will be described later.

  The image display device 180 is based on the capsule information receiving circuit 181 that receives the image and the calculation frequency value transmitted from the capsule endoscope 120, the received image signal, and the signal from the rotating magnetic field control circuit 73. The display unit 82 displays an image.

FIG. 15 is a schematic diagram illustrating a configuration of a capsule endoscope.
As shown in FIG. 15, the capsule endoscope 120 includes an exterior 21 that houses various devices therein, an imaging unit 30 that images an inner wall surface of a body cavity line of a subject, and an imaging unit 30. Is composed of a battery 39 that drives the capsule magnet, an induction magnet generator 40 that generates the induction magnetism by the drive coil 51, and a drive magnet 45 that drives the capsule endoscope 120.

The imaging unit 30 includes a substrate 36A disposed substantially perpendicular to the rotation axis R, an image sensor 31 disposed on the surface of the substrate 36A on the distal end portion 23 side, and an inner wall surface of the body cavity passage of the subject. A lens group 32 for forming an image of the image sensor 31 on the image sensor 31, an LED (Light Emitting Diode) 33 for illuminating the inner wall surface of the body cavity conduit, and signal processing disposed on the surface on the rear end 24 side of the substrate 36A Unit 34 and a wireless element (communication unit) 135 that transmits an image signal to the image display device 80.
The signal processing unit 34 is also provided with a storage unit 134A that stores a calculation frequency based on the resonance frequency of the resonance circuit 43 of the induction magnetism generation unit 40. The storage unit 134A is electrically connected to the wireless element 135, and can store the calculated frequency in the storage unit 134A via the wireless element 135, or can transmit the stored calculation frequency to the outside. It is configured as follows.

Next, the operation of the capsule endoscope guidance system 110 having the above configuration will be described.
Since the outline of the operation of the capsule endoscope guidance system 110 is the same as that of the first embodiment, the description thereof is omitted.

Next, a method for obtaining a calculation frequency used for detecting the position and direction of the capsule endoscope 120 and a method for detecting the position and direction of the capsule endoscope 120 will be described.
FIG. 16 is a flowchart illustrating a procedure from obtaining the frequency characteristic of the magnetic induction coil 42 to storing the obtained frequency characteristic in the storage unit 134A.
First, as shown in FIG. 16, the position detection unit 150 is calibrated (Step 31; preliminary measurement step). That is, the output of the sense coil 52 that is generated when the capsule endoscope 120 is not disposed in the space S, that is, the alternating magnetic field formed by the drive coil 51 is measured.
The specific method for forming the AC magnetic field is the same as that in the first embodiment, and thus the description thereof is omitted.

Next, the capsule endoscope 120 is placed in the space S (Step 32).
Then, the frequency characteristic of the magnetic induction coil 42 mounted on the capsule endoscope 120 is measured (Step 33; measurement step). In the frequency determination unit 150B, the output of the sense coil 52 on which only the AC magnetic field measured in Step 31 is applied is subtracted from the measured frequency characteristics of the magnetic induction coil 42 (a difference is taken).
Thereafter, the frequency determination unit 150B stores the frequency characteristics of the magnetic induction coil 42 in the storage unit 134A via the wireless element 135 (Step 34).

The above-described operation of storing the frequency characteristics in the storage unit 134A is performed at the stage of manufacturing the capsule endoscope 120. Therefore, at the site where the capsule endoscope 120 is actually used, it is not necessary to obtain the frequency characteristic and to store it.
Further, in the work from Step 31 to Step 34, not all of the capsule endoscope guidance system 110 is necessary, and any system that can drive and control one drive coil 51 and one sense coil 52 may be used.

FIGS. 17 and 18 are flowcharts for explaining the procedure for acquiring the frequency characteristics stored in the storage unit 134A and detecting the position and orientation of the capsule endoscope 120. FIG.
Next, a method for detecting the position and direction of the capsule endoscope 120 storing the frequency characteristics will be described.
First, as shown in FIG. 17, when the capsule endoscope 120 is switched on, the transmission unit 135 transmits the data of the frequency characteristics stored in the storage unit 134A to the outside, and these transmitted Is received by the capsule information receiving circuit 181 and input to the frequency determining unit 150B (Step 41).

Thereafter, the frequency determination unit 150B obtains a calculation frequency used for detecting the position and orientation of the capsule endoscope 120 based on the acquired frequency characteristics (Step 42; frequency determination step).
As in the first embodiment, the calculation frequency is selected such that the gain change of the sense coil 52 takes the maximum value and the minimum value. Is a frequency for high frequency side calculation.
In Step 34, the frequencies (low frequency side calculation frequency, high frequency side calculation frequency) used for position and direction detection may be stored in the storage unit 134A. In this way, the calculation frequency can be determined simply by reading the data stored in the storage unit 134A.

