Therapy apparatus for treating tissue by emission of remote crossed focused ultrasound waves

Abstract

To provide a therapy apparatus for treating tissue by the emission of focused ultrasound waves.SOLUTION: A creation surface of a pressure field of focused ultrasound waves is divided into at least N sectors having segments of asymmetrical concave curve with centres of curvature. Centres of curvature (c1, c2, ...) are asymmetrical where the centres of curvature are situated at different distances from a plane of symmetry A1 or from an axis of symmetry S and / or at different depths taken according to the axis of symmetry. Individual axes (a1, a2, ...) intersect between focal zones (Zc1, Zc2, ...) and the creation surface or beyond the focal zones such that a plurality of beams originating from the sectors create a focal coverage zone Zr which is off-axis relative to the plane of symmetry A1 or to the axis of symmetry S. The sectors of this creation surface creates energy deposit zones with profiles corresponding to the focal coverage zones.SELECTED DRAWING: Figure 4

Description

[Technology Field]

[0001] The present invention relates to the technical field of an apparatus or device including an ultrasonic probe formed by a plurality of ultrasonic transducer elements configured to emit high-intensity focused ultrasound (HIFU).

[0002] The object of the present invention is particularly advantageous to be applied in the field of therapeutic procedures using focused ultrasound. [Background technology]

[0003] In particular, the publication "Kennedy, JE, High-intensity focused ultrasound in the treatment of solid tumors. Nat Rev Cancer, 2005. 5(4): p.321-7" indicates that focused ultrasound treatment is known to cause biological damage to tissue through a combination of thermal effects and acoustic cavitation. To perform such treatment, it is necessary to control the applied energy and inflict damage of an appropriate size to the tissue being treated in the shortest possible time. Furthermore, moving the probe requires sensing movement, which not only prolongs treatment time but also reduces accuracy due to manual operation or necessitates the introduction of a robotic system that enables millimeter-level movement. Therefore, it is necessary to plan this treatment to minimize probe movement as much as possible. Furthermore, depending on the tissue being treated, the acoustic window available for treating the tissue may be very limited, making probe movement not always practical (see: "Aubry, JF, et al. The road to clinical use of high-intensity focused ultrasound for liver cancer: technical and clinical consensus. J Ther Ultrasound, 2013. 1: p. 13").

[0004] The shape of such tissue damage directly stems from the shape of the surface of the radiating plane of the ultrasound probe used. For example, the natural geometric focus of a conventional spherical HIFU ultrasound transducer becomes elliptical due to diffraction. Furthermore, prior art has proposed various solutions to increase the size of the area being treated without moving the ultrasound probe.

[0005] European Patent No. 0214782 describes a solution relating to an ultrasonic transducer with a lens for obtaining an annular focus from a transducer with a spherical geometric shape. This special configuration not only expands the focal area to the size of a ring, but also generates a focal range region originating from the intersection of multiple ultrasonic beams at a position on the central axis of the transducer opposite the focal plane of the transducer. The document provides a system for reducing the pressure field in this focal range region to overcome the risk of secondary damage.

[0006] International Publication No. 2011 / 092683 describes a powerful focused ultrasonic probe comprising a first network of ultrasonic transducers for focusing a first beam onto a target volume located at the site of damage, and a second network of ultrasonic transducers for forming a second ultrasonic beam focused onto the same target volume, such that interference between the first and second beams creates an asymmetric ultrasonic region within the target volume. Various embodiments of this probe are described in this document. The main drawbacks are that the formation of two ultrasonic beams at different frequencies necessitates more expensive electronic equipment, more complex diffusing calculations, and the appearance of secondary pressure lobes outside the target volume.

[0007] It should be noted that, as proposed in European Patent No. 0661029, ultrasound therapeutic probes can be used in conjunction with imaging probes. In the same sense, U.S. Patent No. 5,522,869 describes an ultrasound energy therapy device comprising a cylindrical probe having an annular transducer.

[0008] Non-patent document XP55009820 describes a therapeutic probe that includes a rotating radiation surface formed by rotating a concave curve portion having a center of curvature located off-axis from the axis of symmetry around the axis of symmetry. In one cross-section, this radiation surface shows two concave curve portions that are symmetrical with respect to the axis of symmetry, each of which has an acoustic axis passing through the center of curvature and the center of the concave curve portion. Such a transducer forms, on the one hand, a ring of ultrasonic focal points demarcated by a focal plane, and on the other hand, an intersection region of multiple ultrasonic beams. As can be seen from this document, the intersection region of multiple ultrasonic beams corresponding to secondary pressure peaks is located behind the focal plane.

[0009] European Patent No. 2035091 describes an annular HIFU transducer in which a ring-shaped focal region is formed at the center where the central focal point is located.

[0010] European Patent No. 2691154 describes a therapeutic probe including a radiating surface configured such that the ultrasonic emitter forms a first focal region defined on the focal plane and a second focal region located between the first focal region and the radiating surface, the second focal region corresponding to the application areas of multiple ultrasonic beams.

[0011] The paper "Vincenot, J., et al., Electronic beam steering used with a toroidal HIFU transducer substantially increases the coagulated volume. Ultrasound Med Biol, 2013. 39(7): p.1241-54" describes an electron focusing technique that introduces a minimum degree of freedom along an axis perpendicular to the acoustic axis, thereby shifting the damaged area by several millimeters along this axis. This solution is suitable for a wide area (50 cm²). 3 This can be treated in a very short time (2 minutes).

[0012] International Publication No. 2011 / 024074 proposes a solution for adjusting the numerous emitter elements and current generators used in conventional, expensive, and complex electron focusing techniques. This solution aims to effectively reduce the number of current generators by coupling emitter elements via packets, allowing a current generator to supply multiple emitter elements in parallel. Such coupling can be electrically modified to shift the focus according to the shape of the area being treated. While this solution can reduce the cost of control electronics, it cannot reduce the cost of transducers containing hundreds of emitter elements. Manufacturing this type of transducer requires the use of digital microfabrication machines and necessitates multi-element cutting, which is difficult to perform with conventional ceramic transducers due to the problem of electroacoustic coupling between elements.

[0013] International Publication No. 2016 / 144931 similarly discloses a system and process for ultrasonic radiation for tissue regeneration that performs a predetermined scanning cycle. [Overview of the project]

[0014] Analysis of various prior art solutions suggests that treating complex tissue regions with shapes far from the acoustic axis is difficult. Indeed, treating complex shapes with focused ultrasound in the broad sense requires numerous elements (and associated electronic equipment) and long treatment times. In the case of focused ultrasound treatment using a toric transducer, the pressure is maximum along the acoustic axis, suggesting that it is difficult to increase the treatment area relative to the acoustic axis and to treat complex shapes that lack rotational symmetry.

[0015] This is especially true for breast cancer tissue. While the organ is cone-shaped with a ring-like appearance at its apex and varies in size, in most cases there is only one location where the probe can potentially treat the tumor. From this single location, not only must the entire target area, including the tumor, be treated, but also a certain amount of healthy surrounding tissue. This requires not only deep energy delivery, but also delivery along an axis perpendicular to the acoustic axis, so that the final damage extends along this axis as well as along the axis itself.

[0016] This also applies to target regions that have an asymmetrical volume along the acoustic axis, with the distance along the axis perpendicular to the acoustic axis extending along the acoustic axis. This target region can be adapted, for example, to tumors or organs with complex shapes (prostate, kidney, thyroid, etc.). Another shape of the target region relates to a hollow volume extending around a non-linear portion, for example, to treat tumors along arteries or veins, tumors along the digestive tract, tumors along bone, Wilson's duct of the pancreas, urethra, or bile duct.

[0017] The object of the present invention is to correct the shortcomings of various prior art solutions by proposing a novel, low-cost treatment device configured to obtain a volumetric portion of bio-injury that conforms to the complex shape of the tissue being treated, particularly when the acoustic treatment window is limited.

