CN116236711A - Frequency-replaceable multi-frequency focusing ultrasonic transducer - Google Patents

Abstract

The invention discloses a frequency-replaceable multi-frequency focusing ultrasonic transducer which comprises an outer side high-frequency transducer, a middle low-frequency transducer and an inner side low-frequency transducer which are sequentially nested and assembled from an outer ring to an inner ring, wherein the outer side high-frequency transducer is connected with a first power amplifier and a signal source through a first fundamental wave/harmonic band-pass filter, the middle low-frequency transducer is connected with a second power amplifier and the signal source through a second fundamental wave/harmonic band-pass filter, and the inner side low-frequency transducer is connected with a third power amplifier and the signal source through a third fundamental wave/harmonic band-pass filter. The outermost side of the invention is provided with a high-frequency transducer which is used for realizing accurate tissue damage by using a thermal solidification effect. Centrally located is a low frequency transducer for physically enhancing blood brain barrier permeability. The innermost transducer is a low-frequency transducer which emits fixed frequency and is used for stimulating a specific brain region at the fixed frequency to realize nerve regulation, and the invention can be expanded to at least 6 basic working frequencies.

Description

Frequency-replaceable multi-frequency focusing ultrasonic transducer

Technical Field

The invention belongs to the technical field of power ultrasonic transducers, and particularly relates to a frequency-replaceable multi-frequency focusing ultrasonic transducer.

Background

The brain diseases are treated by utilizing different biological actions generated by the focused ultrasound in the brain, and the method is widely applied to scientific research and clinical scenes as a noninvasive and non-invasive treatment method. The research group of Foster at Indiana university, which uses high-intensity focused ultrasound (high-intensity focused ultrasound, HIFU) for clinically treating the prostate cancer, has initiated the application of the focused ultrasound technology in the clinical field. With the change of the guiding mode from ultrasonic imaging to magnetic resonance imaging, the magnetic resonance guided focused ultrasound technology (MRI guided focused ultrasound, MRgFUS) realizes high-precision guiding of focused ultrasound under the condition of complete skull, and the noninvasive focused ultrasound technology is introduced into the treatment of brain diseases.

Focused ultrasound at different frequencies can cause different biological effects within the brain, thereby achieving specific therapeutic effects. The continuous high-frequency focusing ultrasonic wave can form short-time high temperature in brain tissue to make the brain tissue at the focus form thermal coagulation necrosis, so as to damage focus tissue. High frequency thermal coagulation typically employs frequencies above 650kHz, primarily for specific brain nucleus destruction and tumor ablation. The pulse or burst low-frequency focused ultrasound can form stable cavitation effect in brain tissue to strengthen the permeability of blood brain barrier and make macromolecular medicine pass through blood brain barrier to reach focus. The low-frequency disturbance blood brain barrier generally adopts the frequency of 200-650kHz, and is mainly used for delivering drugs, genes and stem cells of brain tumor, neurodegenerative diseases and the like. For some brain regions, specific low frequency ultrasound may stimulate or inhibit neuronal activity in that region, thereby achieving neuromodulation. Low frequency neuromodulation requires the provision of fixed frequency ultrasound in specific brain regions, centered mainly between 20-500 kHz.

The main method for brain disease research and treatment at present is to intervene on the brain disease by using one mode, and single-frequency ultrasound is the main stream treatment means [ Stavarche et al, world Neurosurgery, 2021.145:581-589; hao-Li et al IEEE Transactions on Biomedical Engineering,2014.61 (4): 1350-1360]. However, in MRgFUS treatment of parkinson's disease, high frequency ablation of specific brain nuclei can inhibit symptoms of tremors and the like, low frequency drug delivery can complement dopamine, fundamentally delay progression of the disease, and specific low frequency ultrasound has potential to optimize therapeutic effects. Therefore, the intervention of multiple frequencies is performed simultaneously to form a composite treatment scheme, the comprehensive treatment of symptoms and disease sources can be realized, and the treatment effect is improved. In MRgFUS treatment of brain tumors, high frequency ablation can destroy most of the tumor tissue, while low frequency drug delivery can effectively inhibit surviving tumor tissue or tumor tissue attached to critical brain areas that cannot be ablated. Also, multiple frequency compound treatment regimens may more powerfully eliminate brain tumors. MRgFUS multi-frequency compound therapies are increasingly exhibiting more needs. At the same time, the size and location of the lesion will also have an impact on the optimal treatment frequency, which requires the transducer to be able to change the treatment frequency according to different applications, optimizing the treatment effect. The above-mentioned compound therapeutic scheme and optimization all need to use the ultrasonic wave of multiple frequencies, therefore, the variable frequency multi-frequency ultrasonic transducer becomes the key of MRgFUS compound brain disease treatment.