Then, the position detection unit 150 is calibrated in the same manner as in Step 1 of the first embodiment by using the AC magnetic field at the obtained low frequency side calculation frequency and high frequency side calculation frequency (Step 43; preliminary measurement step) ) Measure the outputs of all sense coils 52 when an AC magnetic field is applied. Here, the measured output is expressed as Vc (f _LOW , N) and Vc (f _HIGH , N), as in the first embodiment.
Thereafter, the center frequency of the bandpass filter 61 is matched with the low frequency side calculation frequency (Step 44). Further, the transmission frequency band of the band pass filter 61 is set to a band that can extract the extreme value of the gain change of the sense coil 52.
Then, the frequency of the alternating magnetic field formed by the drive coil 51 is adjusted to the low frequency side calculation frequency (Step 45). Specifically, the frequency of the alternating magnetic field formed by the drive coil 51 is controlled by controlling the frequency of the alternating current generated by the signal generating circuit 53 to the low frequency side calculation frequency.

Then, an alternating magnetic field having a low frequency side calculation frequency is generated from the drive coil 51, and the induction magnetism induced in the magnetic induction coil 42 is detected by the sense coil 52 (Step 46; detection step). Here, similarly to the first embodiment, V (f _LOW , N) is set to Vs (f _LOW , N) = V (f _LOW , N) −Vc (f _LOW , N), and the sense coil is calculated. Vs (f _LOW , N) is stored as a value calculated based on the output of 52.

Next, the center frequency of the bandpass filter 61 is matched with the high frequency side calculation frequency (Step 47).
Then, the frequency of the alternating magnetic field formed by the drive coil 51 is matched with the frequency for high frequency side calculation (Step 48).
Then, an AC magnetic field having a high frequency side calculation frequency is generated from the drive coil 51, and the induction magnetism induced in the magnetic induction coil 42 is detected by the sense coil 52 (Step 49; detection step). At this time, what is detected is V (f _HIGH , N), and Vs (f _HIGH , N) = V (f _HIGH , N) −Vc (f _HIGH , N) is calculated as in Step 46. , Vs (f _HIGH , N) is stored as a value calculated based on the output of the sense coil 52.
As described above, detection by the low frequency side calculation frequency may be performed first, and then detection by the high frequency side calculation frequency may be performed later. You may detect by the frequency for low frequency side calculation.

Thereafter, the position detection device 150A obtains an output difference (amplitude difference) between the low frequency side calculation frequency and the high frequency side calculation frequency in each sense coil 52, and which is used to estimate the position of the capsule endoscope 120. Whether to use the output difference of the sense coil 52 is selected (Step 50).
Since the selection method of the sense coil 52 is the same as that of the first embodiment, the description thereof is omitted.

  Then, the position detection device 150A calculates the position and orientation of the capsule endoscope 120 based on the output difference of the selected sense coil 52 (Step 51; position calculation step), and calculates the position and orientation (Step 52). .

Next, as shown in FIG. 18, the sense coil 52 used for the next control is selected (Step 53).
That is, the position detection device 150A calculates the magnetic field intensity generated from the magnetic induction coils 42 at the positions of all the sense coils 52 based on the position and orientation of the capsule endoscope 120 calculated in Step 52, and calculates the magnetic field intensity. The necessary number of sense coils 52 in the strong position are selected. When the position and orientation of the capsule endoscope 120 are repeatedly obtained, the sense coil 52 is selected based on the position and orientation of the capsule endoscope 120 calculated in Step 61 described later.

  In this embodiment, the number of sense coils 52 to be selected may be six or more. However, when the number of sense coils 52 is about 10 to 15, the position calculation error can be suppressed small. In addition, the selection method of the sense coil 52 is based on the position and orientation of the capsule endoscope 120 obtained in Step 52 (or Step 61 described later), and all the sense coils 52 by the magnetic field generated from the magnetic induction coil 42 are selected. An output may be obtained by calculation, and a required number of sense coils 52 having a large output may be selected.

Thereafter, the center frequency of the bandpass filter 61 is again matched with the low frequency side calculation frequency (Step 54).
Then, the frequency of the alternating magnetic field formed by the drive coil 51 is adjusted to the low frequency side calculation frequency (Step 55).
Then, an alternating magnetic field having a low frequency side calculation frequency is generated from the drive coil 51, and the induction magnetism induced in the magnetic induction coil 42 is detected by the selected sense coil 52 (Step 56; detection step).

Next, the center frequency of the bandpass filter 61 is matched with the high frequency side calculation frequency (Step 57).
Then, the frequency of the alternating magnetic field formed by the drive coil 51 is matched with the frequency for high frequency side calculation (Step 58).
Then, an AC magnetic field having a high frequency side calculation frequency is generated from the drive coil 51, and the induction magnetism induced in the magnetic induction coil 42 is detected by the selected sense coil 52 (Step 59; detection step).

Then, the position detection device 150A calculates the position and orientation of the capsule endoscope 120 based on the output difference of the sense coil 52 selected in Step 53 (Step 60; position calculation step), and determines the position and orientation (Step 60). Step 61).
In Step 61, the calculated position and orientation data of the capsule endoscope apparatus 120 may be output to another apparatus or the display unit 82.
Thereafter, when the detection of the position and orientation of the capsule endoscope apparatus 120 is continued, the process returns to the above Step 53 to detect the position and orientation.

  According to the above configuration, when calculating the position and orientation of the capsule endoscope 120, the frequency characteristic of the magnetic induction coil 42 stored in advance in the storage unit 134A is acquired, and the low frequency side calculation is performed. The frequency and the frequency for high frequency side calculation are obtained. Therefore, the time required for calculating the position and orientation of the capsule medical device 120 can be shortened as compared with the method of obtaining the calculation frequency by measuring the resonance frequency each time the position of the capsule medical device 120 is detected. it can.

