Patent Description:
An electrical impedance tomography (hereinafter referred to as EIT) measurement apparatus is technology for causing a weak current to flow from a pair of electrodes attached on a body surface and generating an image of a conductivity distribution or a distribution of a conductivity change within a living body from a potential difference generated on the body surface.

Because it is possible to acquire a tomographic image when a weak current flows through an object, EIT measurement has advantages in that there is no exposure problem and in that size reduction, long-time measurement, and real-time measurement are facilitated as compared with X-ray computed tomography (CT).

In the EIT measurement, generally, about <NUM> to <NUM> electrodes are used. These electrodes are attached to the body surface of the periphery of an object portion and signal cables individually connected to the electrodes are routed and connected to a measurement circuit. Recently, a method of integrating a plurality of electrodes and signal cables as a module and facilitating attachment/detachment of the electrodes and setting of a measurement apparatus has been attempted (for example, see Patent Literatures <NUM> and <NUM>). <CIT> discloses impedance measurement in order to measure blood flow to the brain of a person.

However, in all the EIT measurements described above, an operation of attaching a plurality of electrodes on a body surface is required. Therefore, even when it is facilitated to a certain extent by modularization, a fixed burden is considerably imposed on a measurement operator. Also, a physical burden is strong according to a measurement object person (a person to be measured) at the time of attachment of the electrodes.

An objective of aspects of the present invention is to provide systems and methods more easily and precisely acquiring a state of an object.

According to the present invention, a system and a method as defined in the corresponding independent claims are provided. Other embodiments are defined in the corresponding dependent claims.

According to a first aspect of the disclosure, there is provided an image generation apparatus comprising:.

According to a second aspect of the disclosure, there is provided the image generation apparatus according to the first aspect, wherein the intensity of the magnetic field is acquired via the plurality of sensor cells in a state in which at least some of the plurality of electrodes and the plurality of sensor cells are arranged in non-direct contact with a surface of the measurement object.

According to a third aspect of the disclosure, there is provided the image generation apparatus according to the first or second aspect, wherein each of the plurality of sensor cells is a part of an optical pumping atomic magnetic sensor or a magnetic impedance element sensor.

According to a fourth aspect of the disclosure, there is provided the image generation apparatus according to any one of the first to third aspects, further comprising:
a base member in which at least some of the plurality of electrodes and the plurality of sensor cells are provided so that at least some of the plurality of electrodes and the plurality of sensor cells move according to motion of the base member.

According to a fifth aspect of the disclosure, there is provided the image generation apparatus according to any one of the first to fourth aspects, wherein at least one of the plurality of sensor cells is arranged to independently and freely change a distance from the measurement object.

According to a sixth aspect of the disclosure, there is provided the image generation apparatus according to any one of the first to fifth aspects, further comprising:.

According to seventh aspect of the disclosure, there is provided an image generation apparatus comprising:.

According to an eighth aspect of the disclosure, there is provided the image generation apparatus according to the seventh aspect, wherein the magnetic field information acquisition unit is configured to acquire at least intensities of magnetic fields at a plurality of positions surrounding a specific tomographic surface of the measurement obj ect.

According to a ninth aspect of the disclosure, there is provided the image generation apparatus according to the seventh or eighth aspect, wherein the alternating current input unit is configured to input the alternating current via electrodes arranged at a plurality of positions surrounding a specific tomographic surface of the measurement obj ect.

According to a tenth aspect of the disclosure, there is provided the image generation apparatus according to the ninth aspect, wherein the magnetic field information acquisition unit is configured to acquire an intensity of a magnetic field generated on the basis of an alternating current input by the alternating current input unit via the magnetic sensor arranged around the same tomographic surface as the specific tomographic surface.

According to an eleventh aspect of the disclosure, there is provided the image generation apparatus according to any one of the seventh to tenth aspects, wherein the magnetic field information acquisition unit is configured to acquire intensities of magnetic fields at a plurality of positions surrounding another tomographic surface different from one tomographic surface of the measurement object simultaneously with intensities of magnetic fields at a plurality of positions surrounding the one tomographic surface.

According to a twelfth aspect of the disclosure, there is provided the image generation apparatus according to the eleventh aspect, wherein the image generation unit is configured to generate a tomographic image in which the one tomographic surface is represented by combining a first intermediate image generated on the basis of the intensities of the magnetic fields surrounding the one tomographic surface and a second intermediate image generated on the basis of the intensities of the magnetic fields at the plurality of positions surrounding the other tomographic surface.

According to a thirteenth aspect of the disclosure, there is provided the image generation apparatus according to any one of the seventh to twelfth aspects, wherein the alternating current input unit has a non-magnetic material as the electrode.

According to a fourteenth aspect of the disclosure, there is provided the image generation apparatus according to any one of the seventh to thirteenth aspects, wherein the magnetic field information acquisition unit has an optical pumping atomic magnetic sensor as the magnetic sensor.

According to a fifteenth aspect of the disclosure, there is provided the image generation apparatus according to any one of the seventh to fourteenth aspects, wherein the alternating current input unit is configured to input at least the alternating current via electrodes arranged at a plurality of positions surrounding a periphery of a specific tomographic surface of the measurement object.

According to a sixteenth aspect of the disclosure, there is provided an image generation method comprising:.

According to a seventeenth aspect of the disclosure, there is provided an image generation method comprising:.

According to an eighteenth aspect of the disclosure, there is provided a program for causing an image generation apparatus to function as:.

According to a nineteenth aspect of the disclosure, there is provided a conductivity acquisition apparatus comprising:.

According to a twentieth aspect of the disclosure, there is provided an image generation apparatus comprising:.

It is possible to more easily and precisely acquire a state of an object according to the system and method as defined in the appended claims.

Hereinafter, an image generation apparatus according to the first embodiment will be described with reference to the drawings.

<FIG> is a diagram illustrating an overview of the image generation apparatus according to the first embodiment.

The image generation apparatus <NUM> illustrated in <FIG> includes a detection unit <NUM>, a drive unit <NUM>, and a main body unit (a controller) <NUM>, and can acquire a tomographic image of a measurement object person (a person to be measured) X.

The detection unit <NUM> is formed in an annular shape to surround the girth of the measurement object person X at the time of use. Here, the "annular shape" is an overall shape surrounding at least a part of the object and is not limited to a shape which fully continuously surrounds the object. Also, the "annular shape" is not limited to a circle and may be various forms. For example, the "annular shape" can include an annular shape having a partial open section, a ring having an overall shape other than the circle, etc. As will be described below, the detection unit <NUM> has a plurality of electrodes and sensors (a plurality of magnetic sensors, a plurality of sensors, a plurality of sensor cells, and a plurality of sensor heads). The main body unit <NUM> acquires various types of detection signals for the measurement object person X from the detection unit <NUM>. The main body unit <NUM> can acquire a tomographic image of a surface in which the detection unit <NUM> is arranged in the measurement object person X (a tomographic image of the person X to be measured with respect to a surface set according to a position of an axial direction of the detection unit <NUM>) on the basis of the detection signal.

The drive unit <NUM> has a movement body which is fixed to the detection unit <NUM> and moves the detection unit <NUM> along a surface of the object (e.g., an axial direction and an up/down direction (a vertical direction) of the object (a portion to be measured)). In an example, according to linear movement of the movement body, the detection unit <NUM> can linearly move. Also, the movement of the detection unit <NUM> by the drive unit <NUM> is not limited to linear movement. The drive unit <NUM> has a drive mechanism such as, for example, a stepping motor (not illustrated). The drive unit <NUM> changes a position of the detection unit <NUM> (e.g., a position in the vertical direction) on the basis of an electrical signal (an instruction signal) input from the main body unit <NUM>. Thereby, the operator can arbitrarily change a relative position of the detection unit <NUM> with respect to the measurement object person X. It is possible to easily acquire a desired tomographic image of the measurement object person X by moving the detection unit <NUM> using the drive unit <NUM>. In an alternative embodiment, the image generation apparatus <NUM> can have a configuration in which the detection unit <NUM> is moved without using power or in which the drive unit <NUM> is substantially omitted.

