DE102024120075A1 - Device for the application of shock waves - Google Patents

Abstract

A device for applying shock waves to an animal or human body is shown and claimed, comprising a shock wave source arranged in a housing. The shock wave source is focused on a point. The device includes an acoustic lens configured such that the width of a focus of the shock waves generated by the shock wave source in the focal plane along a first transverse axis extending in the focal plane is at least twice as wide as along a second transverse axis extending in the focal plane perpendicular to the first transverse axis. Furthermore, a gel pad with an acoustic lens contained therein for detachable arrangement on a device for generating shock waves is shown and claimed.

Description

The present invention relates to a device for applying shock waves. The device comprises a shock wave source arranged in a housing for generating shock waves with a point-like focus. The invention further relates to a gel pad for detachable attachment to a device for applying shock waves.

Devices for generating and applying focused medical shock waves are known from the prior art. These devices are used, for example, in medical applications where they are generated extracorporeally and applied to an animal or human body. For this purpose, the devices comprise a shock wave source arranged in a housing, which generates sound or shock waves. The shock waves can also be referred to as pressure waves or acoustic waves.

The term "shock waves" is not limited here to shock waves in the strict physical sense. Rather, according to the definition commonly used in shock wave therapy, pressure signals with low amplitudes are referred to as shock waves. These signals exhibit one or more non-linearly steepened pressure slopes with a pressure rise of several tens of megapixels (MPa) over a very short rise time of a few nanoseconds. Even these shock waves in the narrower sense do not necessarily have to be present on the surface of the shock wave source. For a shock wave source to be suitable for medical application, it is sufficient if the pressure pulses at the focus of the shock wave source are sufficiently steep due to superposition and non-linear propagation of the sound waves.

To generate shock waves, piezoelectric elements can be used, for example, arranged in different geometric structures to focus the shock waves onto different areas. One known method is to arrange the piezoelectric elements on a spherical cap, i.e., the surface of a spherical segment, so that the shock waves generated by the piezoelectric elements are focused approximately to a single point. The radiating surface of the shock wave source thus forms a spherical segment. As an alternative to such piezoelectric shock wave sources with a point-like focus, electrohydraulic or electromagnetic shock wave sources are also known, which can likewise exhibit a point-like focus.

Shock wave sources with a point-like focus and a planar radiating surface are also known from the prior art, meaning that the piezoelectric elements generating the shock waves are arranged on a single plane. These shock wave sources have additional elements that reshape the shock waves emitted from the radiating surface, so that the shock wave source as a whole emits shock waves convergently focused onto a point or a circular area.

The focus or focal region of a shock wave source, where the sound pressure reaches its maximum, is, in real-world applications, extended along a longitudinal axis of the shock wave source when the shock waves are focused at a single point. This longitudinal axis is located centrally and perpendicular to the radiating surface and can therefore also be referred to as the central axis. In planes perpendicular to the central axis, the sound pressure drops rapidly. Therefore, the focal region is spatially limited, particularly in directions perpendicular to the central axis. This results in the pressure distribution in the cross-section, i.e., perpendicular to the longitudinal axis, being essentially circular or point-like.

For various medical and technical applications, it can be advantageous to use a so-called line focus instead of a point focus. A line focus is characterized by the fact that the pressure distribution generated by the shock waves in a focal plane of the shock wave generator is not circular, but rather significantly wider along a first transverse axis perpendicular to the longitudinal axis than along a second transverse axis perpendicular to the first. Various specially adapted shock wave sources are known for generating a line focus. For example, the piezoelectric elements of a piezoelectric shock wave source can be arranged such that the focal area in a focal plane is extended along the first transverse axis, while the dimensions of the focal area along the second transverse axis correspond approximately to the dimensions of the focal area of a point- or circularly focused shock wave source.

Against this background, the task for the person skilled in the art is to provide an alternative device by means of which shock waves can be applied that are not focused on a point, but rather form a line focus.

This problem is solved by a device according to claim 1 and a gel cushion according to claim 16. Preferred embodiments The device is the subject of the dependent claims.

According to a first aspect of the invention, a device for applying shock waves is provided, comprising a shock wave source arranged in a housing for generating shock waves. The shock waves emitted convergently from the shock wave source are focused in a focal plane essentially onto a circular area. The device further comprises an acoustic lens arranged between the shock wave source and the focal plane, configured such that, after passing through the acoustic lens, the focus of the shock waves generated by the shock wave source has a first width along a first transverse axis and a second width along a second transverse axis, the first width being at least twice the second width, the second transverse axis being perpendicular to the first transverse axis, and the first and second transverse axes lying in the focal plane.

In other words, a device for applying shock waves is provided, preferably for therapeutic purposes in humans or animals. However, it is also conceivable to use such a device for technical purposes.

