Tubular ultrasonic focusing device

Abstract

The utility model discloses a tubular ultrasonic focusing device which comprises a balloon, a transducer is arranged in the balloon, the transducer emits sound beams for ablation, and a sound beam adjusting structure is distributed in the axial direction of the balloon; a sound beam penetrates through the balloon and the sound beam adjusting structure, and an adjustable weak focusing area is formed on the outer side of the balloon. By adjusting the ultrasonic frequency and the distance between the acoustic structure and the incident plane of the treatment area and through a weak focusing area formed by the acoustic beam adjusting structure, the ablation depth and accuracy can be adjusted, the temperature rise in a target area is synchronous, and the advantages that the ablation effect is uniform and consistent, and the far-end boundary is obvious are achieved; by means of the structure, accurate ablation of branches and trunks of renal arteries can be achieved, thoroughness of ablation is guaranteed, damage to surrounding normal tissue is reduced to the maximum extent, the clinical requirement of'ablating and eliminating 'is met, and effectiveness and safety of treatment are improved.

Description

Technical Field

[0001] The utility model relates to the field of ultrasonic ablation, in particular to a tubular ultrasonic focusing device. Background Art

[0002] In the Symplicity Spyral radiofrequency RDN system, energy devices: four ring-shaped metal electrodes are placed in sequence on a rollable memory metal guidewire. Ablation mechanism: the electrodes contact the blood vessel wall and apply a radiofrequency current with a frequency of 448 kHz to the blood vessel wall. The tissue in the area where the current flows is heated. Ablation depth: the area adjacent to each electrode is less than 4mm in contact, and the ablation temperature can reach greater than 600°C. Ablation range: the ablation points are not in the same axial plane, and only cover a quadrant in the upward direction. Vascular protection: there is no special cooling mechanism, and cooling is only done by arterial blood.

[0003] The Paradise ultrasound RDN system utilizes a tubular piezoelectric ceramic tube placed within a balloon that can flow cooling fluid. The ablation mechanism involves contacting the balloon wall with the blood vessel, while the tubular transducer radially emits 10 MHz ultrasonic energy. Mechanical vibrations cause tissue heating. The ablation depth is annular and symmetrical, with an axial length of 6 mm and a radial outer diameter of up to 8 mm. The ablation range is a 360-degree ring, similar to a "swimming ring." Vascular protection involves cooling fluid flowing through the balloon to ensure that the angle between the blood and the vessel wall (<1 mm thick) is less than 42 degrees. The conventional tubular transducer used in this product exhibits an uneven radial distribution of acoustic field intensity, attenuating roughly as the negative first power of radius. This results in overablation within the target ablation zone, while more distant areas experience inadequate ablation. Furthermore, some of the acoustic field penetrates into more distant, non-targeted areas, potentially causing tissue damage in these areas. Utility Model Content

[0004] In order to solve the above technical problems, the utility model provides a tubular ultrasonic focusing device, including a balloon, a transducer is arranged inside the balloon, the transducer emits a sound beam for ablation, and a sound beam adjustment structure is distributed along the axis of the balloon; the sound beam passes through the balloon and the sound beam adjustment structure to form an adjustable weak focusing area on the outside of the balloon.

[0005] Preferably, the sound beam adjustment structure includes at least one or more acoustic unit structures, and at least one or more of the acoustic unit structures are located on the balloon wall.

[0006] Preferably, the sound beam adjustment structure includes at least one or more acoustic unit structures, and at least one or more acoustic unit structures are located on the outer wall of the transducer.

[0007] Preferably, the sound beam adjustment structure includes at least one or more acoustic unit structures, and at least one or more acoustic unit structures are located in the area between the transducer and the balloon.

[0008] Preferably, at least a plurality of groups of the acoustic unit structures are symmetrically arranged along the axial direction of the balloon, and at least a plurality of groups of the acoustic unit structures are located at both ends of the balloon.

[0009] Preferably, the acoustic unit structure includes a first medium and a second medium, and the first medium and the second medium are arranged at intervals.

[0010] Preferably, the first medium and the second medium are of similar sizes.

[0011] Preferably, the first medium is annular and arranged axially on the outer wall of the balloon.

