Deep transcranial magnetic stimulation positioning navigation system based on time interference

Abstract

The invention belongs to the technical field of transcranial magnetic stimulation medical treatment. The problems that in an existing transcranial magnetic stimulation technology, the focusing performance of a deep specific brain area is not high, positioning is not accurate, and full-path superficial layer tissue is strongly stimulated are solved. According to the deep transcranial magnetic stimulation positioning navigation system based on time interference, based on the time interference principle, stimulation currents with different frequencies are applied to two sets of transmitting coils, low-frequency envelope waves are overlaid in the skull, and therefore the current magnitude is reduced, and the focusing degree is improved. Data support is provided for accurate positioning of the head posture of a patient based on a depth camera, and a multi-degree-of-freedom coil capable of generating an omni-directional magnetic field in space is provided. By reasonably adjusting the amplitude of the current introduced into the coil, the magnetic field can automatically move to the stimulation point of the head of the patient for treatment, the stimulation target is changed by adjusting the electrical parameters, and the low-frequency envelope magnetic field is obtained by modulation at the stimulation target, so that the target neurons are magnetically stimulated.

Description

Technical Field

[0001] The present invention belongs to the field of transcranial magnetic stimulation medical technology, specifically a deep transcranial magnetic stimulation positioning navigation system based on time interference, which can achieve multi-intensity and multi-type transcranial magnetic stimulation by changing different control strategies. It can be used in the medical and health care fields, and can achieve disease treatment, disease prevention and daily health maintenance. Background Art

[0002] According to the latest statistics from IMS health, global sales of psychiatric drugs have exceeded US$36 billion, accounting for 5% of total drug sales. However, in China, the current market size of psychiatric drugs is still relatively small, accounting for about 1.5% of total hospital sales.

[0003] Transcranial Magnetic Stimulation (TMS) is a technique that generates electric current in the local cerebral cortex through a pulsed magnetic field to temporarily activate or inhibit the cortex. However, the widely used form of stimulation is still the traditional single-pulse or multi-pulse stimulation, which has a strong stimulation intensity, especially to the brain surface, muscles and other tissues, which may cause a certain degree of damage, and cannot achieve localized stimulation of the stimulation target area.

[0004] In recent years, researchers have made a lot of attempts to improve the many problems of TMS. Although the design of various forms of coils has reduced the intensity of stimulation to the epidermis and muscle tissue to a certain extent while ensuring good stimulation effects, it is still impossible to achieve localized stimulation of specific tissues and specific areas without stimulating other tissues. Moreover, in the existing field of medical equipment, during transcranial magnetic stimulation treatment, patients are treated by manually operating or fixing the TMS coil with a bracket. Manual operation is very inconvenient, requiring long-term holding of the coil or using a bracket to fix a specific angle; the patient's experience is poor, and during the treatment, the sitting posture should not be adjusted, and repositioning is required after the sitting posture changes; manual positioning is cumbersome and not accurate enough, which greatly reduces the treatment effect on the patient.

[0005] Patent document CN111135465A proposes a deep transcranial magnetic coil stimulation device based on time interference, which utilizes the low-pass characteristics of biological tissues and applies stimulation currents of different frequencies to achieve localized stimulation of brain tissue without stimulating surface tissues such as the epidermis and muscles. However, it only achieves the focusing degree of the patient's stimulation target when the patient is static, and does not improve the patient's neck freedom of movement during treatment. Patent document CN107149722A discloses a transcranial magnetic stimulation treatment device, which controls the six driving mechanisms of the mechanical arm to rotate to corresponding angles. The mechanical arm has a slow response speed, which reduces the treatment effect and efficiency. Most of the existing transcranial magnetic stimulation automatic positioning devices use a mechanical arm to achieve the positioning of the stimulation coil. In the existing TMS positioning cruise mode, the mechanical arm moves slowly and often has a certain hysteresis. In the process of the controller controlling the mechanical arm to move the TMS coil, the human brain may move again, resulting in inaccurate positioning, and the structure of this device is relatively bulky. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention proposes a deep transcranial magnetic stimulation positioning navigation system based on time interference.

