Multi-array-element ultrasonic focusing method and system for nerve regulation and control

Abstract

The invention discloses a multi-array-element ultrasonic focusing method and system for nerve regulation, and the system comprises a control module which is used for designing a user interaction interface based on an embedded system and an FPGA, and setting a phased array algorithm to control the ultrasonic intensity and phase of each channel; the power transmitting module comprises an array circuit which takes a special radio frequency power amplifier as a main body and is used for completing ultrasonic wave column transmission of each channel; the echo signal receiving and processing module is used for analyzing and judging the intensity of the sound echo after filtering the echo in a specified time window; and the array probe module comprises a power transmitting piezoelectric ceramic transducer and a receiving transducer and is used for transmitting and receiving ultrasonic waves. According to the scheme, the working parameters, with the strongest echo, of the transmitting unit are obtained through the iterative algorithm, it can be guaranteed that transcranial post-ultrasound is focused at the original focus, and sound field distortion caused by the skull is overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of neuromodulation, and particularly to a multi-array ultrasonic focusing method and system for neuromodulation. Background Art

[0002] Transcranial magnetic resonance-guided focused ultrasound is a new neuromodulation technology. Different from previous invasive stimulations, it can non-invasively focus on the cortex or deep brain using phased array ultrasound, and its spatial resolution can reach several cubic millimeters. However, during the actual treatment process, due to the huge difference in sound velocity between the skull and the brain tissue, and the absorption of ultrasound energy by the skull, the phase of the sound beam after entering the brain is severely distorted, ultimately resulting in problems such as speckle generation, focal point shift, and insufficient temperature rise.

[0003] The existing solutions are mainly divided into two aspects: on the one hand, using magnetic resonance acoustic radiation force sequences or ultrasonic acoustic radiation force sequences to obtain the sound field distribution map and performing iterative phase compensation algorithms. On the other hand, using computed tomography (CT) scans to obtain skull acoustic information, and through numerical simulation, achieving transcranial focusing to obtain the focal point in advance and then performing iterative phase compensation and correction. The former requires special imaging equipment for observation, and the latter is the result of theoretical calculations, which may have a certain difference from the actual situation. Summary of the Invention

[0004] In view of the above technical problems, the present invention provides a multi-array ultrasonic focusing method and system for neuromodulation.

[0005] The present invention is implemented by the following technical solutions: In a first aspect, a multi-array ultrasonic focusing system for neuromodulation includes the following modules: Control module: Design a user interface based on an embedded system and FPGA, and set a phased array algorithm to control the ultrasonic intensity and phase of each channel. Power transmission module: Includes an array circuit with a dedicated RF power amplifier as the main body to complete the emission of ultrasonic wave trains for each channel. Echo signal receiving and processing module: Analyze and judge the echo intensity of the sound after filtering the echo within a specified time window. Array probe module: Includes a power transmission piezoelectric ceramic transducer and a receiving transducer to transmit and receive ultrasound.

[0006] Specifically, the embedded system of the control module completes the user interface UI, and the FPGA generates multi-channel precise ultrasonic working pulse timing.

[0007] Specifically, the transducer in the array probe module is a multi-element array and is set to be concave; the receiving transducer is arranged at the center of the entire concave multi-element array.

[0008] On the other hand, a multi-element ultrasonic focusing method for neuromodulation, implemented based on the above-mentioned multi-element ultrasonic focusing system for neuromodulation, includes: Step S1: Set a receiving transducer at the center of the ultrasonic transducer array of the array probe module, and align the focus of the central axis of the concave array with the target area to be modulated. Step S2: Specify the phases of each channel. Step S3: Generate ultrasonic pulses with specified phases, emit ultrasonic waves, and receive the ultrasonic echoes at specified time intervals through the receiving transducer within a specified time window. Step S4: The echo signal receiving and processing module judges the intensity of the ultrasonic echoes. Step S5: If the echo with the maximum intensity is obtained for this phase, determine that this phase corresponds to the focal position; if it is not the echo with the maximum intensity, iteratively adjust the phase and repeat Steps S3 - S4.