The current multi-frequency focusing ultrasonic treatment method is mainly focused on utilizing the dual-frequency enhanced cavitation effect to improve the treatment efficiency [ Chinese invention patent CN 200510111026; suo et al Ultrasonics Sonochemistry,2018.41 (August 2017): 419-426]. In the field of body multi-frequency treatment, the dual-frequency can be utilized to enhance the inertial cavitation to improve the tissue damage efficiency and the damage volume, and is mainly used for the tumor tissue damage of body organs. The inertial cavitation can form intense physical actions such as instantaneous high temperature, high pressure and the like, and can generate crushing damage to tissues. The damage range is large, and the strength is not easy to control, so that the method is not suitable for treating brain diseases with complex structures. Moreover, there are mainly dual frequency transducers with two piezoelectric wafers of different center frequencies fixed on the same substrate [ Li et al Ultrasound in Medicine & Biology ",2018.44 (10): 2089-2104 2018; umemura et al IEEE Transactions on Ultrasonics, ferroelectrics and Frequency Control,1996.43 (6): 1054-1062 ]. Or two independent transducers confocal non-coaxially placed [ Suo et al Physics in Medicine and Biology,2015.60 (18): 7403-7418; chinese invention patent CN 03158000]. In the first structure, the piezoelectric wafer is permanently fixed on the substrate, so that the frequency is not easy to replace; the second structure has simple and convenient replacement frequency, but in use, because the two transducers are relatively weak in mutual fixation, focus failure caused by focus movement easily occurs, and the two transducers have relatively high fixation requirements and need to be calibrated frequently.

In the brain multi-frequency treatment field, multi-frequency ultrasound can promote stable cavitation to enhance blood brain barrier disturbance, and spherical phased array transducers are currently used as the main materials. The first main structure is: the spherical surface is provided with a plurality of transmitting elements, all the transmitting elements are focused through phase control, and each transmitting element is internally provided with three high, medium and low frequency array elements, so as to realize multi-frequency focusing ultrasonic [ Deng et al Physics in Medicine and Biology,2016.61 (24): 8476-8501 ]. The advantage of this structure is that the phased array can realize electronic focus shifting and each transmitting element can simultaneously provide three frequencies, and the disadvantage is that the array elements are very many, and the driving circuit and the control system are relatively complex. The second main structure is: each transmitting element is an array element, the frequency bandwidth of each array element is increased by adding a matching layer, and different array elements transmit different frequencies to realize multi-frequency focusing ultrasonic [ Hao-Li et al IEEE Transactions on Biomedical Engineering,2014.61 (4): 1350-1360]. The advantage of this structure is that the number of array elements is relatively small, and the disadvantage is that increasing the bandwidth by adding a matching layer tends to cause the acoustic energy conversion efficiency to be different at different frequencies, resulting in different therapeutic energies at different frequencies. Comprehensive multi-frequency therapeutic equipment capable of simultaneously realizing thermal ablation, blood brain barrier disturbance and nerve regulation is yet to be developed and improved. Therefore, the development of a frequency-variable multi-frequency focused ultrasound transducer becomes one of the key requirements for MRgFUS composite brain disease treatment.

Disclosure of Invention

The invention aims to solve the problems in the prior art, and provides a frequency-replaceable multi-frequency focusing ultrasonic transducer, which is characterized in that: guided by magnetic resonance imaging, the self-focusing ultrasonic transducer can simultaneously provide high-frequency ultrasonic waves capable of realizing tissue thermal coagulation, low-frequency ultrasonic waves capable of realizing blood brain barrier disturbance and specific-frequency ultrasonic waves capable of realizing nerve regulation and control, can simultaneously work at 3 frequencies or work at 6 frequency time sharing and has replaceable frequency.