[0018] To achieve this objective, a therapeutic device for treating tissue by focused ultrasound radiation comprises a therapeutic probe having a transducer that includes multiple ultrasound emitters driven by signals transmitted by a signal generator constituting part of a control circuit, such that the surface of the focused ultrasound pressure field is determined.

[0019] According to the present invention, The generation surface is divided into at least N sectors (N is 2 to 32) such that ultrasonic waves are focused into a focal region defined by the focal plane, and each sector of the generation surface has a finite-length concave curve portion (concave curve segment) that is asymmetric with respect to the plane of symmetry or axis of symmetry in a certain cross-section. The center of curvature (of the concave curve portion) is asymmetrical with respect to the plane of symmetry or the axis of symmetry such that the center of curvature is located at different distances from the plane of symmetry or the axis of symmetry, and / or at different depths along the axis of symmetry. Each concave curve has an individual axis passing through the center of curvature of the concave curve and the center of the concave curve. The individual axes intersect between the focal region and the generation surface, or beyond the focal region, such that multiple beams originating from the sector intersect between the focal region and the generation surface, or beyond the focal region, to form a focal coverage zone that is off-axis with respect to the plane of symmetry or the axis of symmetry and located away from the focal region. The sector of this generation surface is formed by rotating the concave curve portion by 2π / N around the axis of symmetry, or by moving the concave curve portion along a direction perpendicular to the cross-section including the concave curve portion, so that the sector can form an energy-granting region having a contour (profile) corresponding to the focal range region. The concave curve portion of the generated surface extends within the cross-section on either the axis of symmetry or the plane of symmetry, and is spaced apart from each other such that the focal range region is located away from the generated surface.

[0020] According to a preferred feature of the implementation, the generated surface is divided into two sectors.

[0021] Advantageously, the inner end of the generated surface defines the extent of the housing for mounting the ultrasonic imaging probe.

[0022] According to the first modified embodiment, the generation surface is derived from a surface defined by transducer elements arranged in an annular geometric arrangement. The annular geometric arrangement is formed by rotating a concave curved portion around the symmetry axis so as to draw arcs of circles that intersect each other and do not coincide. The circles that intersect each other and do not coincide intersect such that the focal region has a shape that is part of a circle.

[0023] According to an implementation feature, the surface has a shape cut symmetrically with respect to the symmetry axis.

[0024] According to the second modified embodiment, the generation surface is derived from a surface defined by the transducer elements arranged in a cylindrical geometric arrangement. The cylindrical geometric arrangement is formed by moving two of the concave curved portions along a direction perpendicular to the cross section including the concave curved portion by a finite length so that the focal region has a linear shape.

[0025] According to one embodiment, the ultrasonic emitter of the transducer defines a radiation surface corresponding to the generation surface of the pressure field of the focused ultrasonic wave.

[0026] According to another embodiment, the signal generator that forms part of the control circuit is controlled to transmit a signal for driving the ultrasonic emitter arranged in a part (segment) using a delay law or a phase law so that the generation surface of the pressure field of the focused ultrasonic wave is formed.

[0027] According to an advantageous modified embodiment, in the exposure stage, the ultrasonic emitter that forms a sector and a part of a sector that is symmetric to the sector with respect to the symmetry axis is driven by a signal transmitted by the signal generator that forms part of the control circuit so that a corresponding energy application region is formed.

[0028] According to one feature of the present invention, in the exposure stage, the ultrasonic emitter, which forms a sector and a portion of the sector symmetrically opposite to the sector with respect to the axis of symmetry, is driven by a signal transmitted by the signal generator, which constitutes part of the control circuit, such that the corresponding energy-granting region is formed on one side of the plane of symmetry.

[0029] According to another feature of the present invention, in a subsequent exposure step, the ultrasonic emitter, which forms a portion of the sector symmetrically with respect to the sector and the plane of symmetry, is driven by a signal transmitted by the signal generator, which constitutes part of the control circuit, such that the corresponding energy-granting region is formed on the side opposite to the side in which the energy-granting region was formed in the previous exposure step.

[0030] Advantageously, the ultrasonic emitters are arranged along a plurality, particularly several, sectors perpendicular to the plane of symmetry, and in a series of exposure stages, the ultrasonic emitters in the sectors are driven by signals transmitted by the signal generators, which constitute part of the control circuit, such that energy deposit zones are formed on either side of the plane of symmetry.

[0031] According to the present invention, in each of the consecutive exposure stages, the center of curvature is located at a different distance from the plane of symmetry or the axis of symmetry and / or at a different depth along its vertical axis, the ultrasonic emitter is driven by a signal transmitted by the signal generator, which is part of the control circuit, so that off-axis energy deposit zones are obtained.

[0032] According to one embodiment, in a series of exposure stages in which the center of curvature is located at different distances from the plane of symmetry or the axis of symmetry and / or at different depths along the vertical axis, the ultrasonic emitter is driven by a signal transmitted by the signal generator, which is part of the control circuit, so that in these series of exposure stages, off-axis energy-granting regions of the same or different sizes are obtained at different locations.

[0033] According to another embodiment, the energy-granting regions can be concentrically and / or symmetrically and / or asymmetrically and / or superimposed along their vertical axis, such that in a series of exposure stages, the distance and / or depth of the curvature center is changed from one exposure stage to another, by driving the ultrasonic emitter with a signal transmitted by the signal generator which constitutes part of the control circuit.

[0034] According to an additional embodiment, in at least one complementary exposure stage, the ultrasonic emitter is driven by a signal transmitted by the signal generator, which constitutes part of the control circuit, such that the ultrasonic waves are focused in a focal region and a focal range region is obtained that is centered with respect to the plane of symmetry or the axis of symmetry and is located between the focal region and the radiating plane, spaced apart from the focal plane or beyond the focal region.

[0035] The present invention will be better understood from the following detailed description with reference to the attached figures. [Brief explanation of the drawing]

