IL91468A

IL91468A - Apparatus for real-time tracking and imaging of concretions

Info

Publication number: IL91468A
Application number: IL9146889A
Authority: IL
Inventors: Lacoste Francois; Cathignol Dominique; Lacruche Bernard
Original assignee: Technomed Int Sa; Inst Nat Sante Rech Med
Priority date: 1988-08-31
Filing date: 1989-08-30
Publication date: 1994-12-29
Also published as: EP0404871B1; FR2636517B1; JPH03500979A; WO1990001904A1; ATE197664T1; FR2636517A1; IL91468A0; EP0404871A1; DE68929265T2; DE68929265D1

Abstract

The apparatus is comprised of real time imaging means (20), coupling means (22) which couple the imaging means (20) with a pressure wave generator (16) and caracterized in that the coupling means (22) include displacement means (24), imaging means (20) from an external peripheral point of the generator (16) to an other external peripheral point of the generator. The invention offers an extended freedom for positioning the imaging means (20) and improves the resolution and the security of observation of the concretions during their fragmentation.

Description

Apparatus for real-time tracking and imaging of concretions.

The Applicants: TECHNOMED INTERNATIONAL S.A., LE PONANT 1, 11 rue Leblanc, 75015 Paris , France , and INSFRM(Institut National de la Sante et de la Recherche Medicale) 101, rue de Tolbiac , 75013 Paris , France.

The Inventors: 1. Bernard LACRUCHE ; 2. Dominique CATHIGNOL and 3. Francois LACOSTE .

Apparatus for real-time tracking and imaging of concretions BACKGROUND OF THE INVENTION 1. Field of the invention The present invention essentiaLLy reLates to an apparatus for reaL-time tracking - i.e. for detecting, Locating and Locking onto - and imaging concretions.

Concretions occur naturaLly in cavities of mammals, especial Ly human beings. As these concretions form, they rapidLy Lead to an obstruction of the natural passages, inevitably causing serious physiological disorders that can endanger the life of the mammal concerned. 2. Prior art In recent years, various devices have been proposed for destroying concretions into smalL-size fragments that can be evacuated by the natural passages. These devices operate from outside the body using pressure wave generators directed towards the concretion. For example, US patent No. 2 559 227 (RIEBER) discloses a pressure */ave generator comprising a truncated eLlipsoidal reflector 80 in which pressure waves are generated by discharge or an electric arc between two concurrent electrodes at the first focus of the ellipsoid so as to destroy a target, e.g. consisting of a concretion, located at the second focus of the el Lipsoid.

In practice, there occurs a serious problem concerning the correct positioning the target to be destroyed exactly on the second focus of the ellipsoid.

This calls for a detection and exact determination of the position of the target to be destroyed, e.g. a concretion, such as a kidney stone or a biliary concretion.

Various exploratory probes are available for the detection and positioning of such targets, including X-rays or, as is more usualLy preferred, ultrasounds using ultrasonic transducers.

For example, document FR-A-2 502 485 discloses a probe type exploratory apparatus for diagnosis by ultrasound that uses two articulated arms 18,20. A similar description is contained in document FR-A-2 474 186.

Document EP-A-0 169 311 discloses a device for spatially positioning an exploratory probe 28.

The applicants have also proposed a device for spatially positioning an exploratory probe, in document FR-A-2 598 073.

However, it turns out in practice that it is necessary for the practitioner to be abLe to control in real time the position of the concretion and to keep track of its fragmentation during the treatment.

Various solutions have already been put forward for monitoring the position of the concretion and keeping track of its fragmentation during the treatment.

For example, document FR-A-2 587 893 discloses an apparatus for detecting stone fragments, in association with a lithotripter. The lithotripter has a spherical focusing cup 1 serving as a power transducer, and the detection apparatus includes an auxiliary, sector a I ly-scanned transducer 2 fixed to the center of the cup and connected to an echograph 21-22-28. The apparatus has an auxiliary exciter 360 for the power transducer 1, generating pulses at a rate of a few hertz and at low power compared with the firing pulses. During the low power pulses, the echograph receiver is operatively connected to an auxiliary cathode-ray tube 45 that produces an A-type echograph image for detecting the stone fragments.

