Measuring apparatus, measuring method, and program

Abstract

To simply and accurately measure information of the inside of a measurement object without contact.SOLUTION: A measuring apparatus comprises: a plurality of electrode pairs; a distance measuring part which measures, for each electrode, a distance between electrodes constituting the electrode pairs and a surface of a measurement object opposing the electrodes; a current application part which applies AC current to the measurement object via the electrode pairs; a current distribution estimation part which estimates current distribution inside the measurement object; and an image information output part which generates and outputs an image showing information of the inside of the measurement object.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a measuring device, a measuring method, and a program that output an image showing information about the inside of a measurement target. [Background technology]

[0002] Conventionally, there is known a technique of electrical impedance tomography (EIT) in which a weak current is applied from a pair of electrodes attached to the body surface and a distribution of conductivity or a distribution of conductivity changes in a living body is imaged from a potential difference generated on the body surface (see, for example, Patent Document 1). Also known is an image generating device that uses the EIT technique to apply an alternating current to a measurement object from electrodes provided at a position away from the measurement object, detects the magnitude of a magnetic field generated inside the measurement object according to the alternating current, and generates a tomographic image of the measurement object (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-136304 A [Patent Document 2] Patent No. 6583829 Summary of the Invention [Problem to be solved by the invention]

[0004] Such an image generating device can easily obtain a tomographic image because it does not require the attachment of electrodes to the measurement object. However, the distance between the electrodes and the measurement object may differ for each location where the AC current is applied, which may cause an error in the magnitude of the current flowing through the measurement object depending on the position of the electrodes.

[0005] The present invention has been made in consideration of these points, and has an object to enable easy non-contact measurement of information about the inside of a measurement target. [Means for solving the problem]

[0006] In a first aspect of the present invention, a measuring device is provided comprising: a plurality of electrode pairs arranged at a position away from a measured object; a distance measurement unit that measures, for each electrode, the distance between an electrode constituting the electrode pair and the surface of the measured object facing the electrode; a current application unit that applies an alternating current to the measured object via the electrode pair; a magnetic field detection element that detects the magnitude of a magnetic field generated from the measured object in accordance with the alternating current applied by the current application unit; a current distribution estimation unit that estimates a current distribution inside the measured object based on multiple distance measurement results by the distance measurement unit, the magnitude of the alternating current applied by the current application unit, and the magnitude of the magnetic field detected by the magnetic field detection element; and an image information output unit that generates and outputs an image showing information about the inside of the measured object based on the current distribution estimated by the current distribution estimation unit and the magnitude of the magnetic field detected by the magnetic field detection element.

[0007] The distance measurement unit may include a millimeter wave radar that measures the distance from the electrode to a surface of the measurement object facing the electrode, using radio waves in a millimeter wave frequency band.

[0008] The multiple electrode pairs may be arranged around the object to be measured, and the current distribution estimation unit may estimate a cross-sectional shape of the object to be measured based on multiple distance measurement results by the distance measurement unit, and estimate the current distribution within the estimated cross-sectional shape.

[0009] The measurement device may further include an acquisition unit that acquires a tomographic image of the object to be measured, and the current distribution estimation unit may estimate a cross-sectional shape of the object to be measured based on the tomographic image of the object to be measured acquired by the acquisition unit.

[0010] The measurement device may further include a storage unit that stores a standard tomographic image of the object to be measured, and the current distribution estimation unit may estimate a cross-sectional shape of the object to be measured based on the standard tomographic image.

[0011] The image information output section may generate an image showing information about the inside of the cross-sectional shape of the measurement target estimated by the current distribution estimation section.

[0012] The measuring device may further include an acquisition unit that acquires a tomographic image of the measurement object, and the image information output unit may generate an image in which an image showing internal information of the generated cross-sectional shape is superimposed at a corresponding position on the tomographic image of the measurement object.

[0013] The measuring device may further include a control unit that changes the frequency of the alternating current applied to the object to be measured by the current application unit, and the image information output unit may generate an image indicating information about the inside of the object to be measured each time the control unit changes the frequency of the alternating current, and the control unit may detect an abnormality inside the object to be measured by comparing multiple images output by the image information output unit.

[0014] The measuring device may further include a memory unit that stores the image output by the image information output unit, and a control unit that detects internal abnormalities of the object to be measured by comparing the image output by the image information output unit with images previously output by the image information output unit.

[0015] The measuring device may further include a measuring unit having a ring shape or a part of a ring shape surrounding the object to be measured, the measuring unit having a plurality of electrode pairs and the distance measuring unit, and a moving unit that moves at least one of the object to be measured and the measuring unit to change the relative position between the object to be measured and the measuring unit.

[0016] The measurement unit may have a position change unit that changes the positions of the multiple electrode pairs while maintaining a non-contact state between the multiple electrode pairs and the object to be measured so that the distance between the multiple electrode pairs and the object to be measured is within a predetermined distance range.

[0017] The measuring device may further include a bed on which the measurement object is placed, and the measuring unit may be attached to the bed so that its position relative to the bed can be changed.

[0018] The measurement unit may have two rod-shaped members extending parallel to the longitudinal direction of the bed and sandwiching the object to be measured, and a first electrode of the electrode pair may be provided on one of the first rod-shaped members, and a second electrode of the electrode pair, different from the first electrode, may be provided on the other of the two rod-shaped members, different from the first rod-shaped member.

[0019] The measurement unit may further include the magnetic field detection element.

[0020] In a second aspect of the present invention, there is provided a measurement method executed by a computer for measuring internal information of a measured object, the measurement method comprising the steps of: measuring, for each electrode, a distance between an electrode constituting a plurality of electrode pairs arranged at a position away from the measured object and a surface of the measured object facing the electrode; applying an alternating current to the measured object via the plurality of electrode pairs; detecting the magnitude of a magnetic field generated from the measured object in accordance with the applied alternating current; estimating a current distribution inside the measured object based on the results of the plurality of distance measurements, the magnitude of the alternating current applied to the measured object, and the magnitude of the detected magnetic field; and generating and outputting an image showing internal information of the measured object based on the estimated current distribution and the magnitude of the detected magnetic field.