In order to achieve the above purpose, the present invention adopts the following technical scheme:

the frequency-replaceable multi-frequency focusing ultrasonic transducer comprises an outer side high-frequency transducer, a middle low-frequency transducer and an inner side low-frequency transducer which are sequentially nested and assembled from an outer ring to an inner ring, wherein the outer side high-frequency transducer is connected with a first power amplifier and a signal source through a first fundamental wave/harmonic band-pass filter, the middle low-frequency transducer is connected with a second power amplifier and the signal source through a second fundamental wave/harmonic band-pass filter, and the inner side low-frequency transducer is connected with a third power amplifier and the signal source through a third fundamental wave/harmonic band-pass filter.

The piezoelectric wafers of the outer high frequency transducer, the intermediate low frequency transducer, and the inner low frequency transducer are in the same spherical surface and confocal as described above.

As described above, the outer side high-frequency transducer, the middle low-frequency transducer and the inner side low-frequency transducer all comprise ring groove shells and piezoelectric wafer modules buckled on the ring groove shells, angle trimming holes are formed in the ring groove shells, piezoelectric wafers are located in the piezoelectric wafer modules, limiting hole columns are arranged at positions, corresponding to the angle trimming holes, of the inner sides of the piezoelectric wafer modules, the inner ends of the angle trimming screws are movably arranged in the limiting hole columns, the angle trimming screws can rotate along the axes of the limiting hole columns but cannot move along the axial direction of the limiting hole columns, the screw rod parts of the angle trimming screws are connected with threads of the angle trimming holes in an adaptive mode, screw heads of the angle trimming screws do not extend out of the angle trimming holes, the piezoelectric wafer modules of the outer side high-frequency transducer and the middle low-frequency transducer are annular, and the piezoelectric wafer modules of the inner side low-frequency transducer are circular.

The first fundamental wave/harmonic band-pass filter, the second fundamental wave/harmonic band-pass filter, and the third fundamental wave/harmonic band-pass filter are used to realize fundamental wave band-pass filtering or harmonic band-pass filtering as described above.

As mentioned above, the outer shell of the outer high frequency transducer, the outer shell of the middle low frequency transducer, the outer shell of the inner low frequency transducer, the angle fine tuning hole and the angle fine tuning screw are all made of nonmagnetic materials.

The frequency range of the outer high frequency transducer is 650kHz-5 MHz as described above; the frequency range of the middle low-frequency transducer is 200kHz-650kHz; the frequency range of the inner low frequency transducer is 20kHz-500kHz.

Compared with the prior art, the invention has the following advantages:

the invention has 6 basic operating frequencies. By nesting and assembling three transducers capable of working independently, the invention can simultaneously emit ultrasonic waves with three frequencies, and each transducer can be switched between the fundamental wave, namely the ultrasonic wave at the resonance frequency, and the third harmonic wave (namely the ultrasonic wave three times the resonance frequency) by independently configuring a set of fundamental wave/harmonic wave band-pass filter and a set of power amplifier and signal source for each transducer. When the frequencies still cannot meet the treatment requirement, any transducer can be replaced by a transducer with the target frequency according to the requirement, so that the treatment effect is optimized.

Of the three nested transducers, the outermost is a high frequency transducer, typically at a frequency between 650kHz-5 MHz, for precise tissue destruction with thermal coagulation. The thermal coagulation causes irreversible damage to tissues, but the space in the brain is narrow and the structure is complex, and the size of a high-frequency ultrasonic focus is required to be small enough to realize accurate treatment. The high-frequency focusing performance is good, the high-frequency transducer is further assembled on the outermost side, the minimum f value is obtained, namely the ratio f of the curvature radius to the diameter of the transducer is minimum, and the thermal destruction volume is minimized. Centrally located is a low frequency transducer, typically at a frequency between 200kHz and 650kHz, for physically enhancing blood brain barrier permeability. Physical effect of enhancing blood brain barrier permeability is reversible change, has no high requirement on treatment precision, and can improve treatment efficiency when treating slightly larger focus. The low frequency blood brain barrier perturbation transducer is mounted in the middle. The innermost transducer is a low frequency transducer emitting a fixed frequency, typically between 20kHz-500kHz, for stimulating a specific brain region at a fixed frequency to achieve neuromodulation. The ultrasonic nerve regulation and control does not need good focusing quality, and focusing can improve ultrasonic energy and improve treatment efficiency, so that the ultrasonic nerve regulation and control is placed at the innermost side.