[0012] Preferably, the first medium is made of the same material as the balloon.

[0013] The utility model has the following beneficial effects:

[0014] 1. In the present invention, by adjusting the ultrasonic frequency, the distance between the acoustic structure and the incident surface of the treatment area, and the weak focus area formed by the sound beam adjustment structure, the ablation depth and accuracy can be adjusted and the temperature rise in the target area can be synchronized.

[0015] 2. It has the advantages of uniform ablation effect and obvious distal boundary, and can achieve precise ablation of renal artery branches and trunks, which not only ensures the thoroughness of ablation, but also minimizes damage to surrounding normal tissues, meets the clinical requirement of "ablation as much as possible", and improves the effectiveness and safety of treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic structural diagram of a tubular ultrasonic focusing device provided in an embodiment of the present application;

[0017] Figure 2 1 is a schematic structural diagram of a sound beam adjustment structure in a tubular ultrasonic focusing device provided in an embodiment of the present application;

[0018] Figure 3 is a schematic diagram of a treatment state of an acoustic beam adjustment structure in a tubular ultrasound focusing device provided in an embodiment of the present application;

[0019] Figure 4 Schematic diagram of the structure of the balloon in the tubular ultrasound focusing device provided in an embodiment of the present application;

[0020] Figure 5 is a schematic diagram of the comparison of the sound fields in the tubular ultrasonic focusing device provided in the embodiment of the present application;

[0021] Figure 6 is a schematic diagram of temperature field comparison in a tubular ultrasonic focusing device provided in an embodiment of the present application;

[0022] Figure 7 is a schematic diagram of temperature rise comparison in a tubular ultrasonic focusing device provided in an embodiment of the present application;

[0023] Figure 8 is a schematic diagram of ablation depth comparison in a tubular ultrasound focusing device provided in an embodiment of the present application;

[0024] Figure 9 This is a schematic diagram of the temperature rise at different radial points in the tubular ultrasonic focusing device provided in an embodiment of the present application.

[0025] Legend:

[0026] 1. Balloon; 101. Free propagation zone; 102. First coherence zone; 103. Second coherence zone; 2. Transducer; 3. Inner tube; 4. First acoustic unit structure; 41. First medium; 42. Second medium; 5. Second acoustic unit structure. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] See also Figure 1 In this embodiment, a tubular ultrasonic focusing device is provided, including a balloon 1, a transducer 2 is arranged in the balloon 1, the transducer 2 is connected to an inner tube 3, and a balloon cavity is provided between the transducer 2 and the inner wall of the balloon 1, and a cooling liquid can be transported into the balloon cavity through the inner tube 3.

[0029] An acoustic beam adjustment structure is distributed axially along the balloon 1; the acoustic beam passes through the balloon 1 and the acoustic beam adjustment structure to form an adjustable weak focus area outside the balloon 1, so that the ablation depth and accuracy can be adjusted and the temperature rise in the target area is synchronized.

[0030] In one embodiment, the sound beam adjustment structure includes at least one or more acoustic unit structures, and at least one or more of the acoustic unit structures are located on the balloon wall of the balloon 1 .

[0031] In one embodiment, the sound beam adjustment structure includes at least one or more acoustic unit structures, and at least one or more of the acoustic unit structures are located on the outer wall of the transducer 2 .

[0032] In an embodiment, the sound beam adjusting structure comprises at least one or more acoustic unit structures, and the at least one or more acoustic unit structures are located in the region between the transducer 2 and the balloon 2.

[0033] It can be understood that the acoustic unit structure is synchronously introduced into the blood vessel with the balloon 1, and does not have relative displacement with the transducer 2 or the balloon 1, so that the sound beam can pass through the acoustic unit structure and the balloon 1 to form an adjustable weak focusing region outside the balloon 1.

[0034] Further, the acoustic unit structure is arranged in at least multiple groups along the axial symmetry of the balloon 1, and the at least multiple groups of acoustic unit structures are located at both ends of the balloon 1.

[0035] Further, the acoustic unit structure comprises a first medium 41 and a second medium 42, and the first medium 41 and the second medium 42 are arranged in a spaced manner, the sizes of the first medium 41 and the second medium 42 are adjacent, the first medium 41 is annular and arranged on the outer wall of the balloon 1 in an axial direction, and the first medium 41 is made of the same material as the balloon 1.

