A method for locating three-dimensional coordinates of electrodes in vivo based on body surface potential measurement

Abstract

The present invention discloses a method for locating the three-dimensional coordinates of electrodes in the human body based on surface potential measurement. A constant current is circulated on the electrodes on the body surface to measure the potentials of other electrodes on the body surface. A three-dimensional coordinate positioning model of the human body is established by assigning values ​​and spatial coordinates to the current injection, collecting the electrode point potential data set, and the human body electrical impedance model. After the three-dimensional geometric model of the human body is established, a grid is divided, and a corresponding electrical impedance value is assigned to each area. The three-dimensional coordinate position of the electrodes in the human body is solved using the finite element method. The electrode position is displayed on a three-dimensional image using an image processing method. The absolute three-dimensional coordinate position and relative position of the electrode position in the human body can be determined through the image. This method for locating the three-dimensional coordinates of electrodes in the human body does not require large-scale surgical incision, is low-cost, and fast, and can achieve coordinate positioning of electrodes in the human body under minimally invasive surgery.

Description

Technical Field

[0001] The present invention relates to coordinate positioning and bioelectrical impedance imaging technology, mainly involving human body area model establishment, finite element calculation, inverse problem iterative solution and three-dimensional coordinate positioning. Background Art

[0002] Minimally invasive surgery is a technique that uses minimally invasive surgical methods to achieve traditional treatments. Minimally invasive surgery, typically performed using laparoscopes, thoracoscopes, X-rays, and other imaging equipment, offers advantages such as smaller incisions, less pain, and faster recovery.

[0003] However, in some minimally invasive surgeries, it's difficult to get imaging equipment into the affected area. In these cases, multiple, multi-angle X-rays are required to determine the internal position of the catheter, surgical robot, or scalpel within the body and their relative position to the lesion, using X-ray imaging to guide the surgery. However, these multiple, multi-angle X-rays can cause significant radiation damage to both the patient and the surgeon, and it's difficult to determine the three-dimensional coordinates of surgical instruments in real time. Therefore, a method is needed that can locate surgical instruments in the body in real time and with minimal damage to both the patient and the surgeon. Summary of the Invention

[0004] In view of the deficiencies in the above-mentioned prior art, the purpose of the present invention is to provide a method for locating the three-dimensional coordinates of internal electrodes based on surface potential measurement, which realizes real-time positioning of the three-dimensional coordinates of the internal electrodes by setting an electrode through which current flows into the human body and measuring the potential distribution on the surface of the body.

[0005] The technical solution adopted by the present invention is: a method for locating the three-dimensional coordinates of internal electrodes based on body surface potential measurement, comprising the following steps:

[0006] (1) Determine the human body area to be located, establish a three-dimensional geometric model, perform finite element calculations, and obtain the inverse of the coefficient matrix [Se] -1 ;

[0007] (2) Setting the electrode positions: setting one electrode inside the human body and N electrodes on the human body surface; injecting current into the electrodes inside the human body; selecting one electrode on the human body surface to flow current; the current value is I; collecting the measured potential value group V of the remaining electrode points on the human body surface; i =[V i1 V i2 … V ip … V iN-1 ](i=1,2,…,N), where V ip represents the potential vector of the p electrode as the current outflow point when the i-th measurement is taken, i represents the i-th measurement result, p represents the current outflow electrode point, and N represents the number of electrodes;

[0008] (3) Assuming the current vector I 1k =[i 11 i 12 … i 1q ](k=1,2,…),where I 1k represents the k-th hypothetical current vector, q is the number of nodes in the mesh;

[0009] (4) Substitute the current vector and the inverse of the coefficient matrix into the formula [Se] -1 I 1k =U k The potential matrix U is calculated k , in U k The voltage vector corresponding to the row of measuring electrodes is extracted to form U k_elec , calculation error

[0010] Where V is the measured potential matrix, U is the calculated potential matrix, V i Indicates the measured potential value group when the injection electrode point is i, U k_elec Calculate the potential matrix U when representing the kth current vector k Extract the voltage vector corresponding to the row of measuring electrodes, V a represents the measurement potential vector of the ath measurement, U a represents the calculated potential vector corresponding to the a-th measurement, and a represents the measuring electrode point.