The invention has universality, the fundamental frequencies of the outermost transducer and the middle transducer can be set in a low frequency band, and the frequency triples are set in a high frequency band, for example, the frequency of the outermost transducer is 400kHz and 1.2MHz, and the frequency of the middle transducer is 300kHz and 900kHz. In a general scenario, the outermost transducer operates at a high frequency and the middle transducer operates at a low frequency; in the application scene with higher low-frequency treatment precision requirement, the outermost transducer works at low frequency, the treatment precision is improved, and the middle transducer works at high frequency. The flexible frequency setting improves the universality of the invention and can be matched with more treatment scenes.

The back of each transducer is respectively provided with three angle fine tuning holes for adjusting the position of the focus of the transducer and improving the focusing quality. Before primary use or after each transducer replacement, the focus of the invention is corrected, and the position of the focus of the transducer is adjusted through the angle fine adjustment hole, so as to realize focusing. The concave fine adjustment screw can effectively prevent false touch and prevent focusing damage.

Drawings

Fig. 1 is a schematic diagram of the overall structure of the present invention.

In the figure: 1-an outside high frequency transducer; 2-an intermediate low frequency transducer; 3-an inboard low frequency transducer; 8-a first fundamental/harmonic bandpass filter; 9-a second fundamental/harmonic bandpass filter; 10-a third fundamental/harmonic bandpass filter; 11-a first power amplifier and a signal source; 12-a second power amplifier and a signal source; 13-third power amplifier and signal source.

Fig. 2 is a schematic view of the assembly of the present invention.

In the figure: 1-an outside high frequency transducer; 2-an intermediate low frequency transducer; 3-inboard low frequency transducer.

Fig. 3a is a front view of the present invention and fig. 3b is a rear view of the present invention.

In the figure: 1-an outside high frequency transducer; 2-an intermediate low frequency transducer; 3-an inboard low frequency transducer; 4-first angle fine tuning holes; 5-fine tuning the hole at a second angle; 6-third angle fine tuning holes; 7-wire preformed holes.

FIG. 4 is a schematic representation of the use of the present invention.

In the figure: 8-a first fundamental/harmonic bandpass filter; 9-a second fundamental/harmonic bandpass filter; 10-a third fundamental/harmonic bandpass filter; 11-a first power amplifier and a signal source; 12-a second power amplifier and a signal source; 13-a third power amplifier and a signal source; 14-a magnetic resonance imaging apparatus; 15-target animal.

Detailed Description

The present invention will be further described in detail below in conjunction with the following examples, for the purpose of facilitating understanding and practicing the present invention by those of ordinary skill in the art, it being understood that the examples described herein are for the purpose of illustration and explanation only and are not intended to limit the invention.

Example 1:

as shown in fig. 1, 2, 3a and 3b, the present invention includes a frequency-replaceable multi-frequency focused ultrasonic transducer including three transducers, an outer high frequency transducer 1, a middle low frequency transducer 2 and an inner low frequency transducer 3, respectively. The outer side high-frequency transducer 1 and the middle low-frequency transducer 2 are concave self-focusing annular transducers, the inner side low-frequency transducer 3 is a concave self-focusing circular transducer, and the three transducers are assembled together in a nested mode to form a complete multi-frequency ultrasonic transducer. The outer side high-frequency transducer 1, the middle low-frequency transducer 2 and the inner side low-frequency transducer 3 can all work independently, after the assembly, the outer side concave surface of the annular piezoelectric wafer module of the outer side high-frequency transducer 1, the outer side concave surface of the annular piezoelectric wafer module of the middle low-frequency transducer 2 and the outer side concave surface of the circular piezoelectric wafer module of the inner side low-frequency transducer 3 are positioned on the same spherical surface, so that the piezoelectric wafers of the outer side high-frequency transducer 1, the middle low-frequency transducer 2 and the inner side low-frequency transducer 3 are positioned on the same spherical surface, and meanwhile, the central axes of the outer side high-frequency transducer 1, the middle low-frequency transducer 2 and the inner side low-frequency transducer 3 are overlapped and the focuses are overlapped, namely the piezoelectric wafers of the outer side high-frequency transducer 1, the middle low-frequency transducer 2 and the inner side low-frequency transducer 3 are positioned on the same spherical surface and are confocal coaxially.

