JP2005278817A - Position detecting system for inside of examinee's body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a position detecting system for the inside of an examinee's body, capable of detecting the position of a device inserted into the examinee's body and its pointing direction, regardless of the presence of organs. <P>SOLUTION: In an endoscope of a capsule shape 2, a magnetic field generation member 24 floats in a fluid 27 sealed in a case 26, and is so positioned that its image can be projected to a CCD (charge coupled device) 13 through an optical system 32 and a reflecting member 33. The longitudinal side of the permanent magnetic 29 of the magnetic field generation 24 is always kept to point vertically by providing a weight member 30. When the CCD 13 whose view is fixed to the endoscope of the capsule shape 2 captures an image of the magnetic field generation member 24, and the direction between the pointing direction of the endoscope of the capsule shape 2 and the vertical direction is detected. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention introduces an intra-subject introduction apparatus that is introduced into a subject and moves within the subject, and is disposed outside the subject, and acquires position information of the intra-subject introduction apparatus inside the subject. The present invention relates to an in-subject position detection system including a position detection device.

  In recent years, in the field of endoscopes, swallowable capsule endoscopes have been proposed. This capsule endoscope is provided with an imaging function and a wireless communication function. The capsule endoscope is swallowed from the mouth of the subject for observation (examination) until it is spontaneously discharged until it is spontaneously discharged. It has the function of moving and capturing images sequentially.

  While moving inside the body cavity, image data captured inside the body by the capsule endoscope is sequentially transmitted to the outside by wireless communication and stored in a memory provided outside. By carrying a receiver having a wireless communication function and a memory function, the subject can freely act after swallowing the capsule endoscope and before being discharged. After the capsule endoscope is ejected, the doctor or nurse can make a diagnosis by displaying an image of the organ on the display based on the image data stored in the memory.

  With regard to such a capsule endoscope, for example, in order to capture an endoscopic image of a specific organ inside the subject, a function for detecting the position of the capsule endoscope in the subject is provided on the receiver side. Has been proposed. As an example of a capsule endoscope system having such a position detection function, a capsule endoscope system that utilizes a wireless communication function built in the capsule endoscope is known. In other words, the receiver provided outside the subject has a configuration including a plurality of antenna elements, and the radio signals transmitted from the capsule endoscope are received by the individual antenna elements, and received by the respective antenna elements. It has a mechanism for detecting the position of the capsule endoscope in the subject based on the difference in intensity (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2003-19111

  However, the conventional capsule endoscope system has a problem that the position detection accuracy of the capsule endoscope in the subject is low. Hereinafter, this problem will be described in detail.

  As described above, the capsule endoscope system according to the related art detects the position of the capsule endoscope in the subject based on the reception intensity distributions of the plurality of antenna elements included in the receiver. As described in paragraph [0018] of Patent Document 1, the position detection mechanism is configured such that the attenuation of the intensity of the radio signal transmitted from the capsule endoscope depends on the distance from the capsule endoscope. This is done on the assumption that it is uniquely determined.

  However, in reality, components such as organs that exist between the capsule endoscope and the antenna element have different values of relative permittivity, conductivity, and the like. The attenuation rate of the signal strength is a significantly different value. For example, when a liver, blood vessel, or the like is present between the capsule endoscope and the antenna element, a large amount of radio signals are absorbed by the organ, so that the organ does not exist. Compared with the case, the attenuation rate of the radio signal strength is increased, which hinders accurate position detection.

  The present invention has been made in view of the above, and the intra-subject introduction device regardless of the presence of an organ or the like in a state where the intra-subject introduction device such as a capsule endoscope is introduced into the subject. It is an object of the present invention to realize an in-subject position detection system that can detect the position of the target and the direction of the in-subject introduction apparatus.

  In order to solve the above-described problems and achieve the object, an in-subject position detection system according to claim 1 is introduced into a subject and moves inside the subject. An in-subject position detection system comprising a position detection device that is disposed outside a sample and acquires position information of the in-subject introduction device inside the subject. A magnetic field generating member that maintains a state of being directed in a constant direction regardless of a change in the directing direction of the in-sample introducing device and that forms a static magnetic field, and the in-subject introducing device with respect to the directing direction of the magnetic field generating member An azimuth detecting unit that detects a fixed azimuth of a predetermined axis, and a wireless transmission unit that transmits a detection result of the azimuth detecting unit to the outside. The position detecting device includes a static magnetic field formed by the magnetic field generating member. Magnetic field strength detection means for detecting the strength of the magnetic field component parallel to the field, and positional information for deriving positional information of the in-subject introduction device in the subject based on the magnetic field strength detected by the magnetic field strength detection means A derivation unit and a radio reception unit for receiving a radio signal transmitted from the radio transmission unit are provided.

  According to the first aspect of the present invention, the magnetic field generating member that maintains a state directed in a certain direction, the orientation between the pointing direction of the magnetic field generating member, and a predetermined axis set in the in-subject introduction apparatus. Therefore, it is possible to detect which direction the orientation direction of the in-subject introduction apparatus is in the subject.

  In the in-subject position detection system according to claim 2, in the above-described invention, the in-subject introduction apparatus further includes an imaging unit that images the inside of the subject, and the wireless transmission unit includes the imaging unit. The image data picked up by is transmitted to the outside.

  In the in-subject position detection system according to a third aspect of the present invention, in the above invention, the magnetic field generating member is disposed so that an image is projected into a field of view of the imaging means, and the imaging means It is arranged in a state of being fixed in an internal introduction device, and functions as the orientation detection means by imaging a state in which the orientation of the magnetic field generating member with respect to the in-subject introduction device is changed. .