[0011] (5) Assume a new set of current vectors I based on the calculation error 1k+1 , then loop through step (4) until the calculated error e is less than the set error limit;

[0012] (6) The last set of current vectors I obtained in step (5) i_min Keep it, then switch the electrode where the current flows out to another electrode, and repeat the steps (2-5) until all electrodes have been traversed by the outflow node;

[0013] (7) According to the current vector I i_min Perform three-dimensional coordinate imaging of electrodes in the human body.

[0014] Furthermore, the finite element calculation includes meshing the three-dimensional geometric model into a plurality of small regions, numbering each region, and assigning an electrical impedance value σ corresponding to each region; establishing a coefficient matrix [Se] by the finite element method, and calculating the inverse of the coefficient matrix [Se] as [Se] -1 .

[0015] Specifically, step (7) includes finding the average value of all current vectors The maximum value point in the current vector is taken. The row where the maximum value point is located is the node where the current is injected. The internal electrode imaging of the human body is performed in combination with the geometric model established in step (1).

[0016] The present invention further provides an electronic device, comprising:

[0017] a memory for storing executable instructions;

[0018] The processor is configured to implement the aforementioned method for locating the three-dimensional coordinates of the internal electrodes based on the surface potential measurement when executing the executable instructions stored in the memory.

[0019] A computer-readable storage medium stores executable instructions for implementing the aforementioned method for locating the three-dimensional coordinates of electrodes in the body based on body surface potential measurement when executed by a processor.

[0020] This invention features rapid, real-time, and accurate positioning of internal electrodes, minimizing radiation exposure to patients and doctors during surgery. This method utilizes an improved electrical impedance tomography (EIT) algorithm to precisely locate a point within the body, overcoming the low imaging accuracy of traditional EIT algorithms. It also enables real-time, three-dimensional positioning of internal electrodes through surface potential measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a flow chart of a method for locating three-dimensional coordinates of electrodes in vivo based on body surface potential measurement according to the present invention;

[0022] Figure 2 A three-dimensional diagram of the imaging model and electrode points of the present invention;

[0023] Figure 3 A front view of the imaging model and the three-dimensional diagram of the electrode points of the present invention;

[0024] Figure 4 A side view of a three-dimensional diagram of the imaging model and electrode point annotations of the present invention;

[0025] Figure 5 This is a top view of the imaging model and the three-dimensional diagram of the electrode point annotation of the present invention. DETAILED DESCRIPTION

[0026] The present invention will be described in more detail below with reference to the accompanying drawings and embodiments. Since the internal structure is relatively complex, only the relevant structures of the present invention are simplified in the schematic diagram. Figure 1 As shown, the present invention includes the following steps:

[0027] (1) Determine the human body area to be located, establish a three-dimensional geometric model, and perform meshing to divide the geometric model into multiple small areas;

[0028] (2) Number each area and assign the electrical impedance value σ to each area; establish the coefficient matrix [Se] through the finite element method, and calculate the inverse of the coefficient matrix [Se] as [Se] -1 ;

[0029] (3) There is an electrode in the human body, and N electrodes are set on the surface of the human body. Current is injected through the electrodes in the human body, and a current is selected from one surface electrode. The current value is I, and the measured potential value group V of the remaining surface electrode points is collected. i =[V i1 V i2 … V ip … V iN ](i=1,2,…,N), where V ip represents the potential vector of the p electrode as the current outflow point when the i-th measurement is taken, i represents the i-th measurement result, p represents the current outflow electrode point, and N represents the number of electrodes;

[0030] (4) Assume that the current vector I 1k =[i 11 i 12 … i 1q ](k=1,2,…),where I 1k represents the k-th hypothetical current vector, q is the number of nodes in the mesh;

[0031] (5) Substitute the current vector and the inverse of the coefficient matrix into the formula [Se] -1 I 1k =U k The potential matrix U is calculated k , in U k The voltage vector corresponding to the row of measuring electrodes is extracted to form U k_elec , calculation error

[0032] Where V is the measured potential matrix, U is the calculated potential matrix, V i Indicates the measured potential value group when the injection electrode point is i, U k_elec Calculate the potential matrix U when representing the kth current vector k Extract the voltage vector corresponding to the row of measuring electrodes, V a represents the measurement potential vector of the ath measurement, U a represents the calculated potential vector corresponding to the a-th measurement, and a represents the measuring electrode point.

[0033] (6) Assume a new set of current vectors I based on the calculation error 1k+1 , then loop the contents of step (5) until the calculated error e is less than the set error limit and then stop the loop.

