JP2016159090A - Device and method for detecting in vivo signal source position - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for detecting an in vivo signal source position capable of accurately detecting a position of a signal source in a living body by using the less number of electrodes.SOLUTION: The device for detecting an in vivo signal source position comprises: m electrodes to be disposed on a surface of a living body; switching means 30 that connects n external resistors between each of the electrodes and a ground potential; measurement means 40 that measures m×n output voltages V(i is an integer between 1 to m×n) generated in each electrode when the external resistors are connected to the electrodes; approximation means 50 that acquires, from time series data of each output voltage V, approximation waveforms approximating time changes of each of the output voltages V; calculation means 60 that uses the approximation waveforms to calculate correction values Vc(i is an integer between 1 to m×n) of each of the output voltages Vat the same measurement times; and detection means 70 that detects the position of the signal source in the living body on the basis of each of the correction values Vc.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an in-vivo signal source position detecting device and a in-vivo signal source position detecting method for detecting the position of a signal source in a living body.

  In general, an electrical activity in a living body such as an electrocardiogram is measured by attaching an electrode to the surface of the living body and measuring a voltage generated at the electrode.

  For example, Patent Document 1 discloses a method of obtaining a potential distribution in a cross section of a living body passing through the plane by measuring a surface potential at each point on an intersection line (closed curve) between the living body and a predetermined plane. ing.

Japanese Patent Laid-Open No. 11-113867 Japanese Patent No. 5178909

  However, in the method disclosed in Patent Document 1, it is necessary to place and measure a large number of electrodes on a living body without any gaps, so that the burden on the living body is large. If the number of electrodes is small, the burden on the living body is reduced, but only a potential distribution with low resolution can be obtained.

  In order to solve such a problem, the applicant of the present application has proposed a method that can detect the position of a signal source in a living body using a small number of electrodes, as described in Patent Document 2 and PCT / JP2014 / 005732. It is disclosed in the specification. The method disclosed here switches a plurality of resistors between an electrode arranged on the surface of a living body and a ground potential and connects them, and measures the voltage generated in the electrodes when connected to each resistor. It detects the position of the source.

  However, in the above detection method, when measuring the voltage generated at the electrode when connected to each resistor, it takes time to switch the resistance, so that a time difference occurs in the voltage measurement time. In this case, if the voltage change from the in-vivo signal source is large, there is a problem that an error occurs in the position detection of the in-vivo signal source.

  The present invention has been made in view of the above problems, and its main purpose is to use a small number of electrodes to accurately detect the position of a signal source in a living body, Another object of the present invention is to provide an in-vivo signal source position detection method.

An in-vivo signal source position detection apparatus according to the present invention is an in-vivo signal source position detection apparatus that detects the position of a signal source in a living body based on a voltage generated at an electrode arranged on the surface of the living body,
M electrodes arranged on the surface of the living body,
Connection means for connecting n external resistors in parallel between each electrode and the ground potential;
M × n output voltages V _i (i is an integer of 1 to m × n) generated in each electrode when each external resistor is connected in parallel to each electrode by the connecting means in a state where each electrode is arranged on the surface of the living body. Measuring means for measuring)
The measurement of the m × n output voltage V _i as 1 cycle, repeatedly performed, from the time-series measurement data of each output voltage V _i, approximating means for obtaining an approximation waveform that approximates the time variation of the output voltage V _i When,
In each cycle, for each output voltage V _i having a time difference at the measurement time, using the approximate waveform acquired by the approximating means, the correction value Vc _i of each output voltage V _{i at} the same measurement time (i is 1 to 1). m × n integer) calculating means,
For each cycle, based on the correction value Vc _i calculated, characterized by comprising a detecting means for detecting a position of a signal source in vivo.

An in-vivo signal source position detection method according to the present invention is an in-vivo signal source position detection method for detecting the position of a signal source in a living body based on a voltage generated at an electrode arranged on the surface of the living body,
An arrangement step of arranging m electrodes on the surface of the living body;
A connection step of connecting n external resistors in parallel between each electrode and the ground potential;
With each electrode placed on the surface of the living body, m × n output voltages V _i (i is an integer of 1 to m × n) generated at each electrode when each external resistor is connected in parallel to each electrode are measured. Measuring process;
The measurement of the m × n output voltage V _i as 1 cycle, repeatedly performed, from the time-series measurement data of each output voltage V _i, obtaining step of obtaining an approximation waveform that approximates the time variation of the output voltage V _i When,
In each cycle, for each output voltage V _i having a time difference at the measurement time, using an approximate waveform, a correction value Vc _i of each output voltage V _{i at} the same measurement time (i is an integer of 1 to m × n) ) To calculate
For each cycle, based on the correcting value Vc _i calculated, characterized in that it comprises a detection step of detecting a position of a signal source in vivo.

