An acoustic lens and ultrasonic ablation device for ablation of human target tissue

Abstract

This invention belongs to the field of ultrasound control application technology, specifically relating to an acoustic lens and an ultrasound ablation device for ablation of human target tissue. The acoustic lens is a Fresnel lens with a sleeve structure and a stepped surface arrangement. One design method for its surface geometry is as follows: simulating the two-dimensional axially symmetrical three-dimensional sound propagation field of the acoustic lens, dividing the two-dimensional propagation plane of the three-dimensional sound propagation field into a finite number of grid points, maximizing the sound pressure at the target grid point and minimizing the sound pressure at grid points other than the target grid point, iteratively optimizing the surface geometry parameters; the target grid point is a set parameter corresponding to the position of the target tissue relative to the acoustic lens and the morphology of the target tissue. Another design method is based on a method for generating a large-angle, non-diffractive sound bending channel, constructing a bent sound beam functional structure. The ultrasound ablation device consists of an ultrasound transducer and the aforementioned acoustic lens. This invention can reduce damage to normal tissues during HIFU treatment for different target tissues.

Description

Technical Field

[0001] This invention belongs to the field of ultrasonic control application technology, and more specifically, relates to an acoustic lens and ultrasonic ablation device for ablation of human target tissue. Background Technology

[0002] In clinical medicine, ultrasound is widely used in various treatment and diagnostic procedures. It possesses the ability to penetrate biological tissues and generate thermal and mechanical effects without invasive surgery, making it particularly advantageous in treating diseases such as tumors and cardiovascular diseases. Thanks to the rapid development of medical technology in recent years, non-invasive ultrasound therapy has gradually become an important tool in the clinical field. High-intensity focused ultrasound (HIFU), as a non-invasive and radiation-free treatment technique, focuses MHz-frequency ultrasound waves onto the target tissue. Utilizing the excellent directivity, penetrability, and focusing properties of ultrasound, the energy passing through non-treatment areas is insufficient to cause tissue damage. Simultaneously, the generated high-intensity focal spot induces a high-temperature effect in a short time, causing acute thermal coagulation necrosis of the diseased tissue in the target area. This allows for precise treatment of target points within the body without damaging the skin or tissue. Modern medicine has widely accepted HIFU as a non-invasive and radiation-free treatment method, achieving significant results, especially in tumor ablation and the treatment of cardiovascular diseases.

[0003] Despite this, existing HIFU devices have certain limitations in terms of focusing accuracy, control range, and focusing effect. During HIFU treatment, the control of the ultrasound focusing mode is considered a core technology. To achieve effective focused ultrasound in deep lesions, the main focusing methods employed include curved surface self-focusing, phased array focusing, and acoustic lensing focusing. Curved surface self-focusing involves converging the ultrasound beam emitted by array elements at the geometric focal point of a curved surface, thus forming a focused hot spot. Phased array focusing controls the excitation signals of each element in the ultrasound transducer array, adjusting the vibration amplitude and phase of the element surface to form a coherent wavefront with spherical convergence or deflection of ultrasound waves, achieving electronically controlled ultrasound focusing and scanning. Acoustic lensing focusing works similarly to optical focusing, where ultrasound waves are focused after passing through a concave acoustic lens. However, the size and position of the focal point are closely related to the radius of curvature of the acoustic lens. Furthermore, traditional acoustic lensing focuses absorb ultrasound waves, resulting in relatively low focusing efficiency, and the high temperature generated by absorption can cause deformation of the acoustic lens, further affecting focusing accuracy.

[0004] Therefore, existing HIFU devices, especially when ablating target tissues located outside blood vessels, esophagus, or airway, may cause unnecessary damage to non-target tissues such as blood vessel walls, tracheal walls, and esophageal walls. Summary of the Invention

[0005] To address the shortcomings and improvement needs of existing technologies, this invention provides an acoustic lens and ultrasonic ablation device for ablation of human target tissues. Its purpose is to achieve adjustable focal length of the focused acoustic device, thereby reducing damage to non-target tissues during HIFU treatment.