[0007] The present invention solves the technical problem by adopting the following technical solution:

[0008] A deep transcranial magnetic stimulation positioning and navigation system based on time interference. This system is based on the principle of time interference. By applying stimulation currents of different frequencies to two sets of transmitting coils, a low-frequency envelope wave is superimposed in the skull. Compared with the existing transcranial magnetic stimulation method, the coil current is smaller and the focusing degree is higher. Based on the depth camera to provide data support for the precise positioning of the patient's head posture, a multi-degree-of-freedom coil that can generate an omnidirectional magnetic field in space is proposed. By reasonably adjusting the amplitude of the current passed through the three coils, the magnetic field can be automatically moved to the stimulation point on the patient's head for treatment. The stimulation target is changed by adjusting the electrical parameters, and the required low-frequency envelope magnetic field is modulated at the stimulation target, thereby magnetically stimulating the target neurons. Compared with traditional robotic arms, the feedback is rapid, thereby improving the accuracy and efficiency of treatment and reducing the complexity of the equipment.

[0009] Compared with the prior art, the present invention has the following beneficial effects:

[0010] 1. Transcranial magnetic stimulation requires an electric field of 100V / M 2-3cm below the scalp. The current required for traditional repetitive transcranial magnetic stimulation is: amplitude of about 2000A, frequency of 2000Hz. After adopting the time interference method, two three-orthogonal stimulation coil groups with the same base frequency and a difference frequency of 10Hz can superimpose a 10Hz envelope wave in the skull, and simulations have verified that the envelope waveform has the same stimulation effect as the existing TMS pulse wave. If the base frequency is appropriately increased, the required current can be reduced while producing the same stimulation effect in the target area.

[0011] 2. Conventional TMS has an action depth of 2-3 cm and generates a magnetic field strength of 3-4 T, which is similar to magnetic resonance imaging. The present invention appropriately increases the base frequency, thereby reducing the required current within a certain range, thereby reducing the magnetic field strength and improving biosafety;

[0012] 3. Traditional TMS stimulation has a high noise problem. The use of time interference method will reduce the excitation current, reduce the Lorentz force, and reduce the noise;

[0013] 4. Because the stimulation magnetic field is the sum of the magnetic field vectors of three orthogonal transmitting coils, when the synthetic magnetic field meets the stimulation intensity, the magnetic field intensity generated by a single stimulation coil can be significantly reduced, thereby reducing the stimulation current and achieving the purpose of reducing the heating of a single coil, thereby extending the stimulation time.

[0014] 5. A depth camera is used to locate the stimulation target in real time, and three orthogonal stimulation coils are used to track the stimulation target in real time, solving the problem of inaccurate or lagging positioning by manual or robotic arms in the past. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is the overall flow chart of the present invention;

[0016] Figure 2 It is a schematic diagram of vector synthesis of the present invention;

[0017] Figure 3 It is a schematic diagram of the three-dimensional orthogonal transmitting coil of the present invention;

[0018] Figure 4 It is the overall system solution of the present invention;

[0019] Figure 5 Schematic diagram of the stimulation scheme of the present invention. DETAILED DESCRIPTION

[0020] Specific embodiments are given below in conjunction with the accompanying drawings. The specific embodiments are only used to introduce the technical solutions of the present invention in detail and are not intended to limit the protection scope of the present application.

[0021] This paper invents a deep transcranial magnetic stimulation positioning and navigation system based on time interference. This system is based on the principle of time interference. By applying stimulation currents of different frequencies to two sets of transmitting coils, a low-frequency envelope wave is superimposed in the skull, thereby reducing the current size and improving the focusing degree. A three-orthogonal stimulation coil that can generate an omnidirectional magnetic field in space is proposed, which provides data support for the precise positioning of the patient's head posture through a depth camera. By reasonably adjusting the current amplitude passed through the three coils, the magnetic field can be focused on the stimulation point on the patient's head for treatment, thereby improving the efficiency of the previous transcranial magnetic stimulation positioning and navigation method, reducing the burden on doctors, and no longer requiring a robotic arm to reduce the complexity of the equipment. At the same time, the stimulation target is changed by adjusting the electrical parameters to improve the positioning speed, solving the problem of inaccurate or lagging positioning by manual or robotic arms in the past.