[0036] By increasing the ultrasonic frequency of the adjusting transducer 2, the greater the ultrasonic frequency, the greater the ablation range or depth, and the spacing between the multiple groups of acoustic unit structures, the length or width of each acoustic unit structure can also be adjusted, thereby adjusting the focusing depth and width of the weak focusing region. The weak focusing region formed has the characteristics of adjustable ablation depth and precision and synchronous temperature rise in the target region, and has the advantages of uniform ablation effect and obvious distal boundary, which can realize precise ablation of the renal artery branches and trunks, ensure the completeness of ablation, and minimize the damage to the surrounding normal tissues, meet the clinical requirement of "ablation as much as possible", and improve the effectiveness and safety of treatment.

[0037] In a specific embodiment, referring to Figures 2-4 As shown in the figure, the sound beam adjusting structure comprises a first acoustic unit structure 4 and a second acoustic unit structure 5, and the first acoustic unit structure 4 and the second acoustic unit structure 5 are respectively located at both ends of the balloon 1. The first acoustic unit structure 4 and the second acoustic unit structure 5 are arranged axially symmetrically along the balloon 1, and there is a gap between the first acoustic unit structure 4 and the second acoustic unit structure 5.

[0038] In this embodiment, the balloon cavity between the first acoustic unit structure 4 and the transducer 2 forms a first coherence region 102, and the width of the first coherence region 102 is adjacent to the length of the first acoustic unit structure 4. When the transducer 2 is working, a first sound beam is formed in the first coherence region 102, and the first sound beam propagates along the radial direction of the balloon 1.

[0039] After the first acoustic beam passes through the balloon 1 and the first acoustic unit structure 4, it is refracted by the first acoustic unit structure 4 to form two acoustic beams, including a fourth acoustic beam and a fifth acoustic beam:

[0040] The fourth acoustic beam propagates in a direction that forms an obtuse angle with the radial direction of the balloon 1. This means that the fourth acoustic beam propagates in a direction away from the radial center axis of the balloon 1.

[0041] The fifth acoustic beam propagates in a direction that forms an acute angle with the radial direction of the balloon 1 . It can be understood that the fifth acoustic beam propagates in a direction close to the radial center axis of the balloon 1 .

[0042] In this embodiment, the balloon cavity between the second acoustic unit structure 5 and the transducer 2 forms a second coherent zone 103, and the width of the second coherent zone 103 is adjacent to the length of the second acoustic unit structure 5. When the transducer 2 is working, a third sound beam is formed in the second coherent zone 103, and the third sound beam propagates radially along the balloon 1.

[0043] After the second acoustic beam passes through the balloon 1 and the second acoustic unit structure 5, it is refracted by the second acoustic unit structure 5 to form two other acoustic beams, including the sixth acoustic beam and the seventh acoustic beam:

[0044] The seventh acoustic beam propagates in a direction that forms an obtuse angle with the longitudinal direction of the balloon 1. This means that the seventh acoustic beam propagates in a direction away from the radial center axis of the balloon 1.

[0045] The sixth acoustic beam propagates in a direction that forms an acute angle with the radial direction of the balloon 1 . It can be understood that the sixth acoustic beam propagates in a direction close to the radial center axis of the balloon 1 .

[0046] In this embodiment, the balloon cavity at the distance between the first acoustic unit structure 4 and the second acoustic unit structure 5 forms a free propagation zone 101, and the width of the free propagation zone 101 is adjacent to the length of the distance between the first acoustic unit structure 4 and the second acoustic unit structure 5. When the transducer 2 is working, a second sound beam is formed in the free propagation zone 101, and the second sound beam propagates radially along the balloon 1.