  Further, in the in-subject position detection system according to claim 4, in the above invention, the magnetic field strength detection means has a function of detecting the strength of a magnetic field component in a single direction, and the single direction, It arrange | positions so that the output direction of the static magnetic field in a magnetic field generation member may be maintained in a parallel state.

  In the in-subject position detection system according to a fifth aspect of the present invention, in the above invention, the magnetic field generating member has an output direction of a static magnetic field parallel to a vertical direction regardless of a change in a directivity direction of the in-subject introduction apparatus. The magnetic field intensity detecting means maintains the state in which the detection direction of the magnetic field component is parallel to the vertical direction regardless of the posture variation of the subject.

  In the in-subject position detection system according to claim 6, in the above invention, the position detection device includes a plurality of the magnetic field intensity detection means, and the position information derivation means is detected by the plurality of magnetic field detection means. Deriving the distance between the in-subject introduction device and each of the plurality of magnetic field detection means based on the magnetic field strength, and deriving the position of the in-subject introduction device based on the derived distance. Features.

  In the in-subject position detection system according to claim 7, in the above invention, the wireless reception unit includes a plurality of reception antennas, and the position detection device is derived by the position information deriving unit. The apparatus further comprises selection means for selecting the reception antenna to be used for receiving a radio signal based on the position of the in-subject introduction apparatus.

  Further, in the in-subject position detection system according to claim 8, in the above invention, the position detection device includes an image picked up by the image pickup means, and a position of the in-subject introduction device at the time of image pickup. Is further provided with storage means for storing the information in association with each other.

  An in-subject position detection system according to the present invention includes a magnetic field generating member that maintains a state oriented in a certain direction, a directing direction of the magnetic field generating member, and a predetermined axis set in the in-subject introduction apparatus. The azimuth detecting means for detecting the azimuth of the head has an effect that it is possible to detect which direction the orientation of the in-subject introduction apparatus is in the subject.

  An in-subject position detection system that is the best mode for carrying out the present invention (hereinafter simply referred to as “embodiment”) will be described below. Note that the drawings are schematic, and it should be noted that the relationship between the thickness and width of each part, the ratio of the thickness of each part, and the like are different from the actual ones. Of course, the part from which the relationship and ratio of a mutual dimension differ is contained.

  An in-subject position detection system according to an embodiment will be described. The in-subject position detection system according to the present embodiment is introduced into the subject 1 and functions as an example of the in-subject introduction device, and the subject of the capsule endoscope 2 1, a position detection device 3 that detects a position inside, a display device 4 that displays position information of the capsule endoscope 2 detected by the position detection device 3, and between the position detection device 3 and the display device 4. And a portable recording medium 5 for transferring the information.

  The display device 4 is for displaying the position information of the capsule endoscope 2 acquired by the position detection device 3, and is a workstation that displays an image based on data obtained by the portable recording medium 5. The configuration is as follows. Specifically, the display device 4 may be configured to directly display an image by a CRT display, a liquid crystal display, or the like, or may be configured to output an image to another medium such as a printer.

  The portable recording medium 5 is detachable with respect to a position information deriving device 8 and a display device 4 described later, and has a structure capable of outputting and recording information when being inserted into both. Specifically, the portable recording medium 5 is inserted into the position information deriving device 8 while the capsule endoscope 2 is moving in the body cavity of the subject 1, and the position of the capsule endoscope 2 is Record information about. After the capsule endoscope 2 is ejected from the subject 1, the capsule endoscope 2 is taken out from the position information deriving device 8 and inserted into the display device 4, and the recorded data is read out by the display device 4. By transferring data between the position information deriving device 8 and the display device 4 using a portable recording medium 5 such as a Compact Flash (registered trademark) memory (registered trademark), the position information deriving device 8 and the display device 4 Unlike the case where the two are connected by wire, the subject 1 can freely move even when the capsule endoscope 2 is moving inside the subject 1.

  Next, the capsule endoscope 2 will be described. The capsule endoscope 2 functions as an example of the intra-subject introduction apparatus in the claims. FIG. 2 is a block diagram schematically showing the configuration of the capsule endoscope 2. Note that FIG. 2 schematically shows the configuration of the capsule endoscope 2, and the positional relationship between the components shown in FIG. 2 is not necessarily consistent with the actual one. Care must be taken.

  As shown in FIG. 2, the capsule endoscope 2 includes an LED 11 that functions as an illuminating unit for irradiating an imaging region when imaging the inside of the subject 1, and an LED driving circuit that controls the driving state of the LED 11. 12, a CCD 13 that functions as an image pickup unit that picks up a reflected light image from a region irradiated by the LED 11, and a CCD drive circuit 14 that controls the drive state of the CCD 13. In the present embodiment, the CCD 13 not only functions as an imaging unit but also functions as an azimuth detecting unit that detects the directivity direction of the capsule endoscope 2, and details will be described later.

  Also, the capsule endoscope 2 modulates image data picked up by the CCD 13 to generate an RF signal, and transmits as a wireless means for wirelessly transmitting the RF signal output from the transmission circuit 15. An antenna 16 and a system control circuit 17 that controls operations of the LED drive circuit 12, the CCD drive circuit 14, and the transmission circuit 15 are provided.

  By providing these mechanisms, the capsule endoscope 2 acquires image data of the region to be examined illuminated by the LED 11 by the CCD 13 while being introduced into the subject 1. The acquired image data is converted into an RF signal by the transmission circuit 15 and then transmitted to the outside via the transmission antenna 16.

