System for controlled fragmentation of solids by acoustic vortex beams

Abstract

The present invention relates to a system for controlled fragmentation of solid objects with an acoustic vortex beam, the system comprising at least one acoustic beam generator (100) and a feedback and control device (200) for one of the generators (100). Advantageously, the acoustic beam generated by the system is an acoustic vortex beam, and the feedback and control device (200) further comprises a feedback subsystem (12) configured to receive information about the solid object to be fragmented and use it to adapt the operation of the acoustic beam generator (100). Given that shear stress generation is more efficient with vortex beams, the amplitude of the ultrasonic field required to fragment a stone is much lower than with current extracorporeal shock wave lithotripsy techniques. Similarly, the system minimizes unwanted effects on the soft tissue surrounding the solid object.

Description

[Technical Field]

[0001] The present invention relates to techniques for the interaction of ultrasonic acoustic beams with biological tissues and objects. More specifically, the present invention relates to an acoustic vortex beam system for fragmenting hardened masses or stones in a minimally invasive manner. In such a system, the vortex beam may be modulated with respect to intensity, phase, repetition rate, topological charge, etc., according to the size, location, and composition of the mass to be destroyed, as well as the energy the beam imparts to the mass. [Background technology]

[0002] Until the early 1980s, most kidney stones were treated by open surgery. Advances in minimally invasive ureteroscopy (URS) and percutaneous nephrostolithotomy (or nephrolithotomy) (PCNL) techniques, along with the advent of non-invasive extracorporeal shockwave lithotripsy (ESWL) systems, as reported in, for example, Non-Patent Document 1, have led to the demise of open surgery for the removal of kidney stones and / or gallstones.

[0003] The first ESWL treatment was performed in Germany in 1980 using a Dornier "HM1 (Human Model 1)" lithotriptor (see Non-Patent Document 2). The clinical use of ESWL lithotripsy technology has rapidly spread for the fragmentation of kidney stones due to its effectiveness and limited side effects.

[0004] In contrast to URS and PCNL, the goal of ESWL treatment is stone fragmentation, not stone extraction. This is achieved by exposing the stone to a series of high-amplitude ultrasound pulses. These pulses are mechanical waves that generate shear stress and large internal stresses within the stone. After exposure to such mechanical stress, the stone breaks into smaller fragments, which are then naturally expelled by the tissue itself (see Non-Patent Document 3).

[0005] The acoustic energy in ESWL is focused on a relatively small area, i.e., the area surrounding the lithotriptor's focal point and the location of the kidney stone of interest. The focal zone can be small or large, and the amount of energy or maximum pressure applied to it can also be manipulated. Typical focusing values for modern lithotriptors are 50 to 150 MPa, delivered to a 3 to 6 mm focal zone, as mentioned in the previously referenced non-patent document 2. However, large focusing values do not guarantee treatment effectiveness. As the number of focused lithotriptors increases, the number of shock waves that actually impact the stone tends to decrease, with the remainder of the shock wave energy impinging directly on the kidney tissue (see non-patent document 4). Because stones are more likely to remain within the focal zone during treatment if the zone is larger, devices exist that operate at lower pressures and larger focal areas, e.g., 20 MPa over a 20 mm focal point. As reported in the literature (see non-patent documents 5 and 6), lithotriptors with a wider focal zone generate smaller renal lesions and are therefore more advantageous. Furthermore, it has been shown that when the width of the focal spot is larger than the diameter of the stone, the shear wave required to induce large internal stress increases (see Non-Patent Document 7).

[0006] Currently, all lithotriptors require four common components: a mechanism for generating high intensity ultrasound waves, a mechanism for focusing these waves, a coupling means between the generating system and the patient's body, and a system for locating the stone for treatment planning and monitoring.

[0007] There are three main technologies for generating ultrasound: electrohydraulic systems, piezoelectric systems, and electromagnetic systems.

[0008] First, the electrohydraulic generator system generates shock waves by an electric arc located at a first focal point F1 of an ellipsoidal reflector. The device is positioned so that the stone is located at a second geometric focal point, commonly referred to as F2, of the ellipsoidal reflector. Thus, the shock wave front propagates from the first focal point through a water bath, which then acts as an acoustic coupling with the patient's body, to the second geometric focal point of the ellipsoidal reflector where the stone is located.

[0009] Second, piezoelectric systems are based on the vibration of a piezoelectric material exposed to an electric field, which is typically generated by a short, high-voltage pulse between two electrodes. The expansion and contraction of the piezoelectric actuator generates ultrasound waves that propagate to the focal point of the system where the stone is located. As disclosed in the previously referenced non-patent document 3 and also in non-patent document 8, when a piezoelectric system is composed of multiple components, they form a phased array (also known as an array), which allows electronic focusing by time lag of the electrical pulses, allowing the focal point to be dynamically positioned.

[0010] Finally, electromagnetic lithotriptors use an electrodynamic transducer consisting of a coil placed against a metal foil in contact with water. A high voltage pulse is discharged across a capacitor, generating a pulsed current through the coil. The subsequent current pulse through the coil induces a repulsive force against the metal foil, which violently contracts the water and generates an ultrasonic pulse. This process is described in detail in several prior art documents, for example in the previously cited non-patent document 3 or non-patent document 9. Pulse focusing is achieved by using an acoustic lens or a parabolic reflector (see the previously mentioned paper in non-patent document 8).

[0011] One of the mechanisms for stone fragmentation is the activation of cavitation bubbles generated around the stone. Some lithotriptors attempt to optimize this phenomenon by using multiple shock waves, either simultaneously or in rapid succession, to induce bubble collapse around the stone. One way to achieve this is to use a second piezoelectric head to generate a second shock wave co-focused with the first, which significantly improves stone fragmentation. This is known from non-patent documents 10 and 11. Another method is to add an extra electrical excitation system to the lithotriptor to generate two consecutive pulses, as disclosed in non-patent document 12. Finally, dual-head lithotriptors can send shock waves to the same point to optimize fragmentation, as implemented in non-patent documents 13 and 14.

[0012] Two methods of coupling between the ultrasound generating system and the patient's body are commonly used. The first method, called water bath lithotripsy, involves partially immersing the patient's body in water to ensure proper transmission of shock waves into the tissue. The second method, called dry head lithotripsy, involves covering the emitting system with a water balloon and coupling it to the patient's skin with an elastic membrane (see the previously cited paper [8]). In this last technique, it is important to use a coupling gel to ensure the correct impedance coupling between the membrane and the skin. As demonstrated in

[15] , it is necessary to avoid the formation of bubbles in the gel, which significantly reduces the effectiveness of ESWL.

[0013] The use of different sequences during ultrasound beam generation, such as multiple power fluctuation intervals with short pauses, has been shown to improve ESWL lithotripsy outcomes in addition to reducing kidney tissue damage. Using a slow repetition rate of approximately 60 waves per minute results in optimal fragmentation with minimal complications.