This device comprises a shock wave source, which can also be referred to as a shock wave generator or transducer. The shock wave source generates sound waves in the ultrasonic range with high sound pressure or high sound intensity. In an exemplary, preferred embodiment, the shock wave source is a piezoelectric shock wave source composed of a plurality of piezoelectric elements. Alternatively, the shock wave source can also be an electrohydraulic or electromagnetic shock wave source.

Regardless of the specific embodiment of the shock wave source, some of which are described in more detail below as exemplary embodiments, the shock wave source emits shock waves convergently and focused onto an approximately circular area before the shock waves encounter an acoustic lens. The shock wave source therefore has an aperture with a larger diameter than the circular focal area. As already mentioned in the introduction, such a focus can also be called a point focus. The point focus has a focal volume of maximum sound pressure elongated along a longitudinal axis of the shock wave source, the cross-section of which is circular perpendicular to the central axis. Furthermore, the diameter of the cross-section is many times smaller than the dimensions of the focal volume in the direction of the central axis.

In a piezoelectric shock wave source, this can be achieved, for example, by arranging the piezoelectric elements in the shape of a spherical cap, i.e., their arrangement essentially follows a spherical surface. Thus, the piezoelectric elements could, for instance, be arranged on the interior of a spherical segment. In conjunction with simultaneous activation, this arrangement results in the generated shock waves forming a spherical wave and, to a first approximation, being focused to a point. In this preferred embodiment, the shock wave source therefore has a spherical radiating surface.

In alternatively preferred embodiments, the shock wave source can also have differently shaped surfaces. In this case, the shock wave source has a forming element arranged between a radiating surface of the shock wave source and the acoustic lens, configured such that the shock waves emitted from the radiating surface are substantially focused onto the circular surface in the focal plane after passing through the forming element before they reach the acoustic lens. For example, the radiating surface of the shock wave source can be planar. In this case, the shock wave source can, for example, include a multi-part reflector or a lens with which the shock waves emitted from the radiating surface are focused onto a point or a circular surface, respectively. The radiating surfaces can also generate divergent spherical or cylindrical waves, which are transformed by a suitable reflector into a convergent spherical wave focused onto a point, so that the shock wave source, without the acoustic lens, is convergently focused onto a circular surface overall.

The focus of a shock wave source, also known as the focal area or focal zone, is determined by the maximum pressure amplitude distribution in space, which, however, does not necessarily exist simultaneously. It is therefore not necessarily a momentary pressure amplitude distribution, but rather the distribution of maximum pressure amplitudes in space generated by shock waves emitted by the shock wave source.

The dimensions and shape of the focal area or focal volume of a shock wave source depend on how the focal volume is defined. In this case, the focal volume is defined by a relative sound pressure level, specifically the "-6 dB limit" defined in IEC 61846. for lithotripter pulses. The focal volume corresponds to the area in which the sound pressure is greater than or equal to half the maximum pressure generated by the shock wave source.

Alternatively, a definition based on absolute sound pressure is also possible, although this may result in different dimensions for the focal areas. An example of an absolute sound pressure used to define the focal volume is a lower limit of 5 MPa. In this case, all areas where the maximum sound pressure of the shock waves is greater than or equal to 5 MPa are assigned to the focal volume. The value of 5 MPa is commonly used in extracorporeal shock wave therapy, as therapeutic effects are expected above 5 MPa.

The device further comprises an acoustic lens, preferably formed from a single piece. If the lens consists of several components, these can be made of the same material or of different materials. In any case, the components are acoustically connected to one another, for example, via suitable coupling media such as so-called ultrasound gel or water. In a preferred embodiment, the components of a multi-part lens are bonded together by a material-bonded connection.

The acoustic lens can, for example, also be designed as a Fresnel lens in order to achieve the most compact design possible for the acoustic lens.

Furthermore, the acoustic lens preferably has no hollow areas completely enclosed by lens material. In other words, the lens forms a solid body without any enclosed hollow areas where impedance discontinuities could occur.

In another exemplary embodiment, the acoustic lens is in direct contact with the surface of the shock wave source. For example, the piezoelectric elements can be embedded in a matrix of synthetic resin, and the acoustic lens rests directly on the surface of this matrix, which thus forms the radiating surface of the shock wave source. By having the acoustic lens in direct contact with the shock wave source, additional impedance jumps at the interface between the shock wave source and the acoustic lens are avoided. These jumps would occur if additional media, such as water, were located between the shock wave source and the acoustic lens. Alternatively, the lens can also be positioned at a distance from the shock wave source, whereby the position of the shock wave source relative to the lens and the intervening materials must be taken into account when shaping the lens.

The acoustic lens is made of a material whose speed of sound differs from the speed of sound of the material surrounding the lens on the side facing away from the shock wave source. This material is referred to here as the surrounding medium. Examples of the surrounding medium are water, oil, or a gel. When the sound waves generated by the shock wave source pass through the acoustic lens, a time difference occurs. The magnitude of this time difference depends on the distance the sound waves travel within the acoustic lens and the speed of sound in the lens material. The magnitude of the time difference experienced by the shock waves as they pass through the acoustic lens depends on the shape of the lens, its local thickness, and the speed of sound in the lens material.