[0006] To achieve the above objectives, according to one aspect of the present invention, an acoustic lens for ablation of human target tissue is provided, which is a Fresnel acoustic lens with a sleeve structure and a stepped surface arrangement, and its surface geometric parameters are designed in the following manner:

[0007] The three-dimensional sound propagation field of a Fresnel acoustic lens with two-dimensional axial symmetry is simulated. The two-dimensional propagation plane of the three-dimensional sound propagation field is divided into a finite number of grid points n. The surface geometric parameters are iteratively optimized with the goal of maximizing the sound pressure at the target grid point and minimizing the sound pressure at grid points other than the target grid point.

[0008] The target grid points are set parameters that correspond to the position of the target tissue relative to the acoustic lens and the morphology of the target tissue.

[0009] Furthermore, the specific objective is as follows:

[0010] Maximize the ratio of the sum of sound pressures at the points corresponding to the first m sound pressures on the target transmission trajectory in the two-dimensional propagation plane to the sum of sound pressures at all other points outside the target transmission trajectory;

[0011] Wherein, the target transmission trajectory is a set parameter, corresponding to the position of the target tissue relative to the acoustic lens and the morphology of the target tissue; m is a set value. When m is 1, the design of the surface geometry parameters is used to adjust the focal length of the acoustic lens. When m is greater than 1, the design method is used to adjust the size of the focal region of the acoustic lens.

[0012] Furthermore, when the target tissue to be ablated is located around normal tissue, multiple focal zones are determined on the two-dimensional propagation plane based on the relative positions of the target tissue and the normal tissue. These multiple focal zones are connected to form a ring, and the ring area corresponds to the area of ​​normal tissue to be protected. The target is specifically defined as follows:

[0013] Maximize the sound pressure at the center of each focal zone and minimize the sound pressure at the center of the ring.

[0014] Furthermore, a genetic algorithm is used to perform the maximization optimization operation.

[0015] Furthermore, the steps on the surface of the Fresnel acoustic lens are smoothed to form multiple wedges to eliminate the step height difference;

[0016] The surface geometric parameters are the height and width of each wedge.

[0017] The present invention also provides an acoustic lens for ablation of human target tissue, which is a Fresnel acoustic lens with a sleeve structure and a stepped surface arrangement, and its surface geometric parameters are designed in the following way:

[0018] Based on the morphology and location of the target tissue, the curved acoustic beam trajectory of the acoustic lens focal region on the two-dimensional propagation plane is determined; based on the coordinates of each point on the curved acoustic beam trajectory, the phase profile formula of the acoustic lens surface is applied. Integrate to determine the initial phase distribution on the surface of the acoustic lens, where k is the wavenumber of the acoustic wave; determine the height of each step of the acoustic lens based on the correspondence between the height of the acoustic lens steps and the initial phase.

[0019] Among them, using the geometric sound ray propagation theory, the relationship between the wavefront and the slope of the curved sound beam trajectory in Cartesian coordinates is constructed as follows: In the formula, u and v constitute the coordinates (u,v) of any point on the curved sound beam trajectory; according to the triangle side-angle relationship, we can get ξ=v-[-utan(π-θ)]=v-utan(θ); in the formula, ξ is the projection distance of any point on the wavefront surface on the curved sound beam trajectory; f(x) is the Bézier curve generated by the Bézier polynomial, and x is the abscissa of each point on the curved sound beam trajectory.

[0020] The present invention also provides an intracavitary interventional ultrasonic ablation device, comprising: an ultrasonic transducer and an acoustic lens for ablation of human target tissue as described above.

[0021] The ultrasonic transducer is fitted into the hollow cavity of the acoustic lens; mechanical vibration is excited circumferentially by the ultrasonic transducer, causing the acoustic lens to vibrate and generating a sound propagation field.