[0022] The specific TMS positioning navigation method for transcranial magnetic stimulation treatment includes the following steps:

[0023] S1. Post the positioning mark code at the stimulation target point on the patient's head; two depth cameras are arranged on the side and rear of the patient's head, and the hand-eye calibration and initialization of the depth cameras on both sides are performed to keep the active area of ​​the patient's head within the field of view of the depth camera sensor;

[0024] S2, spatially locate the stimulation target of the patient, establish a spatial coordinate system with the depth camera as the origin, and obtain the 3D coordinate values ​​of the patient's facial feature points in the depth camera spatial coordinate system according to the image data;

[0025] S3, first positioning, transforming the 3D coordinates of the patient's actual stimulation site in the depth camera space coordinate system into a spherical coordinate system with the center point of the two three orthogonal stimulation coils as the origin, and obtaining the corresponding coil current amplitude ratio of the magnetic field of the three orthogonal stimulation coils focused at this point according to the coordinates;

[0026] S4. During the operation, when the patient's head moves, the depth camera on the follower side monitors the movement changes of the stimulation target on the patient's head in real time, and adjusts the current amplitude of the three orthogonal stimulation coils to perform real-time follow-up control of the target stimulation target; the spatial position of the stimulation target is obtained in real time, and stimulation target follow-up control treatment is performed to prevent off-target and ineffective treatment.

[0027] The specific magnetic field control principle of the three orthogonal stimulation coils is as follows:

[0028] Vector synthesis is organized into a visual diagram, as follows Figure 2 As shown, according to the principle of vector synthesis and combined with the above figure, the specific vector synthesis mathematical expression is given as follows:

[0029] r=a+b+c

[0030] Combining the diagram and the formula, it can be more clearly seen that the synthetic vector r in space is synthesized by vector a, vector b and vector c. When any of the three vectors changes in phase or amplitude, the synthetic vector r will change. In other words, any vector r of a desired direction and magnitude can be synthesized by three space vectors in different directions by adjusting the amplitude of each vector.

[0031] With the help of the above mathematical description and analysis, it can be made clear that the magnetic vector at any point in three-dimensional space can be synthetically controlled by some means.

[0032] The three circular coils are overlapped to construct a centralized three-dimensional orthogonal energy transfer architecture. Figure 3 As shown, green represents coil 1, blue represents coil 2, and yellow represents coil 3.

[0033] According to the Biot-Savart law, for a single multi-turn circular coil, when the current I is passed through it, the magnetic vector at the center of the coil is:

[0034] B= μ0N I

[0035] 2r

[0036] Magnetic vector B at the center of the coil o The magnitude is proportional to the magnitude of the current I flowing through the coil, and the direction is perpendicular to the plane where the coil is located. This theory is extended to the three orthogonal circular coils shown in the figure above. Assume that the three circular coils are located in the XOY, XOZ and YOZ planes of the three-dimensional coordinate plane with the center of the circle as the origin, and the corresponding currents flowing through the three coils are I1, I2, and I3. The magnetic vector generated by the three coils at the center of the circle is expressed as B o1 , B o2 , B o3 , according to the principle of vector superposition, the synthetic magnetic vector B is:

[0037]

[0038] In the formula, I=I1x+I2y+I3z, x, y, z represent unit vectors on the three coordinate axes respectively, and I represents the composite current vector of the three coils.

[0039] The size and direction of the synthetic magnetic vector B of the three orthogonal circular coils depend on the size and direction of the synthetic current vector I. Without changing the coil structure, the size and direction of the synthetic current vector I can be changed by changing the excitation current of the three orthogonal circular coils, so that the size and direction of the synthetic magnetic vector B can be freely changed, thereby achieving the purpose of omnidirectional controllable magnetic field.

[0040] The red coil located in the YOZ plane is the transmitting coil 1, the green coil located in the XOZ plane is the transmitting coil 2, and the blue coil located in the XOY plane is the transmitting coil 3. The corresponding AC excitation currents i1, i2, and i3 flowing into the three-phase coils are:

[0041]

[0042] Wherein, I1, I2, I3 are the amplitudes of the AC excitation currents i1, i2, i3; ω1, ω2, ω3 are the corresponding angular frequencies; θ1, θ2, θ3 are the corresponding phase angles.