[0047] After the second acoustic beam passes through the balloon 1, since the medium outside the balloon 1 in the free propagation zone 101 is the human tissue on the inner wall of the blood vessel, the second acoustic beam will not undergo obvious refraction. The second acoustic beam, the fifth acoustic beam and the sixth acoustic beam form a weak focusing area with a larger incident surface width close to the balloon 1 and a smaller incident surface width away from the balloon 1. It can be understood that the shape formed by the longitudinal axis of the weak focusing area is close to the trapezoidal structure. It can be further known that since the first acoustic unit structure 4 and the second acoustic unit structure 5 are symmetrically arranged, the formed trapezoidal structure is close to the isosceles trapezoidal structure, which is used to ablate the target treatment area.

[0048] Currently, in order to increase the range or depth of ablation, the technical means used are to increase the ultrasonic frequency of transducer 2. The higher the ultrasonic frequency, the greater the range or depth of ablation. However, the disadvantage is that the mechanical wave vibration causes greater tissue heating, and the accuracy of ablation will also be reduced.

[0049] In this embodiment, the axial positions of the first acoustic unit structure 4 and the second acoustic unit structure 5 in the balloon 1 are adjustable. By adjusting the distance between the first acoustic unit structure 4 and the second acoustic unit structure 5, the width of the weak focusing area close to the balloon 1 and the width away from the balloon 1 can be adjusted.

[0050] When the distance between the first acoustic unit structure 4 and the second acoustic unit structure 5 is larger, the width of the incident surface of the weak focusing area close to the balloon 1 is larger, and the width of the incident surface of the weak focusing area away from the balloon 1 is larger, the ablation area is larger, and the accuracy of ablation will be relatively reduced.

[0051] When the distance between the first acoustic unit structure 4 and the second acoustic unit structure 5 is smaller, the width of the incident surface of the weak focusing area close to the balloon 1 is smaller, and the width of the incident surface of the weak focusing area away from the balloon 1 is smaller, the ablation area is smaller, and the accuracy of ablation will be relatively improved.

[0052] It can be further seen that the heights of the first acoustic unit structure 4 and the second acoustic unit structure 5 in the axial direction of the balloon 1 are adjustable. By adjusting the heights of the first acoustic unit structure 4 and the second acoustic unit structure 5, the width of the incident surface close to the balloon 1 and the width of the incident surface away from the balloon 1 in the weak focusing area can be adjusted.

[0053] When the height of the first acoustic unit structure 4 and the second acoustic unit structure 5 is greater, the width of the incident surface of the weak focusing area close to the balloon 1 is greater, the width of the incident surface of the weak focusing area away from the balloon 1 is greater, the ablation area is larger, and the accuracy of ablation will be relatively reduced.

[0054] When the height of the first acoustic unit structure 4 and the second acoustic unit structure 5 is smaller, the width of the incident surface of the weak focusing area close to the balloon 1 is smaller, and the width of the incident surface of the weak focusing area away from the balloon 1 is smaller, the ablation area is smaller, and the accuracy of ablation will be relatively improved.

[0055] It can be further known that the horizontal widths of the first acoustic unit structure 4 and the second acoustic unit structure 5 are adjustable. When the first acoustic unit structure 4 and the second acoustic unit structure 5 are fixed in the axial position of the balloon 1 and the depth of the weak focusing area formed is certain, by adjusting the widths of the first acoustic unit structure 4 and the second acoustic unit structure 5, the distance between the first acoustic unit structure 4 and the second acoustic unit structure 5 and the incident surface of the treatment area can be adjusted, thereby adjusting the focusing depth.

[0056] By adjusting the ultrasonic frequency, the distance between the acoustic structure and the incident surface of the treatment area, the number of the first acoustic unit structure 4 and the second acoustic unit structure 5, and the height or width of the first acoustic unit structure 4 and the second acoustic unit structure 5, the focusing depth can be changed from 3 to 10 mm, where the focusing depth is the radial distal end of the axial symmetry center and the field strength is 1 / 2 of the field strength at the peak of the treatment area.

[0057] In this embodiment, the weak focus area formed by the first acoustic unit structure 4 and the second acoustic unit structure 5 makes the ablation depth and accuracy adjustable, and has the characteristics of synchronous temperature rise in the target area, and has the advantages of uniform ablation effect and obvious distal boundary. It can achieve precise ablation of renal artery branches and trunks, which not only ensures the thoroughness of ablation, but also minimizes damage to surrounding normal tissues, meets the clinical requirement of "eliminating everything that should be eliminated", and improves the effectiveness and safety of treatment.