[0021] In a third aspect of the present invention, there is provided a program which, when executed by a computer, causes the computer to execute the measurement method of the second aspect. Effect of the Invention

[0022] According to the present invention, an effect is achieved in that information about the inside of a measurement object can be measured in a simple and highly accurate non-contact manner. [Brief description of the drawings]

[0023] [Figure 1] An example of the configuration of a measurement device 100 according to this embodiment is shown together with a measurement target 10. [Diagram 2] An example of the configuration of the measurement unit 110 and the control unit 140 according to this embodiment is shown together with the measurement target 10. [Diagram 3] 1 shows an example of an operation flow of the measurement device 100 according to the present embodiment. [Figure 4] 1 shows an example of a cross-sectional shape of the measurement target 10 estimated by the current distribution estimation unit 143 according to the present embodiment. [Diagram 5] 1 shows an example of the position of the cross-sectional shape of the measurement target 10 estimated by the current distribution estimation unit 143 according to the present embodiment. [Figure 6] 1 shows a first example of the results of simulating the measurement device 100 according to the present embodiment. [Figure 7] 11 shows a second example of the results of simulating the measurement device 100 according to the present embodiment. [Figure 8] 1 shows a first modified example of the measurement unit 110 according to the present embodiment. [Figure 9] 1 shows a second modified example of the measurement unit 110 according to the present embodiment. [Figure 10] 1 shows a first modified example of the measuring device 100 according to the present embodiment. [Figure 11] 2 shows a second modified example of the measuring device 100 according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] <Configuration Example of Measuring Device 100> FIG. 1 shows an example of the configuration of a measuring device 100 according to this embodiment together with a measuring object 10. In FIG. 1, three orthogonal directions are defined as an X direction, a Y direction, and a Z direction. The measuring device 100 generates and outputs an image showing information about the inside of the measuring object 10. The measuring object 10 is, for example, a living body such as a human body. In this embodiment, an example in which the measuring object 10 is a human body will be described. The image showing information about the inside of the measuring object 10 is, for example, a tomographic image of the human body. The image showing information about the inside of the measuring object 10 may also be an image showing an abnormal area such as a tumor.

[0025] The measuring device 100 generates and outputs such an image without contacting the measurement target 10. The measuring device 100 includes a measuring section 110, a moving section 120, a storage section 130, a control section 140, and a display section 150.

[0026] The measuring unit 110 has a ring shape or a part of a ring shape surrounding the measurement object 10. The shape of the measuring unit 110 need only be a shape that surrounds at least a part of the measurement object 10, and does not have to be a circular ring shape. The measuring unit 110 may have, for example, an elliptical shape, a partially interrupted shape, or a cylindrical shape that surrounds the measurement object 10.

[0027] The measurement unit 110 has a plurality of electrodes 21 constituting a plurality of electrode pairs 20, a distance measurement unit 30, a current application unit 40, and a magnetic field detection element 50. By having such members, the measurement unit 110 obtains a detection signal for generating information on the inside of a site surrounding the measurement target 10. The electrode pairs 20, the distance measurement unit 30, the current application unit 40, and the magnetic field detection element 50 will be described later.

[0028] The moving unit 120 moves at least one of the measurement target 10 and the measurement unit 110 to change the relative positions of the measurement target 10 and the measurement unit 110. The moving unit 120 has, for example, an actuator or the like, and moves the measurement unit 110 in a direction parallel or perpendicular to the measurement target 10. It is desirable that the moving unit 120 can move the measurement unit 110 so as to obtain a detection signal of a designated part of the human body from the toes to the top of the head. Fig. 1 shows an example in which the moving unit 120 moves the measurement unit 110 in the Z direction.

[0029] The storage unit 130 is a storage medium including a read only memory (ROM) and a random access memory (RAM). The storage unit 130 may also include a large-capacity storage device such as a hard disk drive (HDD) and / or a solid state drive (SSD). For example, when a computer functions as part of the measuring device 100, the storage unit 130 may store information such as an operating system (OS) that causes the computer to function, and programs. The storage unit 130 may also store various information including a database that is referenced when a program is executed.

[0030] Furthermore, storage unit 130 may store intermediate data, calculation results, thresholds, reference values, parameters, and the like that are generated (or used) by measurement device 100 during operation. Storage unit 130 may also supply the stored data to a request source in response to a request from each unit in measurement device 100. Storage unit 130 may be a database system or the like that is connected via a network.

[0031] The control unit 140 transmits a control signal to each unit of the measuring device 100 to control each unit of the measuring device 100. The control unit 140 controls, for example, the moving unit 120 to move the measuring unit 110. The control unit 140 also acquires a detection signal from the measuring unit 110 to generate an image showing information about the inside of the measurement target 10. The control unit 140 may display the generated image on the display unit 150, or may store the generated image in the storage unit 130 or an external storage device, etc.

[0032] The control unit 140 is, for example, a CPU (Central Processing Unit) of a server or the like. In other words, the CPU functions as the control unit 140 by executing a program stored in the storage unit 130. The storage unit 130 and the control unit 140 may be at least a part of a server.

[0033] The display unit 150 is a display or the like that displays an image generated by the control unit 140. The display unit 150 may display the operating state of the measurement device 100, the OS, the execution state of applications, and the like.

[0034] The above-described measuring device 100 can generate and output a tomographic image of a portion of the measuring object 10 surrounded by the measuring unit 110. The measuring device 100 can also determine whether or not an abnormality has occurred in an organ of the measuring object 10 surrounded by the measuring unit 110. The measuring device 100 can output multiple tomographic images of a wider range of the measuring object 10 and determine whether or not an abnormality has occurred in multiple organs by changing the relative positions of the measuring object 10 and the measuring unit 110. The operation of the measuring device 100 will be described in detail below.

[0035] <Example of configuration of measurement unit 110 and control unit 140> Fig. 2 shows an example of the configuration of the measurement unit 110 and the control unit 140 according to this embodiment, together with the measurement target 10. Fig. 2 shows an example of the configuration of a cross section of the measurement unit 110 and the measurement target 10 in a plane parallel to the XY plane in Fig. 1. The measurement unit 110 has a plurality of electrode pairs 20, a distance measurement unit 30, a current application unit 40, and a magnetic field detection element 50. The control unit 140 has an acquisition unit 141, a synchronization signal extraction unit 142, a current distribution estimation unit 143, an image information output unit 144, and a display control unit 145.

[0036] In the measurement unit 110, for example, the electrodes 21 constituting the electrode pairs 20 and the magnetic field detection elements 50 are provided at predetermined intervals along the circumferential direction of the ring shape. In other words, the multiple electrode pairs 20 and the magnetic field detection elements 50 are provided around the measurement target 10 at positions away from the measurement target 10.

[0037] The electrode pair 20 is composed of two electrodes 21 out of the multiple electrodes 21 provided in the measurement unit 110. The electrode pair 20 is composed of, for example, two electrodes 21 provided at opposing positions across the measurement target 10. Fig. 2 shows an example in which the electrode pair 20 is composed of an electrode 21a and an electrode 21b.