According to the present invention, the acoustic lens is shaped such that the focal area or focal volume of the shock waves applied by the device is at least twice as wide along a first transverse axis as along a second transverse axis perpendicular to the first transverse axis. The first and second transverse axes both run perpendicular to the longitudinal axis in a plane referred to as the focal plane. In other words, the acoustic lens is shaped such that the focal volume is expanded, particularly along a first transverse direction, while the focal volume perpendicular to the first transverse direction and to the longitudinal axis is significantly less expanded. Ideally, the expansion of the focal volume along the second transverse axis is minimal and essentially corresponds to the width that could be achieved for a point focus under comparable conditions. This transforms the point focus actually generated by the shock wave source into a so-called line focus. The focal volume is expanded to at least twice the width along the first transverse axis, while ideally the width along the second transverse axis remains unchanged. In other words, the shock waves emitted convergently from the shock wave source are essentially focused onto a circular area in the focal plane before passing through the acoustic lens. After passing through the acoustic surface, however, a line focus exists.

For the sake of completeness, it should be noted that there is no uniform, homogeneous sound pressure in the area of the line focus. Like the point focus, the line focus also exhibits variations in sound pressure. The line focus is defined by a threshold or limit value for the maximum sound pressure that is observed. Areas of the target volume where the maximum sound pressure is above the threshold are included in the line focus. Areas of the target volume where the maximum sound pressure remains below the threshold are not part of the line focus.

Using an acoustic lens, the focus of a shock wave source can be easily changed so that a line focus is created instead of a point focus, without having to alter the setup of the shock wave source. Rather, it is sufficient to provide a suitably shaped lens made of a suitable lens material and position it appropriately between the shock wave source and the focal plane.

In a preferred embodiment, the substantially circular focus of the shock wave generated by the shock wave source has an initial diameter in the focal plane without a lens. After passing through the acoustic lens, the focus of the shock waves in the focal plane has a width along the first transverse axis that is at least 2.5 times the initial diameter and preferably more than 7 times the initial diameter. Along the second transverse axis, the focus of the shock waves after passing through the acoustic lens in the focal plane has a width that is at most 1.5 times the initial diameter and is preferably substantially equal to the initial diameter.

The actual expansion of the focal area along the first and second transverse axes, compared to an original point focus, also depends on the threshold used to define the focal volume or focal area. In one exemplary embodiment, using the "-6 dB limit" results in an approximately sevenfold increase in the extent of the focal area along the first transverse axis in the focal plane, while using the "5 MPa limit" results in approximately a threefold increase in the extent along the first transverse axis. Similarly, along the second transverse axis, using the "-6 dB limit" results in an increase of the focal area by a factor of 1.5, while the "5 MPa limit" does not increase the size of the focal area.

Furthermore, it is preferred if the speed of sound in the acoustic lens is higher than the speed of sound in the surrounding medium. Preferably, in this case, the acoustic lens has a thickening extending parallel to the first transverse axis. In an exemplary preferred embodiment, this thickening extends perpendicular to the first transverse axis over one-third of the diameter of the acoustic lens. Preferably, the thickening extends over only one-quarter or less of the diameter of the acoustic lens perpendicular to the first transverse axis.

It is further preferred that the thickness of the acoustic lens increases continuously from an edge of the lens to a central plane in transverse planes running parallel to the second transverse axis and perpendicular to the first transverse axis. Thus, in the preferred embodiment, an acoustic lens is defined whose thickness increases continuously from the outside to the inside along transverse planes running parallel to the second transverse axis to a central plane. The central plane is spanned by the central axis and the first transverse axis. It is particularly preferred that the thickness profile along all transverse planes can be described by the same function. Therefore, the decrease in thickness parallel to the second transverse axis away from the central plane is always the same, regardless of the position along the first transverse axis. This choice of acoustic lens shape focuses the shock waves onto the first transverse axis, while preventing them from spreading out towards the second transverse axis.

It is preferred that the thickness of the acoustic lens increases in an S-curve from the edge of the lens towards the central plane in planes parallel to the second transverse axis and perpendicular to the first transverse axis. In other words, the thickness initially increases slowly before transitioning to a steeper, continuous increase. As the lens approaches the central plane, the rate of increase in thickness slows again.

In an alternative preferred embodiment, the speed of sound in the acoustic lens is lower than the speed of sound in the surrounding medium.

In this embodiment, the acoustic lens preferably has a recess running parallel to the first transverse axis. In an exemplary preferred embodiment, this recess extends perpendicular to the first transverse axis over one-third of the diameter of the acoustic lens. Preferably, the recess extends over only one-quarter or less of the diameter of the acoustic lens perpendicular to the first transverse axis.