The main body unit (the controller) <NUM> performs overall control of the image generation process of the image generation apparatus <NUM> such as the acquisition of the detection signal by the detection unit <NUM>, the driving of the detection unit <NUM> using the drive unit <NUM>, and the generation of a tomographic image. A detailed functional configuration of the main body unit <NUM> will be described below.

<FIG> is a diagram illustrating a functional configuration of the main body unit according to the first embodiment.

As illustrated in <FIG>, the main body unit <NUM> according to the present embodiment includes a central processing unit (CPU) <NUM>, a random access memory (RAM) <NUM>, a hard disk drive (HDD) <NUM>, an operation input unit <NUM>, an image display unit <NUM>, and an external interface <NUM>.

The CPU <NUM> controls the overall image generation process of the image generation apparatus <NUM>. The CPU <NUM> exhibits functions serving as an alternating current input unit <NUM>, a magnetic field information acquisition unit <NUM>, and an image generation unit <NUM> by performing an operation on the basis of a measurement program loaded to a predetermined storage region (the RAM <NUM> or the like).

The RAM <NUM> is a storage region serving as a work area of the CPU <NUM> which operates on the basis of the measurement program.

The HDD <NUM> is a storage means which stores various types of programs or a tomographic image or the like generated by the image generation unit <NUM>.

The operation input unit <NUM> is constituted of, for example, a mouse, a keyboard, a touch panel, etc., and receives inputs of various operations by the operator.

The image display unit <NUM> is a liquid crystal display or the like and displays information necessary for an operation of the operator, an acquired tomographic image, or the like.

The external interface <NUM> is a communication interface for communicating with an external device and is particularly connected to the detection unit <NUM> and the drive unit <NUM> via a dedicated communication cable in the present embodiment.

Also, as illustrated in <FIG>, the CPU <NUM>, the RAM <NUM>, the HDD <NUM>, the operation input unit <NUM>, the image display unit <NUM>, and the external interface <NUM> are mutually connected via a system bus <NUM>.

Next, the alternating current input unit <NUM>, the magnetic field information acquisition unit <NUM>, the image generation unit <NUM>, and the drive control unit <NUM> implemented by an operation of the CPU <NUM> based on the measurement program will be briefly described.

The alternating current input unit <NUM> inputs an alternating current to the measurement object person X via a plurality of electrodes <NUM> (illustrated in <FIG>) arranged at positions separated from the measurement object (the measurement object person X).

The magnetic field information acquisition unit <NUM> acquires a magnetic field generated on the basis of the alternating current input by the alternating current input unit <NUM> via a plurality of magnetic sensors (a plurality of sensor cells and a plurality of sensor heads) <NUM> arranged at positions separated from the measurement object person X.

The image generation unit <NUM> generates a tomographic image of the measurement object person X on the basis of the magnetic field acquired by the magnetic field information acquisition unit <NUM>.

The drive control unit <NUM> outputs a predetermined drive instruction signal to the drive unit <NUM> and controls the operation of the drive unit <NUM>.

More specific functions of the alternating current input unit <NUM>, the magnetic field information acquisition unit <NUM>, the image generation unit <NUM>, and the drive control unit <NUM> will be described below.

<FIG> is a first diagram illustrating the structure of the detection unit according to the first embodiment. Also, <FIG> is a second diagram illustrating the structure of the detection unit according to the first embodiment.

In <FIG>, a structure of a side surface of the detection unit <NUM> is illustrated. Also, in <FIG>, a cross-sectional structure of the surface A-A' in <FIG> is schematically illustrated. As illustrated in <FIG> and <FIG>, the detection unit <NUM> includes a base member (a base frame and an annular housing) <NUM>, electrodes <NUM>, and magnetic sensors <NUM>.

In the present embodiment, the base member <NUM> is formed in an annular shape to surround the girth of the measurement object person X (to surround at least a part of the measurement object person) at the time of use. The base member <NUM> is attached to the drive unit <NUM> (<FIG>). A relative position of the base member <NUM> with respect to the measurement object person X is changed on the basis of drive control by the drive unit <NUM>. The base member <NUM> is formed of, for example, an acrylic resin or the like. Various materials can be applied as a material of the base member <NUM>. Preferably, the material of the base member is substantially an insulator and is substantially a non-magnetic material. Also, the base member <NUM> is not limited to a circular annular shape. The overall shape of the base member <NUM> may be, for example, an oval shape or a partially intermittent structure. Alternatively, the base member <NUM> may have a structure in which the overall shape is changeable or a structure capable of being opened/closed.

A plurality of electrodes <NUM> are attached to the base member <NUM> at fixed intervals in a circumferential direction of the base member <NUM> within the same surface as the surface A-A'. The arrangement of the electrodes <NUM> can be variously changed. The electrode <NUM> has, for example, conductivity of copper, aluminum, stainless steel, or the like and is formed of substantially a non-magnetic material. The material of the electrode <NUM> is not limited to the above-described examples.

Similar to the electrodes <NUM>, a plurality of magnetic sensors <NUM> (the plurality of sensors and the plurality of sensor heads) are attached to the base member <NUM> at fixed intervals in the circumferential direction of the base member <NUM> within the same surface as the surface A-A'. The plurality of magnetic sensors (the plurality of sensor heads) <NUM> are arranged within the same surface as the surface in which the plurality of electrodes <NUM> are arranged (<FIG>). The arrangement of the magnetic sensors (sensor heads) <NUM> can be variously changed.

Also, in the present embodiment, an optical pumping atomic magnetic sensor having ultra-high sensitivity at room temperature is used as the magnetic sensor <NUM>. The optical pumping atomic magnetic sensor can observe a magnetic field of the same degree (the order of <NUM>-<NUM> Tesla (T)) as that of a superconducting quantum interference device (SQUID) requiring a cryogenic state.

As illustrated in <FIG>, the alternating current input unit <NUM> controls an alternating current drive circuit 201A and causes an alternating current to flow between two electrodes <NUM> among the plurality of electrodes <NUM>. The alternating current drive circuit 201A is a circuit having an alternating current power supply and a constant current circuit (or a constant voltage circuit) and can output an alternating current of a high frequency (e.g., the order of several kHz to several MHz) according to control by the alternating current input unit <NUM>. Thereby, because a component of the alternating current emitted from the electrode <NUM> to the air is high, it is possible to cause the alternating current to flow inside the measurement object person X without directly attaching the electrode <NUM> to the body surface of the measurement object person X. Also, it can be seen that a change in impedance is significant in the above-described frequency band when a human body serves as a measurement object (see <FIG>).

Also, although not illustrated, the alternating current input unit <NUM> includes a switching unit capable of selecting and connecting an alternating current drive circuit 201A and two arbitrary electrodes <NUM> of the plurality of electrodes <NUM>. The alternating current input unit <NUM> performs a process of causing an alternating current to flow through the measurement person X while sequentially switching a connection of the alternating current drive circuit 201A and each of the plurality of electrodes <NUM>.

As described above, the alternating current input unit <NUM> inputs an alternating current via the electrodes <NUM> arranged at a plurality of positions surrounding a specific tomographic surface of the measurement object person X.

Also, as illustrated in <FIG>, the magnetic field information acquisition unit <NUM> is connected to the magnetic sensors <NUM> and acquires intensities of magnetic fields detected by the magnetic sensor <NUM> as data (magnetic field intensity information). Also, although not illustrated, the magnetic field information acquisition unit <NUM> is also connected in parallel to all the magnetic sensors (the sensor cells and the sensor heads) <NUM> and can simultaneously acquire intensities of magnetic fields generated at positions at which the magnetic sensors <NUM> are arranged. Also, a circuit necessary to acquire the intensity of the magnetic field as electrical data (magnetic field intensity information) such as a band pass filter, an amplifier, or an analog/digital (A/D) converter is inserted into the connection between the magnetic sensor <NUM> and the magnetic field information acquisition unit <NUM>.