[0014] Imaging techniques such as X-ray or fluoroscopy are commonly used to identify and locate stones. This also aligns the system's focal point with the solid object to be fragmented (e.g., a kidney stone) before initiating ESWL treatment. However, a major drawback is the movement of the stone relative to the lithotriptor's focal point during treatment. This is primarily due to the patient's respiratory motion. If no precautions are taken, this can result in more than 50% of the transmitted shock waves not reaching the stone but instead impinging on the kidney tissue, overheating it and further damaging it. To avoid this, dynamic tracking and focusing systems have been developed using ultrasound imaging and piezoelectric lithotriptors (see Non-Patent Document 16) or optical lithotriptors to continuously locate the stone and synchronize shock wave triggering.

[0015] Recently, an acoustic system for monitoring stone fragmentation has been proposed. Using a broadband receiver, acoustic signals are acquired from the reverberation and resonance of the stone under the action of ultrasound. Various parameters of the acquired signal, such as the frequency, correlate with the size of the fragments (see Non-Patent Document 17). This allows for monitoring of the treatment and also for recognizing when the treatment needs to be stopped to reduce unnecessary acoustic energy to healthy kidney tissue. [Prior art documents] [Patent documents]

[0016] [Patent Document 1] U.S. Patent No. 4,865,042 [Non-patent literature]

[0017] [Non-Patent Document 1] N. Bhojani and JE Lingeman, "Shockwave Lithotripsy-New Concepts and Optimizing Treatment Parameters", Urol. Clin. North Am., vol. 40, no. 1, p. 59-66, 2013 [Non-patent document 2] C. Chaussy et al., "Extracorporeally Induced Destruction of Kidney Stones by Shock Waves", Lancet, vol. 316, no. 8207, p. 1265-1268, 1980 [Non-patent document 3] JJ Rassweiler et al., "Shock Wave Technology and Application: An Update", Eur. Urol., vol. 59, no. 5, p. 784-796, 2011 [Non-patent document 4] RO Cleveland et al., "Effect of Stone Motion on in Vitro Comminution Efficiency of Storz Modulith SLX", J. Endourol., vol. 18, no. 7, p. 629-633, 2004 [Non-patent document 5] AP Evan et al., "Independent assessment of a wide-focus, low-pressure electromagnetic lithotripter: absence of renal bioeffects in the pig", BJU Int, vol. 101, no. 3, p. 382-388, 2008 [Non-patent document 6] J. A. McAteer et al., "Independent Evaluation of the Lithogold LG-380 Lithotripter: In Vitro Acoustic Characteristics and Assessment of Renal Injury in the Pig Model", J. Urol., vol. 181, no. 4, p. 665-666, 2009 [Non-Patent Document 7] R. O. Cleveland and O. A. Sapozhnikov, "Modeling elastic wave propagation in kidney stones with application to shock wave lithotripsy", J. Acoust. Soc. Am., vol. 118, no. 4, p. 2667-2676, 2005 [Non-Patent Document 8] T. G. Leighton and R. O. Cleveland, "Lithotripsy", Proc. Inst. Mech. Eng. Part H J. Eng. Med., vol. 224, no. 2, p. 317-342, 2010 [Non-Patent Document 9] W. Folberth et al., "Pressure distribution and energy flow in the focal region of two different electromagnetic shock wave sources", J. Stone Dis., vol. 4, no. 1, p. 1-7, 1992 [Non-Patent Document 10] X. Xi and P. Zhong, "Improvement of stone fragmentation during shock-wave lithotripsy using a combined EH / PEAA shock-wave generator-in vitro experiments," Ultrasound Med. Biol. vol. 26, no. 3, p. 457-467, 2000 [Non-Patent Document 11] AZ Weizer et al., "New Concepts in Shock Wave Lithotripsy," Urol. Clin. North Am. vol. 34, no. 3, p. 375-382, 2007 [Non-Patent Document 12] F. Fernandez et al, "Treatment time reduction using tandem shockwaves for lithotripsy: An in vivo study," J. Endourol. vol. 23, no. 8, p. 1247-1253, 2009 [Non-Patent Document 13] DL Sokolov et al., "Use of a dual-pulse lithotripter to generate a localized and intensified cavitation field," J. Acoust. Soc. Am., vol. 110, no. 3, p. 1685-1695, 2001 [Non-Patent Document 14] DL Sokolov et al., "Dual-pulse lithotripter accelerates stone fragmentation and reduces cell lysis in vitro," Ultrasound Med. Biol. vol. 29, no. 7, p. 1045-1052, 2003 [Non-Patent Document 15] Y. A. Pishchalnikov et al, "Air Pockets Trapped During Routine Coupling in Dry Head Lithotripsy Can Significantly Decrease the Delivery of Shock Wave Energy," J. Urol. vol. 176, no. 6, p. 2706-2710, 2006 [Non-Patent Document 16] C. Bohris et al., "Hit / miss monitoring of ESWL by spectral Doppler ultrasound", Ultrasound Med. Biol., vol. 29, no. 5, p. 705-712, 2003 [Non-Patent Document 17] N. R. Owen et al., "The use of resonant scattering to identify stone fracture in shock wave lithotripsy", J. Acoust. Soc. Am., vol. 121, no. 1, p. EL41-EL47, 2007 [Non-Patent Document 18] S. C. Kim et al., "Cystine calculi: Correlation of CT-visible structure, CT number, and stone morphology with fragmentation by shock wave lithotripsy", Urol. Res., vol. 35, no. 6, p. 319-324, 2007 [Non-Patent Document 19] LJ Wang et al., "Predictions of outcomes of renal stones after extracorporeal shock wave lithotripsy from stone characteristics determined by unenhanced helical computed tomography: A multivariate analysis", Eur. Radiol, vol. 15, no. 11, p. 2238-2243, 2005 [Non-Patent Document 20] JA McAteer et al., "Shock Wave Injury to the Kidney in SWL: Review and Perspective", p. 287-301, 2007 [Non-Patent Document 21] K. Maeda et al., "Energy shielding by cavitation bubble clouds in burst wave lithotripsy," J. Acoust. Soc. Am. vol. 144, no. 5, pp. 2952-2961, 2018 [Non-Patent Document 22] N. Jimenez et al., "Sharp acoustic vortex focusing by Fresnel-spiral zone plates," Applied Physics Letters, 2018, vol. 112, no 20, p. 204101 Summary of the Invention [Problem to be solved by the invention]

[0018] However, although ESWL is widely accepted and widely used, this procedure has several important limitations. First, certain types of kidney stones, such as stones composed of brushite, are highly resistant, and their fragmentation by ESWL is limited. This drawback is crucial because patients with such stones will undergo ESWL and thus be exposed to its complications (minor and severe) without the benefit of achievable fragmentation (see Non-Patent Document 18).