  The capsule endoscope 2 includes a receiving antenna 18 that receives a radio signal transmitted from the position detection device 3 side, and a separation circuit 19 that separates a power feeding signal from a signal received by the receiving antenna 18. Is provided. Furthermore, the capsule endoscope 2 includes a power regeneration circuit 20 that regenerates power from the separated power supply signal, a booster circuit 21 that boosts the regenerated power, and a capacitor 22 that stores the boosted power. Prepare. Further, the capsule endoscope 2 detects the content of the control information signal from the component separated from the power feeding signal by the separation circuit 19 and outputs the detected control information signal to the system control circuit 17. A circuit 23 is provided. The system control circuit 17 also has a function of distributing the driving power supplied from the capacitor 22 to other components.

  By providing these mechanisms, the capsule endoscope 2 first receives a radio signal transmitted from the position detection device 3 side at the reception antenna 18 and feeds power from the received radio signal by the separation circuit 19. Separate the control signal and control information signal. The control information signal separated by the separation circuit 19 is output to the system control circuit 17 through the control information detection circuit 23 and used for driving control of the LED 11, the CCD 13 and the transmission circuit 15. On the other hand, the power supply signal is regenerated as power by the power regeneration circuit 20, and the regenerated power is boosted to a potential suitable for the capacitor 22 by the booster circuit 21 and then stored in the capacitor 22.

  Furthermore, the capsule endoscope 2 includes a magnetic field generating member 24 that outputs a static magnetic field for detecting the position of the capsule endoscope 2 by the position detection device 3. In the present embodiment, the magnetic field generating member 24 is disposed so that the output direction of the magnetic field is always in the vertical direction, and is disposed at a position where its own image is projected into the field of view of the CCD 13. Hereinafter, the magnetic field generating member 24 and the mechanism for holding the magnetic field generating member 24 in the capsule endoscope 2 will be described first, and then the positional relationship between the magnetic field generating member 24 and the CCD 13 will be described.

  FIG. 3 is a schematic diagram showing the specific configuration of the magnetic field generating member 24 and the mechanism for supporting the magnetic field generating member 24 provided in the capsule endoscope 2 and the positional relationship between the magnetic field generating member 24 and the CCD 13. As shown in FIG. 3, the capsule endoscope 2 is transparent in which the position is fixed with respect to the capsule endoscope 2 inside the housing 25 formed by the capsule body portion 35 and the imaging window portion 36. The case member 26 is provided, and a transparent liquid 27 is sealed in the case member 26, and the magnetic field generating member 24 is arranged in a state of floating in the liquid 27. The magnetic field generating member 24 has a configuration including a spherical body 28, a permanent magnet 29, and a weighting member 30.

  The spherical body 28 is for holding the permanent magnet 29 and the weight member 30 inside, and is transparent to such an extent that the permanent magnet 29 can be visually recognized from the outside. The weight member 30 is constituted by a member that is heavier than the other elements constituting the spherical body 28. As a result, the spherical body 28 has a liquid 27 in a state where the weight member 30 is located at the bottom in the vertical downward direction. Floating inside. As shown in FIG. 3, the weight member 30 is arranged so as to be positioned on the direction extension of the output magnetic field from the permanent magnet 29 with respect to the permanent magnet 29.

  The permanent magnet 29 constitutes the magnetic field generating member 24 together with the spherical body 28, and is composed of a permanent magnet having a size that can be accommodated in the spherical body 28, and outputs a static magnetic field in which time fluctuation of the magnetic field strength can be ignored. Is for. As described above, since the weight member 30 has a configuration in which the permanent magnet 29 is disposed on the extension of the magnetic field output direction of the permanent magnet 29 with respect to the permanent magnet 29, the permanent magnet 29 is encapsulated by the action of the weight member 30. Regardless of the change in the directivity direction of the endoscope 2, the state in which the output magnetic field direction is parallel to the vertical direction is maintained.

  Instead of the permanent magnet 29, for example, a coil or the like that generates a static magnetic field by supplying a constant current may be used as the magnetic field generating member. Therefore, it is preferable to configure the magnetic field generating member using the permanent magnet 29.

The static magnetic field generated from the permanent magnet 29 is expressed by closed magnetic field lines that are output from the N pole side and travel outside the permanent magnet 29 and then input to the S pole side again. Here, as shown in FIG. 3, the traveling direction of the magnetic field lines has a place dependency, but the strength of the static magnetic field represented by the density of the magnetic field lines is determined only by the distance from the capsule endoscope 2. It can be considered. That is, the size of the permanent magnet 29 built in the capsule endoscope 2 is so small that it can be ignored as compared with the distance between the capsule endoscope 2 and the magnetic field strength detection devices 6a to 6h. Thus, the magnetic field strength P at a point away from the capsule endoscope 2 by the distance r is expressed by using the proportionality coefficient α,

P = α / r ³ (1)

The relationship is established. The in-subject position detection system according to the present embodiment detects the position of the capsule endoscope 2 based on the relationship shown in the expression (1) as described later.

  Next, the positional relationship between the permanent magnet 29 and the CCD 13 will be described. As described above, the CCD 13 is essentially for capturing an image in the subject 1, and corresponds to the imaging window 36 in the capsule endoscope 2 in order to perform such a function. It is fixed at the position. Specifically, the CCD 13 is fixed at a position where an image in the subject 1 input via the imaging window 36 and the imaging optical system 34 can be imaged.

  With respect to the CCD 13 having such an arrangement, the magnetic field generating member 24 is arranged in a state in which its own image can be projected within the imaging field of view of the CCD 13. Specifically, the capsule endoscope 2 includes an optical system 32 for forming an image of the magnetic field generating member 24, and a reflecting member 33 for reflecting the image that has passed through the optical system 32. An image of the magnetic field generating member 24 is projected into the field of view of the CCD 13.