As described above, the magnetic field information acquisition unit <NUM> acquires the magnetic field intensity information indicating intensities of magnetic fields at a plurality of positions surrounding a specific tomographic surface via the magnetic sensors <NUM> arranged around the same tomographic surface as that of the specific tomographic surface of the measurement object person X surrounded by the electrodes <NUM>.

<FIG> is a diagram illustrating functions of an electrode and a magnetic sensor according to the first embodiment.

The case in which the alternating current input unit <NUM> controls the alternating current drive circuit 201A to cause an alternating current to flow between a pair of adjacent electrodes <NUM> is considered. When the frequency of the alternating current has the order of several MHz, the alternating current is generated to be widened in an arc in the air between the adjacent electrodes <NUM> as illustrated in <FIG>. Thereby, the alternating current (alternating currents I1, I2, etc.) is also input inside the measurement object X. The alternating currents I1, I2, etc. input to the measurement object X have values according to transmission paths inside the measurement object person X.

More specifically, because blood or the like included in the measurement object person X is an electrolyte, electrical impedance is lower inside the measurement object person X than in the air. Accordingly, the alternating current emitted from a position between two electrodes <NUM> to the air is assumed to flow inside the measurement object person X having lower electrical impedance. Then, for example, the alternating currents I2, <NUM>, etc. generally have a larger current value when the measurement object person X is in their fields than when the measurement object person X is not in their fields. Also, even the inside of the measurement object person X, for example, an alternating current passing through an air-filled lung has a smaller current value.

As described above, an alternating current generated between certain electrodes <NUM> has a current value according to a distribution of electrical impedance inside the measurement object X.

Also, as illustrated in <FIG>, magnetic fields H are generated around the alternating currents (the alternating currents I1, I2, etc.). The intensity of the magnetic field H is proportional to the generated alternating current value. The magnetic field information acquisition unit <NUM> detects intensities of the magnetic fields H at positions via the magnetic sensors (the sensor cells and the sensor heads) arranged on the circumference of the base member <NUM>.

The image generation unit <NUM> to be described below generates a tomographic image of the tomographic surface S (a tomographic surface for the surface A-A' of the measurement object person X) within the same surface as those of the electrodes <NUM> and the magnetic sensors <NUM> on the basis of information about the intensities of the magnetic fields H detected by the magnetic sensors <NUM> acquired by the magnetic field information acquisition unit <NUM> here.

Also, the frequency of the input alternating current has the order of several kHz to several MHz so that highly precise measurement is enabled when a human body is a measurement object as described above (see <FIG>). Thus, a magnetic field generated on the basis of the alternating current oscillates at the same frequency. Therefore, in the present embodiment, by using the optical pumping atomic magnetic sensor having high-ultra sensitivity as the magnetic sensor <NUM>, it is possible to precisely detect the intensity of the magnetic field even for the magnetic field oscillating at a relatively high frequency (the order of several MHz). The above-described numeric value is an example and the present invention is not limited thereto.

The form of the magnetic sensor <NUM> is not limited to the optical pumping atomic magnetic sensor. As the magnetic sensor <NUM>, preferably, a so-called high-sensitivity magnetic sensor is used. In an example, the magnetic sensor <NUM> can detect the magnetic field H of the order of at least several kHz with high precision. The above-described numeric value is an example and the present invention is not limited thereto. For example, one selected from among various types such as a magnetic impedance (MI) sensor (a magnetic impedance element sensor) and a superconducting quantum interference device (SQUID) can be used as the magnetic sensor <NUM>.

<FIG> is a flowchart illustrating a processing flow of a CPU according to the first embodiment.

Hereinafter, the processing flow executed by the CPU <NUM> will be sequentially described with reference to <FIG> in a measurement procedure of the image generation apparatus <NUM> according to the present embodiment.

First, when an input operation of a measurement start is received from the operator via the operation input unit <NUM>, the alternating current input unit <NUM> selects a pair of adjacent electrodes <NUM> and is connected to the alternating current drive circuit 201A (<FIG>) (step S10). Next, the alternating current input unit <NUM> inputs a predetermined control signal to the alternating current drive circuit 201A and causes an alternating current having a set frequency and output intensity to be generated between the selected electrodes <NUM> (step S <NUM>). Thereby, an alternating current having a predetermined intensity (alternating currents I1, I2, etc. (<FIG>)) is input inside the measurement object person X.

The magnetic field information acquisition unit <NUM> receives detection signals in parallel from all the magnetic sensors (the sensor cells and the sensor heads) <NUM> (output signals from the sensors) during inputs of alternating currents and acquires magnetic field intensity information indicating intensities of magnetic fields at each position (step S12). Thereby, the magnetic field information acquisition unit <NUM> acquires intensities of magnetic fields generated on the basis of alternating currents input by the alternating current input unit <NUM> at positions at which the magnetic sensors <NUM> are arranged. The magnetic field information acquisition unit <NUM> temporarily stores the acquired magnetic field intensity information in a storage region (the RAM <NUM>, the HDD <NUM>, etc.).

When the magnetic field information is acquired between a pair of adjacent electrodes <NUM>, the alternating current input unit <NUM> selects another pair of adjacent electrodes <NUM> and inputs an alternating current. The alternating current input unit <NUM> iterates the above-described process until all pairs of electrodes are selected (step S13). Thereby, the magnetic field information acquisition unit <NUM> acquires magnetic field intensity information about intensities of magnetic fields in a set of all adjacent electrodes <NUM>.

When the magnetic field intensity information about all the pairs of electrodes <NUM> is acquired (step S13: YES), the image generation unit <NUM> refers to the magnetic field intensity information acquired and stored by the magnetic field information acquisition unit <NUM> to generate a tomographic image of the measurement object person X (step S14). In an example, a technique similar to conventionally known EIT measurement can be used for a technique of generating a tomographic image of the measurement object person X on the basis of the magnetic field intensity information acquired in step S12.

Here, a technique of a process of generating the tomographic image in step S14 will be briefly described. First, in the case of the conventional EIT measurement, a plurality of electrodes are generally attached to a body surface. While a constant current (generally, an alternating current having the order of several kHz) flows between certain selected electrodes, a resistivity distribution in the tomographic surface of the measurement object person is acquired by sequentially measuring a potential difference between other electrodes. In the conventional EIT measurement, the tomographic image is generated using, for example, a known back projection method, on the basis of the resistivity distribution. To reconfigure an image of EIT in real time, it is assumed that (<NUM>) a boundary of a measurement object is circular, (<NUM>) electrodes are arranged at equal intervals, (<NUM>) an initial conductivity distribution is uniform, (<NUM>) a conductivity change is small, and (<NUM>) an object is two-dimensional. First, when a sensitivity matrix S defined using a theory of Geselowitz is used, a relationship between a voltage change Δg and a conductivity change Δc which are measured is as follows.

Here, Δc denotes a change amount when a part of a uniform conductivity distribution cu is changed to c, Δg denotes a change amount when a voltage measured in a boundary according to Δc is changed from gu to g. Each sensitivity coefficient is as follows. <MAT> Here, when a drive electrode and a receive electrode of each set are in a measurement object e, a potential gradient occurring in the receive electrode is denoted by ∇φd and a potential gradient occurring in the drive electrode by conversely applying the same current to the receive electrode is denoted by ∇φr. The sensitivity coefficient S is obtained by assuming that a potential of a point positioned at distances r1 and r2 from a pair of electrodes of two points is φ = (r1)-<NUM> - (r2)-<NUM> in a finite element method. Because it is difficult to significantly obtain an inverse matrix of S, the following result is given when an image is reconfigured as a change rate.