[0022] Furthermore, it can be used for ablation of extracavitary target tissues.

[0023] In summary, the above-described technical solutions conceived in this invention can achieve the following beneficial effects:

[0024] (1) This invention proposes an acoustic lens for ablation of human target tissue, which is a Fresnel acoustic lens with a sleeve structure and a stepped surface. The surface geometric parameters of this acoustic lens can be artificially designed in conjunction with the morphology of the target tissue. Furthermore, the surface geometric parameters can be designed in the following way: the three-dimensional sound propagation field of the Fresnel acoustic lens with two-dimensional axial symmetry is simulated, and the two-dimensional propagation plane of the three-dimensional sound propagation field is divided into a finite number of grid points n. The surface geometric parameters are iteratively optimized with the goal of maximizing the sound pressure at the target grid point and minimizing the sound pressure at grid points other than the target grid point. The target grid point is a set parameter, corresponding to the position of the target tissue relative to the acoustic lens and the morphology of the target tissue. This design method combines the morphology of the target tissue and customizes the artificial structure of the acoustic lens, which can realize the adjustment of the focal length and focal area of ​​the acoustic lens, thereby realizing the focusing of the sound field onto the target tissue and reducing damage to non-target tissues.

[0025] (2) Considering the diffraction of the sound field weakened by the height between each step and the limitation of subsequent processing accuracy, the present invention performs a smoothing process on each Fresnel band of the Fresnel lens to eliminate the step height difference on a single Fresnel band; then the acoustic lens proposed in this invention is a Fresnel acoustic lens with a stepped arrangement on the surface of the sleeve structure, and all the wedge structures constitute the functional structure of the acoustic lens. The above surface geometric parameters are the height and width of each wedge, which simplifies the surface structure of the acoustic lens.

[0026] (3) This invention also proposes another acoustic lens for ablation of human target tissue, the surface geometry of which is designed as follows: based on the morphology and position of the target tissue, the curved acoustic beam trajectory of the acoustic lens focal region on the two-dimensional propagation plane is determined; based on the coordinates of each point on the curved acoustic beam trajectory, the phase distribution of the acoustic lens surface is determined. The initial phase at each step on the surface of the acoustic lens is determined; based on the correspondence between the height of the acoustic lens step and the initial phase, the height of each step of the acoustic lens is determined. In other words, this invention, based on a method for generating large-angle, diffraction-free curved acoustic channels, modulates the phase by changing the height parameters of adjacent ring structures of the acoustic lens, thereby constructing the curved acoustic beam functional structure of the acoustic lens of this invention, which can be used to achieve curved path ablation within human cavities.

[0027] (4) This invention proposes an intracavitary interventional ultrasound ablation device, comprising an ultrasound transducer and an acoustic lens for target tissue ablation as described above. It is an intracavitary interventional high-intensity ultrasound ablation device applicable to extracavitary target tissue ablation. By incorporating acoustic lens structures with different parameters around a cylindrical high-intensity ultrasound transducer, adjustable high-intensity focusing is achieved. Adjustable HIFU focal length significantly broadens its application range, enabling coverage of lesions at different depths, thereby enhancing the comprehensiveness and flexibility of treatment. Simultaneously, adjusting the focal length allows ultrasound energy to be precisely focused on the target tissue, avoiding the influence of ultrasound energy on non-target areas and reducing potential damage to normal tissues or vital organs. Attached Figure Description

[0028] Figure 1 Schematic diagrams of four acoustic lens structures for ablation of human target tissue provided in embodiments of the present invention;

[0029] Figure 2 A three-view diagram of an acoustic lens structure for ablation of human target tissue provided in an embodiment of the present invention;

[0030] Figure 3 Three-view diagram of another acoustic lens structure for ablation of human target tissue provided in an embodiment of the present invention;