  When the CCD 13 and the magnetic field generating member 24 have such a positional relationship, the CCD 13 captures the in-subject image and also the magnetic field generating member 24. As described above, the directivity direction of the magnetic field generating member 24 coincides with the vertical direction regardless of the change in the directivity direction of the capsule endoscope 2, so that the CCD 13 fixed at a predetermined position in the capsule endoscope 2. In this case, the fluctuation state of the directivity direction of the magnetic field generating member 24 with respect to the directivity direction of the capsule endoscope 2 is imaged. In other words, this means that the fluctuation state of the directivity direction of the capsule endoscope 2 with respect to the magnetic field generating member 24 that always points in a certain direction is detected. That is, the image of the magnetic field generating member 24 imaged by the CCD 13 detects the azimuth of a predetermined azimuth axis set in a fixed state with respect to the capsule endoscope 2 with respect to the direction of the magnetic field generating member. From this point of view, the CCD 13 in the present embodiment functions as a direction detection means.

  Next, the position detection device 3 will be described. The position detection device 3 has a function of detecting the position of the capsule endoscope 2 inside the subject 1 and a function of performing wireless communication with the capsule endoscope 2. As shown also in FIG. 1, the position detection device 3 feeds power to the reception antennas A <b> 1 to An for receiving a radio signal transmitted from the capsule endoscope 2 and the capsule endoscope 2. Power feeding antennas B1 to Bm for transmitting radio signals including signals for use, and magnetic field strength detection devices 6a to 6f for detecting the strength of the static magnetic field output from the permanent magnet 29 provided in the capsule endoscope 2, Position information of the capsule endoscope 2 based on the fixing members 7a and 7b for fixing the magnetic field strength detection devices 6a to 6h on the body surface of the subject 1 and the magnetic field strength detected by the magnetic field strength detection devices 6a to 6h. And a position information deriving device 8 for deriving.

  The receiving antennas A1 to An and the feeding antennas B1 to Bm are for receiving and transmitting radio signals to and from the capsule endoscope 2, respectively. Specifically, the receiving antennas A1 to An and the like have a configuration including a loop antenna and a fixing means for fixing the loop antenna on the body surface of the subject 1.

  The magnetic field strength detection devices 6a to 6h are for detecting the magnetic field strength at the place where each of them is disposed. FIG. 4 is a schematic diagram showing a specific configuration of each of the magnetic field strength detection devices 6a to 6h. As shown in FIG. 4, the magnetic field intensity detection devices 6 a to 6 h are arranged so as to cover the spherical body 39 including the magnetic field sensor unit 41 and the outer surface of the spherical body 39 in order to hold the spherical body 39 in a floating state. The liquid 40, a case member 38 for holding the liquid 40, and components provided outside the case member 38 are formed.

  The spherical body 39 includes a magnetic field sensor unit 41, a magnetic field measurement system control unit 42 that controls the driving state of the magnetic field sensor unit 41, and modulation and signal modulation as necessary when performing wireless communication with the outside of the spherical body 39. A transmission / reception unit 45 for performing demodulation and a transmission / reception antenna 46 for performing wireless communication with the outside are provided. In addition, the spherical body 39 includes a battery 43 that holds power for driving the magnetic field sensor unit 41 and the like, a power receiving unit 44 that converts a power feeding signal transmitted from the outside into power, and a power feeding signal transmitted from the outside. And a power receiving antenna 47 for receiving and supplying the power receiving unit.

  Furthermore, the spherical body 39 includes a weight member 48 that is disposed on an extension of the magnetic field detection direction (described later) of the magnetic field sensor unit 41 and is heavier than other components. Since the spherical body 39 is held in a floating state in the liquid 40, the spherical body 39 is always kept in the vertical downward direction by the action of the weighting member 48 regardless of the change in the state of the magnetic field strength detection device 6. Maintain the bottom position.

  The magnetic field sensor unit 41 includes a magnetic field intensity detection sensor such as an MI sensor having a function of detecting a magnetic field traveling in a predetermined direction (hereinafter, this magnetic field direction is referred to as “magnetic field detection direction”). For example, the MI sensor has a configuration using, for example, an FeCoSiB amorphous wire as a magnetosensitive medium, and when a high frequency current is applied to the magnetosensitive medium, the magnetic impedance of the magnetosensitive medium greatly changes due to an external magnetic field. Magnetic field strength is detected using the MI effect. The magnetic field sensor unit 41 includes a magnetic field detection direction indicated by an arrow in FIG. 4 and has a configuration in which a weight member 48 is disposed on an extension of the magnetic field detection direction. The detection direction is always held in a state where it coincides with the vertical direction, and the intensity of the magnetic field component traveling in the vertical direction is detected among the magnetic fields existing in the region where the magnetic field strength detection device 6 is disposed.

  The magnetic field strength detection device 6 includes a power feeding antenna 49 that transmits a power feeding signal to the vicinity of the outside of the case member 38, a transmission / reception antenna 50 that receives the magnetic field strength detected by the magnetic field sensor unit 41, and the power feeding antenna 49. And a transmission / reception unit 52 electrically connected to the transmission / reception antenna 50. The power supply unit 51 and the transmission / reception unit 52 are electrically connected to the control unit 53 and operate under the control of the control unit 53. The control unit 53 is electrically connected to the position information deriving device 8, operates based on the control by the position information deriving device 8, and transmits the magnetic field intensity detected by the magnetic field sensor unit 41 to the position information deriving device 8. It has the function to output it.

  The fixing members 7 a and 7 b are for fixing the magnetic field intensity detection devices 6 a to 6 h to the subject 1. Specifically, the fixing members 7 a and 7 b are formed in an annular shape by, for example, an elastic member, and have a configuration in which the fixing members 7 a and 7 b are fixed in close contact with the body of the subject 1. The magnetic field intensity detectors 6a to 6d and the magnetic field intensity detectors 6e to 6h are fixed to the subject 1 by fixing members 7a and 7b, respectively. The fixing members 7a and 7b are fixed to the body of the subject 1. By tightly fixing to the part, the magnetic field intensity detection devices 6a to 6h are arranged in a state where the relative position to the subject 1 is fixed.