[0036] [Figure 1] Figure 1 is a schematic diagram of a treatment device including a treatment probe, as shown in the first modified embodiment, and has a shape of rotation around an axis of symmetry. [Figure 2] Figure 2 is a schematic diagram showing an example of the pressure field generation surface of focused ultrasound implemented according to the first modified embodiment, and is considered a virtual generation surface. [Figure 3] Figure 3 is a diagram illustrating the guidelines for forming the pressure field generation surface of the focused ultrasound shown in Figure 2. [Figure 4] Figure 4 is an elevation view of a cross-section of a first example of a pressure field generation surface for focused ultrasound, which can be implemented according to the first and second modified embodiments of the probe, and has a pseudo-cylindrical shape. [Figure 5] Figure 5 is a cross-sectional elevation view of a second example of the pressure field generation surface for focused ultrasound, which can be implemented according to the first and second modified embodiments of the probe. [Figure 6] Figure 6 is a cross-sectional elevation view of a third example of the pressure field generation surface for focused ultrasound, which can be implemented according to the first and second modified embodiments of the probe. [Figure 6A] Figure 6A is a cross-sectional elevation view of a fourth example of the pressure field generation surface for focused ultrasound, which can be implemented according to the first and second modified embodiments of the probe. [Figure 7A] Figure 7A is a rear view of a probe implemented according to the first modified embodiment, showing that the surface of the probe is divided into four sectors. [Figure 7B] Figure 7B shows the pressure field generation surface of focused ultrasound formed by the probe shown in Figure 7A. [Figure 7C] Figure 7C shows the pressure field generation surface of focused ultrasound formed by the probe shown in Figure 7A. [Figure 8A] Figure 8A is a cross-sectional view of a probe implemented according to the first modified embodiment, showing the shape of an annular transducer having a central opening. [Figure 8B] Figure 8B is a cross-sectional elevation view showing guidelines for central natural focusing performed by a probe implemented according to the first modified embodiment, with the shape of the annular transducer shown in Figure 8A. [Figure 8C] Figure 8C is a cross-sectional elevation view obtained according to the guidelines for central natural focusing shown in Figure 8B, and photographed perpendicular to the axis of symmetry along the plane Pr, showing the shape of the focal range region of multiple ultrasonic beams at its center. [Figure 9A] Figure 9A is a schematic diagram showing one embodiment of a virtual plane for forming a focused ultrasonic pressure field, which is implemented according to the first modified embodiment and obtained by a transducer as shown in Figure 8A. [Figure 9B] Figure 9B is a cross-sectional elevation view showing the guideline for the transducer shown in Figure 8A to focus so that a virtual plane is formed to create the pressure field of the focused ultrasound shown in Figure 9A, in order to obtain a focal range region which is the off-axis of multiple ultrasonic beams, relative to the focal range region of multiple ultrasonic beams obtained according to the guideline for natural focusing. [Figure 9C] Figure 9C is a cross-sectional elevation view taken perpendicular to the axis of symmetry along plane Pr, showing the shape of the focal range region, which is the off-axis of multiple ultrasonic beams obtained according to the guidelines of the present invention, and the shape of the focal range region, which is obtained according to the guidelines of multiple ultrasonic beams obtained according to natural focusing. [Figure 9D] Figure 9D is a perspective view showing the shape of the focal range region, which is the off-axis position of multiple ultrasonic beams, obtained in accordance with the guidelines of the present invention. [Figure 10A] Figure 10A is a schematic diagram showing another embodiment of a virtual plane for forming a pressure field of focused ultrasonic waves obtained by a transducer as shown in Figure 8A, which is carried out according to the first modified embodiment. [Figure 10B] Figure 10B is a cross-sectional elevation view showing the guideline for the transducer shown in Figure 8A to focus so that a focal range region is obtained that is the off-axis of multiple ultrasonic beams, as shown for the focal range region of multiple ultrasonic beams obtained according to the guideline for natural focusing, and so that a virtual plane is formed to create the pressure field of focused ultrasonic waves shown in Figure 10A. [Figure 10C] Figure 10C is a cross-sectional elevation view taken perpendicular to the axis of symmetry along plane Pr, showing the shape of the focal range region, which is the off-axis of multiple ultrasonic beams obtained according to the guidelines of the present invention, and the shape of the focal range region, which is the multiple ultrasonic beams obtained according to the guidelines for natural focusing. [Figure 10D] Figure 10D is a perspective view showing the shape of the focal range region, which is the off-axis positioning of multiple ultrasonic beams, obtained according to the focusing guidelines shown in Figure 10B. [Figure 10E] Figure 10E is a perspective view showing the combined shape of the focal range region, which is the off-axis of multiple ultrasonic beams, obtained in two consecutive ultrasonic exposure stages corresponding to the guidelines shown in Figures 9B and 10B. [Figure 10F] Figure 10F is a plan view showing the combined shape of the focal range region, which is the off-axis of multiple ultrasonic beams, obtained in two consecutive ultrasonic exposure stages corresponding to the guidelines shown in Figures 9B and 10B. [Figure 11A] Figure 11A is a plan view showing the focal range regions, which are concentric and asymmetrical off-axis during a series of exposure stages. [Figure 11B] Figure 11B is a perspective view showing the focal range regions, which are concentric, symmetrical, and superimposed off-axis, in a series of exposure stages. [Figure 11C] Figure 11C is a perspective view showing the focal range regions, which are concentric, symmetrical, and superimposed off-axis, in a series of exposure stages. [Figure 11D] Figure 11D is a perspective view showing the central natural focusing range region combined with the focal range regions, which are concentric, symmetrical, and superimposed off-axis regions, in successive exposure stages. [Figure 11E] Figure 11E is a plan view showing the natural focusing range region surrounded by a focusing ring having two concentric off-axis focal range regions during a series of exposure stages, which itself is surrounded by a focusing ring having four concentric off-axis focal range regions. [Figure 12] Figure 12 is a perspective view showing an example of a transducer according to a second modified embodiment having a pseudo-cylindrical shape for carrying out the present invention. [Figure 12A] Figure 12A is a perspective view showing the shape of the focal range regions of multiple ultrasonic beams obtained during the exposure phase, following the guidelines for central natural focusing performed by a transducer having a pseudo-cylindrical shape as shown in Figure 12. [Figure 12B] Figure 12B is a perspective view showing the shape of the focal range region, which is the off-axis direction of multiple ultrasonic beams, obtained by the transducer having a pseudo-cylindrical shape as shown in Figure 12, during the exposure phase. [Figure 12C] Figure 12C is a perspective view showing the symmetrical shape of the focal range region, which is the off-axis of multiple ultrasonic beams, obtained in the later exposure stage by the pseudo-cylindrical transducer shown in Figure 12. [Figure 13A] Figure 13A is a perspective view showing an example of a second modified embodiment of the transducer having a pseudo-cylindrical shape as shown in Figure 12. [Figure 13B] Figure 13B is a perspective view showing the symmetrical shape of the focal range region, which is the off-axis positioning of multiple ultrasonic beams, obtained by the transducer shown in Figure 13A during two consecutive exposure stages. [Figure 13C] Figure 13C is a perspective view showing the shape of the focal range region, which is the off-axis movement of multiple ultrasonic beams, obtained by the transducer shown in Figure 13A during a series of exposure phases. [Figure 13D] Figure 13D is a perspective view showing the shape of the focal range region, which is the off-axis of multiple ultrasonic beams obtained by the transducer shown in Figure 13A, in relation to the region of ultrasound that is preserved during a series of exposure stages. [Modes for carrying out the invention]

[0037] As can be seen in more detail from Figure 1, the object of the present invention relates to a therapeutic apparatus I comprising a therapeutic probe 1 configured to treat biological tissue using high-intensity focused ultrasound (HIFU) in a general sense. In particular, the therapeutic probe 1 comprises a transducer 2 including a plurality of ultrasonic emitters 3, such as piezoelectric elements, and the plurality of ultrasonic emitters 3 define the focused ultrasound emission surface 4. These ultrasonic emitters 3 are connected by coaxial cables 5 to a control circuit 7 that transmits signals to drive the ultrasonic emitters 3 via an amplification stage 6. Since the implementation of the control circuit 7 is part of the technical knowledge of those skilled in the art, a detailed description of the control circuit 7 is omitted. This control circuit 7 typically includes a control signal generator, which is connected to the ultrasonic emitters via the amplification stage 6. In this way, each of the ultrasonic emitters 3 is connected to its respective signal generator.

[0038] The signal generator of the control circuit 7 drives ultrasonic emitters 3 located in segments, more precisely in curved or straight sections, so that a surface 8 for forming the pressure field of focused ultrasonic waves is determined. According to the first advantageous embodiment, the signal generator, which is part of the control circuit 7, is controlled to transmit a signal to drive the ultrasonic emitters 3 of the transducer 2 using a delay law or a phase law so that a generation surface 8 for the pressure field of focused ultrasonic waves is formed. This generation surface 8 is considered a virtual generation surface different from the radiating surface 4 of the transducer (Figures 2, 9A, and 10A). According to the second embodiment, the generation surface 8 for the pressure field of focused ultrasonic waves corresponds to the surface 4 of the transducer.

[0039] In other words, the pressure field generation surface 8 of the focused ultrasound corresponds to either the physical transducer, more precisely, the surface 4 of transducer 2, or a virtual generation surface 8 created by applying a phase to the command channel of transducer 2.

[0040] Driving the ultrasonic emitter 3 using the delay law or phase law is well known to those skilled in the art, but for the sake of clarity, the guidelines are explained below.