As described above, the frequency characteristic of the magnetic induction coil 42 is stored in the storage unit 134A, and the stored frequency characteristic is automatically transmitted to the frequency determination unit 150B via the communication unit 135 and the capsule information reception circuit 181. The value may be transmitted, or the value of the frequency characteristic may be described on the exterior 21 of the capsule endoscope apparatus 120, and the value may be input to the frequency determining unit 150B by the practitioner. Moreover, as another description method of the exterior 21, the method described in a package exterior can be mentioned.
Further, the frequency characteristic of the magnetic induction coil 42 may be stored, or a calculation frequency calculated based on the frequency characteristic may be stored in the storage unit 134A.
Further, values such as frequency characteristics may be directly described on the exterior 21 or the like, or values such as frequency characteristics may be classified into a plurality of ranks, and the ranks may be described on the exterior 21 or the like.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. 19 and FIG.
The basic configuration of the capsule endoscope guidance system of the present embodiment is the same as that of the first embodiment, but the configuration of the position detection unit is different from that of the first embodiment. Therefore, in this embodiment, only the periphery of the position detection unit will be described with reference to FIGS. 19 and 20, and the description of the magnetic induction device and the like will be omitted.
FIG. 19 is a schematic diagram showing the arrangement of drive coils and sense coils of the position detection unit.
In addition, since components other than the drive coil and the sense coil of the position detection unit are the same as those in the first embodiment, description thereof is omitted.

The drive coil (drive coil) 251 and the sense coil 52 of the position detection unit (position detection system) 250 are arranged so that three drive coils 251 are perpendicular to the X, Y, and Z axes, respectively, as shown in FIG. The sense coil 52 is disposed on two coil support portions 258 having a planar shape perpendicular to the Y and Z axes, respectively.
As shown in the figure, the drive coil 251 may be a rectangular coil or a Helmholtz coil.

  In the position detection unit 250 having the above configuration, as shown in FIG. 19, the direction of the alternating magnetic field formed by each drive coil 251 is parallel to the X, Y, and Z axis directions, and is independent of each other and orthogonal to each other. It becomes a relationship.

According to the above configuration, an AC magnetic field can be applied to the magnetic induction coil 42 of the capsule endoscope 20 from a direction that is linearly independent and orthogonal to each other, so that it is compared with the first embodiment. Thus, it is easy to generate induced magnetism in the magnetic induction coil 42 regardless of the direction of the magnetic induction coil 42.
Further, since the drive coils 251 are arranged substantially orthogonal to each other, the drive coil selector 55 can easily select a drive coil.

Note that the sense coil 52 may be disposed on the coil support portion 258 perpendicular to the Y and Z axes as described above, or the operation of the capsule endoscope 20 as shown in FIG. You may be provided on the diagonal coil support part 259 arrange | positioned above the range.
With such an arrangement, the sense coil 52 can be arranged without interfering with the subject 1.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIG.
The basic configuration of the capsule endoscope guidance system of the present embodiment is the same as that of the first embodiment, but the configuration of the position detection unit is different from that of the first embodiment. Therefore, in the present embodiment, only the periphery of the position detection unit will be described using FIG. 21, and the description of the magnetic induction device and the like will be omitted.
FIG. 21 is a schematic diagram showing the arrangement of drive coils and sense coils of the position detection unit.
In addition, since components other than the drive coil and the sense coil of the position detection unit are the same as those in the first embodiment, description thereof is omitted.

As shown in FIG. 21, the drive coil (drive coil) 351 and the sense coil 52 of the position detection unit (position detection system) 350 have four drive coils 351 arranged on the same plane, and the sense coil 52 is a capsule type. A planar coil support 358 disposed at a position opposite to the position where the drive coil 351 is disposed via the operating range of the endoscope 20 and a planar coil support disposed on the same side as the position where the drive coil 351 is disposed. It is disposed on the portion 358.
The drive coils 351 are arranged such that the direction of the alternating magnetic field to be formed is primarily independent of each other as indicated by arrows in the figure.

  According to the above configuration, even if the capsule endoscope 20 is located in a region close to or far from the drive coil 351, one of the two coil support portions 358 is connected to the capsule endoscope 20. Close position. Therefore, it is possible to obtain a signal having a sufficient strength for obtaining the position of the capsule endoscope 20 from the sense coil 52.

[Modification of Fourth Embodiment]
Next, a modification of the fourth embodiment of the present invention will be described with reference to FIG.
The basic configuration of the capsule endoscope guidance system of this modification is the same as that of the third embodiment, but the configuration of the position detection unit is different from that of the third embodiment. Therefore, in the present embodiment, only the periphery of the position detection unit will be described using FIG. 22, and the description of the magnetic induction device and the like will be omitted.
FIG. 22 is a schematic diagram showing the arrangement of drive coils and sense coils of the position detection unit.
In addition, since components other than the drive coil and the sense coil of the position detection unit are the same as those in the third embodiment, description thereof is omitted.