As shown in fig. 3a and 3 b. The back parts of the outer high-frequency transducer 1, the middle low-frequency transducer 2 and the inner low-frequency transducer 3 are respectively provided with three angle fine tuning holes (4, 5 and 6) for fine tuning the positions of the focuses of the transducers.

As a preferable scheme, the two angle trimming holes (4, 6) of each transducer (1, 2, 3) are symmetrically distributed along the central axis of the corresponding transducer, the two angle trimming holes which are symmetrically distributed are positioned on a vertical section, the vertical section is perpendicular to the central axis of the transducer, the intersection point of the central axis and the vertical section is taken as a distribution central point, the other angle trimming hole 5 is positioned on the vertical section and forms a 90-degree azimuth angle with the two angle trimming holes which are symmetrically distributed, and the distances between the three angle trimming holes of the transducers (1, 2, 3) and the distribution central point are equal.

And hexagonal screws or angle trimming screws in other shapes are arranged in the angle trimming holes, and the angle trimming screws do not extend out of the angle trimming holes. By screwing the angle trimming screw in any angle trimming hole, the transducer can rotate by taking the connecting line between the other two angle trimming holes as an axis, and in the rotating process, the focus of the transducer can move in a three-dimensional space. The focal point of the transducer can be adjusted within a certain range in a three-dimensional space by matching with screws in the three angle fine adjustment holes. The height of the angle trimming screw is smaller than the height of the back surface of the transducer, namely, the screw head of the angle trimming screw does not extend out of the angle trimming hole, so that the change of the focus position caused by the fact that the angle trimming screw is touched by mistake in use can be avoided. Before the primary use or after any transducer is replaced each time, the focus coincidence state of the frequency-replaceable multi-frequency focusing ultrasonic transducer is required to be checked and corrected, and the reliability of the focus position during treatment is ensured.

Each transducer (1, 2, 3) comprises a ring groove shell and a piezoelectric wafer module buckled on the ring groove shell, an angle fine adjustment hole is formed in the ring groove shell, wherein the piezoelectric wafer module of the outer high-frequency transducer 1 and the middle low-frequency transducer 2 is annular, the piezoelectric wafer module of the inner low-frequency transducer 3 is circular, the piezoelectric wafer is positioned in the piezoelectric wafer module, a limit hole column is arranged at the position corresponding to the angle fine adjustment hole on the inner side of the piezoelectric wafer module, the inner end of the angle fine adjustment screw is movably arranged in the limit hole column, the angle fine adjustment screw can rotate on the axis of the limit hole column but cannot move along the axial direction of the limit hole column, the movement is arranged into an existing structure, the screw rod of the angle fine adjustment screw is matched with a limit groove, and the screw rod of the angle fine adjustment screw is connected with threads of the angle fine adjustment hole in an adaptive mode, so that the piezoelectric wafer module can drive the piezoelectric wafer to rotate by screwing any angle fine adjustment screw in any angle fine adjustment hole, and a connecting line between two other angle fine adjustment holes is used as a shaft.

In the frequency-replaceable multi-frequency focusing ultrasonic transducer, the back of each transducer is provided with a lead wire preformed hole 7 for placing a transducer matching circuit. In order to make each transducer work independently, each transducer needs to be provided with a set of driving circuits. The wires of the drive circuit lead out of the transducer through the lead preformed holes 7. After the driving circuit is connected, the reserved hole is sealed by using a rubber plug or a screw.