[0019] Stone location, size, and composition are the most important predictors of ESWL treatment success. Different types of stones, in descending order of hardness and therefore difficulty of fragmentation, consist of brushite (calcium hydrogen phosphate), cystine, calcium oxalate monohydrate, struvite, calcium oxalate dihydrate, or uric acid. Stone types can be distinguished by measuring radiodensity with X-ray tomography. Stones with a density greater than 900 Hounsfield units (HU) predict the likelihood of ESWL treatment failure (see Non-Patent Document 19). X-ray-based techniques are used as predictors of ESWL stone fragmentation. Other stones, such as those composed of calcium oxalate monohydrate or cystine, are not completely fragmented and require complementary treatment. Finally, minor complications, primarily due to the action of shock waves on healthy tissue, occur very frequently, and in some cases, severe complications occur (see Non-Patent Document 20).

[0020] Current advances in optimizing ESWL outcomes focus on the initial characterization of stone (or calculi) type, location, and size, optimization of treatment parameters such as wave acoustic coupling and repetition rate, and shock wave sequence.

[0021] However, because the tissues surrounding the stone to be fragmented are constantly exposed to high-intensity ultrasound pulses, they are subject to minor or severe complications. These complications include bleeding, thrombosis, arrhythmias, vasoconstriction, hypertension, renal impairment, infection, changes in the autonomic nervous system, and the release of cellular mediators and hormones. The development of tissue damage has been identified as a two-stage sequential process. The first stage consists of initial tissue destruction due to the mechanical impact of the shock wave, which leads to blood accumulation. In the second stage, such accumulation promotes the development of inertial cavitation in the focal zone, which produces the most detrimental effects on tissue (see the previously mentioned paper by [End Page 109]). The development of inertial cavitation is closely linked to shock wave rarefaction, i.e., the amplitude of the minimum pulse pressure. Finally, excessive cavitation generates gas bubbles that act as a barrier to the shock wave (see [End Page 110]). For all these reasons, it is necessary to quantify the cavitation that occurs using different cavitation indices described in the field of fluid mechanics.

[0022] Furthermore, patients have previously experienced significant pain from kidney stones, and ESWL techniques also cause significant pain, in some cases requiring treatment to be discontinued prematurely (see the previously cited article in Non-Patent Document 8). To reduce pain, a weaker, more focused source (and thus a lower amplitude of acoustic waves) is used here, but this remains a major limitation of the prior art.

[0023] On the other hand, acoustic beam focusing techniques are known, as disclosed, for example, in U.S. Pat. No. 6,213,199 (Unemura et al.), entitled "Ultrasonic irradiation system." This document proposes a system of multiple ring acoustic transducers, whose excitation signals have appropriately adjusted delays to achieve focusing on a two-dimensional (2D) (annular or elliptical) planar focal zone and avoid unwanted secondary focusing along the propagation direction. A more recent example of a three-dimensional (3D) spiral vortex beam is disclosed, for example, in Non-Patent Document 22. Vortex beams are longitudinal mechanical waves, typically with frequencies in the ultrasonic range, and the corresponding acoustic field exhibits a phase singularity along one axis. In particular, in cylindrical coordinates r = r(θ, r, z), such a beam may be expressed as follows:

[0024]

number

[0025] where P0 is the pressure value and G r (r) and G z(z) denote the beam shape along the radial (r) and axial (z) coordinates, respectively; M is the topological beam charge (related to the momentum transfer efficiency); and θ is the azimuthal coordinate. A (typically screw-shaped) topological defect creates a null field at the axis of the acoustic beam due to destructive wave interference at that point, as shown in Figure 1. The field maximum has a circular or toroidal distribution around the focal point. However, the field phase (Φ) varies linearly along the azimuthal coordinate, and thus the pressure maximum rotates as a function of time. This allows vortex beams to transfer linear and angular momentum very efficiently to interacting objects. Furthermore, because they can be designed to be focused to a specific region with predetermined physical parameters (intensity, frequency, wave repetition rate, etc.), they allow for the delivery of transferred energy to the object. In this case, these vortex beams allow reaching a volumetric 3D focal zone, thereby allowing the 3D focal zone to be reached in a deliberate and controlled manner, simultaneously and without the need to refocus (electronically or mechanically), and this is not limited to a 2D plane.

[0026] In summary, there is a need to develop new technologies that allow for the efficient fragmentation of stones using mechanical waves with reduced amplitudes, so as to minimize the adverse effects and complications of conventional ESWL procedures as well as the discomfort experienced by the patient. [Means for solving the problem]

[0027] The present invention discloses a system for the non-invasive fragmentation of solid objects using acoustic vortices. It should be noted that one of its most important applications is its use in lithotripsy.

[0028] In certain applications, the object of the present invention is to provide a solution to the problem of insufficient efficiency of ESWL technology, with respect to the amount of energy applied to the surrounding soft tissue, rather than to the solid object to be fragmented (e.g., gallstones or kidney stones). In this sense, the present invention surpasses the current state of the art and provides the necessary method and system for fragmenting stones inside tissue in a non-invasive manner, using a focused ultrasonic vortex beam of finite amplitude, also known as a high-intensity ultrasound beam. However, the present application may be applied, without limitation, to other applications requiring the controlled destruction of solid objects in a non-invasive manner.

[0029] In a first inventive aspect, the present invention relates to a system for controlled fragmentation of solid objects by acoustic shock waves, the system comprising an acoustic beam generator and a feedback and control device, a) The one acoustic beam generator is an electric pulse generation subsystem, said pulse being characterized by a voltage and / or current suitable for fragmenting solid objects; a first transduction subsystem adapted to convert electrical pulses into high intensity acoustic waves or pressure, said transduction being electrohydraulic, electromagnetic, piezoelectric or of any kind; an acoustic beam generation subsystem that generates an acoustic beam from the acoustic waves generated by the conversion subsystem and focuses the beam at a focal region where one or more solid objects to be fractured are located; an acoustic coupling subsystem adapted to couple the acoustic beam to the solid object or objects to be fragmented, thus minimizing attenuation occurring during propagation of acoustic waves to a focal point of the system; a positioning subsystem adapted to adjust the position of said focal point, said positioning subsystem may be electromechanical and allowing the position of the focal point to be adjusted automatically or manually as required by a system operator or user, b) the single feedback and control device allows for varying the direction and intensity of the acoustic waves incident on the single solid object to be crushed; a control subsystem for controlling the acoustic beam generator; a second transduction subsystem adapted to obtain information about the acoustic beam before and after interaction with one or more solid objects; a processing subsystem for processing the information obtained by the second conversion subsystem; and Equipped with.

[0030] Advantageously, in the above system, the acoustic beam is an acoustic vortex beam, and the feedback and control device further comprises a feedback subsystem configured to receive the information processed by the processing subsystem and send it to the control subsystem.