As shown in FIG. 22, the drive coil 351 and the sense coil 52 of the position detection unit (position detection system) 450 have four drive coils 351 arranged on the same plane, and the sense coil 52 is connected to the capsule endoscope 20. On the curved coil support 458 arranged on the same side as the arrangement position of the drive coil 351 and the curved coil support part 458 arranged at a position opposite to the arrangement position of the drive coil 351 through the operation range of Has been placed.
The coil support portion 458 has a curved shape that protrudes outward with respect to the operating range of the capsule endoscope 20, and the sense coil 52 is disposed along the curved shape.
The shape of the coil support portion 52 may be a curved shape that protrudes outward with respect to the moving range as described above, or may be another curved shape, and is not particularly limited.

  According to said structure, since the freedom degree of arrangement | positioning of the sense coil 52 improves, it can prevent that the sense coil 52 interferes with the subject 1.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described with reference to FIGS.
The basic configuration of the capsule endoscope guidance system of the present embodiment is the same as that of the second embodiment, but the configuration of the position detection unit is different from that of the second embodiment. Therefore, in this embodiment, only the periphery of the position detection unit will be described with reference to FIGS.
FIG. 23 is a diagram showing an outline of a capsule endoscope guidance system in the present embodiment.
In addition, the same code | symbol is attached | subjected to the component same as 2nd Embodiment, and the description is abbreviate | omitted.

  As shown in FIG. 23, a capsule endoscope guidance system (capsule medical device guidance system) 510 optically images an inner wall surface of a body cavity conduit and wirelessly transmits an image signal. 120, a position detection unit (position detection system) 550 for detecting the position of the capsule endoscope 120, and the capsule endoscope 120 based on the detected position of the capsule endoscope 120 and the operator's instruction. The magnetic guidance device 70 for guiding and an image display device 180 for displaying an image signal transmitted from the capsule endoscope 120 are schematically configured.

  As shown in FIG. 23, the position detection unit 550 includes a drive coil 51 that generates induced magnetism in a magnetic induction coil (to be described later) in the capsule endoscope 120, and a sense coil that detects induced magnetism generated by the magnetic induction coil. 52, a relative position changing unit (relative position changing unit) 561 for changing the relative positions of the drive coil 51 and the sense coil 52, a relative position measuring unit (relative position measuring unit) 562 for measuring the relative position, and the sense coil 52 Position detector that calculates the position of the capsule endoscope 120 based on the induced magnetism detected by the robot and controls the alternating magnetic field formed by the drive coil 51 (position analysis means, magnetic field frequency variable unit, drive coil control unit) 550A.

The position detection device 550A is provided with a frequency determination unit 150B that calculates a calculation frequency and a current reference value generation unit 550B that generates a reference value. A signal from a sense coil reception circuit and a capsule information reception circuit, which will be described later, are provided. A signal is input. The current reference value generation unit 550B is provided with a storage unit (storage unit) 550C that stores the relative position information of the drive coil 51 and the sense coil 52 and the output information of the sense coil 52 in association with each other. .
Between the position detection device 550A and the drive coil 51, a signal generation circuit 53 for generating an alternating current based on an output from the position detection device 550A and a signal generation circuit 53 based on an output from the position detection device 550A are input. And a drive coil driver 54 for amplifying the alternating current.

  Further, a relative position changing unit 561 is arranged between the position detecting device 550A and the drive coil 51, and a relative position measuring unit 562 is arranged between the relative position changing unit 561 and the position detecting device 550A. The output of the position detection device 550A is arranged to be input to a drive coil unit to be described later via a relative position changing unit 561. The relative position information of the drive coil 51 and the sense coil 52 is acquired from the drive coil unit via the relative position changing unit 561 to the relative position measuring unit 562, and the acquired information is arranged to be input to the position detecting device 550A. Has been.

FIG. 24 is a diagram for explaining the positional relationship between the drive coil unit including the drive coil 51 of FIG. 23 and the sense coil 52.
The position detection unit 550 includes a frame portion 571 formed of an outer frame 571A and an inner frame 571B formed in a substantially spherical shape, and a drive coil unit 551 that is movably disposed between the outer frame 571A and the inner frame 571B. The sense coil 52 arranged on the inner surface of the inner frame 571B is arranged as shown in FIG.

FIG. 25 is a diagram for explaining the outline of the configuration of the drive coil unit 551 of FIG.
As shown in FIG. 25, the drive coil unit 551 includes a substantially rectangular parallelepiped housing 552, drive units 553 arranged at four corners of the surface of the housing 552 facing the outer frame 571A and the inner frame 571B, and a drive coil. 51, a direction changing portion 555 that controls the traveling direction of the drive coil unit 551, and a string-like connection portion 556 that electrically connects the drive coil unit 551 to the drive coil driver 54 and the relative position changing portion 561. It is roughly structured.
The direction changing portion 555 is roughly configured by a sphere portion 557 that protrudes from a surface facing the outer frame 571A, a motor 558 that controls rotation of the sphere portion 557, and a motor circuit 559 that drives and controls the motor 558. Yes.

  Since the outline of the operation of the capsule endoscope guidance system 510 having the above-described configuration is the same as that of the second embodiment, the description thereof is omitted.

Next, a method for detecting the position and orientation of the capsule endoscope 120 in this embodiment will be described.
The method for obtaining the calculation frequency used for detecting the position and direction of the capsule endoscope 120, that is, the operation until the frequency characteristic of the magnetic induction coil 42 is stored in the storage unit 134A (see FIG. 15) is the same as that of the second embodiment. Since it is the same, the description is abbreviate | omitted.