[0009] Specifically, Step S1 further includes: specifying the ultrasonic working frequency and amplitude. The working frequency is set to 500 KHz commonly used for neuromodulation, and the amplitude, according to the medical ultrasonic safety specification, the ultrasonic intensity at the focused area for neuromodulation does not exceed 500 mW / cm 2 .

[0010] Specifically, the phase adjustment in Step S5 specifically includes: Emit ultrasonic waves according to the initial parameters, receive echoes according to the specified depth, measure the echo intensity, and then start the next cycle. Change the phases of each channel. The change of the focal spot in the post-cranial sound field is within a range of a radius of 1 cm at a depth of 6 - 8 cm. Calculate the phase shift focusing according to the homogeneous medium situation. Set the defocusing interval, perform radial defocusing in 12 clock directions, change the focus multiple times in each direction, and calculate the phases of each transducer according to the distances between the focus and each transducer.

[0011] The beneficial effects of the present invention are as follows: When performing clinical treatment navigation and positioning, the present invention does not need to consider the distortion of the sound field. Only the focus of the central axis of the concave array needs to be aligned with the target area to be regulated. Then, ultrasonic waves are emitted, and ultrasonic echoes (i.e., echoes at a specified depth) are received within a specified time window. Due to the non-uniformity of intracranial tissues, the reflected echoes caused by stronger incident sound waves have sufficient intensity. Since the distance traveled by the echoes during transcranial propagation is short, and according to the ultrasonic imaging principle, ultrasonic waves propagate approximately in a straight line in soft tissues. Due to the reflection angle and the transcranial distance, when the sound field is focused at the focus of the central axis of the transmitting array, the receiving transducer can receive the strongest ultrasonic echo. By using an iterative algorithm (parameter space traversal algorithm or genetic algorithm) to obtain the operating parameters of the transmitting unit with the strongest echo, it can be ensured that the ultrasonic waves are focused at the original focus after transcranial propagation, overcoming the sound field distortion caused by the skull. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0013] Figure 1 It is a module architecture diagram of a multi-element ultrasonic focusing system for neuromodulation in an embodiment of the present invention; Figure 2 It is a schematic diagram of the multi-element array structure of an array probe module in an embodiment of the present invention; Figure 3 It is a basic flowchart of a multi-element ultrasonic focusing method for neuromodulation in an embodiment of the present invention; Figure 4 It is a schematic diagram of moving the focus in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated in the drawings here can be arranged and designed in various different configurations.

[0015] It should be noted that: Similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0016] The following will be combined with the attached Figures 1 to 4, some embodiments of the present invention will be described in detail. In the case of no conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0017] The present invention provides a multi-element ultrasonic focusing system for neuromodulation, as Figure 1 shown, which includes the following modules: Control module: Based on an embedded system and FPGA, a user interface is designed to set the phased array algorithm to control the ultrasonic intensity and phase of each channel. Power transmission module: It includes an array circuit with a dedicated RF power amplifier as the main body to complete the transmission of ultrasonic wave trains for each channel. Echo signal receiving and processing module: Analyze and judge the intensity of the acoustic echo after filtering the echo within the specified time window. Array probe module: It includes a power transmission piezoelectric ceramic transducer and a receiving transducer to transmit and receive ultrasonic waves.

[0018] In this embodiment, the embedded system of the control module completes the user interface UI, and the FPGA generates the precise ultrasonic working pulse timing for multiple channels; the transducers in the array probe module are multi-element arrays and are set to be concave; the receiving transducer is arranged at the center of the entire concave multi-element array. Taking a 12-element array probe module as an example, as Figure 2 shown, the multi-element ultrasonic transducer array, the entire transducer has a diameter of 6 cm, each transmitting unit has a diameter of 0.9 cm, the receiving unit has a diameter of 0.9 cm, and the concave curvature radius is 7 cm.