Here, F denotes a normalized sensitivity matrix and denotes a change rate for a certain reference value shown in Δgn = g/gref and Δc = c/cref. That is, the reconfigured image shows a change rate distribution of conductivity. Also, in Equation (<NUM>), the symbol "+" denotes a pseudo inverse matrix of a matrix to which "+" is attached.

Because it is significantly difficult to solve an inverse problem of a magnetic field system, an image analysis technique in the above-described EIT is used from the fact that there is a proportional relationship between a change rate of a magnetic field and a change rate of conductivity which are measured in the present embodiment.

A voltage V between electrodes measured in the EIT is represented as in Equation (<NUM>).

Here, "σ" denotes conductivity of the measurement object (the measurement object person X) (units: S/m and resistivity is ρ = <NUM>/σ), "l" and "s" denote a length (units: m) and a cross-sectional area (units: m<NUM>) when the measurement object is considered to be a rectangular solid, and "I" denotes a current flowing through the measurement object (units: A). That is, if the impedance of the measurement object does not change during measurement, a potential difference V is proportional to the current I.

On the other hand, the magnetic field intensity "H" and the current "I" are generally known to satisfy the relationship of Equation (<NUM>).

That is, the magnetic field intensity H (units: A/m) at a point separated by a distance "r" (units: m) from a direction in which the current I flows in a perpendicular direction is obtained as in Equation (<NUM>) and thereby the magnetic field intensity H and the current I are known to be in a proportional relationship.

Therefore, because the potential difference V and the magnetic field intensity H are also in the proportional relationship, it is possible to acquire an equivalent tomographic image even when an input for the "potential difference V" is replaced with the "magnetic field intensity H" as it is in a known inverse projection method.

Also, a tomographic image generation process to be executed by the image generation unit <NUM> is not limited to a technique using the inverse projection method used in the above-described EIT measurement and another technique may be used. For example, a technique of solving the inverse problem of the magnetic field system may be used on the basis, for example, the acquired magnetic field intensity information.

When the tomographic image is generated in step S14, the image generation unit <NUM> outputs the generated tomographic image to the image display unit <NUM>. The operator can perform diagnosis while viewing the tomographic image displayed on the image display unit <NUM>.

When a process of generating one tomographic image is completed, the drive control unit <NUM> subsequently controls the drive of the drive unit <NUM>. Specifically, the drive control unit <NUM> determines whether all tomographic images for the measurement object person X have been acquired (step S15). Also, a position of a tomographic surface S for which a tomographic image is acquired, the number of acquisitions, or the like is assumed to be determined at the time of a first setting input by the operator.

When all the tomographic images have not been acquired (step S15: NO), the drive control unit <NUM> causes the detection unit <NUM> to be moved in an up/down direction by outputting a predetermined instruction signal to the drive unit <NUM> (step S16). Thereby, the drive unit <NUM> changes a relative position of the detection unit <NUM> with respect to the measurement object person X.

In step S16, the relative position of the detection unit <NUM> with respect to the measurement object person X is changed, the alternating current input unit <NUM>, the magnetic field information acquisition unit <NUM>, and the image generation unit <NUM> iterate processes of the above-described S10 to S14. Thereby, it is possible to further acquire a tomographic image for a different tomographic surface of the measurement object X.

In step S16, the CPU <NUM> ends the process when the scheduled acquisition of all the tomographic images ends (step S15: YES).

As described above, an operation of attaching a plurality of electrodes to a body surface of the measurement object person X is necessary in the case of the conventional EIT measurement.

On the other hand, in the image generation apparatus <NUM> according to the present embodiment, as described using <FIG>, etc., all of the plurality of electrodes <NUM> serving as an output destination of an alternating current input to the measurement object person X and the plurality of magnetic sensors (the plurality of sensors and the plurality of sensor heads) <NUM> which detect the alternating current as a magnetic field intensity are arranged at positions spaced apart from the measurement object person X. The plurality of electrodes <NUM> and the plurality of magnetic sensors (the plurality of sensors and the plurality of sensor heads) <NUM> are arranged in non-direct contact with the surface of the measurement object X. Thereby, it is possible to acquire a tomographic image for a desired tomographic surface of the measurement object person X while the measurement object person X, the electrodes, etc. are fully in a non-contact state (a non-direction contact state).

Thereby, it is possible to not only reduce a burden on an operation in which the operator attaches the electrodes, but also reduce a physical burden on the measurement object person X. The "non-direct contact with the surface of the measurement object X" includes a state in which another physical object is interposed between the electrodes <NUM>/the magnetic sensors <NUM> and the body surface of the measurement object person and includes, for example, a state in which the electrodes <NUM>/the magnetic sensors <NUM> are arranged on an outer surface of the clothing worn by the measurement object person. Additionally and/or alternatively, the detection unit <NUM> can be a type of attachment to the measurement object (the measurement object person). For example, the detection unit <NUM> can have a configuration in which at least some of the electrodes <NUM> and the magnetic sensors <NUM> are provided in the base member <NUM> formed to be worn by the measurement object person (for example, a band type, a cap type, a helmet type, or the like).

Also, although an example in which measurement is performed while the detection unit <NUM> surrounding the girth of the measurement object person X moves in the vertical direction in a state in which the measurement object person X stands in <FIG> or the like in the present embodiment, other embodiments are not limited to such a form. For example, the image generation apparatus <NUM> may have a form in which the detection unit <NUM> is moved in a horizontal direction in a state in which the detection unit <NUM> surrounds the measurement object person X as a state in which the measurement object person X lays on a dedicated bed or the like. Thereby, it is possible to acquire a tomographic image without imposing a physical burden on the measurement object person X even in a situation in which it is difficult for the measurement object person X to raise his/her body.

Also, in the case of the conventional EIT measurement, the case in which electrical impedance may change according to a state of a body surface (the presence/absence of sweat) on its contact surface and an error occurs in a measurement result is assumed.

In this regard, because a contact surface (a body surface) between the electrodes <NUM> and the measurement object person is absent, the image generation apparatus <NUM> according to the present embodiment can eliminate an error factor according to a state of the contact surface.

Also, in the present embodiment, the electrodes <NUM> are formed of a non-magnetic material as described above. Thereby, the presence of the electrodes <NUM> can minimize an influence on detection of the magnetic field strength by the magnetic sensors <NUM>. Thereby, each magnetic sensor <NUM> may precisely detect an intensity of a magnetic field generated at its position without depending upon a positional relationship with the electrodes <NUM> in the base member <NUM>.

According to the above image generation apparatus <NUM> according to the first embodiment, it is possible to more easily and precisely acquire a tomographic image of an object.

Also, the image generation apparatus <NUM> according to the first embodiment can be further modified as follows.

<FIG> is a diagram illustrating a structure of a detection unit according to a modified example of the first embodiment.

In the image generation apparatus <NUM> according to the first embodiment, an optical pumping atomic magnetic sensor is used as the magnetic sensor <NUM>. Thereby, it is possible to precisely detect an intensity of a magnetic field at room temperature even in the magnetic field oscillating on the order of several kHz to several MHz. That is, because it is possible to exclude all components necessary for use at cryogenic temperature like the SQUID, it is possible to reduce a size of an individual magnetic sensor <NUM>. In this case, as illustrated in <FIG>, a number of magnetic sensors <NUM>, as many as possible, may be arranged within the constraints according to an individual size regardless of the arrangement of the electrodes <NUM>.

Specifically, the number of magnetic sensors <NUM> arranged in a circumferential direction of the base member <NUM> may be determined on the basis of only a length D[m] of a width direction of one of the magnetic sensors <NUM> and a circumference R[m] of the base member <NUM> (e.g., Number = R/D).