[0031] Figure 4 Provided for embodiments of the present invention Figure 2 Two-dimensional ultrasonic sound field distribution diagram corresponding to the full-wave numerical simulation of the acoustic lens;

[0032] Figure 5 Provided for embodiments of the present invention Figure 3 Two-dimensional ultrasonic sound field distribution diagram corresponding to the full-wave numerical simulation of the acoustic lens;

[0033] Figure 6 A three-view diagram of an acoustic lens structure for ablation of human target tissue provided in an embodiment of the present invention;

[0034] Figure 7 Provided for embodiments of the present invention Figure 6 Two-dimensional ultrasonic sound field distribution diagram corresponding to the full-wave numerical simulation of the acoustic lens;

[0035] Figure 8 A three-view diagram of an acoustic lens structure for ablation of human target tissue provided in an embodiment of the present invention.

[0036] Figure 9 Provided for embodiments of the present invention Figure 7 Two-dimensional ultrasonic sound field distribution diagram corresponding to the full-wave numerical simulation of the acoustic lens;

[0037] Figure 10This is a schematic diagram of an intracavitary interventional ablation device provided in an embodiment of the present invention. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0039] Example 1

[0040] An acoustic lens for ablation of human target tissue is a Fresnel acoustic lens with a sleeve structure and a stepped surface arrangement, and its surface geometry is designed in the following way:

[0041] The three-dimensional sound propagation field of a Fresnel acoustic lens with two-dimensional axial symmetry is simulated. The two-dimensional propagation plane of the three-dimensional sound propagation field is divided into a finite number of grid points n. The surface geometric parameters are iteratively optimized with the goal of maximizing the sound pressure at the target grid point and minimizing the sound pressure at grid points other than the target grid point. The target grid point is a set parameter, corresponding to the position of the target tissue relative to the acoustic lens and the morphology of the target tissue.

[0042] Acoustic lensing, as a method of high-intensity focused ultrasound, works similarly to optical focusing, where ultrasound waves are focused after passing through a concave acoustic lens. Fresnel lenses, as a special type of optical device, can achieve subwavelength-level focusing, defocusing, and even aberration correction. Compared to traditional spherical lenses, Fresnel lenses are created by dividing the original lens into theoretically countless concentric circular ridges (i.e., Fresnel zones), and then cutting multiple layers with a thickness of mλ / (n-1) along the height direction, where m, λ, and n are the integer order, wavelength, and refractive index of the Fresnel lens, respectively. The design of a Fresnel lens is achieved by folding a 2mπ arc phase in the lens material.

[0043] A Fresnel lens alters the direction of light propagation through Fresnel diffraction generated on its surface. The mathematical model of how a Fresnel lens diffracts a light field and maps it onto the focal plane (i.e., the Fresnel diffraction formula) can be expressed as:

[0044]

[0045] E(u,f) describes the light field at a position f from the focal length of the lens (i.e., the focal plane), where u represents the lateral coordinate on the focal plane; E(x,y) describes the amplitude distribution of the initial light field on the object plane, where x and y represent the lateral and ordinate coordinates on the object plane, respectively, λ is the wavelength of light, and i is the imaginary unit. Analogous to an acoustic lens, the light field intensity E(u,f) on the focal plane should be rewritten as the sound field intensity A(u,f), and the initial light field on the object plane should be rewritten as the initial sound field A(u,f). The corresponding light wavelength should be the same as the sound wavelength. Therefore, the Fresnel diffraction formula for an acoustic lens is:

[0046]

[0047] Based on the above method of classifying traditional folding lenses, a Fresnel acoustic lens with a stepped arrangement was designed, such as... Figure 1 As shown, there are four Fresnel acoustic lenses with sleeve structures whose surfaces are arranged in different stepped patterns. For example, the material of the four acoustic lenses in the figure is aluminum 6063.