It is further preferred if the thickness of the acoustic lens decreases continuously from an edge of the lens to a central plane in transverse planes running parallel to the second transverse axis and perpendicular to the first transverse axis. Thus, in the preferred embodiment, an acoustic lens is defined whose thickness decreases continuously from the outside to the inside along transverse planes running parallel to the second transverse axis to a central plane. The central plane is spanned by the central axis and the first transverse axis.

In particular, it is preferred if the thickness profile along all transverse planes can be described by the same function. Thus, the increase in thickness parallel to the second transverse axis away from the central plane is always the same, regardless of the position along the first transverse axis. This choice of acoustic lens shape focuses the shock waves onto the first transverse axis, while preventing them from spreading out towards the second transverse axis.

It is preferred that the thickness of the acoustic lens decreases in planes parallel to the second transverse axis and perpendicular to the first transverse axis, the transverse planes, following an S-curve from the edge of the lens to the central plane. In other words, the thickness initially decreases slowly before transitioning into a more steep, continuous decrease. As the lens approaches the central plane, the decrease in thickness becomes less pronounced.

In a preferred embodiment, the acoustic lens has a constant thickness along planes parallel to the first transverse axis and perpendicular to the second transverse axis. In other words, the preferred embodiment provides an acoustic lens that can be divided into cross-sectional planes, each with a constant thickness. The thickness of the lens is defined by a normal to the surface of the acoustic lens that points towards the shock wave source. The thickness is thus defined along an axis perpendicular to an outer, for example, convex, surface of the lens. Due to the homogeneous thickness of the lens along the planes, the shock waves experience a uniform phase shift in each plane, resulting in a widening of the focal volume along the first transverse axis.

In a preferred embodiment, the acoustic lens is made of a uniform material and/or by means of an additive manufacturing process.

Furthermore, it is preferred if a surface of the acoustic lens facing the shock wave source runs parallel to a radiation surface of the shock wave source that emits the shock waves, for example, a spherical surface of a matrix material in which the piezoelectric elements are arranged. As already explained, this design leads to a particularly good coupling of the acoustic lens to the shock wave source.

In a preferred embodiment, the acoustic lens is embedded in a gel cushion. The gel cushion can be detachably or permanently attached to the device.

The gel cushion, also known as a gel pad, is made of a material with a different speed of sound than the material of the acoustic lens, enabling the focusing of the shock waves. Preferably, the gel cushion completely encloses the acoustic lens. However, it is also conceivable that the acoustic lens is arranged at the edge of the gel cushion, for example, at the edge of the gel cushion facing the shock wave source.

The use of a gel cushion with an integrated acoustic lens is particularly advantageous when the focus of an existing shock wave application device that can be operated with interchangeable gel cushions needs to be adjusted. By replacing an existing gel cushion without an acoustic lens with one containing an acoustic lens, an existing device that, for example, has a point focus can be transformed into a device that produces a line focus.

In addition, the gel cushion also serves, for example, to improve the coupling of the device to a body. Furthermore, the gel cushion can also form a lead-in section, which allows the penetration depth of the shock waves emitted by the device to be adjusted.

It is further preferred if the acoustic lens has a circumferential rim, preferably made of the same material as the acoustic lens. The circumferential rim is provided for securing the lens in the device. In the preferred embodiment, the acoustic lens thus has a circumferential rim region that is not part of the actually acoustically active lens, i.e., it is not intended for shaping the sound field generated by the shock wave source. Rather, this rim serves to hold the acoustic lens in the device and to clamp it in place. It should be noted that, particularly in the transition area between the actual acoustic lens and this mounting area, there may be deviations from the previously described lens shapes, since the lens does not actively contribute to shaping the shock wave field in these areas.

In a particularly preferred embodiment, a coupling medium is arranged between the acoustic lens and a body into which the shock waves are to be coupled. It is further preferred that the coupling medium be interchangeable in order to adjust the penetration depth of the shock waves. The coupling medium can, for example, be an interchangeable gel pad that forms a pre-spacer.

According to a second aspect, the problem underlying the invention is solved by a gel cushion for detachable arrangement on a device for applying shock waves. The device comprises a shock wave source for generating shock waves, arranged in a housing. The shock waves emitted convergently by the shock wave source are focused in a focal plane essentially onto a circular area. The gel cushion includes an acoustic lens. The gel cushion and the acoustic lens are configured such that, when the gel cushion is arranged on the device, the acoustic lens is positioned between the shock wave source and the focal plane. Furthermore, the gel cushion and the lens are configured such that, after passing through the acoustic lens, the focus of the shock waves generated by the shock wave source is widened in the focal plane such that the focus has a first width along a first transverse axis and a second width along a second transverse axis, wherein the first width is at least twice as large as the second width, wherein the first and second transverse axes lie in the focal plane, and wherein the second transverse axis is perpendicular to the first transverse axis.

The second aspect is therefore not directed at an entire device for generating shock waves, but only at a gel cushion containing an acoustic lens, which can be interchangeably arranged on a device. In particular, the housing of the device and the shock wave source itself are not part of the gel cushion. Such a gel cushion can advantageously allow the focus of a device for applying shock waves to be quickly adjusted from a point focus to a line focus.