Thereby, it is possible to increase the number of detection positions of the magnetic field (i.e., an amount of information about the intensity of the magnetic field) as much as possible in a limited size. It is possible to acquire a tomographic image with higher precision by increasing the resolution of the tomographic image.

Also, in this case, as in the first embodiment, the electrodes <NUM> may be formed of a non-magnetic material.

Also, a processing flow to be executed by the CPU <NUM> according to the first embodiment is not limited to the processing flow illustrated in <FIG>. That is, the CPU <NUM> may acquire magnetic field intensity information in any procedure as long as the magnetic field intensity information in an information amount necessary to generate a tomographic image on the basis of an image generation process (e.g., an inverse projection method or the like) used in the EIT measurement is acquired.

<FIG> is a diagram illustrating functions of the electrode and the magnetic sensor according to the modified example of the first embodiment.

Also, the CPU <NUM> (the alternating current input unit <NUM>) according to the first embodiment has been described as inputting an alternating current while sequentially selecting pairs of electrodes <NUM> adjacent to each other (steps S <NUM> and S11 (<FIG>)). However, the alternating current input unit <NUM> according to another embodiment further includes a combination other than a pair of adjacent electrodes <NUM> to input an alternating current. For example, the alternating current input unit <NUM> may select one electrode <NUM> and another electrode <NUM> located at a position opposite to the one electrode <NUM> to output the alternating current between the electrodes <NUM>.

Also, in <FIG>, it can be seen that an alternating current generated between the electrodes <NUM> adjacent to each other flows as a large current in the vicinity thereof, but an amount of current decreases as a distance from the electrodes <NUM> increases. Therefore, when the alternating current is generated only between the adjacent electrodes <NUM>, a current flowing through the inside of the measurement object X is weak as compared with an amount of current flowing through a side close to the body surface of the measurement object X. Thus, a tomographic image acquired on the basis of only the alternating current generated between the electrodes <NUM> adjacent to each other is reproduced with high precision for a region close to the body surface in a tomographic surface S, but the precision of reproduction may be degraded with respect to a deep region separated from the body surface.

Therefore, as illustrated in <FIG>, for example, an amount of current passing through a deep region within the body of the measurement object person X is increased by causing an alternating current I1 or the like to flow while sequentially selecting pairs of opposite electrodes <NUM>. The magnetic field information acquisition unit <NUM> can precisely reproduce a deep region separated from the body surface by acquiring a magnetic field generated on the basis of a current distribution.

Also, an alternating current may be input by a combination of pairs of two other arbitrary electrodes <NUM> as well as a pair of electrodes <NUM> adjacent to each other or a pair of opposite electrodes <NUM>.

Also, in the image generation apparatus <NUM> according to the first embodiment, the detection unit <NUM> is in a state in which a plurality of electrodes <NUM> and a plurality of magnetic sensors <NUM> are arranged on the same surface (the surface A-A' (<FIG>)). Thereby, it is possible to acquire a magnetic field generated on the basis of an alternating current flowing between the electrodes <NUM> at a high intensity and improve the precision of a tomographic image generated on the basis of the magnetic field. However, the present invention is not limited to such a form in the image generation apparatus <NUM> according to another embodiment. For example, the detection unit <NUM> may be a form in which a plurality of electrodes <NUM> and a plurality of magnetic sensors <NUM> are arranged on different surfaces. Also, the image generation apparatus <NUM> according to another embodiment may be a form having a base member (an annular housing) <NUM> on which the plurality of electrodes <NUM> are arranged and a base member (a housing) on which magnetic sensors <NUM> are arranged.

Next, an image generation apparatus <NUM> according to the second embodiment will be described.

<FIG> is a diagram illustrating a structure of a detection unit according to a second embodiment.

The image generation apparatus <NUM> according to the first embodiment has been described as a form in which the annularly formed detection unit <NUM> surrounds a standing measurement object person X and acquires a plurality of tomographic images of the measurement object person X while moving in a vertical direction according to an operation of the drive unit <NUM>.

The detection unit <NUM> of the image generation apparatus <NUM> according to the present embodiment is cylindrically formed to generally extend in the vertical direction as illustrated in <FIG>. The overall body of the measurement object person X is included inside the cylindrically formed detection unit <NUM>.

Also, in the detection unit <NUM> according to the present embodiment, the plurality of electrodes <NUM> and a plurality of magnetic sensors <NUM> are arranged in the vertical direction as illustrated in <FIG>. A form in which a plurality of electrodes <NUM> and a plurality of magnetic sensors <NUM> are arranged for each of surfaces A1-A1', A2-A2',. is similar to that of the first embodiment. Thereby, the image generation apparatus <NUM> can simultaneously acquire tomographic images of a plurality of positions of the measurement object person X.

Specifically, the alternating current input unit <NUM> according to the present embodiment can cause an alternating current to flow through all of electrodes <NUM> belonging to the surface A1-A1', electrodes <NUM> belonging to the surface A2-A2',. in parallel.

Also, the magnetic field information acquisition unit <NUM> according to the present embodiment can simultaneously acquire magnetic field information from all of magnetic sensors <NUM> belonging to the surface A1-A1', magnetic sensors <NUM> belonging to the surface A2-A2',. That is, the magnetic field information acquisition unit <NUM> can acquire intensities of magnetic fields at a plurality of positions surrounding another tomographic surface different from one tomographic surface simultaneously with intensities of magnetic fields at a plurality of positions surrounding the one tomographic surface of the measurement object person X.

Thereby, the image generation apparatus <NUM> according to the present embodiment can simultaneously generate tomographic images for tomographic surfaces S of the measurement object person X belonging to the surface A1-A1', A2-A2',. on the basis of magnetic field intensity information acquired via the magnetic sensors <NUM> belonging to the surfaces A1-A1', A2-A2',.

Thereby, it is possible to exclude a means (the drive unit <NUM>) for moving the detection unit <NUM> in the image generation apparatus <NUM> according to the first embodiment and to shorten a required time for acquiring a plurality of tomographic images. That is, deviation occurs among the plurality of acquired tomographic images when the measurement object person X moves during movement of the detection unit <NUM> in the first embodiment, but it is possible to reduce deviation among a plurality of tomographic images and execute diagnosis with higher precision by simultaneously acquiring the plurality of tomographic images as in the second embodiment.

Also, the expression of "simultaneously" used in the above description of the image generation apparatus <NUM> is not necessarily limited to the meaning of "at exactly the same time," and a time difference may be in a range in which deviation among a plurality of acquired tomographic images is allowed.

<FIG> is a diagram illustrating a function of an image generation unit according to a modified example of the second embodiment.

The case in which the above-described image generation apparatuses <NUM> according to the first and second embodiments acquire tomographic surfaces of the measurement object person X belonging to the same surface on the basis of magnetic field intensity information acquired by a plurality of electrodes <NUM> and a plurality of magnetic sensors <NUM> located on the same surface has been described.

However, in this case, as illustrated in <FIG>, an alternating current generated between electrodes <NUM> includes alternating current components I2 and I3 flowing through the other surfaces A2-A2' and A3-A3' in addition to an alternating current component I1 flowing through the surface A1-A1' to which the electrodes <NUM> belong. That is, the alternating current flowing between the electrodes <NUM> actually has a component spread in the vertical direction (the alternating current I2, I3, or the like). If so, information about the other tomographic surfaces (the surfaces A2-A2', A3-A3', etc.) as well as information about the tomographic surface belonging to the surface A1-A1' is mixed in a tomographic image generated on the basis of an intensity of a magnetic field detected by the magnetic sensor <NUM> belonging to the surface A1-A1'. Therefore, according to the alternating current component spread in the vertical direction, the generated tomographic image may include information about the other tomographic surfaces and may be blurred.