  Next, the position information deriving device 8 will be described. The position information deriving device 8 has a function of deriving the position of the capsule endoscope 2 based on the magnetic field strength detected by the magnetic field strength detecting devices 6a to 6h. FIG. 5 is a block diagram showing a configuration of the position information deriving device 8.

  First, the position information deriving device 8 has a configuration as a receiving device that receives image data inside the subject 1 wirelessly transmitted from the capsule endoscope 2. Specifically, the position information deriving device 8 demodulates the radio signal received by the antenna selection unit 57 that selects the reception antennas A1 to An to be used for data reception and the selected reception antenna. The receiving circuit 58 that extracts and outputs image data acquired by the capsule endoscope 2 from the wireless signal, and a signal processing unit that performs necessary processing on the output image data 59 and a storage unit 60 for recording image data subjected to image processing.

  The antenna selector 57 is for selecting a receiving antenna that is most suitable for receiving a radio signal transmitted from the capsule endoscope 2. Specifically, the antenna selector 57 grasps the positions of the receiving antennas A1 to An in advance, and receives information related to the position of the capsule endoscope 2 derived by the position calculator 56. Have For this reason, the antenna selection unit 57 selects the reception antenna that is estimated to have the best reception sensitivity in relation to the position of the capsule endoscope 2, and is received by the selected reception antenna. It has a function of outputting a radio signal to the receiving circuit 58.

  The storage unit 60 has a function of storing the image data output from the signal processing unit 59 and the position of the capsule endoscope 2 at the time when the output image data is captured. That is, the position information deriving device 8 has a configuration in which the information obtained in the position calculation unit 56 and the signal processing unit 59 is output to the storage unit 60 as shown in FIG. It has a function of storing these pieces of information in an associated state. As a result, the storage unit 60 stores the image data of a predetermined area inside the subject 1 and the position of the capsule endoscope 2 at the time of capturing the image data.

  The position information deriving device 8 has a configuration as a transmitting device that generates a power feeding signal to be transmitted to the capsule endoscope 2 and outputs it to the power feeding antennas B1 to Bm. Specifically, the position information deriving device 8 receives an oscillator 61 having a function of generating a power feeding signal and a function of defining an oscillation frequency, and a control information signal for controlling the driving state of the capsule endoscope 2. A control information input unit 62 to be generated, a superimposing circuit 63 that combines the power feeding signal and the control information signal, and an amplifier circuit 64 that amplifies the intensity of the combined signal are provided. The signal amplified by the amplifier circuit 64 is sent to the power feeding antennas B <b> 1 to Bm and transmitted to the capsule endoscope 2. The position information deriving device 8 includes a power supply unit including a predetermined power storage device or an AC power adapter, and each component of the position information deriving device 8 uses the power supplied from the power supply unit as driving energy. Yes.

  Further, the position information deriving device 8 has a configuration for deriving the position of the capsule endoscope 2 based on the magnetic field strength detected by the magnetic field strength detecting devices 6a to 6h. Specifically, the position information deriving device 8 determines the distance between each of the magnetic field strength detection devices 6a to 6h and the capsule endoscope 2 based on the magnetic field strength detected by the magnetic field strength detection devices 6a to 6h. A deriving distance deriving unit 55 and a position calculating unit 56 deriving the position of the capsule endoscope 2 based on the distance derived by the distance deriving unit 55 are provided.

  The distance deriving unit 55 is for deriving the distance between the reference device and the selected device and the capsule endoscope 2 based on the input magnetic field strength. Specifically, the distance deriving unit 55 derives the distance between the magnetic field strength detecting device in which the magnetic field strength is detected and the capsule endoscope 2 based on the input magnetic field strength and the equation (1). Has the function of

  The position calculation unit 56 performs a predetermined calculation process based on the distance between the magnetic field intensity detection device selected as the reference device or the like and the capsule endoscope 2 to determine the position of the capsule endoscope 2. It is for deriving. Further, the position calculation unit 56 has a function of deriving the position of the capsule endoscope 2 and then outputting the derivation result to the storage unit 60.

  Next, the position detection of the capsule endoscope 2 using the position information deriving device 8 will be briefly described. FIG. 6 is a flowchart for explaining the position detection operation, and FIG. 7 is a schematic diagram for explaining the position detection operation of the capsule endoscope 2 performed by the position information deriving device 8. In FIG. 7, the position coordinates of the magnetic field strength detection devices 6a to 6h are respectively defined as (0, 0, a), (a, 0, a),... In the orthogonal three-dimensional coordinate system. The position coordinates of the capsule endoscope 2 to be derived are (x, y, z).

  First, the strength of the static magnetic field output from the capsule endoscope 2 is detected by each of the magnetic field strength detection devices 6a to 6h (step S101), and information on the detected magnetic field strength is provided in the position information deriving device 8. It is output to the distance deriving unit 55. Then, the distance deriving unit 55 derives the distance between each of the magnetic field strength detection devices 6a to 6h and the capsule endoscope 2 based on the input magnetic field strength (step S102). Specifically, the distance deriving unit 55 derives the distance by performing the calculation shown in the equation (1). Then, the position calculation unit 56 derives the position of the capsule endoscope 2 in the subject 1 based on the derived distance (step S103), and the storage unit 60 stores information regarding the derived position. The image data transmitted from the capsule endoscope 2 is stored together (step S104).