  According to the present invention, it is possible to provide an in-vivo signal source position detecting apparatus and in-vivo signal source position detecting method capable of accurately detecting the position of a signal source in a living body using a small number of electrodes. it can.

It is the block diagram which showed the outline | summary of the method of detecting the position of the signal source in a biological body. It is the figure which illustrated the method of detecting the position of the signal source in a biological body. It is the table | surface which showed the switching step of the connection state of each electrode and external resistance. It is the figure which showed the method of calculating | requiring the position coordinate of a signal source. (A), (b) is an image figure of the result of having measured the potential of the heart using the in-vivo signal source position detection method. It is the figure which showed the structure of the in-vivo signal source position detection apparatus in one Embodiment of this invention. It is the table | surface which showed the switching step of the connection state of each electrode and external resistance. It is a figure explaining the method of correct | amending the output voltage of each electrode to the data in the same measurement time. It is a figure explaining the method of correct | amending the output voltage of each electrode to the data in the same measurement time. It is the figure explaining the other method of correct | amending the output voltage of each electrode to the data in the same measurement time. It is the figure explaining the other method of correct | amending the output voltage of each electrode to the data in the same measurement time. It is the figure which showed the structure of the in-vivo signal source position detection apparatus in other embodiment of this invention.

  Prior to describing the present invention, an outline of a method for detecting the position of a signal source in a living body disclosed by the applicant of the present application will be described with reference to FIG.

  As shown in FIG. 1, a measurement electrode 21 and a ground electrode 20 are disposed on the surface of the living body 10. The voltage generated at the measurement electrode 21 is amplified by the amplifier 40 and measured as the output voltage Vout. Impedance switching means 30 is disposed between the measurement electrode 21 and the ground electrode 20. Here, a plurality of resistance elements Z1 to Zn are arranged in parallel, and one of the resistance elements Z1 to Zn is selected by the switch SW. Then, when the selected resistive element is connected in parallel to the measurement electrode 21, the voltage Vout generated at the measurement electrode 21 is measured.

  In this way, n pieces of measurement data at time t can be obtained by switching the n pieces of resistance elements Z1 to Zn with the switch SW. Note that the number of measurement electrodes 21 is not limited to one and may be plural. In that case, m × n pieces of measurement data can be obtained by a combination of m pieces of measurement electrodes 21 and n pieces of resistance elements. Thereby, the number of measurement data necessary for detecting the position of the signal source in the living body 10 can be obtained using relatively few measurement electrodes.

  The position of the signal source in the living body 10 can be detected by, for example, the following method using measurement data at time t obtained by switching the resistance elements Z1 to Zn.

  A tomographic image of the living body 10 including the position where the measurement electrode 21 is disposed is acquired, the tomographic image is divided into a lattice shape, and an admittance for the corresponding tissue is disposed around each lattice point. A network including the switched impedance is generated. The position of the signal source in the living body 10 can be obtained under the condition that the signal source is arranged between any grid point of the circuit network and the ground. Furthermore, the time change of the signal source in the living body 10 can be detected by using the measurement data measured in time series.

  2 to 5 are diagrams illustrating a method of detecting the position of a signal source in a living body disclosed by the applicant of the present application in the specification of PCT / JP2014 / 005732.

  As shown in FIG. 2, three electrodes 21, 22, and 23 are arranged on the surface of the living body 10. Further, a first external resistor and a second external resistor that can be switched with each other are connected in parallel between the electrodes 21, 22, 23 and the ground electrode 20. Here, the resistance value of the first external resistor is infinite, and the resistance value of the second external resistor is Rg. Thereby, between each electrode 21,22,23 and the ground electrode 20, it switches by the changeover switch SW between the case where the external resistance is not connected and the case where the external resistance Rg is connected. Here, the ground electrode 20 is disposed on the surface of the living body 10 and is set to the ground potential. However, the ground electrode 20 is not necessarily disposed on the surface of the living body 10.

A voltage from the signal source Vs in the living body 10 is generated at each of the electrodes 21, 22, and 23 disposed on the surface of the living body 10, and the voltage is amplified by the amplifier 40 to output an output voltage Vout. Switches S ₁ , S ₂ , S ₃ are respectively arranged between the electrodes 21, 22, 23 and the amplifier 40, and the respective switches S ₁ , S ₂ , S ₃ are sequentially brought into conduction, whereby each electrode The voltages generated at 21, 22, and 23 are measured as the output voltage Vout.