An equivalent disclosure is made in document FR-A-2 591 467..

In both devices, the A or B type scanner or transducer is located coaxially to the generator producing pressure waves focused on a target-Focus, identified by r or 2 respectively, and having to be adjusted on the concretion to be destroyed, K or 12 respectively.

By virtue of the coaxial position of the transducer or A or B type scanner, it is possible to continuously view the concretion when the Latter is made to coincide with the focus of pressure wave generator cup.

However, these devices are Limited in their scope for spatiaL positioning, even if they are mounted so as to revoLve around their own axis and to be transLatabLe along the symmetry axis of the pressure wave generator.

Yet the possibility of spatially displacing the concretion locating and imaging apparatus appears necessary in order to keep track of any displacement of the concretion, as well as of the fragments produced in the course of the treatment. This is essential to avoid emitting pressure waves that would miss the concretion. The operator should thus be able to stop immediately the emission of pressure waves to proceed to a new locating step.

This is why document EP-A-0 169 311 teaches an ultrasonic locating device 26 located at the end of a complex mechanical structure for the spatial detection of the concretion, to determine its coordinates and subsequently to bring the target-focus 36 of the pressure have generator 6 into coincidence with the concretion to be destroyed, through the use of a complex processing system.

Since the above locating device 26 is somewhat immobilized while the concretion is set into coincidence with the target focus 34 of the pressure wave generator 6, it cannot be used by the practitioner for real-time observation of the concretion.

This is why it can be noted that the document proposes the inclusion of a complementary real-time imaging device formed by an ultrasonic transducer or scanner fixed to a peripheral point of the pressure wave generator 6, with a fixed position directed towards the target-focus 36. This ultrasonic transducer or scanner has a higher resolution than the displaceable ultrasonic device 26 and allows viewing of the destruction of the concretion 34 (see page 13, lines 6 to 16).

Such an. auxiliary ultrasound or scanner device has also been proposed in document EP-A-0 265 742. Here, the two ultrasonic locating devices 33, 35 are located at right angles so as to provide viewing planes that are also at right angles. The position of these ultrasonic transducers or scanner is also fixed with respect to the generator.

But, as has already been mentioned above, concretions or their fragments are raltively frequently displaced in the course of a treatment.

This is particularly true for the treatment of biliary concretions. Indeed, these concretions move much more than kidney stones since they have considerably more space within which to move and can easily escape from the target-focus after recoiling from the shock waves, or as a result of patient movements. Furthermore, patients1 respiratory movements are considerable at the level of vesicle, given that the vesicle and the liver are both in direct contact with the diaphragm. Thus, there is a strong likelihood in this case that a non-negligeable part of the shock or pressure waves does not reach the concretion, owing to the respiratory movements.

All the previously proposed solutions, using a fixed position of the auxiliary ultrasonic locating device or scanner, or using limited axial or two-dimensional displacement relative to the pressure wave generator, have the major drawback of granting little freedom for positioning the locating device making it (in practice) very difficult ( if not impossible in at least some instances ) to locate and view the concretions effectively in real time, especially in the case of biliary concretions, during the course of the treatments.

SUMMARY OF THE INVENTION WITH OBJECTS The present invention therefore aims to solve the new technical problem consisting in providing a solution for controlling and viewing concretions or their fragments in real time, irrespective of their displacement during the course of the treatment.

Another aim of the present invention is to solve the new technical problem consisting in providing a solution for monitoring the position of a concretion in real time and to keep track of the fragmentation during the treatment, practically without limiting the freedom of positioning of the device for real-time tracking and positioning of the concretions, and thus enabling the maximum acoustic window to be sought.