With regard to the design, preferred embodiments and advantages of the acoustic lens and the gel cushion, reference is made to the preceding explanations in order to avoid unnecessary repetition.

• 1 eine schematische Darstellung eines Ausführungsbeispiels einer Vorrichtung zu Applikation von Stoßwellen auf einen tierischen oder einen menschlichen Körper,
• 2 eine perspektivische Ansicht eines ersten Ausführungsbeispiels einer akustischen Linse,
• 3 eine perspektivische Schnittansicht des Ausführungsbeispiels aus 2,
• 4 eine weitere perspektivische Schnittansicht des Ausführungsbeispiels aus 2,
• 5 eine perspektivische Ansicht eines zweiten Ausführungsbeispiels einer akustischen Linse,
• 6 eine perspektivische Schnittansicht des Ausführungsbeispiels aus 5,
• 7 eine weitere perspektivische Schnittansicht des Ausführungsbeispiels aus 5,
• 8 einen Schnittansicht eines Ausführungsbeispiel eines Gelkissens mit einer akustischen Linse und
• 9 eine zweite Schnittansicht des Ausführungsbeispiels aus 8.

The present invention is explained in more detail below with reference to the figures showing an embodiment of a device for generating shock waves, two embodiments of acoustic lenses, and an embodiment of a gel cushion with an acoustic lens.

• 1 a schematic representation of an embodiment of a device for applying shock waves to an animal or human body,
• 2 a perspective view of a first embodiment of an acoustic lens,
• 3 a perspective sectional view of the embodiment from 2 ,
• 4 another perspective sectional view of the embodiment from 2 ,
• 5 a perspective view of a second embodiment of an acoustic lens,
• 6 a perspective sectional view of the embodiment from 5 ,
• 7 another perspective sectional view of the embodiment from 5 ,
• 8 a sectional view of an exemplary embodiment of a gel cushion with an acoustic lens and
• 9 a second sectional view of the embodiment from 8 .

Referring to 1 An exemplary embodiment of a device 1 for applying shock waves to the body of a person or an animal is described below, which is in 1 The device 1 is shown schematically. It comprises a housing 3 in which a shock wave source 5 is arranged. The shock wave source 5 is a piezoelectric shock wave source which, in the exemplary embodiment, comprises a plurality of piezoelectric elements 7 arranged in the form of a spherical cap, i.e., on a spherical segment 9. 1 shows only a few exemplary piezoelectric elements 7 that are embedded in a matrix of resin.

The housing 3 of the device 1 further comprises a coupling surface 11, via which shock waves generated by the shock wave source 5 can be coupled into a human or animal body. The device 1 further comprises an acoustic lens 13, which is also located in 1 shown in section and located directly on a radiation surface 14 of the shock wave source 5 so that as few impedance jumps as possible occur between the shock wave source 5 and the acoustic line 13. 5 A gap between the radiating surface 14 and the acoustic lens 13 is shown only for the purpose of visualizing the different elements of the device 1.

A coupling medium 17 is arranged between the coupling surface 11 and the exit surface 15 of the acoustic lens 13, which points away from the shock wave source 5. This coupling medium forms the coupling surface 11. The coupling medium 17 can, for example, be a replaceable gel pad. The coupling medium 17 also serves to compensate for the different distances between the acoustic lens 13 and the coupling surface 11. In the exemplary embodiment in 1 The coupling medium 17 also forms the surrounding medium 18 of the acoustic lens 13, i.e., the medium that surrounds the acoustic lens 13 on the side facing away from the shock wave source 5. The coupling medium 17 and the surrounding medium 18 are not necessarily identical. For example, the surrounding medium 18 can be located between the acoustic lens 13 and a coupling medium 17.

In the exemplary embodiment in 1 The speed of sound in the acoustic lens 13 can, for example, be higher than in the coupling and surrounding medium 17, 18. Consequently, the shock waves generated by the shock wave source 5 travel a greater distance per unit of time in the acoustic lens than in the surrounding medium 18. An embodiment of such an acoustic lens 13 is described in the 2 , 3 until 4 shown. Alternatively, an acoustic lens 13 can be used in which sound propagates at a lower speed than in the surrounding medium 18. An embodiment of such an acoustic lens 13 is shown in the 5 , 6 until 7 shown.

The dome-shaped shock wave source 5 has a longitudinal axis 19 that runs perpendicularly through the geometric center of the spherical surface 9, on which the piezoelectric elements 7 are arranged, and the geometric center of the radiating surface 14. Without the acoustic lens 13, the shock waves generated by the shock wave source 5 are focused onto a focal volume extending along the longitudinal axis 19. Perpendicular to the longitudinal axis 19, the focal volume has a circular cross-section. The focal plane is defined by a 1 The first transverse axis 21 and a second transverse axis 23 extending into the image plane are shown. The sound field generated by the shock wave source 5 is symmetrical about the longitudinal axis 19 running centrally through the sound field. Therefore, the longitudinal axis 19 is also referred to as the central axis 20, with which the longitudinal axis 19 coincides in this embodiment.