As shown in FIG. 3, by switching the switch SW and the switches S ₁ , S ₂ , S ₃ in Step 1 to Step 6, respectively, between the electrodes 21, 22, 23 and the ground potential, The first resistors V ₁ , V ₂ , V ₃ generated at the electrodes 21, 22, 23 when the external resistor is not connected _, and the external resistor Rg between the electrodes 21, 22, 23 and the ground potential Are connected, the second voltages V ′ ₁ , V ′ ₂ , V ′ ₃ generated at the electrodes 21, 22, 23 are measured. In FIG. 3, the electrodes 21, 22, and 23 are indicated as channels ch ₁ , ch ₂ , and ch ₃ , respectively.

Although detailed description is omitted, the distances L ₁ , L ₂ , and L ₃ between the signal source Vs in the living body 10 and the electrodes 21, 22, and 23 are the first voltage and the second voltage, respectively. Using the ratios V ₁ / V ′ ₁ , V ₂ / V ′ ₂ , V ₃ / V ′ ₃ , they are represented by the formulas (1), (2), and (3).

Here, β is a constant determined by the conductivity of the living body 10 or the like. R _b1 , R _b2 , and R _b3 represent resistance values of internal resistances between the signal source Vs in the living body 10 and the electrodes 21, 22, and 23, respectively.

As shown in FIGS. 4A and 4B, the signal source Vs includes spheres Q ₁ , Q ₂ , and Q ₃ with radii L ₁ , L ₂ , and L ₃ centered on the electrodes 21, 22, and 23. It is considered to exist at the intersection. Accordingly, the three-dimensional position coordinates (x, y, z) of the signal source Vs are obtained by solving the equations (4), (5), (6) of the three spheres Q ₁ , Q ₂ , Q _3. be able to. Here, the position coordinates of the electrodes 21, 22, _23, and the _{(a 1, b 1, c} 1), (a 2, b 2, c 2), (a 3, b 3, c 3).

In this way, an external resistor is connected in parallel between the three electrodes 21, 22, and 23 arranged on the surface of the living body 10 and the ground potential, and the connection state is switched to be generated in each electrode 21, 22, 23. By measuring the voltage ratio V _i / V ′ _i (i = 1, 2, 3), the three-dimensional position of the signal source Vs in the living body 10 can be detected. Thereby, the three-dimensional position of the signal source Vs in the living body can be accurately detected using a small number of electrodes.

In addition, by repeating the measurement of the voltage ratio V _i / V ′ _i (i = 1, 2, 3) as one cycle, the signal source Vs in the living body can be obtained from the time-series measurement data of the voltage ratio in each cycle. The movement trajectory of the three-dimensional position can be detected in real time.

FIGS. 5A and 5B are image diagrams of the results of measuring the cardiac potential using the above method. FIG. 5A shows the voltage waveform (electrocardiogram) of the signal source measured at each electrode. Further, FIG. 5B shows the movement trajectory of the three-dimensional position of the signal source calculated based on the voltage ratio V _i / V ′ _i (i = 1, 2, 3) at each electrode by a broken line. Is. In the movement trajectory shown by the broken line in FIG. 5B, the points P ₁ , P ₂ , P ₃ , R, S, and T are respectively the voltage waveforms P ₁ , P ₂ , and P shown in FIG. The three-dimensional positions of the signal sources corresponding to P ₃ , R, S, and T are shown. As shown in FIG. 5B, it is possible to detect in real time how the signal source in the electrical activity of the heart is moving from the atria to the ventricles.

By the way, in the above method, the changeover switch SW and the switches S1, S2, and S3 are switched, and the first voltages V ₁ , V ₂ , V ₃ , and the second voltage V ′ at the electrodes 21, 22, and 23 are switched. ₁ , V ′ ₂ and V ′ ₃ are measured sequentially. Accordingly, if the potential of the signal source Vs changes within these switching times, an error may occur in the position detection of the signal source Vs. For example, in the electrocardiogram shown in FIG. 5A, when the potential of the signal source Vs changes abruptly like a QRS wave, it is difficult to accurately detect the position of the signal source Vs where the QRS wave is generated. .

  The present invention provides an in-vivo signal source position detection device capable of accurately detecting the position of a signal source in a living body, even when a time difference occurs in the measurement time of an output voltage generated in an electrode when connected to each resistor, And an in-vivo signal source position detection method.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the following embodiment. Moreover, it can change suitably in the range which does not deviate from the range which has the effect of this invention. In the following description, unless otherwise specified, “electrode” refers to a member attached to the surface of a living body, “potential” refers to an electrical level, and “voltage” refers to a measured electrical level.