Therefore, the magnetic field information acquisition unit <NUM> according to the modified example of the present embodiment acquires a magnetic field generated on the basis of an alternating current flowing between the electrodes <NUM> via the magnetic sensors <NUM> belonging to another adjacent surface in addition to the magnetic sensors <NUM> belonging to the same surface as that of the electrodes <NUM>.

For example, as illustrated in <FIG>, the magnetic field information acquisition unit <NUM> acquires magnetic fields generated on the basis of alternating currents flowing between the electrodes <NUM> belonging to the surface A1-A1' via the magnetic sensors <NUM> belonging to the surface A1-A1' and the magnetic sensors <NUM> belonging to the surfaces A2-A2' and A3-A3'.

Also, the image generation unit <NUM> according to the modified example first generates a first intermediate image on the basis of magnetic field intensity information acquired via the magnetic sensors <NUM> belonging to the surface A1-A1'. Here, the first intermediate image is mainly a tomographic image acquired on the basis of the alternating current component I1, but becomes a blurred image because the alternating current components I2, I3, etc. flowing through the other tomographic surfaces are also included.

Further, the image generation unit <NUM> generates second and third intermediate images on the basis of the magnetic field information acquired via the magnetic sensors <NUM> belonging to the surfaces A2-A2', A3-A3'. Here, the second and third intermediate images are mainly tomographic images acquired on the basis of the current components I2 and I3 spread in the vertical direction.

The image generation unit <NUM> according to the present embodiment performs a process of acquiring differences of the second and third intermediate images from the first intermediate image. Specifically, for example, a process of subtracting the "brightness" of a corresponding pixel in the second and third intermediate images from "brightness" of each pixel of the first intermediate image is performed. The image generation unit <NUM> acquires a final image calculated as described above as a tomographic image representing a tomographic surface of the measurement object person X belonging to the surface A1-A1'.

As described above, the image generation apparatus <NUM> according to the modified example of the second embodiment may generate a tomographic image represented by one tomographic surface by combining the first intermediate image generated on the basis of magnetic fields at a plurality of positions surrounding the one tomographic surface and second, third,. intermediate images generated on the basis of magnetic fields at a plurality of positions surrounding other tomographic surfaces.

Thereby, it is possible to acquire a tomographic image with higher precision because it is possible to exclude information acquired on the basis of alternating current components (the alternating current components I2, I3, etc.) flowing through tomographic surfaces other than a desired tomographic surface.

Also, an example in which the image generation apparatus <NUM> according to the above-described modified example is based on the second embodiment including the cylindrical detection unit <NUM> (see <FIG>) is shown, but the present invention may be applied to the first embodiment, i.e., the image generation apparatus <NUM> having the annular detection unit <NUM> (see <FIG>). In this case, at least a plurality of magnetic sensors <NUM> are assumed to be arranged in the vertical direction in the annular detection unit <NUM>.

Also, the case in which the image generation apparatus <NUM> according to the above-described modified example performs a process of subtracting a tomographic image by subtracting the "brightness" for each pixel after the first to third intermediate images are generated has been described, but the first to third intermediate images described here may not be actually generated and displayed. That is, one tomographic image may be generated after pre-subtracting an intensity of a magnetic field which is an observation value of a basis corresponding to the brightness for each pixel of the first to third intermediate images.

Also, the case in which the image generation apparatus <NUM> according to each embodiment described above acquires a tomographic image according to an alternating current of a predetermined fixed frequency (several kHz to several MHz) has been described, but another embodiment is not limited to this form. For example, the image generation apparatus <NUM> according to another embodiment may acquire a tomographic image on the basis of alternating currents of a plurality of different frequencies.

Specifically, the alternating current input unit <NUM> according to another embodiment outputs a frequency designation signal for designating a frequency of an alternating current to the alternating current drive circuit 201A. The alternating current drive circuit 201A outputs an alternating current of a frequency according to the received frequency designation signal.

Also, in this case, the image generation apparatus <NUM> generates a tomographic image for each frequency of an alternating current output from the alternating current drive circuit 201A and acquires a conductivity distribution of the tomographic surface on the basis of frequency characteristics for each pixel constituting a plurality of obtained tomographic images.

For example, the alternating current input unit <NUM> first selects one frequency when the processing flow illustrated in <FIG> starts. Next, the CPU <NUM> acquires a tomographic image by executing processes of steps S10 to S14. Thereafter, the alternating current input unit <NUM> switches the alternating current to another frequency. As described above, the CPU <NUM> iterates the processes of steps S <NUM> to S <NUM> while switching a frequency of the alternating current. The image generation unit <NUM> generates a plurality of tomographic images for each different frequency on the basis of an intensity of a magnetic field generated according to each frequency.

Also, in this case, the CPU <NUM> further exhibits a function serving as a conductivity calculation unit which calculates a conductivity distribution of a tomographic surface of the measurement object person X on the basis of the plurality of tomographic images generated for each different frequency.

Specifically, the conductivity calculation unit extracts conductivities of positions corresponding to one identical pixel among a plurality of tomographic images generated for each frequency and acquires a frequency characteristic of the conductivity for each pixel. The conductivity calculation unit calculates real components (resistance and conductance) and imaginary components (reactance and susceptance) of the conductivity corresponding to the pixel on the basis of frequency characteristics of the conductivity. Thereby, it is possible to acquire a more detailed tomographic image because it is possible to divide the conductivity distribution in the tomographic surface into a real component and an imaginary component and grasp the real and imaginary components.

<FIG> is a diagram illustrating characteristics of an impedance change according to a living body.

As in <FIG>, the case in which a living body (a "fist" in the present experiment) is inserted between two electrodes which are separated in a non-contact type is considered.

The graph illustrated in <FIG> is for the comparison of impedance between two electrodes when the living body is present between the two electrodes and when the living body is not present between the two electrodes. A difference between the presence and absence of the living body is clearly shown when the frequency used in measurement is about several kHz to several MHz according to <FIG> <NUM>(b). Therefore, it is preferable that a frequency used in the acquisition of a tomographic image of the living body be several kHz to several MHz. Also, because impedance is significantly high and a current flowing through the living body is weak in a region of less than a frequency of <NUM>, highly precise measurement may be difficult. Therefore, it is preferable that a frequency to be used in tomographic image generation of the living body be about <NUM>. In this case, it is possible to detect an intensity of a magnetic field about <NUM> with high precision using an "optical pumping atomic magnetic sensor" as the magnetic sensor <NUM>.

The measurement object person X from which a tomographic image is acquired is arranged inside the annularly formed detection unit <NUM>, for example, as illustrated in <FIG>, in the image generation apparatus <NUM> according to each embodiment described above, but the image generation apparatus <NUM> according to another embodiment is not limited to such a form.

For example, as the modified example of the first embodiment, the magnetic field information acquisition unit <NUM> may acquire intensities of magnetic fields at a plurality of positions surrounding the periphery of a specific tomographic surface of the measurement object person X. More specifically, the detection unit <NUM> according to the modified example is attached to a distal end of an endoscope, a catheter, or the like in, for example, a small size in the state illustrated in <FIG>. The detection unit <NUM> is inserted inside a body of the measurement object person X along with the endoscope. In this case, the image generation apparatus <NUM> acquires a tomographic image of a specific tomographic surface via the detection unit <NUM> surrounding the periphery of the specific tomographic surface within the body into which the detection unit <NUM> is inserted.

Here, although only alternating currents which travel around the inside of the base member <NUM> among alternating currents flowing between adjacent electrodes <NUM> are referred to as alternating currents I1 to <NUM>, for example, in <FIG>, there is also an alternating current which actually travels around the outside of the base member <NUM>. Therefore, an alternating current which flows between electrodes <NUM> also changes according to a conductivity distribution of a tomographic surface arranged outside the base member <NUM>. Therefore, the image generation unit <NUM> can acquire a tomographic image of a tomographic surface surrounding the circumference of the detection unit <NUM> by executing a process of reconfiguring an image using an intensity of a magnetic field detected from each of the magnetic sensors <NUM>.