The acoustic lens 13 widens the focus of the shock waves generated by the shock wave source 5 along the first transverse axis 21, while the focus is hardly widened in the direction of the second transverse axis 23, or at least less so than in the direction of the first transverse axis 21. This creates a line focus in which the sound pressure along the first transverse axis 21 forms an extended focal region where the maximum sound pressure lies above a limit value defining the focal region. Perpendicular to the first transverse axis 21, the sound pressure drops significantly even at a short distance from the longitudinal axis 19 or the central axis 20. The plane spanned by the first transverse axis 21 and the longitudinal axis 19 is subsequently referred to as the longitudinal plane.

The acoustic lens 13 in 1 The lens 13 has a circumferential rim 25 that is not part of the acoustically effective lens. This rim 25 is used solely to hold the lens 13 in the device 1. In this embodiment, the rim 25 is made of the same material as the acoustically effective part of the lens 13. The elements holding the lens 13 are in 1 not shown.

The 2 , 3 until 4 show an embodiment of an acoustic lens 13, as used in the embodiment of a device 1 in 1 can be used. The ones in the 2 , 3 until 4 The lens 13 shown is made from a single piece and, in particular, from a uniform material. Specifically, the lens 13 was manufactured from a uniform material using an additive manufacturing process, such as 3D printing. The speed of sound in this material is higher than in the surrounding medium 20, which is in contact with the acoustic lens 13 on the exit surface 15 pointing away from the shock wave source 5. The lens 13 is also solid, meaning it has no holes or cavities in its interior, but is completely filled between its outer surfaces.

In 2 A perspective view of the complete lens 13 is shown, in which the exit surface 15, pointing away from the shock wave source 5, is primarily visible. An outer surface 27 is also shown, which is not part of the acoustically active area of the lens 13 and does not contribute to focusing the shock waves. No shock waves emerge from this surface that are focused onto the focal area. As can be seen in 2 As can already be seen, the acoustic lens 13 has a central thickening 28 which extends along the middle plane, i.e., parallel to the first transverse axis 21 and parallel to the central axis 20. 3 shows a section through the acoustic lens 13 along the midplane. In 4 A section through the acoustic lens 13 is shown along a transverse plane that runs perpendicular to the median plane and parallel to the central axis 20. The transverse plane thus also runs parallel to the second transverse axis 23.

How to especially 3 As can be seen, the acoustic lens 13 has a constant thickness along the median plane, the thickness being defined by the normal to an entrance surface 29. The entrance surface 29 of the acoustic lens 13 is in contact with the shock wave source 5 or its radiating surface 14. The cross-section of the acoustic lens 13 behaves similarly in planes parallel to the median plane. In each of these planes, the acoustic lens 13 has a constant thickness.

In planes parallel to the transverse plane, i.e., perpendicular to the first transverse axis 21, the acoustic lens 13 exhibits a thickness that increases continuously towards the central plane. "Continuously" in this case means that the thickness of the acoustic lens 13 always or permanently increases towards the central plane, but not necessarily by the same amount. Rather, the thickness of the lens 13 in planes parallel to the transverse plane follows an S-shaped profile; that is, the increase in thickness from the edge to the central plane is initially gradual, then increases significantly more sharply, before the increase weakens or flattens out again towards the central plane. The lens 13 thus has its greatest thickness along the central plane. As can be seen in particular... 4 As can be seen, the thickness profile of the acoustic lens 13 is very similar or identical in planes that run perpendicular to the first transverse axis 21.

The 5 , 6 until 7 Figure 1 shows a second embodiment of an acoustic lens 13 for generating a line focus. The acoustic lens 13 according to the second embodiment is also designed to modify the sound field of a shock wave source 5 with a point focus such that the focal area in the focal plane is widened along the first transverse axis 21, while the focal area along the second transverse axis 23 in the focal plane remains essentially unchanged.

In the following, we will only discuss the differences from the first embodiment of an acoustic lens 13, which is described in the 2 , 3 until 4 As shown, I will explain in more detail.

The in the 5 , 6 until 7 The acoustic lens 13 shown was also manufactured using an additive manufacturing process. A material was used in which the speed of sound is lower than the speed of sound in the surrounding medium 18. The shape of the lens 13 of the second embodiment differs significantly from that of the lens 13 of the first embodiment.

In 5 A complete perspective view of line 13 of the second embodiment is shown, primarily depicting the exit surface 15 pointing away from the shock wave source 5. An outer surface 27, which does not contribute to focusing the shock waves, is also partially visible.

The lens 13 has a depression 31 extending parallel to the first transverse axis, which runs along the median plane and thus parallel to the first transverse axis 21 and parallel to the central axis 20. 6 show a section through the acoustic lens 13 along the midplane. In 4 A section through the acoustic lens 13 along the transverse plane is shown, which runs perpendicular to the middle plane and parallel to the central axis 20 and thus also parallel to the second transverse axis 23.