In order to make each transducer individually operable and provide ultrasonic waves of different frequencies, each transducer is individually provided with a set of power amplifier and signal source (first power amplifier and signal source 11, second power amplifier and signal source 12 and third power amplifier and signal source 13). The first power amplifier and signal source 11 provides driving signals for the outer high-frequency transducer 1, the second power amplifier and signal source 12 provides driving signals for the middle low-frequency transducer 2, and the third power amplifier and signal source 13 provides driving signals for the inner low-frequency transducer 3. The high frequency thermal coagulation is typically operated in a continuous mode to ensure efficient energy accumulation while thermal ablation requires a large amount of energy, so the first power amplifier and signal source 11 provides a large power amplification and continuous drive signal, typically at >650kHz continuous drive signal, and provides an ultrasonic signal with peak pressure at >0.42MPa at the focal point. The low frequency perturbed blood brain barrier typically operates in a pulse or burst mode to inhibit temperature rise at the target while the emitted energy is not excessive to avoid inertial cavitation, so the second power amplifier and signal source 12 provides a small power amplification and pulse or burst drive signal, typically at 200kHz-650kHz, burst time of 5-20ms, intervention time >60s, and peak pressure at the focal point of 0.1-0.8 MPa. The low frequency neuromodulation also requires avoidance of excessive temperature rise and inertial cavitation, so the third power amplifier and signal source 13 provides a smaller power amplification and pulsed or bursty drive signal. The signals in the mode are required to be set according to actual requirements, and the regulation and control frequency used among different target areas, depths, functional areas and animal models is large in difference, and the range is usually 20kHz-500kHz.

In order to optimize the treatment effect of each frequency band, each transducer is independently provided with a set of fundamental/harmonic band-pass filters, so that each transducer can additionally provide an operating frequency. The first fundamental wave/harmonic band-pass filter 8 performs frequency switching for the outer high-frequency transducer 1, the second fundamental wave/harmonic band-pass filter 9 performs frequency switching for the middle low-frequency transducer 2, and the third fundamental wave/harmonic band-pass filter 10 performs frequency switching for the inner low-frequency transducer 3. The optimal treatment frequency can be changed by changing the depth of the focus, the surrounding environment of the focus and the position of the nerve regulation brain region. Besides the fundamental wave, the piezoelectric material transducer can emit sound waves at resonance frequency, namely the fundamental wave, the fundamental wave/harmonic wave band-pass filter can emit odd-numbered times of higher harmonic waves of the resonance frequency, the working frequency of each transducer can be switched between the fundamental wave and the higher harmonic wave, the fundamental wave/harmonic wave band-pass filter comprises the fundamental wave band-pass filter and the harmonic wave band-pass filter, the input ends of the fundamental wave band-pass filter and the harmonic wave band-pass filter are respectively connected with two switching ends of the input relay, the fixed ends of the input relay form the input ends of the fundamental wave/harmonic wave band-pass filter, the output ends of the fundamental wave band-pass filter and the harmonic wave band-pass filter are respectively connected with two switching ends of the output relay, the fixed ends of the output relay form the output ends of the fundamental wave/harmonic wave band-pass filter, the fundamental wave band-pass filter and the harmonic band-pass filter of the fundamental wave/harmonic wave band-pass filter are switched by the input relay and the output relay, and the input relay and the output relay are single-pole double-throw relays, and more treatment frequencies are obtained. Because the harmonic energy conversion rate higher than three times is low, the invention only adopts fundamental wave and third harmonic, so each transducer can work at two frequencies of fundamental frequency and frequency tripled, and 6 working frequencies are provided.

The three transducers of the present invention typically provide 6 operating frequencies, any of which may be replaced to achieve the target frequency when these frequencies still fail to meet the therapeutic needs. The replacement transducer needs to have the same dimensional parameters as the original transducer, including but not limited to inner diameter, outer diameter, transducer thickness, radius of curvature of the piezoelectric wafer, etc. When in replacement, the fundamental wave/harmonic band-pass filter matched with the target transducer is replaced together so as to match the replaced working frequency. After the transducer is replaced, the invention needs to be subjected to focusing correction, so that the reliability of the focus position during treatment is ensured. Compared with the method that piezoelectric wafers with different frequencies are arranged on the same substrate, the invention has the advantages that three transducers which independently work are nested and assembled, the replacement is easy, and the universality and the flexibility of the invention are greatly improved.