[0041] The total pressure P(r) at each point in the target region is defined as follows (Chavrier et coll. 2000):

[0042] [Math 1]

[0043] P(r) is the pressure at point r (Pa), dS is the number of elemental sources, ρ is the volumetric mass of the propagation medium, c is the velocity of the ultrasound in the propagation medium, λ is the wavelength, N is the number of driving elements in the transducer, S is the number of planes of each radiation source, u n φ is the normal velocity of element n. n The phase applied to element n is α medium φ is the attenuation coefficient of the medium, f is the operating frequency of the transducer, and finally k is the wavenumber. According to the method known as "maximal response" (Curiel et coll. 2002), the phase originating from each transducer element at the preferred focal point is given by the line integral φ described above. n This is obtained by fixing it to =0.

[0044] Therefore, the phase applied to each element is given as follows in order to obtain the maximum signal at a desirable point.

[0045] [Math 2]

[0046] Im[P(n,m)] and Re[P(n,m)] are, respectively, the imaginary part and the real part of the pressure field at point M sent by transducer element n. In this way, for each element n, the delay time τ n is defined as follows.

[0047]

Equation 3

[0048] Another calculation method is to define the path difference radiated between the natural focus and the preferred focus for each element n. In that case, the delay of each element is the distance between element n and its natural focus as d nat , the distance between element n and the preferred focus as d foc , and the speed of ultrasonic waves in the propagation medium as c,

Equation 4

Equation 5

[0049] As another calculation method, a virtual ultrasonic emitter divided into N elements with different geometries is defined, and the center of the first element of the actual emitter and the center of the first element of the virtual emitter are spatially aligned. The distance d n between each element is calculated for the applied delay,

Equation 6

Equation 7

[0050] As will be better understood in this specification, the shape of the generated surface 8 varies in particular depending on the application mode of the therapeutic device. Therefore, it is advantageous to arrange a probe having a surface 4 of a predetermined shape that is easy for a person skilled in the art to form (for example, as shown in Figure 1), and it is also advantageous to form a generated surface 8 from this surface 4 that has a complex shape to form and is different from the shape of surface 4 (for example, as shown in Figure 2). However, a transducer 2 may be manufactured having a surface 4 with a shape corresponding to the generated surface 8 of the pressure field of focused ultrasound, as shown in Figure 2, for example.

[0051] It should be noted that, according to the first modified embodiment (Figures 1, 2, 3, 7A-7C, 8A-8C, 9A-9D, 10A-10F, and 11A-11E), the generated surface 8 has a shape of rotation around the axis of symmetry S. It should also be noted that, according to the second modified embodiment (Figures 12, 12A-12C, and 13A-13D), it has a tubular pseudo-cylindrical shape, or a form consisting of two cylindrical parts having a plane of symmetry A1. It should be noted that Figures 4, 5, 6, and 6A are cross-sectional views illustrating the generated surface 8 according to the first modified embodiment and the generated surface 8 according to the second modified embodiment. The axis of symmetry S, defined along the vertical direction Z, corresponds to the axis of symmetry or acoustic axis of the surface 4 of the transducer formed in the shape of a plane of rotation. The plane of symmetry A1 is defined on the plane determined by the vertical direction Z and the transverse direction Y. This plane of symmetry is perpendicular to the cross-section Pp, which is defined by axes X and Z among the reference X, Y, and Z. This plane of symmetry A1 is the plane of symmetry or acoustic plane of face 4 of the transducer.

[0052] According to the features of the present invention, as shown in detail in the figures, the generating surface 8 is divided into at least N sectors 81, 82, ... which include an acoustic axis S and are divided by radial cuts along the acoustic axis S, or which extend in a mirror image position with respect to the acoustic surface A1. According to the first modified embodiment, the sectors are radial sectors with respect to the acoustic axis S, each containing a ring-shaped arrangement of ultrasonic emitters 3. On the other hand, in the second modified embodiment, the sectors are mirror image sectors with respect to the acoustic surface A1, containing a linear arrangement of ultrasonic emitters 3. According to the first modified embodiment, the advantageous number of radial sectors N is between 2 and 8, preferably equal to 2 (Figure 2), while in the second modified embodiment, the number of sectors N perpendicular to the acoustic surface A1 is between 2 and 32 (Figures 12 and 13A). Thus, according to these advantageous modified embodiments, the number of ultrasonic emitters 3 in the transducer is limited, and the cost of such a transducer is reduced. For example, in a preferred two-sector modification, each sector may contain 32 ultrasonic emitters 3. For simplicity of explanation, the term sector will be used only for the remainder of this specification.

[0053] The generation surface 8 is divided into N sectors 81, 82, ... such that ultrasound is focused into their respective focal regions Zc1, Zc2, ... The focal regions Zc1, Zc2, ... are defined on the focal planes Pf1, Pf2, ... Figures 2 to 6, 9A, 10A, and 12 show a preferred embodiment in which the generation surface 8 is divided into two sectors 81, 82. Figure 1 shows another embodiment in which the radiation surface 4 is advantageously divided into two sectors 41, 42 to form a generation surface 8 divided into two symmetrically opposing sectors.

[0054] Figure 7A shows another embodiment in which the radiating surface 4 is advantageously divided into four sectors 41, 42, 43, and 44 in order to form a generation surface 8 which is itself divisible into four sectors 81, 82, 83, and 84. Advantageously, the radiating surface 4 is divided into four sectors in order to form a generation surface 8 which is divided into two sectors each by two orthogonal surfaces (Figures 7B and 7C).

[0055] As can be seen more precisely from Figure 4, in the cross section Pp defined by axes X and Z among the reference X, Y, and Z, each sector 81, 82, ... of this generated surface 8 represents a finite-length concave curve portion (concave curve segment) S1, S2, .... As can be seen from the figure, the concave curve portions S1 and S2 of sectors 81 and 82 are separated by their respective ends 8a1, 8b1 and 8a2, 8b2, respectively. In the cross section Pp, the two concave curve portions S1, S2, ... are located on either the plane of symmetry A or the axis of symmetry S.

[0056] In the first modified embodiment, where the generated surface 8 has a shape that rotates around the axis of symmetry, the concave curve portions S1, S2, ... are asymmetric with respect to the axis of symmetry S of the transducer 2 (Figures 1, 2, 3, 7A-7C, 8A-8C, 9A-9D, 10A-10F, and 11A-11E). Alternatively, in the second modified embodiment, where the generated surface 8 has a pseudo-cylindrical shape, the concave curve portions S1, S2, ... are asymmetric with respect to the plane of symmetry A1 of the transducer (Figures 12, 12A-12C, and 13A-13D).

[0057] According to Figures 4, 5, 6, and 6A, which show the generated surface 8 according to the first and second modified embodiments, each of the concave curve portions S1, S2, ... has curvature centers c1, c2, ... corresponding to the ultrasonic focal regions Zc1, Zc2, .... According to the present invention, the concave curve portions S1, S2, ... of the sector are asymmetric with respect to the plane of symmetry A1 or the axis of symmetry S. Furthermore, the curvature centers c1, c2, ... are asymmetric with respect to the plane of symmetry A1 or the axis of symmetry S, and are asymmetric because the curvature centers c1, c2, ... are located at different distances from the plane of symmetry A1 or the axis of symmetry S, and / or at different depths along the vertical direction Z.

[0058] In the example shown in Figure 4, which includes a first sector 81 and a second sector 82, the distance from the curvature center c1 of the first sector 81 to the axis of symmetry S or plane of symmetry A1 is greater than the distance from the curvature center c2 of the second sector 82 to the axis of symmetry S or plane of symmetry A1. These distances are taken along the direction X perpendicular to the axis of symmetry S or plane of symmetry A1. In the example shown in Figure 4, it should be noted that the curvature centers c1 and c2 are located at the same depth along the vertical direction Z (or axis of symmetry S). That is, it should be noted that the curvature centers c1 and c2 are located along the same straight line perpendicular to the axis of symmetry S or plane of symmetry A1. In other words, the curvature centers c1 and c2 are located along the combined focal planes Pf1 and Pf2.