FIG. 26, FIG. 27 and FIG. 28 are flowcharts for explaining the procedure for detecting the position and orientation of the capsule endoscope 120 in the present embodiment.
First, as shown in FIG. 26, the transmission unit 135 transmits the frequency characteristic data stored in the storage unit 134A to the outside, and the capsule information reception circuit 181 receives these transmitted frequency characteristic data. And input to the frequency determination unit 150B (Step 71).

Thereafter, the frequency determination unit 150B obtains a calculation frequency used for detecting the position and orientation of the capsule endoscope 120 based on the acquired frequency characteristics (Step 72; frequency determination step).
As in the first embodiment, the calculation frequency is selected such that the gain change of the sense coil 52 takes the maximum value and the minimum value. Is a frequency for high frequency side calculation.

  Then, the drive coil unit 551 is moved to the end of the movable range (Step 73). Specifically, as shown in FIGS. 23 and 25, a control signal is output from the current reference value generation unit 550B to the relative position changing unit 561, and the relative position changing unit 561 drives the driving unit 553 and the direction changing unit 555. The drive coil unit 551 is moved by the control.

Then, as shown in FIG. 26, the center frequency of the bandpass filter 61 is matched with the low frequency side calculation frequency (Step 74). Further, the transmission frequency band of the band pass filter 61 is set to a band that can extract the extreme value of the gain change of the sense coil 52.
Then, the frequency of the AC magnetic field formed by the drive coil 51 is matched with the low frequency side calculation frequency (Step 75).
Then, an AC magnetic field having a low frequency side calculation frequency is generated from the drive coil 51, and the AC magnetic field is detected by the sense coil 52 (Step 76).

Next, the center frequency of the bandpass filter 61 is matched with the high frequency side calculation frequency (Step 77).
Then, the frequency of the alternating magnetic field formed by the drive coil 51 is matched with the frequency for high frequency side calculation (Step 78).
Then, an AC magnetic field having a high frequency side calculation frequency is generated from the drive coil 51, and the AC magnetic field is detected by the sense coil 52 (Step 79).

Thereafter, the relative position information between the drive coil 51 and the sense coil 52 and the output of the sense coil 52 are associated with each other and stored in the storage unit 550C of the current reference value generation unit 550B as a reference value (Step 80).
Then, the drive coil unit 551 is moved to the next predetermined position (Step 81). The predetermined position is a movable range of the drive coil unit 551, and is set to have a predetermined interval between each predetermined position.
When the reference value has not been acquired at all the predetermined positions, the process returns to Step 74 described above and the acquisition of the reference value is repeated. If the reference values are acquired at all the predetermined positions, the process proceeds to the next step (Step 82).

When the reference values are acquired at all the predetermined positions, the capsule endoscope 120 is arranged, and the drive coil unit 551 is moved to a position where the position of the capsule endoscope 120 can be detected.
Then, as shown in FIG. 28, the center frequency of the bandpass filter 61 is matched with the low frequency side calculation frequency (Step 83).
Then, the frequency of the alternating magnetic field formed by the drive coil 51 is matched with the low frequency side calculation frequency (Step 84).
Then, an AC magnetic field having a low frequency side calculation frequency is generated from the drive coil 51, and the induction magnetism induced in the magnetic induction coil 42 is detected by the sense coil 52 (Step 85).

Next, the center frequency of the bandpass filter 61 is matched with the high frequency side calculation frequency (Step 86).
Then, the frequency of the AC magnetic field formed by the drive coil 51 is matched with the frequency for high frequency side calculation (Step 87).
Then, an AC magnetic field having a high frequency side calculation frequency is generated from the drive coil 51, and the induction magnetism induced in the magnetic induction coil 42 is detected by the sense coil 52 (Step 88).
As described above, detection by the low frequency side calculation frequency may be performed first, and then detection by the high frequency side calculation frequency may be performed later. You may detect by the frequency for low frequency side calculation.

Thereafter, the position detection device 550A obtains an output difference (amplitude difference) between the low frequency side calculation frequency and the high frequency side calculation frequency in each sense coil 52, and which is used to estimate the position of the capsule endoscope 120. It is selected whether to use the output difference of the sense coil 52 (Step 89).
Since the selection method of the sense coil 52 is the same as that of the first embodiment, the description thereof is omitted.

  Then, the current reference value generation unit 550B selects the reference value stored in the storage unit 550C based on the current position of the drive coil 51 and sets it as the current reference value (Step 90). As a reference value to be selected, a reference value acquired at a relative position closest to the current relative position of the drive coil 51 and the sense coil 52 is desirable. By selecting in this way, it is possible to shorten the time required to generate the current reference value.

  The position detection device 550A calculates the position and direction of the capsule endoscope 120 based on the current reference value and the output of the sense coil 52 selected in Step 89 (Step 91), and determines the position and orientation. (Step 92).

Next, as shown in FIG. 27, the sense coil 52 used for the next control is selected (Step 93).
That is, the position detection device 550A estimates the moving direction of the capsule endoscope 120 and the moved position and orientation of the capsule endoscope 120 based on the position and orientation of the capsule endoscope 120 determined in Step 92, and the estimated capsule type The sense coil 52 that increases the output in the position and orientation of the endoscope 120 is selected.