  FIG. 6 is a diagram schematically showing the configuration of the in-vivo signal source position detection apparatus in one embodiment of the present invention.

  As shown in FIG. 6, the in-vivo signal source position detection apparatus according to the present embodiment includes three electrodes 21, 22, 23 arranged on the surface of the living body 10, and each of the electrodes 21, 22, 23 and the ground electrode 20. A switching means (connecting means) 30 for connecting in parallel the first external resistance and the second external resistance that can be switched to each other is provided. Here, the resistance value of the first external resistor is infinite, and the resistance value of the second external resistor is Rg. Thereby, between each electrode 21,22,23 and the ground electrode 20, it switches by the changeover switch SW between the case where the external resistance is not connected and the case where the external resistance Rg is connected. Here, the ground electrode 20 is disposed on the surface of the living body 10 and is set to the ground potential. However, the ground electrode 20 is not necessarily disposed on the surface of the living body 10.

A voltage from the signal source Vs in the living body 10 is generated at each of the electrodes 21, 22, and 23 disposed on the surface of the living body 10, and the voltage is amplified by an amplifier (measuring means) 40 to output an output voltage Vout. Is done. Switches S ₁ , S ₂ , S ₃ are respectively arranged between the electrodes 21, 22, 23 and the amplifier 40, and the respective switches S ₁ , S ₂ , S ₃ are sequentially brought into conduction, whereby each electrode The voltages generated at 21, 22, and 23 are measured as the output voltage Vout.

  FIG. 7 is a table showing the step of switching the connection state between the electrodes 21, 22, 23 and the external resistor.

As shown in FIG. 7, by switching the switch SW and the switches S ₁ , S ₂ , S ₃ in Step 1 to Step 6, respectively, between each electrode 21, 22, 23 and the ground potential, The first output voltages V ₁ , V ₂ , V ₃ generated at the electrodes 21, 22, 23 when the external resistance is not connected, and the external resistance between the electrodes 21, 22, 23 and the ground potential Second output voltages V ′ ₁ , V ′ ₂ , V ′ ₃ generated at the electrodes 21, 22, 23 when Rg is connected are measured. In FIG. 7, the electrodes 21, 22, and 23 are indicated as channels ch ₁ , ch ₂ , and ch ₃ , respectively.

FIG. 7 shows the switching time at each step. Although the switching time is determined by the switching characteristics of the switching means 40, 0.5 ms is illustrated here. In this case, the measurement times of the voltages V ₁ , V ₂ , V ₃ and V ′ ₁ , V ′ ₂ , V ′ ₃ obtained when external resistors are connected to the electrodes 21, 22, 23 are 0, respectively. There is a time difference of 5 ms. That is, the time of one cycle for obtaining the measurement data in steps 1 to 6 is 3 ms (333 Hz).

  As described above, in order to prevent an error from occurring in the position detection of the signal source Vs even when a time difference occurs in the measurement time of the output voltage generated in each of the electrodes 21, 22, and 23 when connected to each resistor. Each output voltage needs to be corrected to data at the same measurement time.

  FIGS. 8 and 9 are diagrams illustrating a method of correcting output voltages generated at the electrodes 21, 22, and 23 when connected to the resistors into data at the same measurement time.

FIG. 8 shows the measurement data of the first output voltages V ₁ , V ₂ , V ₃ generated at the electrodes 21, 22, 23 (channels ch ₁ , ch ₂ , ch ₃ ) when no external resistance is connected. Is shown. In each channel ch ₁ , ch ₂ , and ch ₃ , _three representative black dots indicate time-series measurement data obtained by three cycles of measurement. Note that measurement data of the second output voltages V ′ ₁ , V ′ ₂ , and V ′ ₃ generated in the channels ch ₁ , ch ₂ , and ch ₃ are omitted.

As shown in FIG. 8, the measurement data obtained in the channels ch ₁ , ch ₂ , and ch ₃ in one cycle of measurement are V ₁ (t), V ₂ (t + Δt ₂ ), and V ₃ (t + Δt ₃ ). expressed. Here, Δt ₂ represents the measurement time difference between channels ch ₁ and ch _2, and Δt ₃ represents the measurement time difference between channels ch ₁ and ch ₃ .