Derivation of the position of the capsule endoscope 2 in step S103 will be described. As shown in FIG. 7, in step S102, the distances between the magnetic field intensity detection devices 6a to 6h and the capsule endoscope 2 are derived as ra, rb,. The relationship between the position (x, y, z) of the mirror 2 and the magnetic field intensity detectors 6a to 6h is as follows:

(X-0) ² + (y-0) ² + (za) ² = r _a ² (2)
(X−a) ² + (y−0) ² + (za) ² = r _b ² (3)
(X−a) ² + (y−a) ² + (z−0) ² = r _c ² (4)
(X-0) ² + (ya) ² + (za) ² = r _d ² (5)
^{(X-0) 2 + (} y-0) 2 + (z-0) 2 = r e 2 ··· (6)
(X−a) ² + (y−0) ² + (z−0) ² = r _f ² (7)
(X-a) ² + (ya) ² + (z-0) ² = r _g ² (8)
(X-0) ² + (ya) ² + (z-0) ² = r _h ² (9)

Will be expressed. By solving this equation, the value of the position (x, y, z) of the capsule endoscope 2 is derived. Here, since the position coordinates of the magnetic field intensity detection devices 6a to 6h may slightly vary due to the posture change of the subject 1, the position calculation unit 56 in the present embodiment is (2) The capsule type while adjusting the position coordinates of the magnetic field intensity detectors 6a to 6h using, for example, the maximum likelihood method so that the fluctuation range of the values of x, y, and z derived based on the equations (9) is minimized. The position of the endoscope 2 is derived.

  Next, the direction detection of the capsule endoscope 2 in the subject 1 will be described. As already described with reference to FIG. 3, in the capsule endoscope 2, the magnetic field generating member 24 is arranged to project its own image onto the CCD 13 via the optical system 32 and the reflecting member 33. . Therefore, as shown in FIG. 8, the image 66 captured by the CCD 13 includes not only the in-vivo image 67 that is normally captured but also an image 68 that captures the magnetic field generating member 24.

  The CCD 13 is input through the imaging window 36 and has an intrinsic function of imaging the in-subject image formed through the optical system 34. Therefore, the imaging window 36 and the optical system are used. 34 is arranged at a fixed position with respect to 34. In other words, the imaging field of view of the CCD 13 is fixed with respect to the capsule endoscope 2 and further fixed with respect to the directing direction of the capsule endoscope 2.

  On the other hand, the magnetic field generating member 24 is arranged in a state of floating in the liquid 27 sealed in the case member 26 as shown in FIG. Furthermore, since the magnetic field generating member 24 has a configuration including the weight member 30, the magnetic field generating member 24 is held in the capsule endoscope 2, while the direction of the capsule endoscope 2 changes. Therefore, the state in which the longitudinal direction of the permanent magnet 29 is parallel to the vertical direction is maintained.

  From the above, the image of the magnetic field generating member 24 imaged by the CCD 13 reflects the relationship between the directivity direction of the capsule endoscope 2 and the vertical direction. That is, the magnetic field generating member 24 maintains the state in which the longitudinal direction of the permanent magnet 29 coincides with the vertical direction, while the imaging field of view of the CCD 13 maintains a certain relationship with the directing direction of the capsule endoscope 2. Is maintained. Therefore, the image of the magnetic field generating member 24 imaged on the CCD 13 changes as the directional direction of the capsule endoscope 2 changes, and this change is an azimuth between the directional direction and the vertical direction of the capsule endoscope 2. It reflects changes. As a result, by visually observing the image data captured by the CCD 13, it is possible to detect the orientation of the capsule endoscope 2 at the time of imaging with respect to the vertical direction. Based on the above mechanism, in the present embodiment, the CCD 13 serving as the imaging means also functions as an orientation detection means.

  Next, advantages of the in-subject position detection system according to the present embodiment will be described. First, the in-subject position detection system according to the present embodiment derives the position of the capsule endoscope 2 based on the static magnetic field formed by the magnetic field generating member 24 provided in the capsule endoscope 2. It is said. Unlike an electromagnetic wave or the like, a static magnetic field has a characteristic that the relationship of the formula (1) is well established because it has a characteristic that the intensity is attenuated almost uniquely regardless of a change in relative permittivity in the propagation region. Therefore, position detection can be performed with higher accuracy than in the case of position detection using electromagnetic waves or the like even in a space where there are organs with different relative dielectric constants, such as inside the human body. Has the advantage.

  An advantage of such a static magnetic field is that the burden on the subject 1 is reduced when the capsule endoscope 2 is introduced into the subject 1. That is, for the reason described above, the in-subject position detection system according to the present embodiment has an advantage that a decrease in position detection accuracy due to a difference in the surrounding environment of the capsule endoscope 2 is suppressed. When the capsule endoscope 2 is introduced into the subject 1, there is no need to restrict such as eating and drinking unlike other examination methods. Therefore, the subject 1 can live a normal life even during the examination using the capsule endoscope 2, and the burden on the subject 1 in the examination can be reduced.

  Further, in the in-subject position detection system according to the present embodiment, the magnetic field generating member 24 held in the capsule endoscope 2 is in the direction of the output magnetic field regardless of the change in the directing direction of the capsule endoscope 2. Is maintained parallel to the vertical direction. Further, the magnetic field sensor unit 41 held in the magnetic field detection devices 6a to 6h maintains a state in which the magnetic field detection direction is parallel to the vertical direction, regardless of changes in the posture or the like of the subject 1. For this reason, in the in-subject position detection system according to the present embodiment, the magnetic field output direction by the magnetic field generating member 24 and the magnetic field detection direction of the magnetic field sensor unit 41 are always maintained in a parallel state.