[0059] Figure 5 shows another embodiment in which the distance from the center of curvature c1 to the axis of symmetry S or plane of symmetry A1 is different from the distance from the center of curvature c2 to the axis of symmetry S or plane of symmetry A1, and the depth of the center of curvature c1 along the axis of symmetry S is different from the depth of the center of curvature c2 along the axis of symmetry S. Thus, according to the example shown in Figure 5, the focal plane Pf2 containing the center of curvature c2 is further away from the transducer along the axis of symmetry S than the focal plane Pf1 containing the center of curvature c1. In other words, the centers of curvature c1 and c2 are located on different focal planes Pf1 and Pf2, respectively.

[0060] Of course, even if the curvature centers c1 and c2 have different depths along the axis of symmetry S, but the distance from the curvature centers c1 and c2 to the axis of symmetry S or plane of symmetry A1 is the same, asymmetry can still be considered. Figure 6 shows this embodiment in which the distance from the curvature center c1 to the axis of symmetry S or plane of symmetry A1 is the same as the distance from the curvature center c2 to the axis of symmetry S or plane of symmetry A1, but the depth of the curvature center c1 along the axis of symmetry S is different from the depth of the curvature center c2 along the axis of symmetry S. In this example, the curvature centers c1 and c2 are located on different focal planes Pf1 and Pf2, respectively.

[0061] Each of the concave curved portions S1, S2, ... of the sector has individual axes a1, a2, ... passing through the curvature centers c1, c2, ... of the concave curved portion and the centers of the concave curved portions S1, S2, ....

[0062] According to another feature of the present invention, the individual axes a1, a2, ... of the concave curve portion intersect such that they form an off-axis focal range region Zr with respect to the plane of symmetry A1 or the axis of symmetry S. This focal range region Zr corresponds to the focal range regions of multiple ultrasonic beams originating from sectors 81, 82, ... of the generating plane 8. In the embodiments shown in Figures 4 to 6 and Figure 6A, in the cross section Pp, the focal range region Zr exhibits a cross section having four sides in the shape of a parallelogram, defined by multiple beams originating from each end 8a1, 8b1 and each end 8a2, 8b2 of the respective concave curve portions S1, S2. This ultrasonic focal range region Zr is advantageously used to form large-volume biological injuries. Independent of the use of the focal range region Zr as a therapeutic region, the geometry of the injury formed is controlled by the combination of focal regions Zc1, Zc2, ... and the focal range region Zr. In the present invention, the energy-delivering region corresponds to the focal range region Zr, independently of the energy that may be delivered to other focal regions.

[0063] This focal range region Zr is off-axis in the sense that the individual axes a1, a2, ... intersect at a common intersection I located outside the plane of symmetry A1 or outside the axis of symmetry S. The individual axes a1, a2, ... intersect either at a depth located between the focal range region Zc1, Zc2, ... and the generation plane 8, as shown in Figures 3 to 6 and 12, or on the other side of the focal range region Zc1, Zc2, ..., as shown in Figure 6A. Multiple beams originating from sectors 81, 82, ... intersect such that the focal range region Zr is located spaced apart from the focal planes Pf1, Pf2, ... along the vertical direction Z.

[0064] In the advantageous embodiment, the curved sections S1, S2, ... extend within the cross-section Pp on either the axis of symmetry S or the plane of symmetry A1, and are spaced apart from each other such that the focal range region Zr is located away from the generating surface 8. Therefore, as is clear from Figures 4 to 6 and Figure 6A, the ends 8a1 and 8a2 of the curved sections referred to as the inner section are spaced apart from the axis of symmetry S or the plane of symmetry A1.

[0065] As a result of this arrangement, the generated surface 8, followed by surface 4, shows an opening 10 centered on the axis of symmetry S or the plane of symmetry A1. The inner ends of the curved section located in cross-section Pp, called 8a1 and 8a2, are spaced apart from each other by an inner distance Di ranging from 10 mm to 120 mm along axis X. The choice of distance between these ends changes the position of the focal range region Zr relative to the generated surface 8 (Figures 3, 4, 5, 8B, 9B, and 10B), or, depending on the configuration, changes the shape of the focal range region Zr and its range along axis Z (Figure 6A). Advantageously, this opening 10 functions as a housing for an ultrasound imaging probe.

[0066] In the cross-section Pp, it should be noted that the outer sector ends 8b1 and 8b2 are spaced apart by an outer distance Ds in order to position the focal range region Zr away from the focal plane. In other words, the focal range region Zr does not contact the focal planes Pf1, Pf2, ... Thus, the focal range region Zr and the focal regions Zc1, Zc2, ... are distinct from each other or spaced apart from each other.

[0067] According to another feature of the present invention, in the first modified embodiment, sectors 81, 82, ... of the generating surface 8 are formed by rotating concave curves S1, S2, ... by 2π / N around the axis of symmetry S. Alternatively, in the second modified embodiment, sectors 81, 82, ... of the generating surface 8 are formed by moving (translating) the curves S1, S2, ... along a direction Y perpendicular to the cross section Pp containing the curves S1, S2, ... where N is the number of sectors. The sectors 81, 82, ... extend along an angular range or length of substantially the same value. In this way, if the generating surface 8 is a plane of revolution divided into two sectors, each sector 81, 82 extends along an angular range of 180° (Figure 2).

[0068] Sectors 81, 82, ... located in mirror image positions with respect to the axis of symmetry S or the plane of symmetry A1 form energy-granting regions having contours corresponding to the focal range region Zr and the focal region Zc. According to the first modified embodiment, the sectors of the generation surface 8 are formed by rotating a concave curve portion around the axis of symmetry S, and the focal regions Zc1, Zc2, ... have the shape of a part of a circle. When the generation surface 8 is divided into two sectors 81, 82, the focal regions Zc1, Zc2 are semicircles extending along an angular range of 180° (Figure 3). According to the second modified embodiment, the sectors 81, 82, ... are formed by moving a concave curve portion along a direction Y perpendicular to the cross section Pp containing the curve portion, and the focal regions Zc1, Zc2, ... extend along a straight portion located on a focal plane Pf1, Pf2, ... parallel to direction Y (Figure 12). When the generation surface 8 is divided into two sectors 81 and 82, the focal regions Zc1 and Zc2 extend along two straight sections located on the focal planes Pf1 and Pf2 parallel to direction Y (Figure 12).

[0069] The pressure field generation surface 8 of the focused ultrasonic wave is obtained or implemented by a transducer having a surface 4 configured to obtain the characteristics of the generation surface 8 described above.

[0070] According to the first modified embodiment, the generated surface 8 is a solid of revolution. This generated surface 8 originates from a surface 4 determined by transducer elements, which are advantageously arranged in an annular geometric configuration. The annular geometric configuration is formed by rotating concave curves around an axis of symmetry S such that the focal region has the shape of a part of a circle, tracing arcs of intersecting and non-contiguous circles.

[0071] Face 4 of the transducer corresponds to a portion of the envelope of the intersecting torus, cut along two planes perpendicular to the axis of symmetry S, as shown in Figure 8A.

[0072] According to the second modified embodiment, the generated surface 8 exhibits a pseudo-cylindrical or tubular shape. The surface of this generated surface 8 originates from a surface 4 defined by transducer elements arranged in a cylindrical geometric configuration. The cylindrical geometric configuration is formed by moving two curved sections by a finite length along a direction perpendicular to the cross-section containing the curved sections, such that the focal region has a linear shape.