[0043] In order to achieve multi-degree-of-freedom repetitive transcranial magnetic stimulation, current amplitude control is adopted. An excitation current with consistent frequency and phase is passed through a set of three orthogonal stimulation coils, and a controllable magnetic field is generated by controlling the current amplitude of the transmitting coil.

[0044] Figure 3 The schematic diagram of controllable magnetic field generation is shown. I1, I2, and I3 are the input current vectors of each transmitting coil. o1 , B o2 , B o3 are the corresponding magnetic vectors respectively. According to the superposition principle, the synthetic current vector and synthetic magnetic vector are I and B respectively. The angle between the synthetic current vector I and the positive Z axis is θ, and the angle between the projection line of the synthetic current vector I on the XOY plane and the positive X axis is

[0045] According to the current amplitude control principle, the current amplitudes I1, I2, and I3 of the transmitting coils of each phase should satisfy the following relationship:

[0046]

[0047] Where I represents the magnitude of the synthetic current vector I, θ and Represents the direction, elevation angle θ and azimuth of the composite current vector I is restricted to θ∈[0,π] and

[0048] In summary, under the premise that the frequency and phase of the current flowing through the three coils remain unchanged, we only need to know the amplitude and direction of the final synthetic current vector to obtain the amplitude of the current flowing through the three orthogonal stimulation coils. After the vector direction is determined, when each vector component is simultaneously enlarged or reduced by n times, the direction of the vector will not change, only the magnitude of the vector will change. Therefore, as long as the ratio of each base component of the known vector remains unchanged, the direction of the magnetic vector can be always the same as the desired direction while changing the magnitude of the synthetic magnetic vector.

[0049] This paper also proposes a TMS positioning navigation system for transcranial magnetic stimulation, including:

[0050] Depth camera module: The depth camera obtains the distance of each point in the image from the camera and adds the two-dimensional coordinates of the point in the 2D image to obtain the three-dimensional spatial coordinates of each point in the image, thereby providing support for quickly and accurately obtaining the position of the patient's stimulation target;

[0051] The three-dimensional spatial posture estimation module adopts the three-dimensional spatial posture estimation technology with the functions of marking positioning and recognition, posts the marker code at the patient's stimulation target, and estimates the three-dimensional posture of the patient's head stimulation target by combining the depth camera and the marker code; the three-dimensional posture estimation technology includes spatial positioning of the patient's stimulation target, establishing a spatial coordinate system with the depth camera as the origin, and obtaining the 3D coordinate values ​​of the patient's facial feature points in the depth camera spatial coordinate system according to the image data;

[0052] The calculation processing module, when positioning, transforms the 3D coordinates of the patient's actual stimulation site in the depth camera space coordinate system into spherical coordinates with the center points of the two three orthogonal stimulation coils as the origin, and obtains the corresponding coil current amplitude that focuses the magnetic field of the three orthogonal stimulation coils at this point according to the coordinates;

[0053] Stimulation module: During the treatment, when the patient's head moves, the current amplitude calculated in the calculation processing module is passed through the three orthogonal stimulation coils to stimulate the target stimulation point in a real-time follow-up control manner. Specifically, according to the current amplitude, the three orthogonal stimulation coils in the transmitting mechanism are passed with excitation currents of the same frequency and the same phase.

[0054] The calculation and processing module includes: an initialization submodule, which determines the position and angle of the area to be stimulated in the human brain with the center of the three-orthogonal stimulation coil structure as the origin; determines the desired magnetic field size and direction of the area to be stimulated during the first positioning; and a calculation submodule, which determines the current amplitude of each combination of the three orthogonal stimulation coils based on the magnetic field size and direction, the position and angle.

[0055] The stimulation module also includes: a stimulation adjustment submodule, which calculates the adjusted current amplitudes that should be respectively passed through the three orthogonal stimulation coils according to the position and angle after the movement when the patient's head moves, and then obtains the adjusted current vector for real-time follow-up control.