[0038] In addition, the electrode pair 20 may be composed of a predetermined combination of two electrodes 21, or may be composed of two adjacent electrodes 21. The electrodes 21 are formed of a conductive material such as a metal or an alloy. The electrodes 21 are desirably formed of a non-magnetic material.

[0039] The distance measurement unit 30 measures the distance between each electrode 21 constituting the electrode pair 20 and the surface of the object 10 facing the electrode 21 for each electrode 21. The distance measurement unit 30 measures, for example, a distance La from the electrode 21a to the object 10 and a distance Lb from the electrode 21b to the object 10 on a straight line connecting the electrodes 21a and 21b. The distance measurement unit 30 may measure the shortest distance from the electrode 21 to the object 10.

[0040] Distance measurement unit 30 has a millimeter wave radar that uses radio waves in the millimeter wave frequency band to measure the distance from electrode 21 to the surface of object 10 facing electrode 21. At least a part of the millimeter wave radar passes through clothing or the like to reach the surface of the living body of object 10. Therefore, by using such a millimeter wave radar, distance measurement unit 30 can accurately measure the distance from electrode 21 to object 10 even if object 10 is wearing clothing or the like.

[0041] Furthermore, the distance measurement unit 30 may have a laser measurement device that measures the distance from the electrode 21 to the measurement object 10 by irradiating the measurement object 10 with laser light and detecting the reflected light. It is preferable that the distance measurement unit 30 measures the distance from the electrode 21 to the measurement object 10 in the vicinity of the electrode 21. The distance measurement unit 30 may be provided in the measurement unit 110, for example, so that the distance measurement unit 30 can move to the vicinity of each electrode 21 to measure the distance. Furthermore, a plurality of distance measurement units 30 may be provided in the measurement unit 110.

[0042] The current application unit 40 is connected to each of the multiple electrodes 21 by electrical wiring, and applies an AC current to an electrode pair 20 consisting of two electrodes 21. The current application unit 40 has a circuit having, for example, a switching circuit, an AC power supply, a constant current circuit (or a constant voltage circuit), etc., and is configured to be able to output an AC current of a predetermined frequency to the electrode pair 20 having two predetermined electrodes 21 according to the control by the control unit 140. The predetermined frequency is, for example, several kHz to several MHz.

[0043] When an AC current is applied to the electrode pair 20, a portion of the AC current is radiated from the electrode pair 20 into the air. The magnitude of the AC current radiated into the air is a value according to the impedance of the path along which the AC current travels. For example, if the measurement target 10 is a human body, the impedance inside the measurement target 10 is lower than that in the air because blood and the like inside the human body are electrolytes. Therefore, the AC current radiated from the electrode pair 20 into the air tends to flow toward the inside of the measurement target 10, which has a lower impedance. In this way, the AC current radiated into the air flows into the measurement target 10.

[0044] Therefore, the measuring device 100 according to this embodiment can pass an AC current toward the inside of the measurement target 10 without directly attaching the electrode pair 20 to the surface of the measurement target 10. In other words, the current application unit 40 applies an AC current to the measurement target 10 via the electrode pair 20.

[0045] For example, in response to a control signal received from the control unit 140, the current application unit 40 sequentially repeats an operation of selecting an electrode pair 20 consisting of two electrodes 21 out of the multiple electrodes 21, passing an AC current through the electrode pair 20, and then selecting another electrode pair 20 and passing an AC current through the electrode pair 20. In this case, the current application unit 40 sequentially applies an AC current to the measurement object 10 via more electrode pairs 20, preferably via all of the electrode pairs 20.

[0046] The AC current flowing through the measurement target 10 has a higher current value overall when the measurement target 10 is present compared to when the measurement target 10 is not present. Even inside the measurement target 10, for example, the AC current passing through lungs filled with air has a correspondingly lower current value. In this way, the AC current flowing through a certain electrode pair 20 has a current value according to the impedance distribution inside the measurement target 10. In other words, when an AC current is flowed inside the measurement target 10, a current distribution according to the cross-sectional structure of the measurement target 10 is generated.

[0047] When an AC current flows through the object 10, a magnetic field is generated around the AC current according to the magnitude of the AC current. The magnitude H of the magnetic field is proportional to the magnitude of the AC current. The magnetic field detection element 50 detects the magnitude H of such a magnetic field. In other words, the magnetic field detection element 50 detects the magnitude of the magnetic field generated from the object 10 according to the AC current applied by the current application unit 40.

[0048] The change in potential due to AC current is 1 / r, where r is the distance from the point where the AC current flows. 2 On the other hand, the magnitude of the magnetic field is proportional to the inverse of the distance r from the position where the magnetic field is generated, 1 / r, so even if the magnetic field is located far from the object 10 to be measured, it can be detected with higher sensitivity than when a change in electric potential is detected.

[0049] It is desirable that a plurality of magnetic field detection elements 50 are arranged so as to surround the measurement target 10. The magnetic field detection element 50 is a highly sensitive magnetic sensor capable of detecting a weak magnetic field in units of, for example, nT (nanotesla), pT (picotesla), or fT (femtotesla). The magnetic field detection element 50 is, for example, an optically pumped atomic magnetometer, a magnetic impedance element, a superconducting quantum interference device (SQUID), or the like.

[0050] The acquiring unit 141 acquires the distance measurement result by the distance measuring unit 30 and the magnetic field detection result by the magnetic field detection element 50. The acquiring unit 141 may also acquire a tomographic image of the measurement target 10. The tomographic image is, for example, an image of the measurement target 10 measured in the past by another device or the like. The other device is, for example, a CT, an MRI, or the like.

[0051] The measuring device 100 may further include a communication interface connectable to a network, a LAN, etc., and the acquiring unit 141 may be configured to acquire image information from a CT, an MRI, a database, etc., via the network, the LAN, etc. In addition, when the storage unit 130 stores image information of a tomographic image measured by another device, the acquiring unit 141 may acquire the tomographic image from the storage unit 130.

[0052] Also, for example, like the human body, there are cases where the internal structure of the measurement target 10, such as the head, chest, and abdomen, is known. In this case, the storage unit 130, a database, or the like may store image information of a standard tomographic image of the measurement target 10. Then, the acquisition unit 141 reads and acquires such image information of the standard tomographic image from the storage unit 130, a database, or the like.

[0053] The synchronization signal extractor 142 extracts a signal component synchronized with the AC current applied by the current application unit 40 from the detection signal of the magnetic field detected by the magnetic field detection element 50. For example, the control unit 140 causes the current application unit 40 to generate an AC current at a predetermined timing, and the synchronization signal extractor 142 acquires a signal component synchronized with the AC signal from the detection signal at a timing synchronized with the predetermined timing. The control unit 140 may modulate the AC current at a predetermined frequency and cause it to be generated by the current application unit 40.