Yet another aim of the present invention is to solve the new technical problem consisting in providing a solution for detecting and viewing concretions and their fragments in real time in the course of the treatment, independently of their displacements while accommodating for the displacements of the tracking and spotting device associated to the generator, thereby allowing observation of the target-focus zone, offering the decisive advantage of being easily accessible to the operator in the event of a replacement, and allowing the use of different types of ultrasonic transducers or scanners.

Further, the aim of the present invention is to solve the new technical problem consisting in providing a solution for detecting and viewing concretions in real time by means of a highly manoeuvrable apparatus, resulting in a time saving and a better control of the treatment, and hence in an overall improvement in the efficiency of the treatment.

Still further, the aim of the present invention is to solve the new technical problem consisting in providing a solution for detecting and viewing concretions in real time with the possibility of respiratory synchronization by virtue of the possibility given to the practitioner of determining at which instant during the respiratory cycle the concretion returns to the center of the focal point, normally highlighted by a cross on the echograph image.

All the above technical problems are solved for the first time by the present invention in an extremely simple, reliable and economical manner that is workable on an industrial scale.

Thus, according to a first aspect, the present invention provides an apparatus for real-time tracking and imaging of a concretion in cavities of a mammal, and in particular a human being, to destroy said concretions into fragments that can be evacuated by natural passages using a pressure wave generator directed towards a target-focus put into coincidence with said concretion, comprising image forming means capable of forming a real-time image of said concretion for real-time observation of the latter, and coupling means for coupling said image forming means with said pressure wave generator, said coupling means being provided in the region of the front edge of said generator, from which pressure waves are emitted from said generator, wherein said coupling means are comprised of means for displacing said image forming means from one peripheral point external to said generator to another peripheral point external to said generator.

According to a specific embodiment of the present invention, said displacement means comprise a support that is displaceably mounted on the external periphery of said pressure wave generator. Preferably, said support is comprised of a fixed part and a rotatable part mutually articulated by an articulation axle located substantially perpendicular to the symmetry plane of said generator, said symmetry plane of the generator passing substantially along the longitudinal axis (X-X) of said image forming means.

According to an advantageous embodiment of the present invention, said image forming means are unitary with an intermediate element displaceably mounted in translation in a symmetry plane of said generator.

According to another advantageous embodiment of the apparatus according to the present invention, said image forming means are rotatably mounted with respect to said support.

Preferably, said image forming means are rotatably mounted with respect to said intermediate element.

According to another advantageous embodiment of the apparatus according to the present invention, said intermediate element has a through opening inside which said image forming means are rotatably mounted.

According to an alternative embodiment, said intermediate element is mounted on said support by a rail type coupling system, preferably of the monorail type.

According to another specific characteristic of the apparatus according to the invention, said support has a shoulder section displaceably mounted on the upper edge of said generator.

According to a specific embodiment, said pressure wave generator is a shock wave generator comprising an ellipsoidal reflector.

According to another specific embodiment, said pressure wave generator is an ultrasonic type shock wave generator, e.g. with a spherical cup.

According to another specific embodiment of the apparatus according to the present invention, said image forming means comprise at least one ultrasonic transducer or scanner, preferably of the B type, operating in real time.

According to a second aspect, the present invention also provides a pressure wave generating apparatus, wherein said apparatus is comprised of a real-time tracking and imaging apparatus as defined hereinabove. This pressure wave generating apparatus is preferably a lithotripter. Specifically, the lithotripter is a hydraulic type lithotripter that generates hydraulic shock waves, or an ultrasonic lithotripter that generates ultrasonic waves.

It can thus be seen that the invention offers all the above-mentioned decisive technical advantages.