[0048] Regarding the design of surface geometry parameters, since the surface geometry parameters of the acoustic lens described above can be artificially designed by combining the morphology of the target tissue, this embodiment proposes to simulate the three-dimensional sound propagation field of the Fresnel acoustic lens, which is symmetrical about two-dimensional axis. The two-dimensional propagation plane of the three-dimensional sound propagation field is divided into a finite number of grid points n. The surface geometry parameters are iteratively optimized with the goal of maximizing the sound pressure at the target grid point and minimizing the sound pressure at grid points other than the target grid point. Here, the target grid point is a set parameter, corresponding to the position of the target tissue relative to the acoustic lens and the morphology of the target tissue. This design method combines the morphology of the target tissue to customize the artificial structure of the acoustic lens, which can enable the sound field of the acoustic lens to be focused onto the target tissue and reduce damage to non-target tissues.

[0049] As a preferred implementation method, the above objectives are specifically as follows:

[0050] The goal is to maximize the ratio of the sum of the sound pressures of the first m sound pressure points on the target transmission trajectory in the two-dimensional propagation plane to the sum of the sound pressures of all other points outside the target transmission trajectory. Here, the target transmission trajectory is a set parameter, corresponding to the position of the target tissue relative to the acoustic lens and the morphology of the target tissue. The above m is a set value. When m is 1, the above surface geometry parameter design is used to adjust the focal length of the acoustic lens. When m is greater than 1, the above design method is used to adjust the size of the focal region of the acoustic lens.

[0051] The objective function can be expressed as:

[0052] This embodiment uses this as the objective function and combines optimization algorithms (such as genetic algorithms) to design and determine the acoustic lens parameters, aiming to maximize the sound pressure along a specified path to achieve high-intensity focused ultrasound with adjustable focal length and focal range. In clinical applications, high-intensity focused ultrasound with adjustable focal length is not limited by lesions of fixed depth, adapting to lesions of different depths and locations, precisely controlling the energy distribution of ultrasound waves, and achieving thermal ablation of target tissues at specified locations.

[0053] As an example, Figure 2 and Figure 3 Three-view diagrams of two intracavitary ablation acoustic lens structures are shown, with different surface geometric parameters for the two structures. Figure 2 and Figure 3 The full-wave numerical simulation two-dimensional ultrasonic sound field distributions corresponding to the acoustic lenses are shown as follows: Figure 4 and Figure 5 As shown. Figure 4 The left image is for reference. Figure 2 Full-wave simulation results of a mid-acoustic lens in a two-dimensional propagation cross section. The sound velocity of the background fluid medium is set to 1500 m / s, and the density is set to 1000 kg / m³. 3 The excitation sound source center frequency is set to 9MHz, corresponding to a wavelength of λ = 167μm. The propagation plane focal length is 6.5mm, and the focal range is 4mm, meaning the high-intensity focused focal spot covers 5–9mm. The black solid line represents the normalized intensity distribution along the lateral direction at the focal point. Figure 4 The right image is a 3D view of the left image after rotation symmetrically along a two-dimensional axis. The dark annular area in the cross-section represents a high-intensity focused focal spot, generating high-intensity acoustic energy, which can be used for interventional ablation of target tissues within human cavities such as blood vessels, airways, and esophagus. Optimizing the acoustic lens structure parameters according to the objective function can alter the focal length and focal range, as shown in the reference. Figure 3 The full-wave simulation results of the mid-acoustic lens at the two-dimensional propagation interface are as follows: Figure 5 As shown in the left image, the focal length extends to 9.5mm, and the focal range expands to 6mm. Similarly, Figure 5 The right image is a three-dimensional view formed by rotating the left image symmetrically along a two-dimensional axis. The cross-sectional area is covered by dark annular high-intensity focal spots ranging from 7.4mm to 13.5mm.