[0054] In this way, the synchronization signal extraction unit 142 can reduce the noise components contained in the detection signal by extracting the signal components synchronized with the AC signal from the detection signal detected by the magnetic field detection element 50. If the magnetic field detection element 50 can output a detection signal with low noise components, such an operation and the synchronization signal extraction unit 142 may not be necessary.

[0055] The current distribution estimation unit 143 estimates the distribution of current flowing inside the measurement target 10 based on a plurality of distance measurement results by the distance measurement unit 30, the magnitude of the AC current applied by the current application unit 40, and the magnitude of the magnetic field detected by the magnetic field detection element 50. In the case of conventional EIT measurement as described in Patent Document 1, a plurality of electrodes are usually attached to the surface of the measurement target 10. Then, while an AC current is applied between certain selected electrodes, the potential differences generated between the other electrodes are sequentially measured.

[0056] In contrast, the multiple electrode pairs 20 according to this embodiment are provided at separate positions around the object 10. Therefore, the current distribution estimation unit 143 first estimates the cross-sectional shape of the object 10. Then, in the estimated cross-sectional shape, it estimates the position where the AC current is input from the electrode pairs 20 to the object 10. The position where the AC current is input is the position on the surface of the object 10 where the AC current is applied. In this way, the current distribution estimation unit 143 estimates the current distribution inside the object 10. The above operations will be described later.

[0057] The image information output unit 144 generates and outputs an image showing information about the inside of the measurement target 10 based on the current distribution (or impedance distribution) estimated by the current distribution estimation unit 143 and the magnitude of the magnetic field detected by the magnetic field detection element 50. The image information output unit 144 generates a tomographic image of the measurement target 10 using, for example, a back projection method, a method for solving an inverse problem of an electromagnetic field system, or the like.

[0058] The display control unit 145 displays the tomographic image generated by the image information output unit 144 on the display unit 150. Furthermore, the image information output unit 144 may store the generated tomographic image in the storage unit 130, a database, or the like.

[0059] The measuring device 100 according to the present embodiment described above can output an image showing information about the inside of the measuring object 10 without contacting the measuring object 10. The measuring device 100 may immediately detect the magnetic field generated in response to the applied AC current, and may immediately analyze the detection result. This allows the measuring device 100 to output an image showing information about the inside of the measuring object 10 in almost real time. The operation flow of such a measuring device 100 will be described next.

[0060] <An example of an operation flow of the measuring device 100> 3 shows an example of an operation flow of the measuring device 100 according to this embodiment. First, the control unit 140 receives an instruction to start measuring the measuring object 10 from a user or the like (S81). Here, the measuring object 10 is assumed to be disposed so as to have a predetermined positional relationship with the measuring unit 110. For example, the measuring object 10 may be lying on a bed on which the measuring unit 110 is provided, or alternatively, the measuring object 10 may be standing inside the ring of the annular measuring unit 110.

[0061] Here, the control unit 140 may further receive measurement conditions such as information on the measurement range of the measurement target 10. The control unit 140 receives an instruction for the measurement range, such as the head, neck, chest, abdomen, waist, legs, whole body, etc. In response to the received information, the control unit 140 controls the movement unit 120 to move the measurement unit 110 to the measurement start point of the measurement range.

[0062] Next, the control unit 140 controls the distance measurement unit 30 to measure the distance between the electrodes 21 provided at positions away from the measurement target 10 and the surface of the measurement target 10 facing the electrodes 21 for each electrode 21 (S82). Here, the distance measurement unit 30 is configured to be able to move around the measurement target 10 in the measurement unit 110.

[0063] The control unit 140 moves the distance measurement unit 30 to a predetermined position near the electrode 21 that is the starting point of the distance measurement, and then measures the distance between that electrode 21 and the measurement object 10. The control unit 140 then moves the distance measurement unit 30 to a predetermined position near the next electrode 21, and then measures the distance between that electrode 21 and the measurement object 10. The control unit 140 repeats the movement of the distance measurement unit 30 and the distance measurement operation by the distance measurement unit 30 to measure the distances between all of the electrodes 21 and the measurement object 10.

[0064] Next, the control unit 140 controls the current application unit 40 to apply an AC current to the measurement target 10 via the electrode pairs 20 (S83). Then, the magnetic field detection elements 50 detect the magnitude of the magnetic field generated from the measurement target 10 around the measurement target 10 in response to the applied AC current (S84).

[0065] The control unit 140 applies an AC current to the measurement target 10 for each of the electrode pairs 20 in a predetermined order among the multiple electrode pairs 20. In this manner, it is preferable that the control unit 140 controls each unit so that the AC current is applied to each of the electrode pairs 20 and the magnetic field is detected by all of the magnetic field detection elements 50. Then, the control unit 140 repeats the application of the AC current in S83 and the detection of the magnetic field in S84.

[0066] In this way, the acquiring unit 141 acquires the distance measurement results by the distance measuring unit 30 and the magnetic field detection results by the magnetic field detection elements 50. The acquiring unit 141 may also acquire information on a tomographic image of the object 10 to be measured.

[0067] Next, the current distribution estimation unit 143 estimates the cross-sectional shape of the measurement object 10 based on the multiple distance measurement results by the distance measurement unit 30 (S85). When the acquisition unit 141 acquires a tomographic image of the measurement object 10 by CT, MRI, or the like, the current distribution estimation unit 143 estimates the cross-sectional shape of the measurement object 10 based on the tomographic image. When the acquisition unit 141 acquires a standard tomographic image of the measurement object, the current distribution estimation unit 143 estimates the cross-sectional shape of the measurement object based on the standard tomographic image.

[0068] For example, the current distribution estimation unit 143 determines the contour of the tomographic image as the cross-sectional shape of the measurement target 10. Alternatively, the current distribution estimation unit 143 may determine the cross-sectional shape as a shape represented by a plurality of pixels among the pixels of the tomographic image, the plurality of pixels having a change in luminance, a change in hue, or the like that is greater than a threshold value, and the plurality of pixels are connected to form a closed line segment. Fig. 4 shows an example of the cross-sectional shape of the measurement target 10 estimated by the current distribution estimation unit 143 according to this embodiment.

[0069] Next, the current distribution estimation unit 143 estimates the positions of the cross-sectional shape of the measurement object 10 relative to the multiple electrodes 21 based on the multiple distance measurement results by the distance measurement unit 30 (S86). Here, the positions of the multiple electrodes 21 in the measurement unit 110 can be estimated based on design data or measurement data created in the design and manufacturing stages of the measurement unit 110. The current distribution estimation unit 143 estimates the position of the measurement object 10 by matching the contour of the cross-sectional shape of the measurement object 10 to a position away from the position of each electrode 21 by the distance measured by the distance measurement unit 30.