[0019] The present invention also correspondingly provides a multi-element ultrasonic focusing method for neuromodulation corresponding to the system, as Figure 3 shown, which includes: Step S1: A receiving transducer is set at the center of the ultrasonic transducer array of the array probe module, and the focus of the central axis of the concave array is aligned with the target area to be modulated. Step S2: Specify the phases of each channel. Step S3: Generate ultrasonic pulses with specified phases, transmit ultrasonic waves, and receive the ultrasonic echoes at specified time intervals through the receiving transducer within the specified time window. Step S4: The echo signal receiving and processing module judges the intensity of the ultrasonic echo. Step S5: If the echo obtained at this phase is the echo with the maximum intensity, then determine that this phase is the corresponding position of the focus; if it is not the echo with the maximum intensity, then iteratively adjust the phase and repeat steps S3 - S4.

[0020] In this embodiment, step S1 further includes: specifying the ultrasonic working frequency and amplitude. The working frequency is set to 500KHz commonly used for neuromodulation, and the amplitude, according to the medical ultrasonic safety specification, does not exceed 500mW / cm at the focused area of the ultrasonic intensity for neuromodulation. 2 .

[0021] In this embodiment, the specific steps for adjusting the phase in step S5 include: Transmit ultrasonic waves according to the initial parameters, receive the echoes according to the specified depth, measure the echo intensity, and then start the next cycle; Change the phase of each channel. The change range of the focal spot in the post-cranial acoustic field is within a radius of 1 cm at a depth of 6 - 8 cm, and calculate the phase shift focus according to the homogeneous medium condition; Set the defocus interval, perform radial defocusing in 12 clock directions, change the focus multiple times in each direction, and calculate the phase of each transducer according to the distance between the focus and each transducer.

[0022] In practical applications, this method uses a receiving transducer set at the center of the transmitting ultrasonic transducer array. When performing neuromodulation, the power ultrasonic transducer for treatment emits ultrasonic waves, and the transducer receives the acoustic echoes at specified time intervals. The phased array acoustic echo reception can obtain the focus where the maximum echo is generated. If the focus is not at the original focus, the phases of each ultrasonic emission are iteratively adjusted to ensure that the ultrasonic focusing point is at the curvature center of the original concave transducer.

[0023] When performing clinical treatment navigation and positioning, there is no need to consider the distortion of the acoustic field. Just align the focus on the central axis of the concave array with the target area to be modulated. Transmit ultrasonic waves and receive the ultrasonic echoes within the specified time window (i.e., the echoes at the specified depth). Due to the inhomogeneity of the intracranial tissues, the reflected echoes caused by the stronger incident acoustic waves have sufficient intensity. Since the distance traveled by the echoes during transcranial propagation is short and the ultrasonic waves approximately propagate in a straight line in soft tissues according to the ultrasonic imaging principle, due to the reflection angle and the transcranial distance, when the acoustic field is focused at the focus on the central axis of the transmitting array, the receiving transducer can receive the strongest ultrasonic echo. By using an iterative algorithm (parameter space traversal algorithm or genetic algorithm) to obtain the working parameters of the transmitting unit with the strongest echo, it is possible to ensure that the ultrasonic waves are focused at the original focus after passing through the skull, overcoming the distortion of the acoustic field caused by the skull.

[0024] In one embodiment, the specific process of this method is as follows: (1) Working initialization: Specify the ultrasonic working frequencies, amplitudes, and phases of each channel. The working frequency is set to 500KHz commonly used for neuromodulation, the amplitude, according to the medical ultrasonic safety specification, does not exceed 500mW / cm2 at the focused area of the ultrasonic intensity for neuromodulation. According to the electrical characteristics of the transducer itself, the voltage is set to 20V per channel in this example, and the phases are all set to 0.

[0025] (2) Phase adjustment stage: Emit ultrasound according to the initial parameters. The ultrasound pulse width is 2 ms. Receive the echo according to the specified depth. For example, at a depth of 6 cm, the echo time at this point is the distance divided by the speed of sound multiplied by 2, that is, t = 6 cm ÷ 1500 m / s × 2 = 80 us (microseconds). The time interval for receiving the echo is 20 us. After measuring the echo intensity, start the next cycle. The repeat cycle time is 20 ms, which is sufficient to avoid the interference of other echoes.