[0054] It should be noted that the above target transmission trajectory is as follows: Figure 4 The red area shown in the left figure represents the straight line trajectory in the r direction. Figure 4 The red area in the left figure is a two-dimensional cross-sectional view of the three-dimensional focal region in the r direction. By determining a value greater than 1 for m, the size of the acoustic lens focal region in the lateral direction can be adjusted. The size of the acoustic lens focal region in the direction perpendicular to the two-dimensional propagation plane is not designed for adjustment, because in actual medical operations, the front and rear positions of the acoustic lens in the cavity can be adjusted to meet the ablation of target tissues at different front and rear positions.

[0055] As another preferred embodiment, when the target tissue to be ablated is located around normal tissue, multiple focal zones are determined on the aforementioned two-dimensional propagation plane based on the relative positions of the target tissue and the normal tissue. These multiple focal zones are connected to form a ring, and the ring area corresponds to the area of ​​normal tissue to be protected. Specifically, the target is:

[0056] Maximize the sound pressure at the center of each focal region and minimize the sound pressure at the center of the aforementioned ring. As an example, considering two ring regions, the objective can be expressed as the following objective function:

[0057] MaximumF obj =|p(r0,z0)| 2 ;

[0058] MaximumF obj =|p(r1,z0)| 2 ;

[0059] MaximumF obj =|p(r2,z0)| 2 ;

[0060] MaximumF obj =|p(r3,z0±2λ)| 2 ;

[0061] MaximumF obj =|p(r4,z0±2λ)| 2 ;

[0062] MinimumF obj =|p(r3,z0)| 2 ;

[0063] MinimumF obj =|p(r4,z0)| 2 ;

[0064] The coordinate points (r0,z0), (r1,z0), (r2,z0), (r3,z0±2λ), (r4,z0±2λ), (r3,z0), and (r4,z0) in the cylindrical coordinate system are shown in Figure 7.

[0065] As an example, Figure 6 The diagram shows a three-view drawing of an intracavitary interventional ablation acoustic lens structure. The full-wave numerical simulation of the two-dimensional ultrasound sound field distribution corresponding to the acoustic lens of this structure is shown in the figure. Figure 7 As shown.

[0066] By optimizing the structural parameters of the acoustic lens, the acoustic bottle bundle is constructed. (Refer to...) Figure 6The full-wave simulation results of the mid-acoustic lens at the two-dimensional propagation interface are as follows: Figure 7 As shown in the left figure, two low-energy regions with adjustable positions are created on the two-dimensional propagation interface, which are the areas to be protected along the ablation path. Similarly, Figure 7 The right image is a three-dimensional view formed by rotating the left image symmetrically along a two-dimensional axis. There are two light-colored, low-intensity rings in the cross-sectional area, representing the ablation zone of non-target tissues to be protected, such as blood vessel walls and esophageal walls, along the ablation path.

[0067] like Figure 7 When the two-dimensional propagation plane is rotated symmetrically along a two-dimensional axis, the entire three-dimensional sound propagation field of the acoustic lens is formed. The aforementioned annular region will then correspond to a cavity in this three-dimensional sound propagation field, serving as a cavity protection area during the ablation operation. This area is where the normal tissue is located. This preferred embodiment fully considers the practical situation where the target tissue to be ablated is located around normal tissue, avoiding the influence of ultrasound energy on non-target areas in such complex scenarios. It minimizes potential damage to normal tissue or vital organs, achieving target tissue ablation with a protected area. This demonstrates the high application flexibility and practical feasibility of this embodiment.

[0068] In high-intensity focused ultrasound (HIFU) therapy, by creating a cavity protection zone: 1) it can effectively isolate and protect surrounding normal tissue structures, especially for lesions near sensitive organs or structures, such as nerves and blood vessels; 2) it enhances the positioning accuracy of HIFU therapy, allowing physicians to more precisely control the focusing of ultrasound energy and improve the precision of treatment; 3) it expands the indications for treatment, as the cavity protection zone allows lesions that are originally in sensitive locations or near important structures to receive HIFU therapy, increasing the treatment range.