[0058] It can be understood that in other embodiments, in specific implementations, the first acoustic unit structure 4 and the second acoustic unit structure 5 can also be set asymmetrically, the height and width of the first acoustic unit structure 4 and the second acoustic unit structure 5 can be different, and the longitudinal axis of the formed weak focus area is also a trapezoidal structure, which is used to ablate the treatment target area.

[0059] In this embodiment, the transducer 2 is a tubular transducer, and the transducer 2 is sleeved on the inner tube 3 along the axial direction. It has a simple structure, low cost, and stable working performance.

[0060] Furthermore, the second acoustic unit structure 5 is symmetrically arranged with the first acoustic unit structure 4. The first acoustic unit structure 4 includes a first medium 41 and a second medium 42. A first medium 41 and a second medium 42 constitute a minimum unit, and the first medium 41 and the second medium 42 are adjacent in size. A plurality of minimum units are arranged to constitute the first acoustic unit structure 4. The sound velocity of the material corresponding to the first medium 41 is C1, and the sound velocity of the material corresponding to the second medium 42 is C2. The frequency of the sound wave emitted by the transducer 2 is f, and the preset height of the minimum unit composed of the first medium 41 and the second medium 42 is d.

[0061]

[0062] When the beam propagates in the minimum unit of height d, the sub-beams passing through the first medium 41 and the second medium 42 respectively will produce a phase difference close to π~π. Preferably, the sub-beams of the first medium 41 and the second medium 42 produce a phase difference close to π, and the width w of the minimum unit is equal to or close to d.

[0063] In this embodiment, the first medium 41 is made of the same material as the balloon 1 , and is annularly disposed on the outer wall of the balloon 1 . Several annular first media 41 are axially arranged on the outer wall of the balloon 1 , with a gap between adjacent first media 41 .

[0064] In one embodiment, the first medium 41 and the balloon 1 are both made of nylon, and the first medium 41 and the balloon 1 are integrally formed, which can save processing costs.

[0065] In this embodiment, the second medium 42 is human tissue on the inner wall of the blood vessel. When the balloon 1 enters the blood vessel, the human tissue on the inner wall of the blood vessel is embedded in the gap between the first medium 41 to form the second medium 42 .

[0066] In a specific implementation, during treatment, the transducer 2 generates an acoustic beam, and the first acoustic beam is refracted through the first medium 41 and the second medium 42 of the first acoustic unit structure 4 to form two acoustic beams, including a fourth acoustic beam and a fifth acoustic beam:

[0067] The fourth acoustic beam propagates in a direction that forms an obtuse angle with the radial direction of the balloon 1. This means that the fourth acoustic beam propagates in a direction away from the radial center axis of the balloon 1.

[0068] The fifth acoustic beam propagates in a direction that forms an acute angle with the radial direction of the balloon 1 . It can be understood that the fifth acoustic beam propagates in a direction close to the radial center axis of the balloon 1 .

[0069] After the second acoustic beam passes through the balloon 1 and the second acoustic unit structure 5, it is refracted by the second acoustic unit structure 5 to form two other acoustic beams, including the sixth acoustic beam and the seventh acoustic beam:

[0070] The seventh acoustic beam propagates in a direction that forms an obtuse angle with the longitudinal direction of the balloon 1. This means that the seventh acoustic beam propagates in a direction away from the radial center axis of the balloon 1.

[0071] The sixth acoustic beam propagates in a direction that forms an acute angle with the radial direction of the balloon 1 . It can be understood that the sixth acoustic beam propagates in a direction close to the radial center axis of the balloon 1 .

[0072] After the second acoustic beam passes through the balloon 1, since the medium outside the balloon 1 in the free propagation zone 101 is the human tissue on the inner wall of the blood vessel, the second acoustic beam will not undergo obvious refraction. The second acoustic beam, the fifth acoustic beam and the sixth acoustic beam form a weak focusing area with a larger incident surface width close to the balloon 1 and a smaller incident surface width away from the balloon 1. It can be understood that the shape formed by the longitudinal axis of the weak focusing area is close to the trapezoidal structure. It can be further known that since the first acoustic unit structure 4 and the second acoustic unit structure 5 are symmetrically arranged, the formed trapezoidal structure is close to the isosceles trapezoidal structure, which is used to ablate the target treatment area.