[0056] This article also proposes an electronic device, including a processor, a memory, and a program or instruction stored in the memory and executable on the processor, wherein the program or instruction is executed by the processor to implement the steps of the above-mentioned positioning and navigation method. At the same time, a readable storage medium is proposed, wherein the program or instruction is stored on the readable storage medium, and the steps of the above-mentioned positioning and navigation method are implemented when the program or instruction is executed by the processor.

[0057] The present disclosure is not limited to the above-mentioned specific implementation modes, which are merely illustrative and not restrictive. Under the guidance of the present disclosure, ordinary technicians in this field can make many forms without departing from the scope of protection of the present disclosure and the claims, all of which are protected by the present disclosure.

Claims

1. A deep transcranial magnetic stimulation positioning navigation system based on time interference, Features: S1. This system is based on the principle of time interference. By applying stimulation currents of different frequencies to two sets of transmitting coils, a low-frequency envelope wave is superimposed in the skull to stimulate the nerves. S2. Using a three-dimensional spatial posture estimation technology with marker positioning and recognition functions, posting a marker code at the patient's stimulation target, and estimating the three-dimensional posture of the patient's head stimulation target by combining a depth camera and the marker code; The three-dimensional posture estimation technology includes spatially locating the patient's stimulation target, establishing a spatial coordinate system with the depth camera as the origin, and obtaining the 3D coordinate values ​​of the patient's facial feature points in the depth camera's spatial coordinate system based on the image data; S3. During the first positioning, the 3D coordinates of the patient's actual stimulation site in the depth camera space coordinate system are transformed into spherical coordinates with the center points of the two three orthogonal stimulation coils as the origin, and the corresponding coil current amplitude ratio for focusing the magnetic field of the three orthogonal stimulation coils at this point is obtained based on the coordinates; S4. During the stimulation, when the patient's head moves, the depth camera on the follower side monitors the movement changes of the stimulation target on the patient's head in real time, and stimulates the target stimulation target in a real-time following control manner by adjusting the current amplitude of the three orthogonal stimulation coils.

2. The positioning navigation system according to claim 1, Features: The step of adjusting the current amplitude of the three orthogonal stimulation coils comprises: S41, determining the position and angle of the area to be stimulated in the human brain with the center of the three orthogonal stimulation coil structure as the origin; S42, determining the desired magnetic field size and direction of the area to be stimulated during the first positioning; S43, determining the current amplitude of each combination of three orthogonal stimulation coils according to the magnitude and direction of the magnetic field, the position and the angle; S44. According to the current amplitude, the three orthogonal stimulation coils in the transmitting mechanism are supplied with excitation currents of the same frequency and the same phase.

3. The positioning navigation system according to claim 2, Features: The step of adjusting the current amplitude of the three orthogonal stimulation coils also includes: S45. When the patient's head moves, the adjusted current amplitudes that should be respectively passed through the three orthogonal stimulation coils are calculated according to the position and angle after the movement, and then the adjusted current vector is obtained to perform real-time follow-up control.

4. The positioning navigation system according to claim 3, Features: The steps of obtaining the adjusted current vector and performing real-time following control include: S46, determining the expected magnetic field size and direction of the area to be stimulated according to actual needs; S47, according to the magnitude and direction of the desired magnetic field, the magnitude and direction of the synthetic current vector are determined according to the Biot-Savart law, thereby determining the current amplitude of each stimulation coil in the three orthogonal stimulation coils; S48. According to the current amplitude calculated in step S37, the three orthogonal stimulation coils in the transmitting mechanism are supplied with excitation currents of the same frequency and phase.