[0069] Considering the diffraction of the sound field weakened by the height between each step, and the limitations of subsequent processing accuracy, as a preferred implementation, each Fresnel band of the Fresnel lens is smoothed to eliminate the step height difference on a single Fresnel band. In this case, the acoustic lens proposed in this embodiment is a Fresnel acoustic lens with a sleeve structure and a stepped surface arrangement. All wedge structures constitute the functional structure of the acoustic lens, and the above surface geometric parameters are the height and width of each wedge.

[0070] Example 2

[0071] An acoustic lens for ablation of human target tissue is a Fresnel acoustic lens with a sleeve structure and a stepped surface arrangement, and its surface geometry is designed in the following way:

[0072] Based on the morphology and location of the target tissue, the curved acoustic beam trajectory of the acoustic lens focal region on the two-dimensional propagation plane is determined; based on the coordinates of each point on the curved acoustic beam trajectory, the phase profile formula of the acoustic lens surface is used. Integrating, the initial phase distribution on the surface of the acoustic lens is determined, where k is the wavenumber of the sound wave. Based on the correspondence between the height of the acoustic lens steps and the initial phase, the height of each step of the acoustic lens is determined. Using the geometric ray propagation theory, the relationship between the wavefront and the slope of the curved sound beam trajectory is constructed in Cartesian coordinates as follows: In the formula, u and v constitute the coordinates (u,v) of any point on the curved sound beam trajectory; according to the triangle side-angle relationship, we can get ξ=v-[-utan(π-θ)]=v-utan(θ); where ξ is the projection distance of any point on the wavefront onto the curved sound beam trajectory; f(x) is the Bézier curve generated by the Bézier polynomial p(t), and x is the abscissa of each point on the curved sound beam trajectory. t is a parameter, and n is the Bessel order.

[0073] This embodiment is based on a method for generating large-angle, non-diffractive, curved acoustic channels. By changing the height parameters of adjacent ring structures of the acoustic lens, the phase is modulated to form the curved acoustic beam functional structure of the acoustic lens in this embodiment, thereby achieving ablation of curved paths within the human body cavity.

[0074] As an example, Figure 8 The diagram shows a three-view drawing of one type of intracavitary interventional ablation acoustic lens structure. The full-wave numerical simulation of the two-dimensional ultrasound sound field distribution corresponding to this acoustic lens structure is shown below. Figure 9 As shown.

[0075] Based on a method for generating large-angle, diffraction-free curved acoustic channels, an acoustic lens functional structure for curved acoustic beams was constructed to achieve curved path ablation. (Refer to...) Figure 8 The full-wave simulation results of the mid-acoustic lens at the two-dimensional propagation interface are as follows: Figure 9 As shown.

[0076] The acoustic artificial lens designed based on the generation method of large-angle non-diffraction acoustic bending channel provides the possibility for ablation of complex or hard-to-access target lesions: 1) Through the self-bending path, high-intensity focused ultrasound (HIFU) can more comprehensively cover the target tissue, especially those lesions with irregular shapes or varying sizes. This comprehensive coverage helps improve treatment efficacy and reduce the risk of residual lesions; 2) Enhanced treatment precision: self-bending thermal ablation provides more precise thermal energy control, allowing physicians to adjust the energy distribution according to the specific conditions of the lesion, achieving higher precision treatment; 3) The precisely controlled thermal ablation process reduces damage to non-target tissues, thereby alleviating patient pain and discomfort, and improving treatment safety and patient acceptance.

[0077] Example 3

[0078] An intracavitary interventional ultrasonic ablation device includes: an ultrasonic transducer and an acoustic lens for ablation of human target tissue as described in Embodiment 1 or Embodiment 2 above; the ultrasonic transducer is fitted into the hollow cavity of the acoustic lens; mechanical vibration is excited by the upper ultrasonic transducer along the circumferential direction, causing the acoustic lens to vibrate and generating an acoustic propagation field.