Thereafter, the center frequency of the bandpass filter 61 is again matched with the low frequency side calculation frequency (Step 94).
Then, the frequency of the AC magnetic field formed by the drive coil 51 is adjusted to the low frequency side calculation frequency (Step 95).
Then, an AC magnetic field having a low frequency side calculation frequency is generated from the drive coil 51, and the induction magnetism induced in the magnetic induction coil 42 is detected by the sense coil 52 (Step 96).

Next, the center frequency of the bandpass filter 61 is matched with the high frequency side calculation frequency (Step 97).
Then, the frequency of the alternating magnetic field formed by the drive coil 51 is adjusted to the frequency for high frequency side calculation (Step 98).
Then, an AC magnetic field having a high frequency side calculation frequency is generated from the drive coil 51, and the induction magnetism induced in the magnetic induction coil 42 is detected by the sense coil 52 (Step 99).

  Based on the current position of the drive coil 51, the reference value stored in the storage unit 550C is selected and set as the current reference value (Step 90). As a reference value to be selected, a reference value acquired at a relative position closest to the current relative position of the drive coil 51 and the sense coil 52 is desirable.

Then, the position detecting device 550A calculates the position and orientation of the capsule endoscope 120 based on the current reference value in Step 90 and the output of the sense coil 52 selected in Step 93 (Step 101). Determine (Step 102).
Thereafter, when the detection of the position and orientation of the capsule endoscope apparatus 120 is continued, the process returns to Step 93 described above to detect the position and orientation (Step 103).

According to the configuration described above, the position and orientation of the capsule endoscope 120 can be obtained even if the relative position of the drive coil 51 and the sense coil 52 can be changed.
Since the reference value and the position and relative position of the drive coil 51 are stored in advance, even when the relative positions of the drive coil 51 and the sense coil 52 at the time of detecting the position of the capsule endoscope 120 are different from each other, There is no need to measure reference values.

  The current reference value generation method as described above may be used, or the current reference value generation unit 550B obtains a predetermined approximate expression that associates the relative position with the reference value, and is based on the predetermined approximate expression and the current relative position. The current reference value may be generated. According to this generation method, since the current reference value is generated based on a predetermined approximate expression, for example, the current reference value with higher accuracy is compared with the method in which the reference value stored in the storage unit 550C is used as it is as the current reference value. A value can be generated. Further, any of the known approximate expressions can be used as the predetermined approximate expression and is not particularly limited.

(Capsule endoscope position detection system)
The capsule endoscope position detection system according to the present invention will be described below with reference to FIG.
FIG. 29 is a diagram showing an outline of a position detection system for a capsule endoscope according to the present invention.
The capsule endoscope position detection system 610 according to the present invention includes only the position detection device 150 of the capsule endoscope guidance system 110 described above. Therefore, the components, operations, and effects of the capsule endoscope position detection system 610 are the same as those of the capsule endoscope guidance system 110, and thus description thereof is omitted with reference to FIG.
In addition, as described above, the present invention has been described by applying the capsule endoscope position detection system, the capsule medical device guidance system, and the capsule medical device position detection method. What is swallowed is not only a capsule endoscope but also a capsule medical device (for example, a DDS capsule that holds a drug and releases a drug material at a target site in a body cavity, a chemical sensor, a blood sensor, a DNA probe, etc. It can be used for various capsule-type medical devices such as a sensor capsule that mounts and acquires information in the body cavity, and an indwelling capsule that is placed in the body and measures pH, etc. The magnetic induction coil is also used at the tip of the endoscope. The position detection system shown in the present invention can be placed on the tip of a catheter, forceps, etc. The position detection system for a medical device that functions in a body cavity. It can also be used as a system.
The sense coil 52 may be any magnetic sensor that can detect a magnetic field, and various sensors such as a GMR sensor, an MI sensor, a Hall element, and a SQUID magnetometer can be used.