BRIEF DESCRIPTION OF THE DRAWINGS Other aims, characterist cs and advantages of the invention shall be brought out more clearly in the light of the following description made with reference to the appended drawings depicting a presently preferred embodiment of the invention, given merely as an example, and which therefore in no way restrict the scope of the invention. In the drawings: - figure 1 is an axial cross-sectional view (along the cross-section I-I of figure 2) of a pressure wave generating apparatus, in this case formed by a hydraulic lithotripter having an ellipsoidal reflector of the type described by RIEBER in patent US 2,559,927 or in patent FR-A-2,240,795, fitted with an apparatus for real-time tracking and imaging according to the invention ; - figure 2 is a view along the cross-section II-II of figure 1, revealing the top and the entire reflector depicted in figure 1; and - figure 3 is a sectional view along the cross-section III-III of figure 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to figures 1 to 3, there is shown an apparatus according to the invention generally designated by reference numeral 10, for real-time tracking and imaging of a concretion 12 in a cavity of the body of a mammal, in this particular case a human being, the concretion being destined to be destroyed into fragments that can be evacuated by natural passages, using a pressure wave generator, generally designated by reference numeral 16. This generator is capable of generating pressure waves directed towards a target focus FC that is made to coincide with the concretion 12, as is clearly apparent from figure 1.

The real-time concretion tracking and imaging apparatus comprises image forming means 20 capable of forming a real-time image of the concretion 12. Such image forming means are well known and preferably according to the invention include an ultrasonic transducer or scanner, in particular a B-type scanner, also known as a sectorial scanning ultrasonic probe. Such image forming means are well known to the man of the art specialized in ultrasounds or echography, and shall therefore not be described here in detail.

The apparatus 10 also includes means, genrally designated by reference numeraL 22, for coupling the image forming means Q0 with the pressure wave generator 16. These coupling means 22 are provided at the front edge of the pressure wave generator 16 from which the pressure waves (O.P.) are emitted by the generator from the emitting focus Fa as shown by the dotted broken lines designated by O.P.

According to the present invention, the apparatus 10 is characterized in that the coupling means 22 include means generally designated by reference numeral 24 for displacing the image forming means from one external peripheral point, e.g. ^ (figure 2) of generator 16.

According to a specific embodiment, the image forming means 20 are unitary with a support 26 that is displaceably mounted on the external periphery of the wave generator 16, as can be clearly seen and understood from figures 1 to 3.

According to an advantageous specific embodiment of the invention, the support 26 includes a fixed part 28 and a rotatable part 30, which are mutually articulated by an articulation axle 32 located substantially perpendicularly to the symmetry plane of the generator 16 passing substantially along the longitudinal axes X-X of the image forming means 20, which is the cross-section of figure 1. Thus, since the generator 16 is generally located so that the focal axis F1-FC is vertical, the articulation axle 32 is located substantially horizontally so that the rotatable part 30 rotates in a vertical plane.

According to another specific characteristic, the support element 26 has a shoulder section 34 which in this case is naturally unitary to the fixed part 28 and is slidably mounted on the upper edge 36, clearly visible in figure 2, of the generator 16 whiLe being connected to the latter. As an example, this displacement can be implemented by a system of ball bearings, or a rail system, both of which are well known in the art.

According to a preferred embodiment, the support 26 is mounted so as to be displaceable relative to the generator 16 over a large displacement angle, preferably greater than 90°, and, better still, greater than 360°.

According to a specific embodiment, the fixed part 28 of the support 26 is mounted so as to be displaceable, e.g. by its shoulder section 34, over the upper edge 36 of the generator 16, by means of a rail-type coupling system, preferably a monorail.

According to a opecific embodiment of the invention, the image-forming means 20 arc unitary with an intermediate element 40 mounted so as to be displaceable in translation along a plane that is substantially perpend cular to the articulation axis 32, which preferably coincides with the symmetry plane of the generator 16.

According to another specific embodiment of the invention, the image forming means 20 are unitary with an intermediate element 40 mounted so as to be displaceable in translation along a plane that is substantially perpendicular to the articulation axle 32, which preferably coincides with the symmetry plane of the generator 16.

According to another specific embodiment of the invention, the image forming means 20 are mounted so as to be rotatabLe relative to the support 26, and in particular to the intermediate element 40.