[0031] In a preferred embodiment of the present invention, the acoustic vortex beam is a high-intensity ultrasonic acoustic vortex beam. The vortex beam is focused on the stone, generating torque, shear stress, and large internal stresses that efficiently fragment the stone. As a result of the acoustic vortex, ultrasonic excitation energy (in the form of longitudinal waves) is converted very efficiently into mechanical energy (as transverse waves). Because shear stress is generated more efficiently using this type of beam, the ultrasonic field amplitude required to fragment the stone is much lower than with current extracorporeal shock wave lithotripsy techniques, thereby reducing unwanted effects on soft tissue, such as bleeding or damage to surrounding tissue due to cavitation. Acoustic vortex generation technology is known and is not essential for the purpose of this patent. In fact, multiple vortex beam configurations can be used for this purpose if the phase defect can be adjusted along the axis.

[0032] In another embodiment of the present invention, the feedback and control device further comprises an imaging subsystem, which also comprises a monitoring subsystem for monitoring one or more solid objects, which includes a means for graphical representation to provide information to a user of the system regarding the fragmentation method. The imaging system allows monitoring of the solid objects (locating, tracking, and measuring their position and their surroundings). In another preferred embodiment of the present invention, a sensor for measuring the temperature around the focal point may be included to control the dosage of energy applied to the solid objects. In an advantageous embodiment of the present invention, the monitoring subsystem comprises a method of pulse-echo ultrasound imaging. In other embodiments of the present invention, further imaging methods (fluoroscopy, X-ray, etc.) may be used, which may in turn require other transduction mechanisms. As a result of the monitoring subsystem, a user of the system can monitor the treatment and decide to interrupt it if necessary (e.g., if the patient reports pain or if the acoustic waves have excessive amplitude).

[0033] In some preferred embodiments of the invention, the information processing subsystem includes real-time measurements of cavitation generated around the focal point, and the feedback subsystem further takes into account at least the evolution or state of said cavitation in order to readjust physical parameters describing the acoustic beam incident on the focal point, for example, the amplitude or repetition rate of the acoustic beam may be reduced if excessive cavitation is present.

[0034] In some specific embodiments of the invention, the first electromechanical transduction subsystem is electrohydraulic, the acoustic beam generation subsystem comprises a reflector having a helical ellipsoid that generates vortices by reflection, and the positioning subsystem is mechanical and responsible for aligning the focal point of the system with respect to the solid object to be fractured.

[0035] In another preferred embodiment of the invention, the first transduction subsystem is electromagnetic and the acoustic beam generation subsystem comprises a helical parabolic reflector. Further, in the above embodiment, the positioning subsystem is preferably mechanical and serves to align the focal point of the system with respect to the solid object to be fractured.

[0036] In another advantageous embodiment of the invention, the first conversion subsystem is electromagnetic, while the acoustic beam generation subsystem comprises an acoustic lens that requires a mechanical positioning subsystem to adjust the focus. In yet another even more advantageous embodiment, the acoustic lens has a helical or helical ellipsoidal phase profile.

[0037] In another particular embodiment of the invention, the beam-generating first transducer subsystem is piezoelectric. In this case, the acoustic beam-generating subsystem comprises a multi-element phased array immersed in a fluid. Unlike the particular embodiment described above, the positioning system is preferably electronic and allows for configuring the delays applied to the excitation signals of each of the channels of the phased array to reposition the focal point of the system without the need for mechanical alignment.

[0038] In a further embodiment of the invention, the first transduction subsystem comprises a single piezoelectric transducer immersed in a fluid, the placement of the transducer on the helical spheroid is provided by an acoustic beam generation subsystem, and the system further comprises a mechanical positioning subsystem that adjusts the focus of the system.

[0039] Another additional embodiment of the present invention consists in replacing the single transducer in the above-described embodiment with a multi-element piezoelectric transducer, each element being arranged on a helical spheroid. In this sense, in this embodiment, the first transduction subsystem comprises a multi-element piezoelectric transducer immersed in a fluid, the positioning of each of the multiple channels on the helical spheroid is provided by an acoustic beam generation and focusing subsystem, and the system further comprises a mechanical positioning subsystem for adjusting the focus of the system.

[0040] Another preferred embodiment of the present invention includes a piezoelectric first transduction subsystem that generates acoustic waves, and the acoustic beam generation (and focusing) subsystem further comprises an acoustic lens. In some even more advantageous embodiments, the acoustic lens may have a helical or helical ellipsoidal phase profile.

[0041] A preferred use of the system for crushing solids consists of its application in the field of stone crushing.

[0042] In a further preferred embodiment of the present invention, the feedback and control device comprises a plurality of actuators for readjusting the focus of the system according to patient movement, for example to offset misalignment of the focus caused by the patient's breathing. In such cases, the actuators may be pressure pads, abdominal air sensors, tracheal breath sound monitors, or similar sensors for detecting breathing. This readjustment of the focus is preferably performed in real time.

[0043] Within the scope of the present invention, an array or phased array or arrangement is preferably understood as a matrix of a plurality of acoustic transducers, each element of which may be adjusted to emit a beam with predetermined physical properties (amplitude, frequency, phase, etc.). The transducer may then be a single element (single transducer) or may be divided into multiple elements (also known as sectors or channels) each operating as an independent transducer. An acoustic lens is also understood to be a device capable of focusing sound in a manner similar to how an optical lens focuses.

[0044] In the context of the present invention, once acoustic waves are formed and directed towards the location where they are to act, they are called acoustic beams. An acoustic beam refers to acoustic waves that have already been formed.

[0045] Furthermore, a vortex beam is to be understood as an acoustic beam having an acoustic field with a phase defect along an axis (called the "propagation axis"), whether two-dimensional or three-dimensional. Thus, a 2D vortex beam may have a circular or elliptical shape, while a 3D beam may have a helical shape. The zone in which the beam is focused is a 3D focal region extending along the direction of the beam's propagation. The focal point of the system is to be understood as a region that preferably substantially corresponds to the center of gravity of the focal region. Within the scope of the present invention, the expression "substantially" is also to be understood as being identical or within a variation margin of ±15%. [Brief explanation of the drawings]