[0070] Fig. 5 shows an example of the position of the cross-sectional shape of the object 10 estimated by the current distribution estimation unit 143 according to this embodiment. In Fig. 5, the positions of six electrodes 21, from electrode 21a to electrode 21f, are indicated by black dots, and the current distribution estimation unit 143 estimates the positions of the cross-sectional shape of the object 10 relative to the six electrodes 21.

[0071] 5, the distance from the position of electrode 21n measured by distance measurement unit 30 to the measurement target 10 is defined as Ln (n=a, b, c,...). The current distribution estimation unit 143 estimates the position of the cross-sectional shape by, for example, drawing an arc of radius Ln centered on the position of electrode 21n and matching the cross-sectional shape of the measurement target 10 so that the cross-sectional shape is tangent to the arc.

[0072] Next, the current distribution estimation unit 143 estimates the position on the surface of the object 10 to which the AC current is input, based on the estimated positional relationship between the multiple electrodes 21 and the object 10 (S87). The AC current output from one electrode pair 20 is input to the surface of the object 10 facing the one electrode pair 20. Here, the position at which the AC current output from one electrode pair 20 is input to the surface of the object 10 may be approximated to the position with the shortest distance from the one electrode pair 20 to the object 10.

[0073] In this way, the distance from one electrode 21 to the measurement target 10 measured by the distance measurement unit 30 can be approximated to the distance from the one electrode 21 to the position where the AC current output from the one electrode 21 is input to the surface of the measurement target 10. In other words, in the example of Fig. 5, the point where the cross-sectional shape of the measurement target 10 and the arc of radius Ln meet can be estimated as the position where the AC current output from the electrode 21n is input to the surface of the measurement target 10.

[0074] Next, the current distribution estimation unit 143 estimates the current distribution flowing inside the cross-sectional shape of the object 10 based on the position where the AC current was input to the object 10, the magnitude of the AC current, and the magnitude of the magnetic field detected by the magnetic field detection element 50 (S88). For example, the current distribution estimation unit 143 sets the estimation result of the position where the AC current was input as the attachment position of the electrodes for the conventional EIT measurement. Then, the current distribution estimation unit 143 applies the detection result of the magnetic field detection element 50 to the conventional EIT measurement to estimate the current distribution flowing inside the object 10 or the impedance distribution inside the object 10.

[0075] Next, the image information output unit 144 generates and outputs a tomographic image of the measurement target 10 based on the current distribution estimated by the current distribution estimation unit 143 and the magnitude of the magnetic field detected by the magnetic field detection element 50 (S89). In this manner, the image information output unit 144 generates an image showing information on the inside of the cross-sectional shape of the measurement target 10 estimated by the current distribution estimation unit 143. The operation of the image information output unit 144 is known, for example, as described in Patent Document 2, and therefore a detailed description thereof will be omitted.

[0076] In other words, in the measuring device 100, the operations of S88 and S89 from estimating the position where the alternating current is applied on the surface of the object to be measured 10 to generating a tomographic image from the position where the alternating current is applied and the detection results of the magnetic field are almost the same as the operations of the image generating device described in Patent Document 2.

[0077] In addition, the current distribution estimation unit 143 may estimate the distribution of current flowing inside the measurement object 10 by further using information on the tomographic image of the measurement object 10 acquired by the acquisition unit 141. The current distribution estimation unit 143 identifies boundary conditions such as the impedance of each part in the tomographic image of the measurement object 10, for example, and estimates the distribution of current flowing inside the measurement object 10 using the identified boundary conditions.

[0078] In this case, the current distribution estimation unit 143 uses the parts where impedance changes, such as the shape of the measurement object 10 and the shape of an organ, which can be identified from the tomographic image of the measurement object 10, as boundary conditions of the finite element method used in the conventional method. The current distribution estimation unit 143 can more accurately estimate the distribution of the current flowing inside the measurement object 10 by more accurately identifying the boundary conditions from the tomographic image. Therefore, the image information output unit 144 can output a more precise tomographic image.

[0079] In addition, since the standard impedance or conductivity of each part of the human body has been measured in the past, such a value can be used. It is preferable that such measurement results are stored in the storage unit 130 or a database. In this case, the acquisition unit 141 may also acquire such information.

[0080] Next, the display control unit 145 displays the tomographic image generated by the image information output unit 144 on the display unit 150 (S90). As described above, the measuring device 100 according to this embodiment can measure a tomographic image of the measuring object 10 by applying an alternating current to the measuring object 10. In this manner, the measuring device 100 does not require irradiation of X-rays, irradiation of a magnetic field by an RF coil, analysis of gamma rays, etc., and can simply measure a tomographic image of the measuring object 10 in real time. Furthermore, the measuring device 100 can measure a tomographic image with higher accuracy than conventional methods by estimating the position where the alternating current is applied to the measuring object 10.

[0081] Since the tomographic image generated by the measuring device 100 is based on the impedance distribution inside the measurement target 10, it is possible to clearly observe the state of the lungs filled with air by comparing it with a tomographic image measured by CT, MRI, etc. As described above, the measuring device 100 can generate and output information that cannot be easily obtained from a tomographic image measured by CT, MRI, etc. Therefore, the display control unit 145 may cause the display unit 150 to display the tomographic image generated by the image information output unit 144 together with the tomographic image measured by CT, MRI, etc.

[0082] For example, when the acquiring unit 141 acquires a tomographic image by CT, MRI, or the like, the image information output unit 144 generates an image by superimposing an image showing the internal information of the generated cross-sectional shape on a corresponding position of the tomographic image of the measurement object 10. This enables the measuring device 100 to output an image in which information on the measurement result of the measuring device 100 is added to the tomographic image by CT, MRI, or the like.

[0083] Alternatively or in addition, the measuring device 100 may compare the image generated by the image information output unit 144 this time with an image previously output by the measuring device 100. For example, the storage unit 130 stores the image output by the image information output unit 144. The display control unit 145 then displays the tomographic image generated by the image information output unit 144 together with the past measurement results on the display unit 150, and displays an image showing the location where a difference occurs from the past image, superimposed on the tomographic image. This makes it easy to check whether or not a change has occurred in the internal state of the measurement target 10.