When the treatment scene does not need to use three frequencies at the same time, only the needed transducer, the matched fundamental wave/harmonic wave band-pass filter, the power amplifier and the signal source are started.

The frequency-replaceable multi-frequency focusing ultrasonic transducer can be used in combination with the magnetic resonance imaging equipment 14, if an ultrasonic probe or an imaging instrument such as an optical microscope is required to be configured, and three frequencies are not required to be used simultaneously, the inner low-frequency transducer 3 and the middle low-frequency transducer 2 can be removed, and the ultrasonic probe or the imaging instrument of the optical microscope can be placed in a hollow area, so that the real-time monitoring of the treatment effect can be realized, and the universality and the flexibility of the ultrasonic transducer are further improved.

The metal fittings such as the angle trimming screw and the like used in the invention are all made of nonmagnetic copper materials; the adhesive and the sealing material are both nonmagnetic materials. The first fundamental wave/harmonic band-pass filter 8, the second fundamental wave/harmonic band-pass filter 9, the third fundamental wave/harmonic band-pass filter 10, the first power amplifier and signal source 11, the second power amplifier and signal source 12 and the third power amplifier and signal source 13 can contain magnetic accessories, but in use, the magnetic accessories are required to be placed outside the magnetic field of the magnetic resonance imaging device 14 and drive signals are conducted through wires. The above settings are all non-magnetized designs that match the magnetic resonance imaging apparatus 14, ensuring the safety of the subject, operator and the invention.

The use of the present invention is briefly described below with reference to examples.

Referring to fig. 4, the present embodiment is shown with a mouse as the target animal 15, but the subject of the present invention is not limited to the mouse. After the frequency-replaceable multi-frequency focusing ultrasonic transducer is assembled and focused, the frequency-replaceable multi-frequency focusing ultrasonic transducer is fixed with the magnetic resonance imaging device 14, so that the relative positions of the focus and the magnetic resonance imaging device 14 are kept unchanged. The first fundamental wave/harmonic band-pass filter 8, the second fundamental wave/harmonic band-pass filter 9, the third fundamental wave/harmonic band-pass filter 10, the first power amplifier and signal source 11, the second power amplifier and signal source 12 and the third power amplifier and signal source 13 are arranged outside the magnetic field of the magnetic resonance imaging device 14 and are connected with the transducer through connecting wires. According to the actual treatment scene, the ultrasonic emission mode, treatment time and output power of the outer side high-frequency transducer 1, the middle low-frequency transducer 2 and the inner side low-frequency transducer 3 are set, and the ultrasonic emission mode, the treatment time and the output power are input into the first power amplifier and signal source 11, the second power amplifier and signal source 12 and the third power amplifier and signal source 13; the treatment frequency of each transducer is designed, and the frequency setting is completed by the first fundamental wave/harmonic wave band-pass filter 8, the second fundamental wave/harmonic wave band-pass filter 9 and the third fundamental wave/harmonic wave band-pass filter 10. After determining the focus position of the brain of the target animal 15 by using the magnetic resonance imaging method, the focus can be moved until the focus starts to treat. When the focus positions of the high-frequency treatment and the low-frequency treatment coincide, the high-frequency treatment and the low-frequency treatment are started simultaneously. When the focus positions of the high-frequency treatment and the low-frequency treatment do not coincide, after the high-frequency treatment is finished, the focus is moved to the focus of the low-frequency treatment to carry out the treatment, and then the focus is moved to the brain region of the low-frequency nerve regulation and control to carry out the treatment, so that the treatment flow of the brain of the target animal 15 is completed.