[0026] Change the phase of each channel. According to previous test experience, the change of the acoustic field focal spot after transcranial is within a range of a radius of 1 cm at a depth of 6 - 8 cm. Calculate the phase displacement focus according to the homogeneous medium situation, with a defocus interval of 5 mm. Defocus radially in 12 clock directions, and change the focus 4 times in each direction. Calculate the phase of each transducer according to the distance between the focus and each transducer. After all directions are adjusted in clockwise order, a total of 24 times are completed, which takes 0.48 s. More transducer units or more refined phase steps may result in more time consumption. The defocus points are as Figure 4 shown.

[0027] (3) Determination of phase parameters For example, if the second working parameter corresponds to the maximum intensity, then the second working parameter is the subsequent treatment working parameter.

[0028] For the foregoing embodiments, for the sake of simple description, they are all expressed as a series of action combinations. However, those skilled in the art should know that this application is not limited by the described action sequence, because according to this application, some steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification belong to preferred embodiments, and the actions involved are not necessarily essential to this application.

[0029] In the above embodiments, the basic principles, main features and advantages of the present invention are described. Those skilled in the art of this industry should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, any changes and modifications made by those skilled in the art that do not depart from the spirit and scope of the present invention should fall within the protection scope of the appended claims of the present invention.

Claims

1. A multi-element ultrasound focusing system for neural regulation, characterized in that: Includes the following modules: Control module: Design the user interface based on the embedded system and FPGA, and set the phased array algorithm to control the ultrasonic intensity and phase of each channel; Power transmission module: including an array circuit with a dedicated RF power amplifier as the main body, completing the transmission of ultrasonic trains in each channel; Echo signal receiving and processing module: the echo within the specified time window is filtered and the intensity of the acoustic echo is analyzed and judged; Array probe module: includes a power transmitting piezoelectric ceramic transducer and a receiving transducer to transmit and receive ultrasound.

2. A multi-element ultrasonic focusing system for neural regulation as claimed in claim 1, characterized in that: The control module embedded system completes the user interface UI, and the FPGA generates a multi-channel precise ultrasonic working pulse timing.

3. The multi-element ultrasonic focusing system for neural regulation according to claim 1, characterized in that: The transducer in the array probe module is a multi-element array and is arranged in a concave surface; the receiving transducer is arranged at the center of the entire concave multi-element array.

4. A multi-element ultrasonic focusing method for neural regulation, implemented based on a multi-element ultrasonic focusing system for neural regulation according to any one of claims 1 to 3, characterized in that: include: Step S1: a receiving transducer is arranged at the center of the transmitting ultrasonic transducer array of the array probe module, and the focal point of the central axis of the concave array is aligned with the target area to be regulated; Step S2: specify the phase of each channel; Step S3: Generate an ultrasonic pulse wave of a specified phase, transmit ultrasound, and receive ultrasonic echoes of a specified time interval through a receiving transducer in a specified time window; Step S4: the echo signal receiving and processing module determines the intensity of the ultrasonic echo; Step S5: If the phase obtains the maximum intensity echo, the phase is determined to be the position corresponding to the focus; if it is not the maximum intensity echo, the phase is iteratively adjusted and steps S3 to S4 are repeated.

5. The multi-element ultrasonic focusing method for neural regulation according to claim 4, characterized in that: The step S1 also includes: specifying the ultrasonic working frequency and amplitude, the working frequency is set to 500KHz commonly used for nerve regulation, the amplitude is based on the medical ultrasound safety specification, and the ultrasound intensity used for nerve regulation is not more than 500mW / cm at the focus. 2 .

6. The multi-element ultrasonic focusing method for neural regulation according to claim 4, characterized in that: The step S5 of adjusting the phase specifically includes: Transmit ultrasound according to the initial parameters, receive echoes according to the specified depth, and start the next cycle after measuring the echo intensity; Change the phase of each channel. The focal spot of the transcranial sound field changes within a radius of 1 cm at a depth of 6 to 8 cm. The phase shift is calculated based on the uniform medium condition. Set the focus shift interval, shift the focus radially in 12 clock directions, change the focus multiple times in each direction, and calculate the phase of each transducer based on the distance between the focus and each transducer.

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