[0034] (7) The last set of current vectors I obtained in step (6) i_min Keep it,

[0035] (8) Then switch the electrode where the current flows out to another electrode, and repeat the steps (3-7) until all electrodes have been traversed by the outflow node;

[0036] (9) Calculate the average value of all current vectors obtained Take the maximum value point in the current vector. The row of the maximum value point is the node of the injection current point. Combined with the geometric model established in step (1), perform electrode imaging inside the human body. The maximum value point in the current vector corresponds to the node of the injection current. The position of the injection current node is displayed at the corresponding position of the model.

[0037] like Figure 2-5 As shown in FIG. 1 , the imaging model obtained by the method of the present invention is shown, wherein the small circles represent the locations of the electrodes in the human body.

[0038] The embodiments described above are merely intended to help understand and illustrate the present invention. After reading the embodiments described above, a skilled person can modify or transform the present invention based on the principles of the present invention. Such modifications or transformations are also within the technical scope of the claims of the present invention.

Claims

1. A method for locating the three-dimensional coordinates of electrodes in vivo based on body surface potential measurement, characterized in that: The following steps are involved: (1) Determine the human body area to be located, establish a three-dimensional geometric model, perform finite element calculations, and obtain the inverse of the coefficient matrix [Se] -1 ; (2) Setting the electrode positions: setting one electrode inside the human body and N electrodes on the human body surface; injecting current into the electrodes inside the human body; selecting one electrode on the human body surface to flow current; the current value is I; collecting the measured potential value group V of the remaining electrode points on the human body surface; i =[V i1 V i2 …V ip …V iN-1 ](i=1,2,…,N), where V ip represents the potential vector of the p electrode as the current outflow point when the i-th measurement is taken, i represents the i-th measurement result, p represents the current outflow electrode point, and N represents the number of electrodes; (3) Assuming the current vector I 1k =[i 11 i 12 …i 1q ](k=1,2,…),where I 1k represents the k-th hypothetical current vector, q is the number of nodes in the mesh; (4) Substitute the current vector and the inverse of the coefficient matrix into the formula [Se] -1 I 1k =U k The potential matrix U is calculated k , in U k The voltage vector corresponding to the row of measuring electrodes is extracted to form U k_elec , calculation error Where V is the measured potential matrix, U is the calculated potential matrix, V i Indicates the measured potential value group when the injection electrode point is i, U k_elec Calculate the potential matrix U when representing the kth current vector k Extract the voltage vector corresponding to the row of measuring electrodes, V a represents the measurement potential vector of the ath measurement, U a represents the calculated potential vector corresponding to the a-th measurement, where a represents the measuring electrode point; (5) Assume a new set of current vectors I based on the calculation error 1k+1 , then loop through step (4) until the calculated error e is less than the set error limit; (6) The last set of current vectors I obtained in step (5) i_min Keep it, then switch the electrode where the current flows out to another electrode, and repeat the steps (2-5) until the outflow node has traversed all electrodes; (7) According to the current vector I i_min Perform three-dimensional coordinate imaging of electrodes in the human body.

2. The method for three-dimensional coordinate positioning of internal electrodes based on body surface potential measurement according to claim 1, characterized in that: The finite element calculation includes meshing the three-dimensional geometric model into multiple small areas, numbering each area, and assigning an electrical impedance value σ corresponding to each area; establishing a coefficient matrix [Se] through the finite element method, and calculating the inverse of the coefficient matrix [Se] as [Se] -1 .

3. The method for locating three-dimensional coordinates of electrodes in vivo based on body surface potential measurement according to claim 1, characterized in that: The step (7) includes finding the average value of all current vectors The maximum value point in the current vector is taken. The row where the maximum value point is located is the node where the current is injected. The internal electrode imaging of the human body is performed in combination with the geometric model established in step (1).

4. An electronic device, characterized in that: include: a memory for storing executable instructions; The processor is configured to implement the method for locating the three-dimensional coordinates of the internal electrode according to body surface potential measurement as described in any one of claims 1 to 3 when executing the executable instructions stored in the memory.

5. A computer-readable storage medium, characterized in that Executable instructions are stored for implementing the method for three-dimensional coordinate positioning of internal electrodes based on body surface potential measurement as described in any one of claims 1 to 3 when executed by a processor.

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