[0073] Figure 8A shows a preferred exemplary embodiment of the surface 4 of the transducer 2, which is defined by a concave curve based on an intersecting annular geometric arrangement.

[0074] As can be seen from Figure 8B, in cross-section Pp, the radial plane 4 includes two concave curve sections S'1 and S'2 that trace the arcs of a first circle E'1 with center c'1 and a second circle E'2 with a different center c'2 than the center c'1 of the first circle E'1. The first circle E'1 and the second circle E'2 intersect each other without coinciding. One of the two concave curve sections, S'1 (on the right in Figure 8B), traces the arc of the first circle E'1, and this arc of the first circle E'1 is located inside the second circle E'2. Similarly, the other concave curve section S'2 (on the left in Figure 8B) traces the arc of the second circle E'2, and this arc of the second circle E'2 is located inside the first circle E'1.

[0075] In cross-section Pp, the radiating surface 4 exhibits two finite-length concave curves S'1 and S'2 that are symmetric with respect to the axis of symmetry S. Therefore, each of the concave portions S'1 and S'2 of the radiating surface 4 focuses ultrasound to the centers c'1 and c'2 of the circle in their respective ultrasound focal regions Zc'1 and Zc'2. The respective ultrasound focal regions Zc'1 and Zc'2 are located on the other side of the axis of symmetry S with respect to the corresponding radiating surfaces 4S'1 and S'2. These ultrasound focal regions Zc'1 and Zc'2 are defined in the focal plane Pf'.

[0076] According to the first modified embodiment, the individual axes of the concave curve sections S'1 and S'2 intersect the axis of symmetry S at a common intersection I' located on this axis of symmetry S. The common intersection of the individual axes is located between the radiating surface 4 and the focal regions Zc'1 and Zc'2, or on the other side of the focal surface Pf'. Therefore, the multiple beams of the radiating surface 4 intersect to form a range region Z'r of multiple ultrasonic beams that are symmetric with respect to the axis of symmetry S. This focal range region Z'r of multiple ultrasonic beams is called the natural range and is centered on the axis of symmetry S.

[0077] According to the first modified embodiment, the transducer exhibits a rotational shape. This radiating surface 4 is obtained by rotating the concave curve portion indicated by S'1 and S'2 around the axis of symmetry S, and when considering the intersection, the center of curvature of the concave curve portion is located on the side opposite the axis of symmetry S. In the plane XY, Figure 8C shows the natural shape of the focal range region Z'r obtained by such a rotating transducer. In the case of a torus transducer, it should be noted that the transducer also applies pressure to the focal plane of the circular shape represented by the focal regions Zc'1 and Zc'2 (Figure 8B).

[0078] According to the first modified embodiment, the radiating surface 4 is a surface of rotation. This radiating surface 4 includes, for example, a series of ultrasonic transducer elements 3 mounted concentrically with respect to each other and with respect to the axis of symmetry S. Of course, as shown in Figure 8A, it is possible to cut the radiating surface 4 symmetrically with respect to the axis of symmetry S such that the transducers are limited to a portion of intersecting rings having a width of, for example, 5 mm to 250 mm. According to this embodiment, the transducer 2 includes a series of ultrasonic transducer elements 3 mounted concentrically with respect to each other and with respect to the axis of symmetry S such that the transducer elements 3 are arranged in the shape of a ring-shaped portion.

[0079] According to the second modified embodiment, the transducer 2 has a radiating surface 4 that includes two parts (or portions) of a cylinder. This radiating surface 4 is obtained by forming finite-length concave curves S'1 and S'2 that are symmetric with respect to the plane of symmetry A1, in accordance with the guidelines described above, and by moving these two concave curves S'1 and S'2 along a direction Y perpendicular to the cross section Pp containing the concave curve portion. Thus, each portion of the radiating surface 4 focuses in front of, behind, or above the plane of symmetry A1 along a straight portion extending in a focal plane parallel to direction Y. The individual axes of the concave curves S'1 and S'2 cut off the plane of symmetry A1 at the intersecting axis I'' included in the plane of symmetry A1 (Figure 12A). As described above for the first modified embodiment, in the natural exposure stage, the multiple beams of the radiating surface 4 intersect to form a range region Z'r of multiple ultrasonic beams that are symmetric with respect to the plane of symmetry A1. This focal range region Z'r of multiple ultrasonic beams is called natural and is centered on the plane of symmetry A1.

[0080] Using the probe 1 having the radiating surface 4 described above, a generation surface 8 is created according to the present invention, whose features were previously explained. In the following description, the generation surface 8 is divided into two sectors 81 and 82 as a preferred embodiment, but the object of the present invention can also be applied to a generation surface 8 containing more sectors. It should be noted that the transducer 2 corresponds to a physical or actual transducer held in the user's hand. It should also be noted that the generation surface 8 is formed by two virtual semi-transducers simulated by dividing the two sectors into several emitter elements and then applying a phase to each of the channels of the physical transducer. To determine these phases, it is simply a matter of calculating the propagation time of the ultrasound between the transducer 2 and the generation surface 8 for each emitter element. According to the present invention, two virtual transducers are formed to move a focusing element without moving elements that have a geometric arrangement specific to a physical transducer, such as an acoustic axis or symmetry axis. The following description describes an advantageous embodiment in which a signal generator constituting part of the control circuit 7 is controlled to transmit a signal that drives a ring-shaped ultrasonic emitter 3 such that a pressure field generation surface 8 of focused ultrasonic waves is formed, using a delay law or a phase law.

[0081] As an example, Figures 9A to 9D and 10A to 10F show the operation of the ultrasonic emitter 3 of the transducer shown in Figures 8A to 8C such that a generation surface 8 of the type of the first modified embodiment, which includes two sectors 81 and 82, is formed.

[0082] A signal generator, which constitutes part of the control circuit 7, is controlled to transmit a signal that drives an ultrasonic emitter 3 to form a part of sector 42 that is symmetrically opposite sector 41 with respect to sector 41 and sector 41 with respect to the symmetry axis S, such that a corresponding energy-granting region is formed during the exposure phase.

[0083] During the exposure phase, the ultrasonic emitters 3 of two sectors 41 and 42 are driven to generate a pressure field generation surface 8 of focused ultrasound, and the generation surface 8 is driven to form two radiating surfaces. Each of the two radiating surfaces is obtained by rotating different concave curves s1 and s2 around the axis of symmetry S. In this way, the centers of curvature c1 and c2 can be independently positioned for each sector 81 and 82 on the side opposite or not opposite the curve with respect to the axis of symmetry. Accordingly, as shown in Figures 9B and 9C, an off-axis energy-granting region Zr1 can be formed with respect to the axis of rotation. By driving the ultrasonic emitters 3 that form part of sector 81 and the symmetrically opposite sector 82, an arched energy-granting region Zr1 with a contour corresponding to the energy-granting region, particularly the focal range region, is formed. This guideline is applied to the entire sector constituting the transducer and effectively improves the shape of the pressure-granting region.

[0084] In the second exposure stage, precisely shown in Figures 10A to 10D, the ultrasonic emitters 3 of two sectors 41 and 42 are driven to form an arched energy-granting region Zr2 having a contour corresponding to the focal range region, symmetric to the arched energy-granting region Zr1 shown in Figure 9D. To perform this second exposure stage, the control circuit drives the entire surface of the transducer again by inverting the phase applied between the sectors based on the above guidelines.

[0085] It should be noted that the signal generator, which constitutes part of the control circuit 7, is controlled to transmit signals that drive ultrasonic emitters that form parts of a sector and symmetrically opposite sectors with respect to the symmetry axis, such that corresponding energy-granting regions are formed for each set of sectors during consecutive exposure stages. In the example shown (Figures 10E to 10F), a coagulation crown can be formed by two consecutive ultrasonic exposures.