[0046] [Figure 1] Figure 1 shows the acoustic field of a focused vortex beam. (a) The magnitude of the normalized acoustic field in the sagittal plane P(x,y=0,z), shown as |P| / P0. (b) The phase φ of the acoustic field in the sagittal plane. (c) The magnitude of the normalized acoustic field in the transverse plane P(x,y,z=F) across the focal zone. (d) The phase of the acoustic field in the transverse plane relative to the focal zone. [Figure 2]FIG. 2 shows a diagram of a system for the fragmentation of solids by (ultrasonic) acoustic vortices, which is the object of the present invention, for lithotripsy applications. [Figure 3] Figure 3 shows the scheme of a preferred embodiment of the invention, in which the acoustic beam generating subsystem (3) is electrohydraulic and includes a helical ellipsoid reflector. The vortex beam (13) is directed to the focal point (14) of the system, which coincides with the location of the solid object to be fragmented (in this case, a kidney stone). [Figure 4] FIG. 4 shows in more detail the helical spheroid reflector used to generate and focus the vortex beam of FIG. [Figure 5] Figure 5 shows the scheme of a preferred embodiment of the system of the present invention, which includes an electromagnetic acoustic beam generating subsystem (3) and a helical parabolic reflector. The vortex beam (13) is directed to the focal point (14) of the system, which coincides with the location of the solid material to be crushed. [Figure 6] FIG. 6 contains a detailed view of the construction of the electromagnetic spiral parabolic reflector referenced in FIG. 5 and used in the acoustic beam generation subsystem (3). [Figure 7] Figure 7 shows an embodiment of the system of the present invention having an electromagnetic vortex generator including a helical phase acoustic lens acting as the acoustic beam generating subsystem (3). The vortex beam (13) is directed to the focal point (14) of the system, which coincides with the location of the solid object to be fractured. [Figure 8] FIG. 8 includes a detailed view of the helical phase acoustic lens for the electromagnetic vortex generating system shown in FIG. [Figure 9] Figure 9 shows a preferred embodiment in which the vortex generator comprises a multi-element piezoelectric transducer in a phased array configuration as the electromechanical transduction subsystem (2). The vortex beam (13) is directed towards the focal point (14) of the system, which coincides with the location of the solid object to be crushed. [Figure 10] FIG. 10 shows a detailed view of the phased array piezoelectric vortex generation system shown in FIG. [Figure 11]Figure 11 shows a specific embodiment in which the electromechanical transduction subsystem (2) comprises a spherically focused single-element piezoelectric helical spheroidal transducer. The vortex beam (13) is directed to the focal point (14) of the system, which coincides with the location of the solid object to be crushed. [Figure 12] FIG. 12 shows a detailed view of the spherically focused single-element piezoelectric helical spheroidal transducer shown in FIG. [Figure 13] Figure 13 shows a specific embodiment in which the electromechanical transduction subsystem (2) is implemented by a spherically focused multi-element piezoelectric helical spheroidal transducer. The vortex beam (13) is directed to the focal point (14) of the system, which coincides with the location of the solid object to be crushed. [Figure 14] FIG. 14 shows a detailed view of a spherically focused multi-element piezoelectric vortex generation system arranged on a helical surface (15). DETAILED DESCRIPTION OF THE INVENTION

[0047] To supplement the description of the invention, there are attached a set of drawings which form an integral part of the description and which illustrate several preferred embodiments of the invention. However, such embodiments should not be understood as limiting the scope of the invention, but rather as merely examples of different ways in which the invention may be practiced.

[0048] Figure 2 shows a preferred embodiment of a system for the fragmentation of solid objects according to the present invention, which preferably comprises at least two devices: a preferably ultrasonic and high intensity acoustic beam generator (100) and a feedback and control device (200).

[0049] First, the acoustic beam generator (100) is responsible for generating an acoustic beam, preferably ultrasound, and for properly directing it to the zone where the stone is located in order to cause the stone to fragment. This device (100) is formed by at least the following subsystems: - an electronic power generation subsystem (1) adapted to generate high voltage and / or high current electrical pulses; - a first transduction subsystem (2), preferably electromechanical, for converting the electrical pulses provided by the generation subsystem (1) into high-intensity ultrasonic waves. an acoustic beam generation subsystem (3) responsible for generating and directing one or more vortex beams from the ultrasound waves obtained in the first transformation subsystem (2); - an acoustic coupling subsystem (4) between the acoustic beam generator (100) and the object to be fragmented (e.g., a stone inside the patient's body) in order to minimize the attenuation of the ultrasound waves that form vortices during propagation, which has a significant negative impact on the efficiency of the treatment (6). a positioning subsystem (5), which may be electronic or mechanical, that aligns the focus of the beam formed and focused by the acoustic beam generation subsystem (3) so that it is incident on the location where the stone to be fragmented is located.

[0050] Once the acoustic beam generator (100) is configured, it then performs the treatment (6), which consists of directing acoustic waves towards the solid object to be fragmented.

[0051] Regarding the treatment feedback and control device (200), said device is responsible for obtaining information about the location, characteristics, and condition of the stone before, during, and / or after the treatment (6). Based on an estimation of the stone's location and size, the device (200) provides control signals that allow adjustment of the position of the system's focal point (14) and, if appropriate, other parameters of the vortex (such as the topological charge). Generally, the device (200) comprises at least the following components: a control subsystem (7) of the ultrasonic vortex beam generation subsystem (3), configured to modify the physical parameters of the beam (amplitude, intensity, frequency, etc.) by manipulating one or more of the subsystems (1, 2, 3, 4, 5) of the acoustic beam generator (100), said subsystem (7) must allow the system operator to interrupt the treatment at will (for example, if the patient reports excessive pain) or else allow automatic stopping of the electrical pulse generation subsystem (1) if some critical threshold is exceeded (excessive temperature in the area surrounding the treated zone or too high a cavitation index). a second electromechanical transduction subsystem (8) configured to acquire signals of the acoustic beam before, during and / or after the treatment; - an imaging subsystem (9) for imaging the solid object to be crushed and / or the surrounding area, preferably an ultrasound image. a monitoring subsystem (10) for monitoring the treatment, preferably in real time, providing the operator operating the system with information about the treatment, in particular comprising a monitor or any means for graphical representation displaying an image of the solid object and other parameters of interest derived therefrom, the tracking information about the solid object (stone) provided by the monitoring subsystem (10) being used to adjust the focus of the high intensity acoustic beam generator (100); - a processing subsystem (11) for processing the acquired information, including means for analyzing the energy in different frequency bands of interest, with the aim of assessing in real time the effectiveness of the treatment (6) (for example, by calculating various cavitation indices or other similar parameters that may be relevant for predicting the risk of serious side effects during the treatment), so that this information also appears in the means for monitoring or graphical representation of the monitoring subsystem (10). - a feedback subsystem (12) that notifies the control subsystem (7) of the need to adjust the beam (e.g., by changing the amplitude, frequency, and repetition rate of the electrical pulse generation subsystem (1)) based on the stone tracking performed by the monitoring subsystem (10), based on information extracted by the information processing subsystem (11) (e.g., ultrasound signals), and / or based on other measurements (e.g., temperature increase in the vicinity of the zone where the beam is focused).

[0052] The components (1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 12) within each subsystem are preferably interconnected as shown in FIG.

[0053] The feedback and control device (200), and in particular the acquisition and information processing subsystem (11), is responsible for calculating different acoustic indices that modulate the feedback subsystem (12), which then informs the control subsystem (7) of the changes that must be made in the pulse generation subsystem. These indices modulate, preferably in real time, the intensity of the pulses and, therefore, the amplitude and repetition rate of the ultrasound waves. To this end, the system calculates a cavitation index by integrating the energy of the acquired signal and filtering it over different bandwidths. The parameters defined below are not exclusive; those skilled in the art will be able to define other similar parameters. In particular, these acoustic indices are obtained from the Fourier transform of the acoustic signal and are denoted P(ω).