1 is a schematic view of a capsule endoscope guidance system according to a first embodiment of the present invention. It is a perspective view of the capsule endoscope guidance system of FIG. It is the schematic which shows the cross section of the capsule type endoscope guidance system of FIG. It is the schematic which shows the circuit structure of the sense coil receiving circuit of FIG. It is the schematic which shows the structure of the capsule type endoscope of FIG. It is a flowchart which shows the calculation method frequency in this embodiment, and the position and direction detection procedure of a capsule endoscope. It is a flowchart which shows the calculation method frequency in this embodiment, and the position and direction detection procedure of a capsule endoscope. It is a graph which shows the frequency characteristic in a resonance circuit. It is a figure which shows the other arrangement | positioning relationship of a drive coil and a sense coil. It is a figure which shows the other arrangement | positioning relationship of a drive coil and a sense coil. It is a figure which shows the arrangement | positioning relationship of a drive coil and a magnetic induction coil. It is a figure which shows the arrangement | positioning relationship of a drive coil and a sense coil. It is a figure explaining an impulse-like magnetic field. It is a schematic diagram of a capsule type endoscope guidance system concerning a 2nd embodiment of the present invention. It is the schematic which shows the structure of the capsule type endoscope of FIG. It is a flowchart which shows the procedure until calculating | requiring the frequency characteristic of a magnetic induction coil and storing in the memory | storage part 134A. It is a flowchart which shows the procedure which detects the position and direction of a capsule type | mold endoscope. It is a flowchart which shows the procedure which detects the position and direction of a capsule type | mold endoscope. It is a figure which shows the arrangement | positioning relationship of the drive coil and sense coil which concern on the 3rd Embodiment of this invention. It is the schematic which shows the cross section of a capsule type endoscope guidance system. Drive coil and sense coil according to the fourth embodiment of the present invention It is a figure which shows the arrangement | positioning relationship of the drive coil and sense coil which concern on the modification of the 4th Embodiment of this invention. It is a figure which shows the outline of the capsule type endoscope guidance system which concerns on the 5th Embodiment of this invention. It is a figure which shows the positional relationship of a drive coil unit, a sense coil, etc. of FIG. It is a figure which shows the outline of a structure of the drive coil unit of FIG. It is a flowchart which shows the detection procedure of the position and orientation of a capsule endoscope in this embodiment. It is a flowchart which shows the detection procedure of the position and orientation of a capsule endoscope in this embodiment. It is a flowchart which shows the detection procedure of the position and orientation of a capsule endoscope in this embodiment. It is a figure which shows the outline of the position detection system of the capsule endoscope by this invention.

Explanation of symbols

1 Subject 10, 110, 510 Capsule type endoscope guidance system (capsule type medical device guidance system)
20,120 Capsule endoscope (capsule medical device)
25 Spiral part (spiral mechanism)
30 Imaging unit (imaging means)
42 Magnetic induction coil 45 Driving magnet (permanent magnet)
50, 150, 250, 350, 450, 550 Position detection unit (position detection system)
50A, 150A, 550A Position detection device (position analysis means, magnetic field frequency variable unit, drive coil control unit)
50B, 150B calculation frequency determination unit (frequency determination unit)
51,251,351 Drive coil (drive coil)
52 Sense coil (magnetic sensor)
56 Sense coil selector (magnetic sensor selection means)
61 Band pass filter (BPF, band limiting unit)
71 3-axis Helmholtz coil unit (magnetic field generating means, electromagnet)
71X, 71Y, 71Z Helmholtz coils (electromagnets)
73 Rotating magnetic field control circuit (magnetic field direction control means)
82 Display section (display means, image control means)
135 Wireless device (communication unit)
550B current reference value generation unit 550C storage unit (storage unit)
561 Relative position changing unit (relative position changing means)
562 Relative position measuring unit (relative position measuring means)
610 Position detection system R Rotation axis (longitudinal axis)
S space

Claims (20)