9, in the channel ch _3, time-series measurement data of V _3, a diagram depicting a fitting curve (approximate waveform) C approximating the time variation of V _3. As shown in FIG. 9, by using this fitting curve C, the measurement data V of the channel ch _{3 at} the same measurement time t as the measurement data V ₁ (t) of the channel ch ₁ corresponding to the switching time (Δt ₃ ). ₃ (t + Δt ₃ ) correction value Vc ₃ (t) (white circle point in the figure) can be obtained.

In a similar manner, for the measurement data _V 2 channels _{ch 2 (t + Δt 2)} , using the fitting curve obtained from the time-series measurement data of _{V 2,} the correction value Vc ₂ in accordance with the switching time (Delta] t ₂₎ (T) can be obtained. Further, the measurement data V ₁ (2) of the channel ch ₁ is measured in the same manner for the measurement data of the second output voltages V ′ ₁ , V ′ ₂ , V ′ ₃ generated in the channels ch ₁ , ch ₂ , ch _3. Correction values Vc ′ ₁ (t), Vc ′ ₂ (t), and Vc ′ ₃ (t) at the same measurement time t as t) can be obtained.

Thus, for each cycle, fitting curves (approximate waveforms) obtained from time-series measurement data of V _i (i = 1, 2, 3) and V ′ _i (i = 1, 2, 3) are obtained. The correction values Vc _i and Vc ′ _i at the same measurement time can be obtained.

By obtaining the ratio Vc _i / Vc ′ _i (i = 1, 2, 3) from the correction values Vc _i and Vc ′ _i thus obtained, the expressions (1) to (3) and the expression ( Using 4) to (5), the position of the signal source Vs in the living body can be accurately detected.

  The method for obtaining the fitting curve (approximate waveform) is not particularly limited, and for example, not only multidimensional interpolation but also linear interpolation may be used.

  As shown in FIG. 6, the in-vivo signal source position detection apparatus according to the present embodiment further includes an approximation unit 50, a calculation unit 60, and a detection unit in addition to the configuration shown in FIG. 2.

In the approximating means 50 connected to the amplifier (measuring means) 40, the first output voltage V _i (i = 1, 2, 3) and the second output voltage V ′ _i (i = 1, 2, 3). The measurement is repeated as one cycle, and the first output voltage V _i and the second output voltage V ′ _i are obtained from the time series measurement data of the first output voltage V _i and the second output voltage V ′ _i . A fitting curve (approximate waveform) that approximates a time change is acquired.

In addition, the calculating means 60 connected to the approximating means 50 acquires the first output voltage V _i and the second output voltage V ′ _i having a time difference at the measurement time in each cycle by the approximating means 50. Using the fitting curve, correction values Vc _i and Vc ′ _i for the first output voltage V _i and the second output voltage V ′ _{i at} the same measurement time are calculated.

Further, the detection means 70 connected to the calculation means 60 obtains the ratio Vc _i / Vc ′ _i (i = 1, 2, 3) of the correction values Vc _i and Vc ′ _i calculated for each cycle. The position of the signal source Vs in the living body is detected based on the two ratios Vc _i / Vc ′ _i .

According to this embodiment, using the fitting curve (approximate waveform) acquired by the approximating means 50, the correction values Vc _i of the output voltages V _i and V ′ _i (i = 1, 2, 3) at the same measurement time. And Vc ′ _i (i = 1, 2, 3) are calculated, and based on the calculated correction values Vc _i and Vc ′ _i , the position of the in-vivo signal source Vs is detected to connect to each resistor. Even when there is a time difference between the measurement times of the output voltages V _i and V ′ _i sometimes occurring at the electrodes 21, 22, and 23, the position of the signal source Vs can be detected with high accuracy.

In this embodiment, the time difference between the measurement times of the output voltages V _i and V ′ _i generated at the electrodes 21, 22, 23 when connected to the resistors is the switching means 30, and the electrodes 21, 22, 23 and the external resistors This is caused by the switching time when switching between. In this case, since the switching time (for example, 0.5 ms) becomes a measurement time difference, as shown in FIG. 9, the output voltage is shifted by shifting the time by the measurement time difference using a fitting curve (approximate waveform). Correction values Vc _i and Vc ′ _i for V _i and V ′ _i can be easily calculated.

  By the way, the signal source Vs and each circuit composed of the electrodes 21, 22, and 23 are influenced by the capacitor component of the living body. For this reason, a difference may occur in the time during which the voltage generated by the signal source Vs is transmitted to the electrodes 21, 22, and 23.

If this time difference cannot be ignored, the time difference at the measurement time of the output voltages V _i and V ′ _i (i = 1, 2, 3) generated at the electrodes 21, 22, 23 is the switching time when switching the external resistance. In addition, a time difference due to the influence of the capacitor component of the living body is added.