[0054] First, the stable cavitation index is defined as follows:

[0055]

number

[0056] where ω is the fundamental frequency of the ultrasound emission (the fundamental frequency of a sine wave burst, or the center frequency of the pulse in the case of pulsed excitation), and N=ω max / ω0, where ω max is the maximum frequency allowed by the bandwidth of the acquisition system.

[0057] Subharmonic cavitation index (I SH ) is calculated from the subharmonic component power spectrum, i.e.,

[0058]

number

[0059] Ultraharmonic cavitation index (I UH ) is calculated by integrating the power spectrum of all the fundamental frequency superharmonics, i.e.,

[0060]

number

[0061] Inertial cavitation index (I IC ) is calculated by integrating the entire spectrum of the acoustic signal and subtracting the power spectrum of the fundamental frequency harmonics:

[0062]

number

[0063] Finally, the broadband cavitation index (I BB) is calculated by integrating the spectrum of the acoustic signal and subtracting the power spectrum of the fundamental frequency harmonics and ultraharmonics.

[0064]

number

[0065] In this way, the cavitation index signal fluctuates based on the cavitation activity around the focal point (14), where the stone to be fragmented is preferably located. These indices are used to modulate the control signals of the power generation system by an acoustic feedback system. The indices are further displayed by a graphic interface for monitoring the treatment (6) in real time and providing information related to the tracking and / or optional interruption of the treatment (6).

[0066] A number of preferred embodiments of the acoustic beam generating device (100) are described below.

[0067] Figure 3 shows a preferred embodiment of the present invention, in which an electric pulse generation subsystem (1) electrically excites a spark plug immersed in a fluid, which acts as a first electro-hydraulic conversion subsystem (2). After applying a certain voltage to the spark plug, the dielectric breaks down, generating an electric arc between its terminals. This causes a large current of electrons to flow between the two terminals, resulting in an instantaneous increase in the temperature of the fluid. The temperature increase then generates gas bubbles, which violently expand and then contract under the hydrodynamic pressure of the remaining fluid. This process generates a spherical, transient, high-amplitude acoustic wave that propagates throughout the fluid. The system includes a helical ellipsoid reflector as the acoustic beam generation subsystem (3), which reflects the wavefront toward the location of the stone to be fragmented. Due to the characteristics of the helical ellipsoid reflector, a vortex beam is generated by reflection, and according to the coordinate system shown in Figure 4, the wavefront is focused at a focal point F2, where the stone fragmentation occurs. To ensure optimal transmission of the wavefront, the system uses an acoustic coupling subsystem (4), which may be an elastic membrane, a layer of coupling gel, or a water balloon coupled to the patient's skin by a water bath. It should be noted that the helical ellipsoid reflector is arranged in a helical plane that can provide a differential acoustic delay (Δt) as a function of the azimuthal coordinate (θ) equal to:

[0068]

number

[0069] where ω is the design angular frequency and M is the topological charge of the beam. Since the beam propagates in a fluid where a constant propagation velocity can be assumed, such a delay occurs when the acoustic path difference (ΔL) is equal to:

[0070]

number

[0071] where λ0 = 2πc0 / ω0 is the design wavelength and c0 is the sound speed in the fluid. If a is the maximum value of the semi-minor axis of the helical ellipsoidal reflector, then the foci F1 and F2 and the elliptical constant a p If an elliptic curve with (θ)=[2a-ΔL(θ)] / 2 is defined, the semi-axes (b x and b y ) is the azimuthal coordinate

number

number

[0072]

number

number

number

[0073] In equations (4)-(6), the azimuth angle θ is between 0 and 2π, and by convention the elevation angle Φ is between 0 and π. If it is further taken into account that the semi-axes of the reflector geometrically limit its aperture (A), i.e., if A<2α, the maximum elevation angle is Φ max =tan -1 (A / 2F2), while the central gap (A) between the electro-hydraulic electrical pulse generation subsystem (1) and the second conversion subsystem (8) used to monitor the treatment (6) is given by h ) diameter, minimum height is Φ min =tan -1 (A h / 2F2). At very low frequencies, the phase difference becomes so small that the reflector behaves as an ellipsoidal reflector. Thus, at both low and high frequencies, the helical ellipsoidal reflector ensures that all acoustic energy is focused at the focal point F2. Because the position of the focal point cannot be controlled electronically but is set by the focal point of the helical ellipsoidal reflector, a mechanical movement system is required to align the focal point (14), F2, with respect to the stone. The main drawback of this embodiment is its short service life due to erosion of the spark plug with use.

[0074] In a preferred alternative embodiment, the ultrasonic large-amplitude acoustic (vortex) beam generation subsystem (3) requires the prior operation of an electromagnetic first transduction subsystem (2) and includes a helical parabolic reflector for beam generation and focusing, as shown in FIG. 5. The system uses a high-current electrical pulse generation subsystem (1) for electrical excitation by a coil fixed to a movable elastic cylinder positioned at the axis of the system and immersed in a fluid. Similar to the electromechanical transducers found in dynamic speakers, induction of the coil generates a force that first expands and then contracts the cylinder. The electromagnetic transduction process generates a large-amplitude, transient, cylindrical pressure acoustic wavefront, which propagates along the fluid along a radial coordinate perpendicular to the axis of the system. A reflector with a helical parabolic surface, hereinafter referred to as F, is used to redirect the wavefront onto a focal point (14), where stone fragmentation occurs. The acoustic coupling subsystem (4) may be, among others, a water balloon coupled to the patient's skin by an elastic membrane, a layer of coupling gel, or a water bath. It should be noted that the design of the reflector (shown in Figure 6) ensures simultaneously the focusing of the wavefront onto the focal point and the occurrence of a phase defect at that point. For that purpose, the acoustic path difference must satisfy the conditions of equations (2)-(3). The design of the reflector is carried out by considering a helical paraboloid formed by a parabolic profile with the focal point set at the point r(θ,r,z)=(0,0,F). The parabolic profile is formed by dividing the plane below the system placed at z=0 into the point r(θ,r,z)=(θ,r c(θ), 0) where the coordinate r c (θ)=R m -(m'Mθλ0 / 2π), and R m is the initial radius and m' is the factor required to align the phase and offset the curvature of the paraboloid. Using the approach

number

[0075]

number

[0076] In cylindrical coordinate representation r=r(θ,r,z), the reflector surface is defined by the following equation:

[0077]

number

[0078] Here, 0<θ<2π and 0 <z<z max where z max is the height of the cylindrical electromagnetic generator. Because the position of the focal spot cannot be controlled electronically but is set by the focal spot of the helical parabolic reflector, this embodiment also requires a mechanical system to align the focal spot (14) with the stone to be fragmented.