[0073] SeeFigure 5 As shown, Figure 5 Figure A in the figure shows the prior art, in which the balloon is not provided with a sound beam adjustment structure, and the sound field distribution generated by the transducer is relatively uniform.

[0074] Figure 5 Figure B in the figure shows that in the present invention, the balloon is provided with a sound beam adjustment structure, and the sound field generated by the transducer has an obvious weak focusing area.

[0075] The utility model also provides a tubular ultrasound focusing method, which uses the tubular ultrasound focusing device to ablate the treatment target area.

[0076] See Figure 6 As shown, Figure 6 Figure A shows the uniform distribution of the temperature field when a conventional ultrasonic ablation catheter is ablated for 5 seconds in the prior art.

[0077] Figure 6 Figure B in the figure shows that in the present invention, the balloon is provided with a sound beam adjustment structure, and the temperature field has an obvious weak focusing area.

[0078] See Figures 7-8 As shown, Figure 7 In Figure A of the prior art, the temperature rise of the conventional ultrasonic ablation catheter in the treatment area extends from the inside to the outside, and the temperature rise lasts for a long time.

[0079] Figure 8 In the present invention, the balloon is provided with an acoustic beam adjustment structure, and the ultrasonic ablation catheter is heated synchronously in the treatment area, and the temperature rise time is short, the radial depth of ablation is greater, and the effect is better. A bulge is generated at 3-4 mm, reflecting the focusing effect.

[0080] See Figure 9 As shown, in the initial stage (within 4 seconds), the temperature rise rate of the ultrasonic ablation catheter of the present invention is about 1.5-2 times that of the conventional ultrasonic ablation catheter, and the temperature rise is faster.

[0081] It can be understood that the tubular ultrasound focusing device of the present application can also be used for renal artery denervation to treat hypertension, pulmonary artery denervation to treat pulmonary hypertension, hepatic artery denervation to treat diabetes, visceral nerve ablation to treat heart failure, and targeted lung denervation to treat chronic obstructive pulmonary disease.

[0082] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A tubular ultrasound focusing device, comprising a balloon (1), wherein a transducer (2) is arranged in the balloon (1), and the transducer (2) emits an acoustic beam for ablation, characterized in that: An acoustic beam adjustment structure is distributed along the axial direction of the balloon (1); The sound beam passes through the balloon (1) and the sound beam adjustment structure to form an adjustable weak focusing area outside the balloon (1).

2. The tubular ultrasonic focusing device according to claim 1, characterized in that: The acoustic beam adjustment structure includes at least one or more acoustic unit structures, and at least one or more of the acoustic unit structures are located on the balloon wall of the balloon (1).

3. The tubular ultrasonic focusing device according to claim 1, characterized in that: The sound beam adjustment structure includes at least one or more acoustic unit structures, and at least one or more of the acoustic unit structures are located on the outer wall of the transducer (2).

4. The tubular ultrasonic focusing device according to claim 1, characterized in that: The acoustic beam adjustment structure includes at least one or more acoustic unit structures, and at least one or more of the acoustic unit structures are located in the area between the transducer (2) and the balloon (1).

5. The tubular ultrasonic focusing device according to claim 4, characterized in that: At least a plurality of groups of the acoustic unit structures are arranged symmetrically along the axial direction of the balloon (1), and at least a plurality of groups of the acoustic unit structures are located at both ends of the balloon (1).

6. The tubular ultrasonic focusing device according to claim 5, characterized in that: The acoustic unit structure comprises a first medium (41) and a second medium (42), and the first medium (41) and the second medium (42) are arranged in an alternating manner.

7. The tubular ultrasonic focusing device according to claim 6, characterized in that: The first medium (41) and the second medium (42) are of similar sizes.

8. The tubular ultrasonic focusing device according to claim 7, characterized in that: The first medium (41) is annular and arranged along the axial direction on the outer wall of the balloon (1).

9. The tubular ultrasonic focusing device according to claim 8, characterized in that: The first medium (41) is made of the same material as the balloon (1).

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