In this case, the switching time when switching the external resistance can be known, but it is difficult to know the influence of the capacitor component of the living body from the voltage generated by the signal source Vs. Therefore, in the method as shown in FIG. 9, the correction values Vc _i and Vc ′ _i (i = 1, 2, 3) of the output voltages V _i and V ′ _i (i = 1, 2, 3) are obtained. Is difficult.

10 and 11, when it is difficult to know the time difference measurement time of the output voltage _{V i} and V _'i generated to each electrode 21,22,23 (i = 1,2,3), the output voltage _{V i} And a method for obtaining correction values Vc _i and Vc ′ _i (i = 1, 2, 3) of V ′ _i .

FIG. 10 shows measurement data of the first voltages V ₁ and V ₃ generated at the electrodes 21 and 23 (channels ch ₁ and ch ₃ ) when no external resistance is connected. In each channel ch ₁ and ch ₃ , the points indicated by two representative black circles indicate time-series measurement data obtained by two cycles of measurement.

As shown in FIG. 10, the measurement data obtained in the channels ch ₁ and ch ₃ in one cycle measurement are expressed as V ₁ (t) and V ₃ (t + Δt ₃ ). Here, Δt ₃ represents a measurement time difference between the channels ch ₁ and ch ₃ .

11, the channel _ch 1, ch _3, time-series measurement data of _{V 1} and _{V 3,} depicting the fitting curve (approximate waveform) _{C 1} and _{C 3} to approximate the time variation of _{V 1} and _{V 3} FIG. Here, fitting curve _{C 3,} as shown in FIG. 11, characterized point of fitting curve _C 1, _{C 3,} for example, the time axis to fit the fitting curve _C 1, peaks of _{C 3 K} 1, _{K 3} It is shifted.

Here, it is considered that the change in the output voltage measured in the channels ch ₁ and ch ₃ at the same measurement time t approximates the voltage change in the signal source Vs. Therefore, in the fitting curve C ₃ , the point (white dot in the figure) with respect to the same time t as V ₁ (t) is the correction value of the measurement data V ₃ (t + Δt ₃ ) of the channel ch _{3 at} the same measurement time t. Vc ₃ (t).

In the same way, for the measurement data V ₂ (t + Δt ₂ ) of channel ch ₂ , the feature points of the fitting curve obtained from the time-series measurement data of V ₂ are matched with the feature points of the fitting curve of V _1. Thus, the correction value Vc ₂ (t) at the same measurement time t as the measurement data V ₁ (t) can be obtained. Further, the measurement data V ₁ (2) of the channel ch ₁ is measured in the same manner for the measurement data of the second output voltages V ′ ₁ , V ′ ₂ , V ′ ₃ generated in the channels ch ₁ , ch ₂ , ch _3. Correction values Vc ′ ₁ (t), Vc ′ ₂ (t), and Vc ′ ₃ (t) at the same measurement time t as t) can be obtained.

In this way, the fitting curve (approximate waveform) obtained from the time-series measurement data of V _i (i = 1, 2, 3) and V ′ _i (i = 1, 2, 3) is obtained for each cycle. By matching the characteristic points, correction values Vc _i and Vc ′ _i at the same measurement time can be obtained.

  As mentioned above, although this invention was demonstrated by suitable embodiment, such description is not a limitation matter and of course various modifications are possible.

  For example, in the above-described embodiment, the case where the number of electrodes arranged on the surface of the living body 10 is three and the number of external resistors is two has been described as an example. However, of course, the present invention is not limited to this. It may be.

That is, when the number of electrodes arranged on the surface of the living body is m and the number of external resistors connected in parallel between each electrode and the ground potential is n, the in-vivo signal source position detecting device in the present invention Measuring means for measuring m × n output voltages V _i (i is an integer from 1 to m × n) generated at each electrode when each external resistor is connected in parallel to the electrode, and m × n output voltages V _i measurements as one cycle, repeatedly performed, from the time-series measurement data of each output voltage V _i, the approximate means for obtaining an approximation waveform that approximates the time variation of the output voltage V _i, in each cycle, measurement time For each output voltage V _i having a time difference, using the approximate waveform acquired by the approximating means, the correction value Vc _i of each output voltage V _{i at} the same measurement time (i is an integer of 1 to m × n) And a calculation means for calculating Based on the correction value Vc _i which is provided with a detecting means for detecting a position of a signal source in vivo.

  In the above embodiment, the first external resistor and the second external resistor are switched between each other in parallel by the switching means 30 between the electrodes 21, 22, 23 and the ground electrode 20. The switching means 30 is not necessarily used.