How to especially 6 As can be seen, the acoustic lens 13 has a constant thickness along the median plane and in planes parallel to the median plane, the thickness also being defined in this embodiment along the normal to the entrance surface 29. The cross-section of the acoustic lens 13 behaves accordingly in planes parallel to the median plane. In each of these planes, the acoustic lens 13 has a constant thickness.

In planes running parallel to the transverse plane, i.e., perpendicular to the first transverse axis 21, the acoustic lens 13, on the other hand, has a thickness that decreases continuously towards the median plane, as shown in 7 This can be seen. The decreasing thickness towards the center means that lens 13 is thinnest in the region of the median plane. In other words, lens 13 has the smallest thickness in the region of the median plane. Therefore, the cut edge in 6 only shown as a thin line.

The decrease in the thickness of lens 13 in planes parallel to the transverse plane follows an S-shaped profile; that is, the decrease or reduction in thickness is initially slight from the edge towards the central plane, then increases significantly more, before the decrease weakens or flattens out again towards the central plane. As can be seen in particular... 7 The thickness profile of the acoustic lens 13 can be seen in planes perpendicular to the The first transverse axis 21 runs very similarly or identically.

In the 8 and 9 Two sectional views of an embodiment of a gel cushion 33 with an acoustic lens 13 are shown. The shape of the acoustic lens 13 essentially corresponds to the shape of the one shown in the 2 , 3 until 4 The exemplary embodiment shown is described below. To avoid unnecessary repetition, we therefore refer to the corresponding explanations regarding the shape of lens 13. 2 , 3 until 4 An acoustic lens 13 with a different shape could also be arranged in the gel cushion 33. For example, the acoustic lens 13 could have the shape described in the 5 , 6 until 7 The acoustic lens 13 is arranged in the gel cushion 33 in the shape shown. In any case, the acoustic lens 13 is made of a material that has a different speed of sound compared to the rest of the material of the gel cushion 33.

The gel cushion 33 surrounds the acoustic lens 13 in which it is located. 8 and 9 The illustrated embodiment is fully integrated and forms a unit with it that can be detachably attached to a device 1 for applying shock waves. In particular, the gel pad 33 can be arranged on a device 1 that would otherwise be operated with conventional gel pads without an acoustic lens, i.e., a device in which the gel pad is used, for example, to improve the coupling of the device to a human body or to adjust the penetration depth, but which always has a point-like focus. The focus of such a device can be adjusted by the gel pad 33 and transformed into a line-like focus 35, which is located in the 8 and 9 shown schematically. In principle, however, it would also be conceivable to integrate the gel cushion firmly into a device 1.

When the gel pad 33 with the acoustic lens 13 is attached to a conventional device for applying shock waves, a contact surface 37 of the gel pad 33 rests against a radiation surface 13 of the shock wave source. An opposing coupling surface 11, on the other hand, is intended to rest against a human or animal body into which the shock waves are to be coupled. Thus, the acoustic lens 13 is located between the shock wave source of the device and a focal plane defined by a first transverse axis 21 and a second transverse axis 23.

The gel of the gel cushion 33 thus constitutes an environmental medium 18 and a coupling medium 17 for the acoustic lens 13, since the acoustic lens 13 is completely enclosed by the gel. The gel cushion 33 serves, firstly, to couple the acoustic lens 13 to the shock wave source, and secondly, to improve the coupling of the device to a human or animal body. Furthermore, the depth of the focal area within the body into which the shock waves are coupled can be shifted by adjusting the dimensions of the gel cushion 33, particularly in the direction of the longitudinal axis 19 or the central axis 20.

The acoustic lens 13 described above advantageously transforms the originally point-like focus of the shock wave source 5 into a line focus. This represents a simple and cost-effective measure for achieving an elongated focus, which is particularly useful for treating elongated target areas in a human or animal body. In particular, the integration of the acoustic lens 13 into a replaceable gel pad 33 allows for the cost-effective adaptation of existing shock wave application devices.

Reference symbol list

1

device

3

Housing

5

Shock wave source

7

piezoelectric elements

9

spherical segment

11

Coupling area

13

acoustic lens

14

Radiating surface

15

Exit surface

17

Coupling medium

18

surrounding medium

19

Longitudinal axis

20

central axis

21

first transverse axis

23

second transverse axis

25

surrounding edge

27

outer surface

28

thickening

29

Entrance surface

31

in-depth

33

Gel cushion

35

focus

37

Plant surface

Claims (16)