5. The positioning navigation system according to claim 3, Features: The steps of determining the current amplitude of each combination of three orthogonal stimulation coils include: S51, the size and direction of the synthetic magnetic vector of the three orthogonal circular coils depend on the size and direction of the synthetic current vector. Without changing the coil structure, the size and direction of the synthetic current vector can be changed by changing the excitation current of the three orthogonal circular coils, so that the size and direction of the synthetic magnetic vector can be freely changed, so that the magnetic field in all directions can be controlled; S52, the transmitting coil 1 located in the YOZ plane, the transmitting coil 2 located in the XOZ plane, and the transmitting coil 3 located in the XOY plane flow into the corresponding AC excitation current i of the three-phase coils 1 、i 2 、i 3 for: In the formula, I 1 ,I 2 ,I 3 is the AC excitation current i 1 、i 2 、i 3 The amplitude of 1 ,ω 2 ,ω 3 is the corresponding angular frequency; θ 1 ,θ 2 ,θ 3 is the corresponding phase angle; S53. To achieve multi-degree-of-freedom repetitive transcranial magnetic stimulation, an excitation current with consistent frequency and phase is passed through a set of three orthogonal stimulation coils, and a controllable magnetic field is generated by controlling the current amplitude of the transmitting coil; S54, according to the current amplitude control principle, the current amplitude I of each phase transmitting coil is passed 1 ,I 2 ,I 3 The following relationship should be satisfied: Where I represents the magnitude of the synthetic current vector I; θ and Represents the direction, elevation angle θ and azimuth of the composite current vector I is restricted to θ∈[0,π] and S55. During the stimulation, when the patient's head moves, the follower side depth camera monitors the movement changes of the stimulation target on the patient's head in real time, determines the position and angle of the area to be stimulated in the human brain with the center of the three-orthogonal stimulation coil structure as the origin according to the actual situation, and determines the expected magnetic field size and direction of the area to be stimulated according to actual needs.

6. A deep transcranial magnetic stimulation positioning navigation system based on time interference, Features: The device comprises: Depth camera module: The depth camera obtains the distance of each point in the image from the camera and adds the two-dimensional coordinates of the point in the 2D image to obtain the three-dimensional spatial coordinates of each point in the image, thereby providing support for quickly and accurately obtaining the position of the patient's stimulation target; The three-dimensional spatial posture estimation module adopts the three-dimensional spatial posture estimation technology with the functions of marking positioning and recognition, posts the marker code at the patient's stimulation target, and estimates the three-dimensional posture of the patient's head stimulation target by combining the depth camera and the marker code; the three-dimensional posture estimation technology includes spatial positioning of the patient's stimulation target, establishing a spatial coordinate system with the depth camera as the origin, and obtaining the 3D coordinate values ​​of the patient's facial feature points in the depth camera spatial coordinate system according to the image data; The calculation processing module, when positioning, transforms the 3D coordinates of the patient's actual stimulation site in the depth camera space coordinate system into spherical coordinates with the center points of the two three orthogonal stimulation coils as the origin, and obtains the corresponding coil current amplitude that focuses the magnetic field of the three orthogonal stimulation coils at this point according to the coordinates; Stimulation module: During the treatment, when the patient's head moves, the current amplitude calculated in the calculation and processing module is passed through the three orthogonal stimulation coils to stimulate the target stimulation point in a real-time follow-up control manner.

7. The positioning navigation system according to claim 6, Features: The calculation processing module includes: The initialization submodule determines the position and angle of the area to be stimulated in the human brain with the center of the three orthogonal stimulation coil structure as the origin; determines the expected magnetic field size and direction of the area to be stimulated during the first positioning; A calculation submodule, determining the current amplitude of each combination of three orthogonal stimulation coils according to the magnitude and direction of the magnetic field, the position and the angle; The stimulation module further comprises: according to the current amplitude, passing the excitation current with the same frequency and the same phase to the three orthogonal stimulation coils in the transmitting mechanism.

8. The positioning navigation system according to claim 6, Features: The stimulation module also includes: a stimulation adjustment submodule, which calculates the adjusted current amplitudes that should be respectively passed through the three orthogonal stimulation coils according to the position and angle after the movement when the patient's head moves, and then obtains the adjusted current vector for real-time follow-up control.

9. An electronic device, It is characterized in that It includes a processor, a memory, and a program or instruction stored in the memory and executable on the processor, wherein when the program or instruction is executed by the processor, a deep transcranial magnetic stimulation positioning and navigation system based on time interference as described in any one of claims 1 to 5 is implemented.

10. A readable storage medium, It is characterized in that The readable storage medium stores programs or instructions, and when the programs or instructions are executed by the processor, a deep transcranial magnetic stimulation positioning and navigation system based on time interference as described in any one of claims 1 to 5 is implemented.

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