[0079] In another preferred embodiment, the generation of high-intensity vortices comprises an electromagnetic first transduction subsystem (2) having a planar and circular or annular shape, coupled to a helical phase lens, as shown in FIG. 7. The system uses a high-current electrical pulse generation subsystem (1) to electrically excite a coil fixed to a movable circular or annular surface, which is located on one of its faces and in contact with the fluid. Induction of the coil generates a force that displaces the circular or annular surface axially in a transient manner. This process generates a flat, transient, high-amplitude acoustic wavefront, which propagates along the fluid along the axis of the system. The system uses a helical phase lens to control the wavefront. The wavefront is generated by transmission (without the need for a reflector as in the previous embodiment) and is focused to a focal point (F) where stone fragmentation occurs. FIG. 8 details an acoustic lens model based on the refraction of acoustic waves when passing through a medium with a different acoustic propagation velocity than that in the fluid. The lens material has a propagation velocity (c) greater than that in the fluid (c). n ), the lens is biconcave. This occurs when the fluid is water and the lens material (e.g., metal, plastic, or polymer) is solid. Conversely, if the lens material has a lower propagation velocity than the fluid, the lens is biconvex. The lens consists of a spherical surface on one side and a helical ellipsoid on the second side. The design of acoustic lenses is described in detail below. A helical ellipsoid may be defined in cylindrical coordinates by a rotating elliptical profile with parameters that vary as a function of the azimuthal angle θ. The eccentricity (ε) of such an elliptical profile is constant, ε=c0 / c n while the focus of the profile is given by:

[0080]

number

[0081] where F is the geometric focus of the lens, and m' has a value close to 1 in this case and can be calculated numerically. Finally, the major semi-axis of the helical ellipsoid is given by a(θ)=c(θ) / ε, and the minor semi-axis is

number

[0082]

number

[0083] The other lens surface, the spherical surface, is given by the surface:

[0084]

number

[0085] Here, the radius of curvature is R c =(F s +Δz)(1-ε), where F s is the focal point of the concave lens, and Δz is its thickness at its axis. The use of a spherical lens on the lower surface is optional, but it reduces the limitation on the maximum aperture of the helical ellipsoidal lens. For example, at the focal point F s Using a lens with F = 4F, the system creates a large aperture vortex generator, thus allowing for higher acoustic intensity in the focal zone. Because the position of the focal spot cannot be controlled electronically but is set by the helical phase acoustic lens, a mechanical system is required to align the focal spot (14) with respect to the stone.

[0086] In another preferred embodiment, the high-intensity acoustic beam generating subsystem (3) comprises a multi-element piezoelectric system configured as a phased array, as shown in FIG. 9. The system uses a multi-channel high-voltage electrical pulse generating subsystem (1) to electrically excite an array of piezoelectric transducers arranged on a sphere and immersed in the fluid. Under the action of a transient electric field, the piezoelectric transducers constituting the first transduction subsystem (2) are deformed, contracting and expanding the fluid and generating a focused, transient, high-amplitude acoustic wavefront that converges at the center of the sphere. The radius of the sphere corresponds to the focal point (14) of the system where stone fragmentation occurs. The shape of the piezoelectric elements may be sector-shaped, circular, or hexagonal, among others, and their arrangement on the sphere preferably follows a regular pattern in polar coordinates or any other pattern, periodic or not. Assuming that the piezoelectric elements of the phased array are positioned equidistant from each other in polar coordinates, a series of delays must be applied to each of the voltage pulses of the phased array, as detailed in Figure 10, to control the wavefront and generate the acoustic vortices. The value of each delay (τ) depends on the position θ of each piezoelectric element, given by τ = (Mθ) / ω0. This phased array thereby allows us to delay each of the channels of the electronic excitation system and move the focal point F of the system until the beam is phase-aligned. This configuration allows the vortex to be generated at point r. F (x,y,z)=(F x ,F y ,F z ), the delay that must be applied to each of the elements of the phased array (which are centered at the point r0(x,y,z)) is calculated by:

[0087]

number

[0088] On the other hand, in the case of a phased array arranged on a sphere, the above equation is transformed into the following equation:

[0089]

number

[0090] Piezoelectric systems allow the generation of long duration excitation signals, where the phase delay is a complex coefficient φ(r,r F )=exp(iω0Δt), where the term ω0Δt is used to delay the sinusoidal signal or burst if the excitation is not transient. This process allows for stone fragmentation by injecting a smaller amplitude beam, which mitigates unwanted therapeutic effects.

[0091] Another particularly advantageous implementation is shown in Figure 11, which is a variation of the system shown in Figure 9. Because a phased array requires electronic control of the delay applied to each channel (which adds complexity to the design), the design of Figure 11 uses a single high-voltage electrical pulse generation subsystem (1) that excites a first transduction subsystem (2) consisting of a single piezoelectric transducer. The surface of the piezoelectric element is a helical spheroid, as shown in Figure 12, which may be expressed as the azimuthal rotation of a circular arc section, where the radius of curvature of the arc, Rc(θ), is given by:

[0092]

number

[0093] As a result of the above curvature, a path difference occurs between the beams at the design frequency ω = 2πc / λ, which generates a vortex with a topological charge M. For the design of the helical spheroid, its definition in spherical coordinates r = r(θ, φ, r) is considered, given by:

[0094]

number

number

number

[0095] Here, 0<θ<2π, and the upper and lower limits of the elevation angle are Φ min =tan -1 (A h / 2F2) and Φ max =tan -1 (A / 2F2), where A is the transducer aperture and A h is the diameter of the gap below the transducer, which may be zero. Piezoelectric acoustic beam generating subsystems (3), which generate an acoustic beam by means of a single-element transducer with a helical surface, have a vortex at the focal point (14), the position of which is uncontrollable, and as a result, a mechanical positioning subsystem (5) is required to align the focal point with the stone to be fragmented, as is the case with electrohydraulic and electromagnetic generators.

[0096] A more advantageous embodiment of the present invention includes a first transduction subsystem (2) formed by multiple piezoelectric elements arranged in a helical surface, as shown in FIG. 13. In this way, the complications associated with fabricating a single piezoelectric transducer with a helical surface, as previously shown in FIGS. 11 and 12, are avoided. The multiple piezoelectric elements (transducers) shown in FIG. 13 may be excited by a single electrical signal, which reduces the cost and complexity of the system compared to the phased array systems of FIGS. 11-12. The piezoelectric acoustic beam generation subsystem (3), which generates an acoustic beam using a multi-element transducer with a helical surface, has a vortex at the focal point (14), the position of which is uncontrollable if the same signal is used for all elements. As a result, a mechanical positioning subsystem (5) is required to align the focal point (14) with respect to the stone. The curvature of the helical surface is shown in detail in FIG. 14 and is described by Equations (15)-(18). The shape of the multiple piezoelectric elements may be sector-shaped or any other shape (circular, hexagonal, etc.).