  By adopting such a configuration, the in-subject position detection system according to the present embodiment has the advantage that highly sensitive magnetic field strength detection is possible. That is, most of the static magnetic field output from the magnetic field generating member 24 travels in the direction parallel to the magnetic field output direction even outside the subject 1, so the magnetic field detection direction of the magnetic field sensor unit 41 is the magnetic field generating member. By being parallel to the magnetic field direction by 24, it becomes possible to efficiently detect the static magnetic field output from the magnetic field generating member 24, and to detect the magnetic field strength with high sensitivity. In order to enjoy such an advantage, the magnetic field detection direction of the magnetic field sensor unit 41 and the magnetic field output direction of the magnetic field generating member 24 need only be parallel, and it is not always necessary that both be parallel to the vertical direction.

  Furthermore, the in-subject position detection system according to the present embodiment can simplify the configuration of the magnetic field sensor unit particularly with respect to the magnetic field detection devices 6a to 6h. That is, when the magnetic field output direction from the magnetic field generating member 24 and the magnetic field detection direction of the magnetic field sensor unit do not have a correlation, the magnetic field detection device needs to include a magnetic field strength detection mechanism in the three-axis directions. In general, it is necessary to provide a magnetic field sensor unit having a magnetic field detection direction with respect to each of the x direction, the y direction, and the z direction. In contrast, the in-subject position detection system according to the present embodiment is arranged in a state where the magnetic field detection direction of the magnetic field sensor unit 41 matches the magnetic field output direction of the magnetic field generation member 24. A mechanism having a magnetic field detection function only in one direction can be used, and the configuration of the magnetic field detection mechanism can be simplified.

  Further, the in-subject position detection system according to the present embodiment has an advantage that the influence of the geomagnetic component can be eliminated. That is, the magnetic field output direction from the magnetic field generating member 24 is the vertical direction, and the magnetic field strength detection devices 6a to 6h have a function of detecting the strength of the magnetic field component in the vertical direction. On the other hand, since the geomagnetic component travels in a direction substantially perpendicular to the vertical direction, that is, in a substantially horizontal direction, the magnetic field intensity detection devices 6a to 6h do not inherently detect the intensity of the geomagnetic component, and are special. It is possible to eliminate the influence of the geomagnetic component without providing a simple filtering mechanism.

  Further, the in-subject position detection system according to the present embodiment detects a change in the direction of the capsule endoscope 2 by utilizing the fact that the magnetic field generating member 24 always points in one direction (vertical direction). It has a mechanism to do. As described above, the configuration in which the directivity direction of the magnetic field generating member 24 is kept constant is primarily for convenience in detecting the position of the capsule endoscope 2, but in this embodiment, Furthermore, the directivity direction of the capsule endoscope 2 is detected using such a configuration. By detecting the directivity direction of the capsule endoscope 2 using such a configuration, simple and accurate azimuth detection can be performed.

  In the in-subject position detection system according to the present embodiment, the CCD 13 serving as an imaging unit is also functioned as a direction detection unit. Therefore, it is not necessary to have a configuration in which the azimuth detecting means is separately arranged, and it is possible to prevent the capsule endoscope 2 that is required to be downsized because it is introduced into the subject 1 from being enlarged.

  In addition, there is another advantage by providing the imaging unit with a function as a direction detection unit. That is, as a result of the CCD 13 functioning as the direction detecting means, the image captured by the CCD 13 has the contents shown in FIG. The in-subject image 67 shown in FIG. 8 and the image 68 that is an image of the magnetic field generating member 24 are naturally taken simultaneously by the CCD 13. This means that information on the directivity direction of the capsule endoscope 2 at the time of imaging is always added to the in-vivo image captured by the CCD 13, and by having such a configuration, Doctors, nurses, and the like have the advantage of being able to always detect the orientation direction of the capsule endoscope 2 when observing the in-subject image displayed on the display device 4. Become.

  As described above, the present invention has been described over the embodiments. However, the present invention is not limited to the above, and those skilled in the art can conceive various examples, modifications, and application examples. For example, in the present embodiment, a configuration in which a CCD serving as an imaging unit is used as the direction detection unit is employed. However, the configuration is not limited to this configuration, and the direction detection unit may be provided separately from the imaging unit. As an azimuth detecting means in such a case, for example, a magnetic field sensor fixed in the capsule endoscope 2 is newly provided, and based on a change in the detection direction of the magnetic field from the magnetic field generating member 24 detected by the magnetic field sensor. It is possible to perform azimuth detection.

  In the embodiment, the plurality of magnetic field strength detection devices 6 and the magnetic field strength detection devices 6 are arranged on the outer surface of the subject 1 so as to detect the vertices of the cube. There is no need to limit. That is, for the magnetic field strength detection device 6 and the like, it is sufficient if the relative position with respect to the subject 1 is grasped in advance, and if such a relative position is used, the position can be detected without being arranged in a cube shape. Also, the number of magnetic field strength detection devices 6 and the like need not be limited to eight, and a system using a single magnetic field strength detection device 6 or the like can be constructed as the simplest configuration. That is, the capsule endoscope 2 that is an intra-subject introducing device does not move arbitrarily within the subject 1, but moves according to a predetermined route in a predetermined organ such as the esophagus, stomach, small intestine, and large intestine. Have Therefore, it is possible to grasp the movement path of the in-subject introduction apparatus in advance to some extent, using the path information grasped in advance and the strength of the static magnetic field received by a single magnetic field strength detection device. Thus, the position of the in-subject introduction device may be detected.

  In addition, the radio signals output from the power feeding antennas B1 to Bm do not necessarily have to superimpose the control information signal and the power feeding signal, and further, from the position detection device to the capsule endoscope. It is good also as a structure which does not perform radio | wireless transmission. Further, a configuration may be adopted in which a power feeding signal and a signal other than the control information signal are superimposed and transmitted. Further, the position detection device 3 may be configured to only receive a radio signal output from the capsule endoscope.