[0084] The image information output section 144 may output the generated tomographic image superimposed on a previously measured tomographic image. The control section 140 may detect an abnormality inside the measurement object 10 by comparing the image output by the image information output section 144 with an image previously output by the image information output section 144. The control section 140 determines that an abnormality has occurred inside the measurement object 10, for example, when a correlation value between the image output by the image information output section 144 and an image previously output by the image information output section 144 is equal to or greater than a threshold value. The threshold value may be set by a user, or may be determined in advance for each measurement object 10.

[0085] Since the measuring device 100 can output a tomographic image simply and quickly, it is also possible to periodically output a tomographic image of the measuring object 10 to check a change in the state of the measuring object 10. When the measuring device 100 periodically measures the measuring object 10, the control unit 140 may determine that an abnormality may occur in the measuring object 10 if a correlation value between a tomographic image at the start of a predetermined period and a tomographic image at the end of the predetermined period is equal to or greater than a threshold value corresponding to the length of the predetermined period, and output the determined result. As an example, when a user performs a measurement every week, the control unit 140 determines that an abnormality may occur in the measuring object 10 if a difference between a tomographic image three months ago and the most recent tomographic image is equal to or greater than a threshold value. By operating the control unit 140 in this manner, for example, a tumor occurring in the body can be detected early.

[0086] In the above description of the measurement device 100 according to the present embodiment, the current application section 40 outputs an AC current of a predetermined frequency to the measurement target 10, but the present invention is not limited to this. The current application section 40 may be configured to be able to change the frequency of the AC current applied to the measurement target 10, for example.

[0087] In this case, the control unit 140 controls, for example, the current application unit 40 to change the frequency of the alternating current that the current application unit 40 applies to the measurement target 10. Then, the image information output unit 144 generates and outputs an image showing information about the inside of the measurement target 10 every time the control unit 140 changes the frequency of the alternating current.

[0088] For example, the control unit 140 extracts the conductivity of a portion corresponding to the same pixel from among a plurality of tomographic images generated for each frequency, and acquires the frequency characteristics of the conductivity for each pixel. Then, from such frequency characteristics of the conductivity, the control unit 140 calculates the real component (resistance, conductance) and the imaginary component (reactance, susceptance) of the conductivity corresponding to the pixel.

[0089] As described above, the control unit 140 can specify the conductivity distribution on the tomographic plane by dividing it into real and imaginary components, so that a more detailed tomographic image can be generated. Note that normal cells and abnormal cells have different conductivities. Therefore, the control unit 140 can use such a conductivity distribution to determine whether or not the living body is cancerous.

[0090] The control unit 140 can also detect abnormalities inside the measurement target 10 by comparing multiple images output by the image information output unit 144. The image information output unit 144 may add information on whether or not the target has become cancerous to the tomographic image and output the image. The measuring device 100 can also periodically output such tomographic images to attempt early detection of cancer.

[0091] <Simulation of tomographic images> Fig. 6 shows a first example of the results of simulating the measurement device 100 according to this embodiment. The measurement object 10 is the abdomen of a normal human body. Fig. 6 shows the results of a simulation of an operation in which an AC current is applied from a plurality of electrode pairs 20 surrounding the measurement object 10, and a tomographic image of the measurement object 10 is output.

[0092] Fig. 6(A) is an image of the real part showing the real component of the conductivity distribution on the cross-sectional surface of the measurement object 10. Fig. 6(B) is an image of the imaginary part showing the imaginary component of the conductivity distribution on the cross-sectional surface of the measurement object 10. It can be seen from Fig. 6(A) and Fig. 6(B) that a cross-sectional image of a normal human body is generated.

[0093] FIG. 7 shows a second example of the results of simulating the measurement device 100 according to this embodiment. The measurement object 10 is the abdomen of a human body in which cancer has developed. FIG. 7(A) is an image of a real part showing the real component of the conductivity distribution in a cross-sectional plane of the measurement object 10. FIG. 7(B) is an image of an imaginary part showing the imaginary component of the conductivity distribution in a cross-sectional plane of the measurement object 10. From FIG. 7(A) and FIG. 7(B), it can be seen that a cross-sectional image of a human body is generated. It can also be seen that there is an area showing an abnormal part within the white circle in FIG. 7(A) and FIG. 7(B). By comparing FIG. 6 with FIG. 7, it can be seen that the measurement device 100 can detect an abnormal part of the measurement object 10.

[0094] <Other Configuration Examples of the Measuring Device 100> The above description has been given of an example in which the measuring device 100 according to the present embodiment uses the electrode pair 20 and the magnetic field detection element 50 provided at a position away from the measuring object 10 to output an image showing information about the inside of the measuring object 10. Here, the closer the electrode pair 20 and the magnetic field detection element 50 are to the measuring object 10, the more the measurement error can be reduced.

[0095] Therefore, it is desirable that the measuring unit 110 is formed so as to minimize the gap between the measuring unit 110 and the measurement target 10. The measuring device 100 may include a plurality of measuring units 110 having different shapes for each measurement site, such as the head, chest, and abdomen, of the measurement target 10, and measuring units 110 of different sizes may be used corresponding to the measurement sites.

[0096] Alternatively, at least a part of the measurement unit 110 may be configured so that the distance from the measurement object 10 can be changed so that the distance between the electrode pair 20 and the magnetic field detection element 50 and the measurement object 10 can be adjusted.

[0097] Fig. 8 shows a first modified example of the measurement unit 110 according to this embodiment. Fig. 6 shows a configuration example of a cross section of the measurement unit 110 in a plane parallel to the XY plane in Fig. 1. The measurement unit 110 of the first modified example has a position change unit 111 in which the electrode pairs 20 are provided. The position change unit 111 changes the positions of the multiple electrode pairs 20 while keeping the multiple electrode pairs 20 and the measurement target 10 in a non-contact state so that the distance between the multiple electrode pairs 20 and the measurement target 10 falls within a predetermined distance range.

[0098] The position changer 111 of the first modified example is configured to change the gap between the measurement target 10, like the aperture of a camera. For example, the size of the measurement target 10 shown in FIG. 8(A) is larger than that of the measurement target 10 shown in FIG. 8(B). Therefore, the position changer 111 moves the positions of the multiple electrodes 21 to positions closer to the outer edge of the measurement unit 110 in FIG. 8(A). On the other hand, the position changer 111 moves the positions of the multiple electrodes 21 to positions closer to the center of the measurement unit 110 in FIG. 8(B). The control unit 140 may control the position changer 111 to adjust the position of the position changer 111 based on the distance measurement result of the distance measurement unit 30.

[0099] Fig. 9 shows a second modified example of the measuring unit 110 according to this embodiment. Like Fig. 8, Fig. 9 shows a configuration example of a cross section of the measuring unit 110 in a plane parallel to the XY plane of Fig. 1. The measuring unit 110 of the second modified example is configured so that the position changing unit 111 is movable toward the measuring object 10. Also, the size of the measuring object 10 shown in Fig. 9(A) is larger than the measuring object 10 shown in Fig. 9(B).