According to the image generation apparatus <NUM> according to the above-described modified example, it is possible to precisely evaluate a local tomographic surface within the body of the measurement object person X because the application of an alternating current and the measurement of an intensity of a magnetic field are performed in a non-contact type from the inside of the body of the measurement object person X.

Next, a conductivity acquisition apparatus obtained by further simplifying the first embodiment and the above-described modified examples will be described.

<FIG> is a diagram illustrating a function of a conductivity acquisition apparatus according to a modified example of the first embodiment.

The conductivity acquisition apparatus 1A according to the present modified example includes the detection unit <NUM> as illustrated in <FIG>. In an example, specifically, as illustrated in <FIG>, the detection unit <NUM> includes a pair of electrodes <NUM> attached in the vicinity of both ends of a base member (a cylindrical housing) 101A and a magnetic sensor <NUM> arranged between the pair of electrodes <NUM>.

The pair of electrodes <NUM> are annularly formed along the overall circumference of the base member 101A in a circumferential direction. By forming the pair of electrodes <NUM> as described above, an alternating current I flowing between the pair of electrodes <NUM> travels around paths spread in an arc in the air in all orientations of a centrifugal direction of the base member 101A (see <FIG>).

The pair of electrodes <NUM> are connected to the alternating current input unit <NUM> and the alternating current drive circuit 201A (not illustrated in <FIG>). Also, the magnetic sensor <NUM> is connected to the magnetic field information acquisition unit <NUM> (not illustrated in <FIG>). Also, because the alternating current input unit <NUM>, the alternating current drive circuit 201A, and the magnetic field information acquisition unit <NUM> have the same function as those of each embodiment described above, description thereof will be omitted. Here, it is preferable for the alternating current input unit <NUM> to have a function of outputting a frequency designation signal for designating a frequency of an alternating current.

Also, the conductivity acquisition apparatus 1A according to the present modified example includes a conductivity acquisition unit (not illustrated) which acquires conductivity of the measurement object person X around a region in which the magnetic sensor <NUM> is arranged on the basis of an intensity of a magnetic field acquired by the magnetic field information acquisition unit <NUM> in place of the image generation unit <NUM>.

<FIG> illustrates examples in which the base member 101A is inserted into a body inside X' of the measurement object person X. Here, as examples, <FIG> illustrates the case in which the conductivity of the body inside X' surrounding the detection unit <NUM> is high and <FIG> illustrates the case in which the conductivity of the body inside X' surrounding the detection unit <NUM> is low.

Because an alternating current I which flows through the body inside X' increases when the conductivity of the body inside X' is high, an alternating current I flowing between a pair of electrodes <NUM> travels around a path widened in a radial direction with respect to an extending axis of the base member 101A as illustrated in <FIG>. Thereby, an intensity of a magnetic field detected by the magnetic sensor <NUM> is relatively decreased because a magnetic field H generated by the alternating current I is generally far away from the magnetic sensor <NUM>. On the other hand, because an alternating current I which flows through the body inside X' decreases when the conductivity of the body inside X' is low, an alternating current I flowing between a pair of electrodes <NUM> travels around a path narrowed in a radial direction with respect to an extending axis of the base member 101A as illustrated in <FIG>. Thereby, an intensity of a magnetic field detected by the magnetic sensor <NUM> is relatively increased because a magnetic field H generated by the alternating current I is generally close to the magnetic sensor <NUM>.

Thereby, the magnetic field information acquisition unit <NUM> acquires an intensity of a magnetic field according to the conductivity of the body inside X'. Also, the magnetic field information acquisition unit <NUM> may detect a plurality of intensities of magnetic fields for each different frequency on the basis of frequency control of the alternating current input unit <NUM>.

Also, the above-described conductivity acquisition unit calculates conductivity around the base member 101A on the basis of an intensity of a magnetic field acquired by the magnetic field information acquisition unit <NUM>. In this case, the above-described conductivity acquisition unit calculates conductivity σ according to the acquired intensity of the magnetic field using, for example, Equation (<NUM>), Equation (<NUM>), a predefined length l, a cross-sectional area s, or the like. Also, the above-described conductivity acquisition unit may calculate a real component and an imaginary component of the conductivity σ on the basis of a frequency characteristic of the acquired intensity of the magnetic field.

Also, a medical device such as an endoscope for observing an inside of a human body has been conventionally developed. With this medical device, it is possible to observe a video of the inside by embedding an optical system into a main body and inserting a distal end into the body. However, because the above-described endoscope or the like is operated by optical observation, it is impossible to grasp a characteristic that an optical change (i.e., a change in appearance) is not shown in an observation surface.

On the other hand, according to the conductivity acquisition apparatus 1A according to the present modified example, a state of the body inside X' around the detection unit <NUM> is evaluated on the basis of conductivity at its position. Thereby, the operator can also grasp a symptom not visually apparent in the observation surface according to a difference of conductivity at its position. For example, even when a cancerous cell is located at a position which is not visually apparent, the conductivity acquisition apparatus 1A according to the present embodiment can discover the cancerous cell according to a conductivity difference between the cancerous cell and a normal cell.

Also, because the conductivity acquisition apparatus 1A according to the present modified example can acquire conductivity in a state in which all of the detection unit <NUM> (the electrodes <NUM> and the magnetic sensor <NUM>) is arranged at a position separated from an inner wall surface within the body, it is possible to easily acquire conductivity within the body and further contribute to the reduction of a burden on the measurement object person.

Also, because the detection unit <NUM> according to the present modified example is configured to have only a pair of electrodes <NUM> and one magnetic sensor <NUM>, the configuration of the detection unit <NUM> is simplified more than the image generation apparatus <NUM> according to each embodiment described above and the size reduction and the cost reduction of the apparatus can be promoted.

Also, the conductivity acquisition apparatus 1A according to the present modified example is not limited to a state in which the conductivity acquisition apparatus 1A is attached to a distal end of the endoscope or the catheter and inserted into a body of the measurement object person X (<FIG>). Alternatively, the conductivity acquisition apparatus 1A may cause the detection unit <NUM> to be in the vicinity of a body surface of the measurement object person X and acquire conductivity in the vicinity of the body surface. At least some of the electrodes <NUM> and the magnetic sensor <NUM> are arranged in non-direct contact with the body surface in the vicinity of the body surface. According to an unclaimed example, at least some of the electrodes <NUM> and the magnetic sensor <NUM> are at least temporarily arranged in direct contact with the body surface.

Also, the conductivity acquisition apparatus 1A is not limited to an annularly formed structure to surround the overall circumference of the base member (the cylindrical housing) 101A in the circumferential direction. Alternatively, the conductivity acquisition apparatus 1A may be formed to surround, for example, only a part of the base member 101A in the circumferential direction (to partially extend in the circumferential direction of the base member 101A). Also, the electrodes <NUM> are not limited to an annular shape in the conductivity acquisition apparatus 1A. Alternatively, the electrodes <NUM> may be formed in another shape such as plate shape. In this case, orientations in which plate surfaces of the two electrodes <NUM> are directed are arranged to be toward an orientation of any of a direction vertical to an extending axis direction of the base member 101A, i.e., the circumferential direction of the base member 101A (and the same orientation). If so, an alternating current particularly strong in a range of a part of the base member 101A in the circumferential direction is emitted in the air. Thereby, the operator can acquire a conductivity distribution of only a desired partial region within the body inside X' surrounding the circumference of the base member 101A by manipulating an orientation of the circumferential direction of the base member 101A to a desired orientation.

Likewise, for the conductivity acquisition apparatus 1A, a direction, a density, or the like of an alternating current may be adjusted by attaching a shield electrode or a guard electrode in the vicinity of a region in which the electrodes <NUM> are arranged.