  In the embodiment, no particular mention is made regarding the selection of the feeding antennas B1 to Bm. However, as in the case of the receiving antennas A1 to An, an optimal one is selected based on the position of the capsule endoscope 2. It is good also as a structure which selects and performs wireless transmission. That is, in order to improve the supply efficiency of the power supply signal and the like, the radio signal is not transmitted uniformly from all the power supply antennas, but by using the position information of the capsule endoscope 2, It is also possible to perform antenna selection corresponding to the directivity direction of the receiving antenna 18 provided in the endoscope 2.

1 is a schematic diagram showing an overall configuration of an in-subject position detection system according to an embodiment. It is a block diagram which shows the structure of the capsule endoscope with which the position detection system in a subject is equipped. It is a figure for demonstrating the positional relationship of the magnetic field generating member with which a capsule endoscope is equipped, and CCD. It is a block diagram which shows the structure of the magnetic field intensity detection apparatus with which the position detection system in a subject is equipped. It is a block diagram which shows the structure of the positional information derivation | leading-out apparatus with which the position detection system in a subject is equipped. It is a flowchart for demonstrating the position detection operation | movement of the capsule endoscope in embodiment. It is a schematic diagram for demonstrating the position detection operation | movement of a capsule type | mold endoscope. It is a schematic diagram which shows the content of the image imaged by CCD.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Subject 2 Capsule endoscope 3 Position detection apparatus 4 Display apparatus 5 Portable recording medium 6a-6h Magnetic field intensity detection apparatus 7a, 7b Fixed member 8 Position information derivation apparatus 11 LED
12 LED drive circuit 13 CCD
DESCRIPTION OF SYMBOLS 14 CCD drive circuit 15 Transmission circuit 16 Transmission antenna 17 System control circuit 18 Reception antenna 19 Separation circuit 20 Power regeneration circuit 21 Booster circuit 22 Capacitor 23 Control information detection circuit 24 Magnetic field generating member 25 Case 26 Case member 27 Liquid 28 Spherical Body 29 Permanent magnet 30 Weight member 32 Optical system 33 Reflective member 34 Optical system 35 Capsule body part 36 Imaging window part 38 Case member 39 Spherical body 40 Liquid 41 Magnetic field sensor part 42 Magnetic field measurement system control part 43 Electric power storage unit 44 Power receiving unit 45 Transmission / reception unit 46 transmitting / receiving antenna 47 receiving antenna 48 weighting member 49 feeding antenna 50 transmitting / receiving antenna 51 feeding unit 52 transmitting / receiving unit 53 control unit 55 distance deriving unit 56 position calculating unit 57 antenna selecting unit 58 receiving circuit 59 Signal processing unit 60 Storage unit 61 Oscillator 62 Control information input unit 63 Superimposition circuit 64 Amplification circuit

Claims (8)

An in-subject introduction device that is introduced into the subject and moves within the subject, and a position detection device that is disposed outside the subject and acquires position information of the in-subject introduction device within the subject; An in-subject position detection system comprising:
The in-subject introduction device comprises:
A magnetic field generating member that maintains a state oriented in a certain direction regardless of a change in the orientation direction of the in-subject introduction apparatus and forms a static magnetic field;
Azimuth detecting means for detecting the azimuth of a predetermined axis fixed with respect to the in-subject introduction apparatus with respect to the directional direction of the magnetic field generating member;
Wireless transmission means for transmitting the detection result of the azimuth detection means to the outside;
With
The position detection device includes:
Magnetic field strength detection means for detecting the strength of a magnetic field component parallel to the static magnetic field formed by the magnetic field generating member;
Position information deriving means for deriving position information of the in-subject introduction apparatus in the subject based on the magnetic field strength detected by the magnetic field strength detecting means;
Wireless receiving means for receiving a wireless signal transmitted from the wireless transmitting means;
An in-subject position detection system comprising: The in-subject introduction device further includes an imaging means for imaging the inside of the subject,
The in-subject position detection system according to claim 1, wherein the wireless transmission unit transmits image data captured by the imaging unit to the outside. The magnetic field generating member is arranged so that an image is projected into the field of view of the imaging means,
The imaging means is arranged in a fixed state in the intra-subject introduction apparatus, and the orientation detection means is configured to take an image of a state in which the orientation of the magnetic field generating member with respect to the intra-subject introduction apparatus varies. The in-subject position detection system according to claim 2, which functions as:   The magnetic field strength detecting means has a function of detecting the strength of the magnetic field component in a single direction, and is arranged so that the single direction and the output direction of the static magnetic field in the magnetic field generating member are maintained in parallel. The in-subject position detection system according to claim 1. The magnetic field generating member maintains a state in which the output direction of the static magnetic field is parallel to the vertical direction regardless of the change in the directivity direction of the in-subject introduction apparatus,
The in-subject position detection according to claim 1 or 2, wherein the magnetic field intensity detection means maintains a state in which the detection direction of the magnetic field component is parallel to the vertical direction regardless of the posture variation of the subject. system. The position detection device includes a plurality of the magnetic field strength detection means,
The position information deriving unit derives a distance between the in-subject introduction device and each of the plurality of magnetic field detecting units based on the magnetic field strength detected by the plurality of magnetic field detecting units, and sets the derived distance to The in-subject position detection system according to claim 1, wherein the position of the in-subject introduction apparatus is derived based on the position. The wireless receiving means includes a plurality of receiving antennas,
The position detection device further includes selection means for selecting the reception antenna to be used for receiving a radio signal based on the position of the in-subject introduction device derived by the position information deriving means. The in-subject position detection system according to claim 5.   The said position detection apparatus is further provided with the memory | storage means which matches and memorize | stores the image imaged by the said imaging means, and the position of the said in-subject introduction apparatus at the time of imaging of this image. The in-subject position detection system described in 1.

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