[0086] In the embodiments shown in Figures 10E to 10F, the coagulation crown exhibits a constant contour or width. Of course, the contour or width of the arched energy-granting region can be varied from one exposure stage to another, as can the height along direction Z, with respect to their positions relative to the axis of symmetry S.

[0087] Therefore, generally, the signal generators that constitute part of the control circuit 7 are controlled to transmit signals that drive the ultrasonic emitter such that, in each of the consecutive exposure stages, the curvature centers c1, c2, ... are located at different distances from the plane of symmetry A1 or the axis of symmetry S, and / or at different depths along the vertical axis Z, in order to obtain an off-axis energy application region.

[0088] Therefore, the signal generators that constitute part of the control circuit 7 are controlled in successive exposure stages so that off-axis energy-granting regions of the same or different sizes at different positions are obtained in successive exposure stages, and are controlled to transmit signals that drive the ultrasonic emitter so that the curvature centers c1, c2, ... are located at different distances from the plane of symmetry A1 or the axis of symmetry S, and / or at different depths along the vertical axis Z for each exposure stage.

[0089] In the example shown in Figures 10E to 10F, the entire ultrasonic emitter of two sectors 81 and 82 undergoes two drive stages in which the phase is calculated so that the focal range regions Zr1 and Zr2 are symmetric with respect to the axis of symmetry S. During the second drive cycle, the concave curve portion S1 is converted to S2 and the concave curve portion S2 is converted to S1, which is reflected in the region of the generated surface 8.

[0090] Figure 11A shows an embodiment in which the entire ultrasonic emitter of two sectors 81, 82 undergoes two drive stages in a single exposure cycle. In the drive stages, the phase is calculated such that the focal range regions Zr1, Zr2 are asymmetric with respect to the axis of symmetry S. In this example, the two drive stages are performed using curvature centers c1, c2 arranged in a manner adapted to obtain asymmetric focal range regions Zr1, Zr2.

[0091] The centers of curvature are located spaced apart from each other. Alternatively, they may be at different distances from the plane of symmetry A1 or the axis of symmetry S, but at the same depth. Alternatively, they may be at the same distance from the plane of symmetry A1 or the axis of symmetry S, but at different depths. Alternatively, such that they are at different distances from the plane of symmetry A1 or the axis of symmetry S, and at different depths relative to the plane of symmetry A1 or the axis of symmetry S, It is thought that exposure stages can be carried out sequentially, from one exposure stage to another.

[0092] Therefore, it is conceivable that, by driving the ultrasonic emitter such that the distance and / or depth of the center of curvature changes from one exposure stage to another during a series of exposure stages, the focal range can be concentric and / or symmetrical and / or asymmetrical and / or superimposed with respect to the vertical axis Z. Thus, the exposure stages can be combined "infinitely" depending more or less on the complex shape of the volume being treated.

[0093] Figure 11B shows an embodiment in which a signal generator, which is part of the control circuit 7, is controlled so that the entire ultrasonic emitter of two sectors 81 and 82 goes through two drive stages. In the drive stages, the phase is calculated so that the focal range regions Zr1 and Zr2 are symmetric with respect to the axis of symmetry S. These two drive stages form exposure cycles that are repeated at different depths along the vertical axis Z so that an energy-granting crown is obtained. This crown forms a cylindrical shape that has the same width and height from one exposure stage to the other.

[0094] Figure 11C shows another embodiment in which a signal generator, which is part of the control circuit 7, is controlled to transmit a signal that drives the ultrasonic emitter 3 such that the focal range region Zr is located at different distances and different depths along the vertical axis Z, in order to obtain a focal range region with a variable width and / or height that is superimposed.

[0095] In the example described above, the energy-granting volume is hollow, i.e., not in contact with the axis of symmetry S. Of course, a signal generator, which constitutes part of the control circuit, can be controlled to transmit a signal that drives the ultrasonic emitter such that, in at least one complementary exposure step, the ultrasonic waves are focused in the focal region and a focal range region Z'r is obtained that is centered with respect to the plane of symmetry A1 or the axis of symmetry S and is located spaced apart from the focal plane or beyond the focal region between the focal region and the radiating plane. Thus, a complementary exposure step, referred to as "natural," according to the guidelines shown in Figures 8A and 8B, can be performed for one or each exposure step to complete the energy-granting volume. Of course, this complementary exposure step can be performed for one and / or the other of the embodiments described herein. Thus, Figure 11D shows the execution of a complementary exposure step for the modification shown in Figure 11B.

[0096] Figure 11E shows a plan view of the natural focal range region Z'r, which is centered on the axis of symmetry S and surrounded by the focal crown K formed by two consecutive ultrasonic exposures, as described earlier. It should be noted that this figure shows that four consecutive ultrasonic exposures, embodied by a generation surface 8 divided into four sectors to form four focal range regions Zr1 to Zr4, generate formations around the additional focal crown, the focal crown K.

[0097] As an example, the following description illustrates the implementation of the generated surface 8 according to the second modified embodiment. In this example shown in Figure 12, the first focal region has a double-line shape. The conditions for implementing the present invention, described in relation to Figures 10A to 10F and 11A to 11E for the first modified embodiment, also apply to the pseudo-cylindrical generated surface 8.

[0098] According to the present invention, the ultrasonic emitter 3 is driven using a delay law or a phase law so as to be cut parallel to the plane of symmetry A1 and to form a generating plane 8. The ultrasonic emitter is arranged along at least two sectors, and according to the example shown in Figure 12, has two sectors 81, 82 arranged symmetrically with respect to the plane of symmetry A1.

[0099] Therefore, the signal generator, which constitutes part of the control circuit, is controlled to transmit a signal to drive an ultrasonic emitter that forms a sector located on one side of the symmetry plane A1 and a portion of the symmetrically opposite sector, so as to form a corresponding energy-granting region during the exposure phase. Thus, an energy-granting volume Zr1 (or focal range region Zr1) can be formed on one side of the symmetry plane A1, spaced away from this plane (Figure 12B). Similarly, an energy-granting volume Zr2 (or focal range region Zr2) can be formed on the other side of the symmetry plane A1, spaced away from this plane (Figure 12C).

[0100] According to another advantageous embodiment, the ultrasonic emitters are arranged along a plurality of sectors perpendicular to the plane of symmetry A1 and are positioned opposite to the plane of symmetry A1. In the example shown in Figure 13A, nine sectors are located on either side of the plane of symmetry A1, with each sector on one side facing a sector on the other side. Thus, a signal generator, which is part of the control circuit, is controlled to transmit a signal to drive ultrasonic emitters forming a sector and part of the opposing sector, using a delay law or a phase law, so that a corresponding energy-granting region is formed on one side of the plane of symmetry during the exposure phase (Figure 13A). The ultrasonic emitters of the opposing sectors can form an energy-granting volume on either side of the plane of symmetry A1. Figure 13B shows the implementation of two energy-granting volumes located on either side of the plane of symmetry A1. The thickness of the energy-granting volume corresponds to the width of one sector of the transducer.

[0101] As explained earlier, the shape, size, and position of each energy-granting volume can be changed, particularly by utilizing the position of the center of curvature. By driving different sectors of the transducer in succession, a hollow energy-granting volume with variable thickness is formed (Figure 13C).

[0102] This solution is particularly advantageous for treating target regions extending along non-linear segments T, for example, tumors along arteries or veins, tumors along the gastrointestinal tract, tumors along bone, Wilson's duct of the pancreas, tumors along the urethra or bile duct (Figure 13D).

[0103] From the above description, it is clear that the objective of the present invention is to effectively reduce the number of emitters by forming movement of the focal region in the depth direction (along the acoustic axis) and movement in a plane parallel to the transducer (perpendicular to the acoustic axis). In contrast to prior art that proposes forming a focal point and moving it in space (electron focusing), the objective of the present invention is to directly form a volume (part of the crown) obtained by calculating a "virtual" generation surface or a "virtual" transducer, and to move this volume without going through a large number of emitters. Therefore, this invention can reduce not only the cost of control electronics but also the cost of transducers.