[0100] 9(A), the position changer 111 moves the positions of the multiple electrodes 21 to a position closer to the outer edge of the measurement unit 110, and moves the positions of the multiple electrodes 21 to a position closer to the center of the measurement unit 110 in FIG. 9(B) in the measurement unit 110 of the above first and second modified examples may be provided with a magnetic field detection element 50 in the position changer 111. This allows the electrode pair 20 and / or the magnetic field detection element 50 to move to a position closer to the measurement target 10 even if the size of the measurement target 10 changes, thereby reducing the measurement error of the measurement device 100.

[0101] Although the measuring device 100 according to the present embodiment has been described above as an example in which the moving unit 120 moves the measuring unit 110, the present invention is not limited to this. The measuring device 100 may further include a bed on which the measurement target 10 is placed, and the moving unit 120 may move the bed. In this case, it is preferable that the measuring unit 110 is attached to the bed so that the position relative to the bed can be changed.

[0102] FIG. 10 shows a first modified example of the measuring device 100 according to this embodiment. FIG. 10 is a schematic diagram in which the moving unit 120, the storage unit 130, the control unit 140, and the display unit 150 are omitted. The measuring device 100 has a bed 210. FIG. 10 is a diagram of the bed 210 viewed from the ceiling side. The moving unit 120 may move the measuring unit 110 relative to the fixed bed 210, or alternatively or in addition, may move the bed 210 with the measuring unit 110 fixed. The moving unit 120 may move the measuring unit 110 in the Z direction, for example, or may rotate the measuring unit 110 around the Z direction as an axis.

[0103] For example, the measurement unit 110 is provided with a plurality of electrodes 21, a distance measurement unit 30, a current application unit 40, and a magnetic field detection element 50 so that the configuration excluding the bed 210 in the A-A' cross section of Fig. 10 is as shown in Fig. 2. This allows the measurement device 100 of the first modified example to easily and accurately measure information about the inside of the measurement target 10 in a non-contact manner. Therefore, for example, even if a person is bedridden in bed 210, the internal state of the body can be easily observed.

[0104] Fig. 11 shows a second modified example of the measuring device 100 according to this embodiment. Like Fig. 10, Fig. 11 is a schematic diagram in which the moving unit 120, the storage unit 130, the control unit 140, and the display unit 150 are omitted, and shows an example in which the measuring device 100 has a bed 210. Fig. 11(A) is a diagram of the bed 210 as seen from the ceiling side, and Fig. 11(B) shows an outline of the B-B' cross section of Fig. 11(A).

[0105] The measuring unit 110 of the measuring device 100 of the second modified example has two rod-shaped members that extend parallel to the longitudinal direction (Z direction) of the bed 210 and sandwich the measurement target 10. Here, the two rod-shaped members are a first rod-shaped member 221 and a second rod-shaped member 222. One first electrode (electrode 21a) constituting the electrode pair 20 is provided on the first rod-shaped member 221, one of the two rod-shaped members, and the other second electrode (electrode 21b), which is different from the first electrode of the electrode pair 20, is provided on the other second rod-shaped member 222, which is different from the first rod-shaped member 221, of the two rod-shaped members.

[0106] The first rod-shaped member 221 and the second rod-shaped member 222 are, for example, connected to a connection member 223, and constitute a part of the annular measuring unit 110. The first rod-shaped member 221 and the second rod-shaped member 222 are, for example, configured to be rotatable about the longitudinal direction of the bed 210 as the rotation axis. This allows the two electrodes 21 constituting the electrode pair 20 to apply AC currents to the measurement object 10 from various angles on the XY plane while remaining opposed to each other.

[0107] Alternatively, the first rod-shaped member 221 and the second rod-shaped member 222 may be configured to be movable in the X direction. The bed 210 may move in the X direction while the first rod-shaped member 221 and the second rod-shaped member 222 are fixed. Even with this configuration, the two electrodes 21 constituting the electrode pair 20 can apply an AC current to various positions of the measurement target 10 on the XY plane while remaining opposed to each other.

[0108] Even in the measuring device 100 of the first and second variants described above, the electrode pair 20 can apply an alternating current to various positions on the object to be measured 10 from a distance, and the multiple magnetic field detection elements 50 can detect the magnitude of the magnetic field generated in response to the alternating current.

[0109] In addition, the measurement devices 100 of the first and second modified examples can apply AC current to one electrode pair 20 from different positions while the measurement unit 110 is moving, so that the number of electrode pairs 20 can be reduced. The measurement device 100 can also reduce the number of magnetic field detection elements 50. As an example, the measurement device 100 may have one electrode pair 20, or alternatively or in addition, the number of magnetic field detection elements 50 may be one.

[0110] In the measuring device 100 of the second modified example, it is preferable that the distance measurement unit 30 measures the distance while the measurement unit 110 is moving. For example, the control unit 140 first moves the measurement unit 110 for distance measurement by the distance measurement unit 30. Then, the control unit 140 moves the measurement unit 110 to the same position as the position to which the measurement unit 110 was moved for measuring the distance, for distance measurement by the distance measurement unit 30, application of an AC current by one electrode pair 20, and detection of a magnetic field by the magnetic field detection element 50.

[0111] Alternatively, when the measurement unit 110 moves to a predetermined position, the control unit 140 may execute distance measurement by the distance measurement unit 30, application of an AC current by one electrode pair 20, and detection of a magnetic field by the magnetic field detection element 50. This also makes it possible to reduce the number of distance measurement units 30.

[0112] In the above description of the measuring device 100 according to the present embodiment, an example in which the magnetic field detection element 50 is mounted on the measuring unit 110 has been described, but the present invention is not limited to this. For example, the magnetic field detection element 50 may be provided on the bed 210. Moreover, the magnetic field detection element 50 may be provided on both the measuring unit 110 and the bed 210.

[0113] The measuring device 100 according to the present embodiment has been described above with reference to an example in which the current distribution estimation unit 143 estimates the cross-sectional shape of the object 10 based on a tomographic image of the object 10, but is not limited thereto. For example, the distance measurement unit 30 may also measure the irradiation direction of a radar or laser irradiated toward the object 10 when measuring the distance between the electrode 21 and the object 10.

[0114] In this way, the current distribution estimation unit 143 can estimate the cross-sectional shape of the measurement object 10 based on the distance from each electrode 21 to the measurement object 10 and the direction in which the measurement object 10 is irradiated with the radar or laser. Alternatively, a shape measuring device may be provided separately from the distance measurement unit 30, which scans the laser light toward the measurement object 10 on the XY plane to measure the shape of the measurement object 10.