Device (1) for applying shock waves with a shock wave source (5) arranged in a housing (3) for generating shock waves, wherein the shock waves emitted convergently by the shock wave source (5) are focused substantially on a circular area in a focal plane, wherein the device (1) further comprises an acoustic lens (13) arranged between the shock wave source (5) and the focal plane and configured such that, after passing through the acoustic lens (13), a focus of the shock waves generated by the shock wave source (5) is widened in the focal plane such that the focus has a first width along a first transverse axis (21) and a second width along a second transverse axis (23), wherein the first width is at least twice as large as the second width, wherein the first transverse axis (21) and the second transverse axis (23) lie in the focal plane and wherein the second transverse axis (23) is perpendicular to the first transverse axis (21). Device (1) according Claim 1 , wherein the shock wave source (5) has a spherical radiating surface (14). Device (1) according Claim 1 , wherein the shock wave source (5) has a forming element arranged between a radiating surface (14) of the shock wave source (5) and the acoustic lens (13), which is configured such that the shock waves emitted from the radiating surface (14) are substantially focused on the circular surface in the focal plane after passing through the forming element before they meet the acoustic lens. Device (1) according to one of the preceding claims, wherein the substantially circular area onto which the shock waves convergently emitted by the shock wave source (5) are focused in the focal plane without a lens (13) has an output diameter in the focal plane, whereby the width of the focus of the shock waves after passing through the acoustic lens (13) in the focal plane along the first transverse axis (21) is at least 2.5 times the output diameter and preferably more than 7 times the output diameter, and whereby the width of the focus of the shock waves after passing through the acoustic lens (13) in the focal plane along the second transverse axis (23) has a width that is at most 1.5 times the output diameter and is preferably substantially equal to the output diameter. Device (1) according to one of the preceding claims, wherein the acoustic lens (13) is made of a material in which the speed of sound is greater than in an environment medium of the acoustic lens (13). Device (1) according Claim 5 , wherein the acoustic lens (13) has a thickening extending parallel to the first transverse axis (21), wherein the thickness of the acoustic lens (13) preferably increases continuously in planes extending parallel to the second transverse axis (23) and perpendicular to the first transverse axis (21) from an edge (25) of the lens (13) to a central plane, and wherein the thickness of the acoustic lens (13) further preferably increases in planes extending parallel to the second transverse axis (23) and perpendicular to the first transverse axis (21) from the edge (25) of the lens (13) to the central plane following an S-curve. Device (1) according to one of the preceding claims, wherein the acoustic lens (13) is made of a material in which the speed of sound is lower than in the surrounding medium of the acoustic lens (13). Device (1) according Claim 7 , wherein the acoustic lens (13) has a depression extending parallel to the first transverse axis (21), wherein the thickness of the acoustic lens (13) preferably decreases continuously in planes extending parallel to the second transverse axis (23) and perpendicular to the first transverse axis (21) from an edge (25) of the lens (13) to a central plane, and wherein the thickness of the acoustic lens (13) further preferably decreases in planes extending parallel to the second transverse axis (23) and perpendicular to the first transverse axis (21) from the edge (25) of the lens (13) to the central plane following an S-curve. Device (1) according to one of the preceding claims, wherein the acoustic lens (13) has a constant thickness along planes running parallel to the first transverse axis (21) and perpendicular to the second transverse axis (23). Device (1) according to one of the preceding claims, wherein the acoustic lens (13) is made of a uniform material. Device (1) according to one of the preceding claims, wherein the acoustic lens (13) was manufactured using an additive manufacturing process. Device (1) according to one of the preceding claims, wherein an entrance surface (29) of the acoustic lens (13) directing towards the shock wave source (5) is parallel to the emitting surface (14) from which the shock waves are emitted. Device (1) according to one of the preceding claims, wherein the acoustic lens (13) is embedded in a gel cushion (33), wherein the gel cushion (33) is detachably connected to the device (1) or wherein the gel cushion (33) is permanently connected to the device (1). Device (1) according to one of the Claims 1 until 12 , wherein the acoustic lens (13) has a circumferential rim (25) which is provided for fastening the lens (13) in the device (1), wherein the circumferential rim (25) is preferably made of the same material as the acoustic lens (13). Device (1) according to one of the preceding claims, wherein the shock wave source (5) comprises a plurality of piezoelectric elements (7) arranged on a spherical surface (9). Gel cushion (33) for detachable arrangement on a device (1) for applying shock waves, wherein the device (1) comprises a shock wave source (5) arranged in a housing (3) for generating shock waves, wherein the shock waves emitted convergently by the shock wave source (5) are focused substantially on a circular area in a focal plane, the gel cushion (33) comprising an acoustic lens (13), and the gel cushion (33) and the acoustic lens (13) are configured such that, when the gel cushion (33) is arranged on the device (1), the acoustic lens (13) is positioned between the shock wave source (5) and the focal plane, and that, after passing through the acoustic lens (13), the focus of the shock waves generated by the shock wave source (5) is widened in the focal plane such that the focus has a first width along a first transverse axis (21) and a second width along a second transverse axis (23), the first width being at least twice as large as the second width, wherein the first transverse axis (21) and the second transverse axis (23) lie in the focal plane and wherein the second transverse axis (23) is perpendicular to the first transverse axis (21).