  That is, each electrode 21, 22, 23 is composed of an adjacent electrode 21 a, 21 b, electrode 22 a, 22 b, and electrode 23 a, 23 b, and the first electrode 21 a, 22 a, 23 a has a first One circuit is formed by connecting the external resistor Rg1, and another circuit is formed by connecting the second external resistor Rg2 to the electrodes 21b, 22b, and 23b on the other side.

  Thereby, the 1st and 2nd voltage which arises in each electrode 21,22,23 can be measured, and the position of signal source Vs in a living body can be detected.

FIG. 12 is a diagram illustrating a configuration of the in-vivo signal source position detection apparatus when the switching unit 30 is not used. In the figure, the signal source Vs, and the internal resistance R _b1 between the signal source Vs and each electrode 21 (21a, 21b), 22 (22a, 22b), 23 (23a, 23b) and the ground electrode 20, R _b2 , R _b3 , and R _b0 are omitted.

As shown in FIG. 12, the first electrode 21 (21a, 21b), 22 (22a, 22b), 23 (23a, 23b) disposed on the surface of the living body 10 and the ground electrode 20 The external resistor Rg1 and the second external resistor Rg2 are connected in parallel. A first external output voltage V ₁ generated when the first external resistor Rg1 is connected in parallel between the electrode 21a and the ground electrode 20, and a second external voltage between the electrode 21b and the ground electrode 20 is provided. The second output voltage V ′ ₁ generated when the resistor Rg2 is connected in parallel is amplified and measured by the amplifiers 40A ₁ and 40B ₁ , respectively. Similarly, the _second output voltage V ₂ generated when the first external resistor Rg1 is connected in parallel between the electrode 22a and the ground electrode 20, and the _second output voltage V ₂ between the electrode 22b and the ground electrode 20 is connected. The second output voltage V ′ ₂ generated when the external resistor Rg2 is connected in parallel is measured after being amplified by the amplifiers 40A ₂ and 40B ₂ , and the first external resistor between the electrode 23a and the ground electrode 20 is measured. the first output voltage V ₃ which occurs when the Rg1 connected in _parallel, and between the electrodes 23b and the ground electrode 20, the second output voltage V _'3 that occurs when the parallel connection of a second external resistor Rg2 , Amplified by the amplifiers 40A ₃ and 40B ₃ and measured. In this case, the first external resistor Rg1 and the second external resistor Rg2 are provided between the electrodes 21 (21a, 21b), 22 (22a, 22b), 23 (23a, 23b) and the ground electrode 20. The connection means for connecting in parallel can be performed by wiring or the like.

In this case, the time difference between the measurement times of the output voltages V _i and V ′ _i generated in the electrodes 21 (21a, 21b), 22 (22a, 22b), and 23 (23a, 23b) when connected to the resistors is There is nothing depending on the switching time when switching the external resistance, and the time difference is due to the difference in distance from the signal source Vs to each electrode 21 (21a, 21b), 22 (22a, 22b), 23 (23a, 23b). Therefore, in this case, the correction values Vc _i and Vc ′ _i (i = 1, 2, 3) of the output voltages V _i and V ′ _i can be obtained by the method shown in FIGS.

10 Living body
20 Ground electrode
21, 22, 23 electrodes
30 switching means
40 Amplifier (measuring means)
50 Approximate means
60 Calculation means
70 detection means

Claims (6)