Claims

1. A treatment device for treating tissue by emitting focused ultrasound, comprising: The treatment device comprises a treatment probe having a transducer (2) including a number of ultrasound emitters (3) defining a radiation plane (4) of focused ultrasound waves having an axis of symmetry (S) corresponding to an acoustic axis or a plane of symmetry (A1) corresponding to an acoustic plane, the ultrasound emitters being driven by signals transmitted by a signal generator forming part of a control circuit (7) so as to define a generation plane (8) of a pressure field of the focused ultrasound waves; The generation plane (8) is the focal plane (Pf 1 , Pf 2 , ...) 1 , Zc 2 At least N sectors (8 , . . . ) are arranged so that the ultrasonic waves are focused on the 1 , 8 2 , ...) (N is from 2 to 32), and the sectors of this generating surface are divided into cross sections (P p ) having finite length concave curved portions (S1, S2, ...) that are asymmetric with respect to the symmetry plane (A1) or the symmetry axis (S), Its center of curvature (c 1 , c 2 , ...) are asymmetric with respect to the plane of symmetry (A1) or the axis of symmetry (S) such that the centers of curvature are located at different distances from the plane of symmetry (A1) or the axis of symmetry (S) and / or at different positions in the direction along the axis of symmetry, Each of the concave curved portions (S1, S2, ...) has a center of curvature (c 1 , c 2 , ...) and the center of the concave curved portion (S1, S2, ...) 1 , a 2 , ...) The individual axes (a 1 , a 2 , ...) are the beams originating from the sectors in the focal region (Zc 1 , Zc 2 , ...) and the generation surface (8), or between the focal region (Zc 1 , Zc 2 , ...) on the opposite side of the generation plane, and deviates from the symmetry plane (A1) or the symmetry axis (S) to the focal plane (Pf 1 , Pf 2 , ...) to form a focal range region (Zr) located at a distance from the focal region (Zc 1 , Zc 2 , ...) and the generation plane (8) or on the opposite side of the generation plane with respect to the focal region, The sector of this generating surface (8) is 1 , 8 2 by rotating the concave curved portion (S1, S2, ...) by 2π / N around the axis of symmetry (S) or by moving the concave curved portion along a direction (Y) perpendicular to the cross section (Pp) including the concave curved portion (S1, S2, ...) so that the concave curved portion (S1, S2, ...) can form an energy application region having a contour corresponding to the focal range region (Zr); The concave curved portions (S1, S2, ...) of the generation surface (8) extend within the cross section (Pp) on either side of the symmetry axis (S) or the symmetry plane (A1), and are spaced apart from each other so that the focal range region (Zr) is located at a position spaced apart from the generation surface. A treatment device characterized by:

2. 2. The treatment device according to claim 1, characterized in that the generation surface (8) is divided into two sectors.

3. In the generating surface (8), the inner end (8a 1 , 8a 2 2. The treatment device according to claim 1, characterized in that the aforesaid first and second electrodes (a) and (b) define a housing for mounting an ultrasound imaging probe.

4. 4. The treatment device according to claim 1, wherein the generating surface (8) originates from a surface (4) defined by transducer elements arranged in a circular geometric arrangement, the circular geometric arrangement being formed by rotating a concave curved section around the axis of symmetry (S) to describe arcs of mutually intersecting and non-coincident circles, the mutually intersecting and non-coincident circles intersecting such that the focal region has the shape of a portion of a circle.

5. 5. The treatment device according to claim 4, characterized in that the surface (4) has a shape that is symmetrically cut about the axis of symmetry (S).

6. The treatment device according to any one of claims 1 to 3, characterized in that the generation surface (8) is derived from a surface (4) defined by transducer elements arranged in a cylindrical geometric arrangement, the cylindrical geometric arrangement being formed by moving two of the concave curved portions by a finite length along a direction (Y) perpendicular to the cross section (Pp) including the concave curved portions so that the focal region has a linear shape.

7. The treatment device according to any one of claims 1 to 6, characterized in that the ultrasound emitter (3) of the transducer (2) defines a radiation surface (4) which corresponds to the generation surface (8) of the pressure field of focused ultrasound.

8. The treatment device according to any one of claims 1 to 6, characterized in that the signal generator forming part of the control circuit (7) is controlled to transmit signals for driving the ultrasound emitters (3) arranged in the part using a delay law or a phase law so that the generation surface (8) of the pressure field of focused ultrasound is formed.

9. In the exposure phase, the sector (8 1 , 8 2 9. The treatment device according to claim 1 , characterized in that the ultrasound emitters forming part of sectors symmetrically opposed to the axis of symmetry ( , ...) are driven by signals transmitted by the signal generator forming part of the control circuit (7) such that corresponding energy deposition areas are formed.

10. In the exposure phase, the sector (8 1 , 8 2 9. The therapeutic device according to claim 1, characterized in that the ultrasound emitters (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 109, 108, 109, 109, 108, 109, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 1

11. In the later exposure stage, the sector (8 1 , 8 2 11. The treatment device according to claim 10, characterized in that the ultrasound emitters (3) forming part of sectors symmetrically opposed to the plane of symmetry (A1) ( , ...) are driven by signals transmitted by the signal generator forming part of the control circuit (7) such that a corresponding energy deposition area is formed on a side opposite to the side on which the energy deposition area was formed in the previous exposure phase.

12. 12. The treatment device according to claim 10 or 11, characterized in that the ultrasound emitters (3) are arranged along a number of sectors perpendicular to the plane of symmetry (A1), and in successive exposure phases the ultrasound emitters of a sector are driven by signals transmitted by the signal generator forming part of the control circuit (7) such that energy deposition areas are formed on either side of the plane of symmetry (A1).

13. The center of curvature (c 1 , c 2 13. The treatment device according to claim 1, characterized in that in each successive exposure phase, in which the ultrasound emitters (1, 2, ...) are located at different distances from the plane of symmetry (A1) or the axis of symmetry (S) and / or at different positions in the direction along the axis of symmetry (S), the ultrasound emitters are driven by signals transmitted by the signal generator forming part of the control circuit (7) so as to obtain an energy deposition area outside the plane of symmetry (A1) or the axis of symmetry (S).

14. The center of curvature (c 1 , c 2 14. The treatment device according to claim 13, characterized in that in successive exposure phases, in which the ultrasound emitters (A1, ...) are located at different distances from the plane of symmetry (A1) or the axis of symmetry (S) and / or at different positions in the direction along the axis of symmetry (S), the ultrasound emitters are driven by signals transmitted by the signal generator forming part of the control circuit (7) in order to obtain, in these successive exposure phases, energy deposition areas at different positions, having the same or different sizes, outside the plane of symmetry (A1) or the axis of symmetry (S).

15. 15. The treatment device according to any one of claims 9 to 14, characterized in that in successive exposure stages, the energy application areas can be concentric and / or symmetric and / or asymmetric and / or overlapped along the axis of symmetry (S), by driving the ultrasound emitters by signals transmitted by a signal generator constituting part of the control circuit (7), such that the distance and / or the position of the centre of curvature is varied from one exposure stage to another.

16. 16. The treatment device according to claim 1, characterized in that, during at least one supplementary exposure phase, the ultrasound emitter (3) is driven by a signal transmitted by the signal generator (7), which constitutes part of the control circuit (7), in such a way that the ultrasound is focused in a focal region, resulting in a focal range region that is centered with respect to the plane of symmetry (A1) or the axis of symmetry (S) and located at a distance from the focal plane between the focal region and the generation plane (8) or on the opposite side of the generation plane with respect to the focal region.

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