[0079] By selecting acoustic lenses with different functional structural geometric parameters (i.e., the aforementioned planar geometric parameters), the adjustable focal length and focal range of HIFU can be effectively achieved.

[0080] like Figure 10 An intracavitary interventional ultrasound ablation device is shown. As a focused acoustic device, it consists of a high-intensity ultrasound transducer and an acoustic lens as described in Embodiment 1 or Embodiment 2 above. That is, in practice, high-intensity ultrasound focusing outside the blood vessel can be achieved by adjusting the geometric parameters of the acoustic lens and introducing a fluid-structure interaction effect, i.e., for ablation of target tissues outside the blood vessel.

[0081] In summary, this invention proposes an innovative acoustic device design based on the Fresnel lens principle. This design utilizes optimization algorithms to adjust the geometric parameters of the acoustic lens, precisely controlling the HIFU focal spot, focal range, and intensity to achieve accurate thermal ablation of target tissues. Furthermore, this design improves the precision of ultrasound therapy while avoiding damage to non-target tissues such as blood vessel walls, increasing the personalization and flexibility of treatment, and demonstrating excellent operability and adaptability when used in conjunction with existing HIFU devices. The application of this invention is expected to bring substantial improvements to the clinical application of HIFU, enhancing treatment outcomes and reducing patient suffering.

[0082] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An acoustic lens for ablation of a target tissue in a human body, characterized in that, It is a Fresnel acoustic lens with a sleeve structure and a stepped surface, and its surface geometry is designed in the following way: The three-dimensional sound propagation field of a Fresnel acoustic lens with two-dimensional axial symmetry is simulated. The two-dimensional propagation plane of the three-dimensional sound propagation field is divided into a finite number of grid points n. The surface geometric parameters are iteratively optimized with the goal of maximizing the sound pressure at the target grid point and minimizing the sound pressure at grid points other than the target grid point. The target grid points are set parameters that correspond to the position of the target tissue relative to the acoustic lens and the morphology of the target tissue.

2. The acoustic lens of claim 1, wherein, The specific objective is as follows: Maximize the ratio of the sum of sound pressures at the points corresponding to the first m sound pressures on the target transmission trajectory in the two-dimensional propagation plane to the sum of sound pressures at all other points outside the target transmission trajectory; Wherein, the target transmission trajectory is a set parameter, corresponding to the position of the target tissue relative to the acoustic lens and the morphology of the target tissue; m is a set value, when m is 1, the surface geometric parameters are designed to adjust the focal length of the acoustic lens, when m is greater than 1, the surface geometric parameters are designed to adjust the size of the focal region of the acoustic lens.

3. The acoustic lens of claim 1, wherein, When the target tissue to be ablated is located around normal tissue, multiple focal zones are determined on the two-dimensional propagation plane based on the relative positions of the target tissue and the normal tissue. These multiple focal zones are connected to form a ring, and the ring area corresponds to the area of ​​normal tissue to be protected. The target is specifically: Maximize the sound pressure at the center of each focal zone and minimize the sound pressure at the center of the ring.

4. The acoustic lens of any one of claims 1 to 3, wherein, A genetic algorithm is used to perform the maximization optimization operation.

5. The acoustic lens of any one of claims 1 to 3, wherein, The steps on the surface of the Fresnel acoustic lens are smoothed to form multiple wedges to eliminate the step height difference. The surface geometric parameters are the height and width of each wedge.

6. An intracavitary ultrasound ablation device for the human body, characterized in that include: An ultrasonic transducer and an acoustic lens for ablation of human target tissue as described in any one of claims 1 to 5; The ultrasonic transducer is fitted into the hollow cavity of the acoustic lens; mechanical vibration is excited circumferentially by the ultrasonic transducer, causing the acoustic lens to vibrate and generating a sound propagation field.

7. An ultrasonic ablation device for intracavitary intervention in a human body according to claim 6, wherein Used for ablation of extracavitary target tissues.

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