[0115] The measuring device 100 may also use a technique for measuring the distance to the measuring object 10 and the shape of the measuring object 10 by irradiating the measuring object 10 with a laser light and measuring the reflected light or scattered light. The measuring device 100 may use an optical distance measuring technique such as LiDAR (Light Detection And Ranging). The measuring device 100 may also use ToF (Time-of-Flight) distance measuring technique.

[0116] Alternatively, the measuring device 100 may use a technique of measuring the distance to the measurement object 10 and the shape of the measurement object 10 by irradiating the measurement object 10 with ultrasonic waves and detecting a reflected signal, a transmitted signal, a scattered signal, etc. based on the irradiated ultrasonic waves with an ultrasonic sensor. The measuring device 100 may measure the distance to the measurement object 10 and the shape of the measurement object 10 by measuring acoustic impedance.

[0117] Alternatively, the measuring device 100 may use image processing to measure the distance to the measurement target 10 and the shape of the measurement target 10. Here, the measuring device 100 may use photogrammetry, image measurement using a camera with two or more lenses, or the like.

[0118] Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, all or part of the device can be configured by distributing or integrating functionally or physically in any unit. In addition, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effect of the new embodiment resulting from the combination combines the effect of the original embodiment. [Explanation of symbols]

[0119] 10 Measurement Object 20 electrode pairs 21 electrodes 30 Distance measurement unit 40 Current application section 50 Magnetic field detection element 100 Measuring Equipment 110 Measuring section 111 Position change section 120 Mobile Unit 130 Storage section 140 Control section 141 Acquisition Department 142 Synchronization signal extraction unit 143 Current distribution estimation section 144 Image information output unit 145 Display control unit 150 Display section 210 Beds 221 First rod-shaped member 222 Second rod-shaped member 223 Connection parts

Claims

1. A plurality of electrode pairs provided at positions away from the measurement object; a distance measurement unit that measures a distance between an electrode constituting the electrode pair and a surface of the measurement target facing the electrode for each electrode; a current applying unit that applies an AC current to the object to be measured via the electrode pair; a magnetic field detection element that detects the magnitude of a magnetic field generated from the object to be measured in response to the AC current applied by the current application unit; a current distribution estimation unit that estimates a current distribution inside the measurement object based on a plurality of distance measurement results by the distance measurement unit, the magnitude of the AC current applied by the current application unit, and the magnitude of the magnetic field detected by the magnetic field detection element; an image information output unit that generates and outputs an image showing information about the inside of the measurement target based on the current distribution estimated by the current distribution estimation unit and the magnitude of the magnetic field detected by the magnetic field detection element; A measuring device comprising:

2. The measurement device according to claim 1 , wherein the distance measurement unit includes a millimeter wave radar that measures the distance from the electrode to a surface of the measurement target facing the electrode by using radio waves in a millimeter wave frequency band.

3. The plurality of electrode pairs are provided around the measurement object, the current distribution estimation unit estimates a cross-sectional shape of the measurement object based on a plurality of distance measurement results by the distance measurement unit, and estimates a current distribution within the estimated cross-sectional shape.

2. The measuring device of claim 1.

4. An acquisition unit for acquiring a tomographic image of the measurement object, The current distribution estimation unit estimates a cross-sectional shape of the measurement object based on the tomographic image of the measurement object acquired by the acquisition unit.

4. The measuring device according to claim 3.

5. A storage unit that stores a standard tomographic image of the measurement object, The current distribution estimation unit estimates a cross-sectional shape of the measurement object based on the standard tomographic image.

4. The measuring device according to claim 3.

6. The measuring device according to claim 3 , wherein the image information output section generates an image showing information about an interior of the cross-sectional shape of the measurement target estimated by the current distribution estimation section.

7. An acquisition unit for acquiring a tomographic image of the measurement object, The image information output unit generates an image in which an image showing information about the inside of the generated cross-sectional shape is superimposed on a corresponding position of the tomographic image of the measurement target.

7. The measuring device according to claim 6.

8. A control unit that changes a frequency of the AC current applied to the object to be measured by the current application unit, the image information output unit generates an image showing information about an inside of the object to be measured each time the control unit changes the frequency of the AC current; The control unit detects an abnormality inside the measurement target by comparing the multiple images output by the image information output unit.

2. The measuring device of claim 1.

9. a storage unit that stores the image output by the image information output unit; a control unit that detects an abnormality inside the measurement target by comparing the image output by the image information output unit with an image previously output by the image information output unit; The measurement device of claim 1 further comprising:

10. A measurement unit having a ring shape or a part of a ring shape surrounding the measurement object, the measurement unit having a plurality of electrode pairs and the distance measurement unit; a moving unit that moves at least one of the measurement object and the measurement unit to change a relative position between the measurement object and the measurement unit; The measurement device of claim 1 further comprising:

11. The measurement device according to claim 10, wherein the measurement unit has a position changing unit that changes positions of the plurality of electrode pairs while maintaining a non-contact state between the plurality of electrode pairs and the object to be measured so that a distance between the plurality of electrode pairs and the object to be measured is within a predetermined distance range.

12. Further comprising a bed on which the measurement object is placed, The measuring device according to claim 10 , wherein the measuring unit is attached to the bed so that a position of the measuring unit relative to the bed can be changed.

13. The measurement unit has two rod-shaped members extending parallel to the longitudinal direction of the bed and sandwiching the measurement target therebetween, a first electrode of the electrode pair is provided on one of the two rod-shaped members, and a second electrode different from the first electrode of the electrode pair is provided on the other of the two rod-shaped members, the second electrode different from the first rod-shaped member; 13. The measuring device of claim 12.

14. The measuring device according to claim 10 , wherein the measuring section further comprises the magnetic field detection element.

15. A computer-implemented measurement method for measuring internal information of a measurement target, comprising the steps of: measuring a distance between an electrode constituting a plurality of electrode pairs provided at a position away from a measurement object and a surface of the measurement object facing the electrode for each of the electrodes; applying an alternating current to the object to be measured via a plurality of the electrode pairs; Detecting the magnitude of a magnetic field generated from the measurement object in response to the applied AC current; estimating a current distribution inside the object based on a plurality of distance measurements, the magnitude of the AC current applied to the object, and the magnitude of the detected magnetic field; generating and outputting an image showing information about the inside of the object to be measured based on the estimated current distribution and the magnitude of the detected magnetic field; A measurement method comprising:

16. A program that, when executed by a computer, causes the computer to carry out the measurement method according to claim 15.

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