The treatment frequency and the output power need to be adjusted according to the target position and the depth, and preferred parameters of the embodiment are as follows: the frequency of the external high-frequency transducer 1 and the first power amplifier and the signal source 11 was set to 1.5MHz, and the output power was set to 10W/cm ² The drive signal is set to a continuous form for a duration of 1 minute; the frequency of the intermediate low frequency transducer 2 and the second power amplifier and the signal source 12 is 650kHz, and the output power is 1W/cm ² The drive signal is set to 10 millisecond burst, pulse repetition rate 1Hz, duration 5 minutes; the frequency of the inner low-frequency transducer 3 and the third power amplifier and the signal source 13 is set to be 500kHz, and the output power is set to be 3W/cm ² The drive signal was set to a pulse form, a pulse repetition rate of 1.5kHz, and a duration of 0.06 seconds. The magnetic resonance imaging apparatus 14 is a 3.0T small animal imaging apparatus (sign, GE Healthcare, USA).

The specific embodiments described herein are offered by way of example only to illustrate the spirit of the invention. Those skilled in the art may make various modifications or additions to the described embodiments or substitutions thereof without departing from the spirit of the invention or exceeding the scope of the invention as defined in the accompanying claims.

Claims (6)

1. The frequency-replaceable multi-frequency focusing ultrasonic transducer is characterized by comprising an outer side high-frequency transducer (1), a middle low-frequency transducer (2) and an inner side low-frequency transducer (3) which are sequentially nested and assembled from an outer ring to an inner ring, wherein the outer side high-frequency transducer (1) is connected with a first power amplifier and a signal source (11) through a first fundamental wave/harmonic band-pass filter (8), the middle low-frequency transducer (2) is connected with a second power amplifier and a signal source (12) through a second fundamental wave/harmonic band-pass filter (9), and the inner side low-frequency transducer (3) is connected with a third power amplifier and a signal source (13) through a third fundamental wave/harmonic band-pass filter (10).

2. A frequency-interchangeable multi-frequency focused ultrasound transducer according to claim 1, characterized in that the piezoelectric wafers of the outer high frequency transducer (1), the middle low frequency transducer (2) and the inner low frequency transducer (3) are in the same sphere and confocal.

3. The frequency-replaceable multi-frequency focusing ultrasonic transducer according to claim 1, wherein the outer side high-frequency transducer (1), the middle low-frequency transducer (2) and the inner side low-frequency transducer (3) all comprise ring groove shells and piezoelectric wafer modules buckled on the ring groove shells, angle fine-tuning holes are formed in the ring groove shells, piezoelectric wafers are located in the piezoelectric wafer modules, limiting hole columns are arranged at positions, corresponding to the angle fine-tuning holes, on the inner sides of the piezoelectric wafer modules, inner ends of the angle fine-tuning screws are movably arranged in the limiting hole columns, the angle fine-tuning screws can rotate on axes of the limiting hole columns but cannot move along the axial direction of the limiting hole columns, screw rod parts of the angle fine-tuning screws are connected with threads of the angle fine-tuning holes in an adaptive mode, screw heads of the angle fine-tuning screws do not extend out of the angle fine-tuning holes, the piezoelectric wafer modules of the outer side high-frequency transducer (1) and the middle low-frequency transducer (2) are annular, and the piezoelectric wafer modules of the inner side low-frequency transducer (3) are circular.

4. The frequency-replaceable multi-frequency focused ultrasound transducer of claim 1, wherein the first fundamental/harmonic bandpass filter (8), the second fundamental/harmonic bandpass filter (9), and the third fundamental/harmonic bandpass filter (10) are configured to implement fundamental bandpass filtering or harmonic bandpass filtering.

5. The frequency-replaceable multi-frequency focused ultrasound transducer according to any one of claims 1-4, wherein the outer housing of the outer high frequency transducer (1), the outer housing of the middle low frequency transducer (2), the outer housing of the inner low frequency transducer (3), the angle trimming hole and the angle trimming screw are all nonmagnetic materials.

6. The frequency-interchangeable multi-frequency focused ultrasound transducer according to claim 5, characterized in that the frequency range of the outer high frequency transducer (1) is 650kHz-5 MHz; the frequency range of the middle low-frequency transducer (2) is 200kHz-650kHz; the frequency range of the inner low frequency transducer (3) is 20kHz-500kHz.

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