[0097] Another preferred embodiment of the present invention includes a first piezoelectric transducer subsystem (2) having a transducer, which may be single-element or multiple-element, and a helical ellipsoidal phase acoustic lens for generating focused vortices. The acoustic lens is disposed on one or more piezoelectric transducers, each of which is excited by a pulsed or sinusoidal high-voltage signal. The use of the acoustic lens allows for control of beam focusing while simultaneously enabling the generation of vortices with any topological charge without requiring the use of multi-channel electronics to individually excite each element. Because the lenses are removable and easily replaceable components of the system, several lenses may be exchanged to adjust the focal length, topological charge, design frequency, and beam width, and thus the acoustic focusing characteristics depending on the treatment to be performed. The lens design is given by Equations (10)-(12). If the piezoelectric system is placed on the surface of a flat circle, the lens will be flat on its underside. If the same signal is used for all piezo elements, or if a single piezo element is used and set by the lens, the focal point (14) cannot be controlled electronically and a mechanical movement system is required to align the focal point with the stone.

[0098] In embodiments in which the acoustic beam generator (100) includes an electrohydraulic, electromagnetic, or piezoelectric transducer (whether a single or multi-element transducer), the mechanical positioning subsystem (5) includes at least one actuator that allows the focal point (14) of the system to be realigned.

[0099] Various preferred embodiments of the feedback and control system (200) are described below.

[0100] In a preferred embodiment of the present invention, the second electromechanical transduction subsystem (8) comprises a phased array of piezoelectric transducers that provides a pulse-echo mode ultrasound imaging subsystem (9).

[0101] In another more advantageous embodiment, the treatment monitoring subsystem (10) further comprises means for recording the patient's natural movements (e.g., breathing) in real time, comprising at least one movement sensor, and the recorded data is used by the control subsystem (7) to automatically correct misalignment of the system's focal point (14) due to patient movement (voluntary or involuntary).

[0102] In some alternative embodiments of the present invention, the feedback and control device (200) may be omitted. Such solutions are considered suboptimal because they do not allow for continuous monitoring and modification of the ultrasound treatment. They also require applying a predefined sequence of electrical pulses, after which the treatment is interrupted to acquire some type of image (by x-ray, ultrasound, etc.) and allow for evaluation of the results. [Explanation of symbols]

[0103] (1) Electrical pulse generation subsystem (2) First conversion subsystem (3) Acoustic beam generation subsystem (4) Acoustic Coupling Subsystem (5) Positioning subsystem (6) Treatment (application of an acoustic beam to the solid to be crushed) (7) Control Subsystem (of Acoustic Beam Generation Subsystem) (8) Second Conversion Subsystem (9) Imaging Subsystem (10) Monitoring Subsystem (11) Information Processing Subsystem (12) Feedback Subsystem (13) Vortex beam (14) The focal point of the system (preferably substantially coincident with the location of the stone or mass to be fragmented). (15) Helical spheroid (100) Acoustic beam generator (200) Feedback and Control Devices

Claims

1. A system for controlled fragmentation of solid objects by acoustic beams, comprising at least one acoustic beam generator (100) and one feedback and control device (200), The one acoustic beam generating device (100) comprises: an electrical pulse generation subsystem (1) for generating electrical pulses; a first conversion subsystem (2) adapted to convert the electrical pulses generated by the electrical pulse generation subsystem (1) into acoustic waves; an acoustic beam generation subsystem (3) for generating an acoustic beam from the acoustic waves generated by the first conversion subsystem (2) and directing the acoustic beam to a focal point (14) contained in a focal region in which one or more solid objects to be fragmented are located; an acoustic coupling subsystem (4) adapted to couple said acoustic beam to said solid object or objects to be fragmented; a positioning subsystem (5) adapted to adjust the position of said focal point (14), The one feedback and control device (200) comprises: a control subsystem (7) for controlling said acoustic beam generator (100); a second transformation subsystem (8) adapted to obtain information about said acoustic beam; a processing subsystem (11) for processing the information obtained by said second conversion subsystem (8), - said acoustic beam is an acoustic vortex beam, said feedback and control system (200) further comprises a feedback subsystem (12) configured to receive information processed by said processing subsystem (11) and send it to said control subsystem (7); system.

2. the acoustic beam is an ultrasonic acoustic vortex beam; The system of claim 1 .

3. The feedback and control device (200) a pulse-echo ultrasound imaging subsystem (9); a monitoring subsystem (10) for monitoring said one or more solid objects, said monitoring subsystem (10) comprising means for graphical representation of information associated with said one or more solid objects; 3. The system according to claim 1 or 2.

4. the processing subsystem (11) comprising means for real-time measurement of cavitation occurring at the focal point (14); The feedback subsystem (12) is further configured to process real-time measurements of the cavitation and readjust the acoustic beam to be incident on the focal point (14). A system according to any one of claims 1 to 3.

5. said first conversion subsystem (2) being electro-hydraulic; the acoustic beam generating subsystem (3) comprises a reflector having a helical ellipsoid that generates a vortex by reflection; The positioning subsystem (5) is further mechanical for aligning the focal point (14) with respect to the solid material to be crushed. A system according to any one of claims 1 to 4.

6. the first conversion subsystem (2) is electromagnetic; the acoustic beam generating subsystem (3) comprises a helical parabolic reflector; The positioning subsystem (5) is further mechanical for aligning the focal point (14) with respect to the solid material to be crushed. A system according to any one of claims 1 to 4.

7. the first conversion subsystem (2) is electromagnetic; The acoustic beam generating subsystem (3) comprises an acoustic lens. A system according to any one of claims 1 to 4.

8. The acoustic lens further has a helical or helical ellipsoidal phase profile. The system of claim 7.

9. said first transducer subsystem (2) being piezoelectric; the acoustic beam generating subsystem (3) comprises a multi-element phased array immersed in a fluid; the positioning subsystem (5) is electronic and configures a delay to be applied to the excitation signal of each of the channels of the multi-element phased array to reposition the focal spot (14); A system according to any one of claims 1 to 4.

10. the first transduction subsystem (2) comprises a single piezoelectric transducer immersed in a fluid; The arrangement of the piezoelectric transducers on the helical spheroid is provided by the acoustic beam generation subsystem (3); The system further comprises a mechanical positioning subsystem (5) for adjusting the focal point (14). A system according to any one of claims 1 to 4.

11. the first transduction subsystem (2) comprises a multi-element piezoelectric transducer immersed in a fluid; the arrangement of each of the plurality of channels on the helical spheroid is provided by the acoustic beam generation subsystem (3); The system further comprises a mechanical positioning subsystem (5) for adjusting the focal point (14). A system according to any one of claims 1 to 4.

12. said first transducer subsystem (2) being piezoelectric; The acoustic beam generating subsystem (3) comprises an acoustic lens. A system according to any one of claims 1 to 4.

13. the acoustic lens has a helical or helical ellipsoidal phase profile. The system of claim 12.

14. A system according to any one of claims 1 to 13 for use in lithotripsy.

15. The feedback and control system (200) comprises a plurality of actuators for readjusting the focal point (14).

15. The system of claim 14.

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