A position detection system for a capsule medical device to be put into a body of a subject,
A magnetic induction coil mounted on the capsule medical device;
A drive coil that is arranged outside the operating range of the capsule medical device and generates an alternating magnetic field that acts on the magnetic induction coil;
A plurality of magnetic sensors arranged outside the operating range of the capsule medical device and detecting the induced magnetism generated by the magnetic induction coil;
A frequency determination unit for obtaining a calculation frequency used for calculating the position and orientation of the capsule medical device based on the resonance frequency of the magnetic induction coil;
The output of the magnetic sensor when only the AC magnetic field acts on the magnetic sensor using the calculation frequency, and the output of the magnetic sensor when the AC magnetic field and the induction magnetism act on the magnetic sensor. Position analysis means for calculating the position and orientation of the capsule medical device based on the difference, and
A capsule medical device position detection system that limits the frequency of the alternating magnetic field and / or the output frequency band of the magnetic sensor used for the analysis of the position analysis means based on the calculation frequency.   The position detection system for a capsule medical device according to claim 1, wherein the frequency determination unit obtains the calculation frequency based on an output of the magnetic sensor when the induced magnetism acts on the magnetic sensor. A magnetic field frequency variable unit that temporally changes the frequency of the alternating magnetic field;
When the induction magnetism generated from the magnetic induction coil acts on the magnetic sensor by an alternating magnetic field that changes in frequency with time, the frequency determination unit determines the calculation frequency based on the frequency characteristics of the output of the magnetic sensor. The position detection system for a capsule medical device according to claim 1, wherein An impulse magnetic field generator for generating an impulse magnetic field by applying an impulse drive voltage to the drive coil;
2. The capsule medical device according to claim 1, wherein the frequency determination unit obtains the calculation frequency based on an output of the magnetic sensor when induced magnetism generated from the magnetic induction coil is acted on by the impulse-like magnetic field. Position detection system. A mixed magnetic field generator for generating the alternating magnetic field in which a plurality of different frequencies are mixed;
A variable band limiting unit that limits the output frequency band of the magnetic sensor and can change the range of the limit,
The frequency determination unit is an output of the magnetic sensor when induced magnetism generated from the magnetic induction coil is acted on by the AC magnetic field in which a plurality of different frequencies are mixed, and is obtained via the variable band limiting unit. The capsule medical device position detection system according to claim 1, wherein the calculation frequency is obtained based on a frequency at which the output of the magnetic sensor changes. In the capsule medical device, a transmission unit for transmitting a frequency value related to a resonance frequency of the magnetic induction coil stored in advance to the frequency determination unit is provided,
2. The capsule medical device according to claim 1, wherein the frequency determination unit receives a frequency value related to the resonance frequency from the transmission unit, and determines the calculation frequency based on the received frequency related to the resonance frequency. Position detection system.   The position detection system for a capsule medical device according to any one of claims 1 to 6, further comprising a drive coil control unit that controls the drive coil based on the calculation frequency.   The capsule medical device position detection system according to claim 1, further comprising: a band limiting unit that limits a band of an output frequency of the magnetic sensor based on the calculation frequency.   The position detection system of a capsule medical device according to any one of claims 1 to 8, wherein the plurality of magnetic sensors are arranged in a plurality of directions so as to face an operating range of the capsule medical device.   The position detection system for a capsule medical device according to any one of claims 1 to 9, further comprising a magnetic sensor selection unit that selectively uses an output signal having a strong signal output among output signals of the plurality of magnetic sensors.   The position detection system for a capsule medical device according to any one of claims 1 to 10, wherein the drive coil and the magnetic sensor are arranged at positions facing each other across an operating range of the capsule medical device. A relative position changing means for changing a relative position between the drive coil and the magnetic sensor;
Relative position measuring means for measuring the relative position;
A storage unit that stores in advance the output value of the magnetic sensor when only the AC magnetic field acts as a reference value, and stores the position of the magnetic sensor and the relative position in association with the reference value at that time,
Based on the current position of the magnetic sensor, the current relative position of the drive coil and the magnetic sensor, and the reference value stored in the storage unit,
The position of the capsule medical device according to any one of claims 1 to 11, further comprising: a current reference value generation unit that generates, as a current reference value, an output value of the magnetic sensor when only the current AC magnetic field is applied. Detection system.   The position detection system for a capsule medical device according to claim 12, wherein the current reference value generation unit generates the reference value associated with the relative position closest to the current relative position as the current reference value. The current reference value generation unit obtains a predetermined approximate expression that associates the relative position and the reference value,
13. The capsule medical device position detection system according to claim 12, wherein the current reference value is generated based on the predetermined approximate expression and the current relative position. The position detection system according to any one of claims 1 to 14,
A permanent magnet mounted on the capsule medical device;
A magnetic field generating means arranged outside the operating range of the capsule medical device and generating a magnetic field to act on the permanent magnet;
A capsule medical device guidance system comprising: a magnetic field direction control unit configured to control a direction of a magnetic field applied to the permanent magnet by the magnetic field generation unit. The magnetic field generating means includes three pairs of frame-shaped electromagnets arranged to face each other in a direction orthogonal to each other,
A space in which the subject can be placed is provided inside the electromagnet,
The capsule medical device guidance system according to claim 15, wherein the drive coil and the magnetic sensor are arranged around a space in which the subject can be placed.   The capsule medical device according to claim 15 or 16, wherein a helical mechanism that converts a rotational force around a longitudinal axis of the capsule medical device into a propulsive force in a longitudinal direction is provided on an outer surface of the capsule medical device. Guidance system. The capsule medical device includes an imaging unit having an optical axis along the longitudinal axis of the capsule medical device, and a display unit that displays an image captured by the imaging unit.
An image control means for rotating the image picked up by the image pickup means in the reverse direction and displaying the image on the display means based on rotation information about the longitudinal axis of the capsule medical device by the magnetic field direction control means. 18. The capsule medical device guidance system according to 17. A capsule medical device that is equipped with a magnetic induction coil for position detection and is inserted into the body of the subject,
A position detection system having a drive coil that generates an alternating magnetic field that acts on the magnetic induction coil, and a plurality of magnetic sensors that detect induction magnetism generated by the magnetic induction coil;
A method for detecting the position of a capsule medical device using
A preliminary measurement step of measuring frequency characteristics of the magnetic sensor when only the alternating magnetic field is applied;
A measurement step of measuring frequency characteristics of the magnetic sensor when the alternating magnetic field and the induction magnetism are applied;
A frequency determining step for determining a calculation frequency used to calculate the position and orientation of the capsule medical device based on the frequency characteristics measured in the preliminary measurement step and the measurement step;
A detection step of detecting an output of the magnetic sensor when the AC magnetic field and the induction magnetism act on the calculation frequency;
A position calculation step of calculating a position and an orientation of the capsule medical device based on the detected output of the magnetic sensor. A capsule-type medical device having a magnetic induction coil for position detection and a transmission unit for transmitting a frequency value related to a resonance frequency of the magnetic induction coil to the outside;
Position detection of a capsule medical device using a position detection system having a drive coil that generates an alternating magnetic field that acts on the magnetic induction coil and a plurality of magnetic sensors that detect induction magnetism generated by the magnetic induction coil A method,
A frequency for acquiring a frequency related to the resonance frequency transmitted by the transmission unit and determining a calculation frequency used for calculating the position and orientation of the capsule medical device based on the acquired frequency related to the resonance frequency A decision step;
A measurement step of measuring frequency characteristics of the magnetic sensor when only an alternating magnetic field of the calculation frequency is applied;
A detection step of detecting an output of the magnetic sensor when the induction magnetism generated by the alternating magnetic field having the calculation frequency and the alternating magnetic field having the calculation frequency is applied;
A position calculating step of calculating a position of the capsule medical device based on the detected output of the magnetic sensor.

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