An in-vivo signal source position detecting device for detecting a position of a signal source in a living body by a voltage generated in an electrode arranged on the surface of the living body,
M electrodes arranged on the surface of the living body,
Connection means for connecting n external resistors in parallel between each of the electrodes and the ground potential;
In a state where the electrodes are arranged on the surface of the living body, m × n output voltages V _i (i is 1 to m) generated at the electrodes when the connecting means connects the external resistors to the electrodes in parallel. A measuring means for measuring (an integer of xn),
As the (m × n) 1 cycle measured output voltage V _i, repeatedly performed, from the time-series measurement data of each output voltage V _i, approximation to obtain an approximation waveform that approximates the time variation of the output voltage V _i Means,
In each cycle, for each output voltage V _i having a time difference at the measurement time, using the approximate waveform acquired by the approximating means, a correction value Vc _i (i is a value for each output voltage V _{i at} the same measurement time). A calculating means for calculating an integer of 1 to mxn),
For each cycle, based on the correction value Vc _i the calculated, and a detection means for detecting a position of a signal source in vivo, in vivo signal source position detector. The connection means comprises switching means for switching n external resistors in parallel at a predetermined switching time between the electrodes and the ground potential,
The calculation means uses the approximate waveform acquired by the approximation means for each output voltage V _i having a time difference in measurement time in each cycle, and outputs each output at the same measurement time according to the switching time. The in-vivo signal source position detection apparatus according to claim 1, wherein a correction value Vc _i for the voltage V _i is calculated. In each cycle, the calculating means matches each output voltage V _i having a time difference in measurement time with each feature voltage point of each approximate waveform acquired by the approximating means, thereby obtaining each output voltage at the same measurement time. The in-vivo signal source position detection apparatus according to claim 1, wherein a correction value Vc _i for V _i is calculated. The electrodes arranged on the surface of the living body consist of at least three,
In the connecting means, the external resistance is composed of two parts, a first external resistance and a second external resistance,
In the measurement means, a first output voltage V _i (i = 1, 2, 3) generated in each electrode when the first external resistor is connected in parallel to each electrode, and the second output to each electrode. Measuring a second output voltage V ′ _i (i = 1, 2, 3) generated in each electrode when an external resistor is connected in parallel;
In the approximating means, the measurement of the first output voltage V _i and the second output voltage V ′ _i is repeatedly performed as one cycle, and the first output voltage V _i and the second output voltage V ′ are repeated. from the time-series measurement data of the _i, we obtain the approximate waveform approximating the time variation of the first output voltage V _i and the second output voltage V _'i,
In the calculation means, in each cycle, the first output voltage V _i and the second output voltage V ′ _i having a time difference in measurement time are the same using the approximate waveform acquired by the approximation means. Correction values Vc _i (i = 1, 2, 3) and Vc ′ _i (i = 1, 2, 3) of the first output voltage V _i and the second output voltage V ′ _i at the measurement time of Calculate
In the detection means, for each cycle, a ratio Vc _i / Vc ′ _i (i = 1, 2, 3) between the calculated correction values Vc _i and Vc ′ _i is obtained, and these three ratios Vc _i / Vc ′. _The in-vivo signal source position detection device according to claim 1, wherein the in-vivo signal source position is detected based on _i (i = 1, 2, 3). An in-vivo signal source position detection method for detecting a position of a signal source in a living body based on a voltage generated in an electrode disposed on a living body surface,
An arrangement step of arranging m electrodes on the surface of the living body;
A connection step of connecting n external resistors in parallel between each of the electrodes and the ground potential;
M × n output voltages V _i (i is an integer of 1 to m × n) generated in each electrode when the external resistors are connected in parallel to the electrodes in a state where the electrodes are arranged on the surface of the living body. Measuring process for measuring
Acquiring Examples of m × n 1 cycle measured output voltage V _i, repeated, time-series measurement data of each output voltage V _i, to obtain the approximate waveform approximating the time variation of the output voltage V _i Process,
In each cycle, for each output voltage V _i having a time difference at the measurement time, using the approximate waveform, a correction value Vc _i of each output voltage V _{i at} the same measurement time (where i is 1 to m × n). An integer), and
For each cycle, based on the correction value Vc _i the calculated, and a detection step of detecting a position of a signal source in vivo, in vivo signal source position detection method. In the arranging step, the electrode is composed of three pieces,
In the connecting step, the external resistor is composed of a first external resistor and a second external resistor,
In the measurement step, a first output voltage V _i (i = 1, 2, 3) generated in each electrode when the first external resistor is connected in parallel to each electrode, and the second output to each electrode Measuring a second output voltage V ′ _i (i = 1, 2, 3) generated in each electrode when an external resistor is connected in parallel;
In the acquisition step, the measurement of the first output voltage V _i and the second output voltage V ′ _i is repeatedly performed as one cycle, and the first output voltage V _i and the second output voltage V ′ are repeated. from the time-series measurement data of the _i, we obtain the approximate waveform approximating the time variation of the first output voltage V _i and the second output voltage V _'i,
In the calculation step, for each of the first output voltage V _i and the second output voltage V ′ _i having a time difference in measurement time in each cycle, the approximate waveform is used for the first output voltage V _i and the second output voltage V ′ _i . Correction values Vc _i (i = 1, 2, 3) and Vc ′ _i (i = 1, 2, 3) of the first output voltage V _i and the second output voltage V ′ _i are calculated,
In the detection step, a ratio Vc _i / Vc ′ _i (i = 1, 2, 3) between the calculated correction values Vc _i and Vc ′ _i is obtained for each cycle, and these three ratios Vc _i / Vc are obtained. The in-vivo signal source position detection method according to claim 5, wherein the position of the in-vivo signal source is detected based on ' _i (i = 1, 2, 3).

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