Also, in each modified example described above, the "position separated from the measurement object (the measurement object person X)" is assumed to include the meanings of a "position separated from the inner wall surface within the body of the measurement object person X," a "position having a gap from the inner wall surface within the body of the measurement object person X," and a "position arranged in non-direct contact with respect to an inner surface within the body of the measurement object person X.

Also, in the embodiments illustrated in <FIG>, <FIG>, etc., the image generation apparatus <NUM> includes a plurality of electrodes <NUM>; a plurality of magnetic sensors (a plurality of sensor cells and a plurality of sensor heads) <NUM>; and a main body unit (a controller) <NUM> configured to provide a tomographic image of a measurement object on the basis of an intensity of a magnetic field generated by an alternating current supplied via the electrodes <NUM>, wherein the controller <NUM> is configured to acquire intensities of magnetic fields via the magnetic sensors <NUM> in a state in which the electrodes and the magnetic sensors are arranged substantially in non-direct contact with the surface of the measurement object. In another embodiment, the main body unit <NUM> can be configured to acquire an intensity of a magnetic field via the magnetic sensor <NUM> in a state in which at least some of the plurality of electrodes <NUM> and the plurality of magnetic sensors (the plurality of sensor cells and the plurality of sensor heads) are substantially in contact with the surface of the measurement object. In any form, it is possible to implement high flexibility of an arrangement of the electrodes <NUM> and the magnetic sensors, high operability, simplification of a configuration, etc. Therefore, the image generation apparatus <NUM> has advantages of the reduction of a burden on the operator or the measurement object person, the reduction of an apparatus cost or an installation space, etc..

As illustrated in <FIG>, in an embodiment, the detection unit <NUM> can include a base member <NUM> configured to be freely modified. In an example, at least some of a plurality of electrodes and a plurality of magnetic sensors (a plurality of sensor cells and a plurality of sensor heads) are provided in the base member <NUM> so that at least some of the plurality of electrodes and the plurality of magnetic sensors (see <FIG>, etc.) move according to motion of the base member <NUM>. The base member <NUM> can be configured to have at least one joint and at least two beams. Alternatively, the base member <NUM> can be configured to have a flexible structure having appropriate flexibility and appropriate rigidity. Alternatively, the base member <NUM> can be configured to have at least one open section and/or configured to be able to be assembled and disassembled. According to modification of the base member <NUM>, it is possible to adjust the arrangement of the electrodes and the magnetic sensors according to the modification of the base member <NUM>. The adjustment of the arrangement of the electrodes and the magnetic sensors is advantageous for the improvement of measurement precision.

Also, in an embodiment, a plurality of magnetic sensors can be arranged so that at least one of the magnetic sensors independently and freely changes a distance from the measurement object. For example, in a state in which a distance (a first distance) from the measurement object in one magnetic sensor (a sensor cell and a sensor head) is uniformly maintained, it is possible to change a distance (a second distance) from the measurement object in at least one other magnetic sensor. As a result, the first distance and the second distance can be substantially the same value. When distances of the plurality of magnetic sensors from the body surface are substantially the same, this is advantageous for the improvement of the measurement precision.

As illustrated in <FIG>, in an embodiment, the image generation apparatus <NUM> includes a position information sensor <NUM> capable of detecting at least one of (a) a position for a reference point, (b) a distance from the measurement object, and (c) a relative positional relationship with the measurement object, with respect to at least one of the plurality of sensor cells. Alternatively, the position information sensor <NUM> can be configured to be able to detect at least some of a position, a posture, and a contour (a surface shape) of the measurement object with respect to at least a part of the detection unit <NUM>. Alternatively, the position information sensor <NUM> can be configured to be able to detect a relatively positional relationship between the detection unit <NUM> and the measurement object. In the main body unit (the controller) <NUM>, a position information acquisition unit <NUM> can acquire at least one of (a) a position for a reference point (coordinates for an origin), (b) a distance from the measurement object, and (c) a relative positional relationship with the measurement object, with respect to at least one of a plurality of magnetic sensors (a plurality of sensor cells and a plurality of sensor heads) on the basis of an output signal from the position information sensor <NUM>. On the basis of this position information, control related to at least one of the electrodes and the magnetic sensors can be adjusted. For example, the main body unit <NUM> can adjust supply control of the alternating current on the basis of an output signal from the position information sensor <NUM>. Alternatively, the main body unit <NUM> can correct calculation control based on an output signal from the magnetic sensor on the basis of the output signal from the position information sensor <NUM>. The main body unit <NUM> can calculate an intensity of a magnetic field on the basis of an output from the position information sensor <NUM> and outputs from the plurality of magnetic sensors. This control is advantageous for the improvement of measurement precision.

Also, a process may be executed by recording a program for implementing a function of the CPU <NUM> in each embodiment described above on a computer-readable recording medium and causing a computer system to read and execute the program recorded on the recording medium. Also, the "computer system" used here is assumed to include an operating system (OS) and hardware such as peripheral devices. In addition, the "computer-readable recording medium" refers to a storage device including a flexible disk, a magneto-optical disc, a read only memory (ROM), or a portable medium such as a compact disc (CD)-ROM, and a hard disk embedded in the computer system. Furthermore, the "computer-readable recording medium" is assumed to include a medium that holds a program for a constant period of time, such as a volatile memory (a random access memory (RAM)) inside a computer system serving as a server or a client when the program is transmitted via a network such as the Internet or a communication circuit such as a telephone circuit.

Also, the above-described program may be transmitted from a computer system storing the program in a storage device or the like via a transmission medium or transmitted to another computer system by transmission waves in a transmission medium. Here, the "transmission medium" for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) like the Internet or a communication circuit (communication line) like a telephone circuit. Also, the above-described program may be a program for implementing some of the above-described functions. Further, the above-described program may be a program, i.e., a so-called differential file (differential program), capable of implementing the above-described function in combination with a program already recorded on the computer system.

Claim 1:
A system for generating an image of a measurement subject of a living body or acquiring a conductivity of a measurement subject of a living body, the system comprising:
either a first set of a plurality of electrodes (<NUM>) and a plurality of sensor cells (<NUM>) or a second set of a pair of electrodes (<NUM>) and a sensor cell (<NUM>),
the system further comprising
a base member (<NUM>) on which two electrodes (<NUM>) of the plurality of electrodes and a sensor cell (<NUM>) of the plurality of sensor cells (<NUM>) of the first set or the pair of electrodes (<NUM>) and the sensor cell (<NUM>) of the second set are provided such that the sensor cell (<NUM>) is arranged between the two electrodes (<NUM>) or between the pair of electrodes (<NUM>);
an alternating current input unit (<NUM>) configured to input an alternating current of a high frequency in a range from several kHz to <NUM> to a measurement subject (X, X') of a living body via the two electrodes (<NUM>) of the first set or via the pair of electrodes (<NUM>) of the second set such that the alternating current flowing between the two electrodes (<NUM>) or the pair of electrodes (<NUM>) travels through air or the measurement subject (X, X') without directly attaching the electrodes (<NUM>) to a body surface of the measurement subject (X, X');
a magnetic field information acquisition unit (<NUM>) configured to acquire an intensity of a magnetic field generated on the basis of the alternating current input by the alternating current input unit (<NUM>) via the sensor cell (<NUM>) arranged at a position separated from the measurement subject (X, X'); and
an image generation unit (<NUM>) or a conductivity acquisition unit, the image generation unit (<NUM>) being configured to generate a tomographic image of the measurement subject (X, X') on the basis of the intensity of the magnetic field acquired by the magnetic field information acquisition unit (<NUM>), the conductivity acquisition unit being configured to acquire a conductivity of the measurement subject (X, X') on the basis of the intensity of the magnetic field acquired by the magnetic field information acquisition unit (<NUM>).