According to an advantageous embodiment, the intermediate element 40 has a through opening 42 in which the image forming means 20 are rotatably mounted. In general, the image forming means 20 are held in a sealed housing having a substantially cylindrical shape, as depicted in figures 1 and 3. Locking means 44 such as a screw can naturally be provided at an arbitrary location.

According to another specific embodiment of the invention, the intermediate element 40 is mounted so as to be displaceable along the support 28, and more specifically along its rotatable part 30, preferably by a rail type coupling system 46, and again preferably of the monorail type 48, as is clearly visible in figure 3. Such a monorail 48 coupling system 46 is well known in mechanical engineering and shall therefore not be described in detail. It offers the advantage of allowing very precise translational displacement and of being very easily lockable in any position by locking means 50, 52, such as screws. There can be provided, on at least one apparent lateral face of the rotatabLe part of the support 28, a rule 54 on which is marked the position of the image forming means 20 at which the target-focus FC appears at the center of the ecograph image. The rule 54 preferably also indicates the distance separating the front end 20a of the image forming means 20 from the target-focus FC.

According to another specific embodiment of the invention, the cross-section of the fixed part 28 of the support 26 has the shape of an "L" abutting the generator 16, as is clearLy visible from figure 1, with the vertical bar 28a of the L bearing the shoulder section 34, and the horizontal bar 28b bearing the rotation axle 32 at its free end. Preferably, the shape of the rotatable part 30 is such that, with the above configuration, the rotable part 30 presents its face bearing the monorail 48 when in a rest position, as shown in figure 1, that is resting on the upper end of the fixed part 28, along a direction subtending an angle substantially equal to a 45° with respect to the horizontal. Consequently, the longitudinal axis X-X of the image forming means 20 are also disposed at an angle of approximately 45°, which is a preferential angle for the acoustic window. For an easier support of the rotatable part 30 on the fixed part 28, and in particular the upper edge of the L-shaped fixed part 28, there can be provided a flattened portion 60 at the junction between the shoulder section 34 and the vertical bar 28a. Preferably, the rotation axle 32 is devised in such a way that it is possible to lock the rotatable part 30 in any vertical position relative to the fixed part, by use of appropriate locking means well known to the man of the art, such as screws (not shown).

It should be noted that the structures depicted in figures 1 to 3 form an integral part of the invention, and hence form an integral part of the description.

With the real time tracking and imaging apparatus according to the present invention and as described above, there is provided a great freedom in the positioning of the image forming means 20. This enables the optimum acoustic window to be selected to obtain a high-quality echographic image. This makes it possible in virtually all cases to keep track of the fragmentation of the concretions in an accurate manner. Furthermore, the structural characteristics of the inventive apparatus grants exceptional manoeuvrability to the image forming means 20, giving a virtually limitless choice of acoustic windows, which in turn allows the image forming means 20 - such as a B type scanner or echograph -to operate at maximum performance, while ensuring optimum ease of use.

Also, it is extremely easy to change the image forming means 20 for other image forming means, e.g. having different emission frequencies for easier detection of concretions that may otherwise be too deep or too superficial.

Further, the invention makes it extremely easy to view the zone in which passes the pressure waves emitted by the pressure wave generator 16. It is possible to view the complete passage zone by making the image forming means 20 rotate around the longitudinal axis X-X.

The apparatus according to the invention provides the operator with continuous information on the fragmentation process. Should the concretion leave the focal zone FC, the operator becomes immediately informed. He/she then knows that the subsequently emitted pressure waves will be without effect since they will not reach the concretion.

By interrupting the emission of pressure waves and re-positioning the concretion on the focal point, the operator ensures that all the emitted pressure waves contribute towards fragmenting the concretion.

As a result, the number of pressure waves used in a treatment is theoretically reduced, since useless shots are eliminated. This leads to a time saving and a better management of the treatment time. The concretion is always relocalized at the right moment.

The invention also grants the possibility of synchronization with respiratory movements.

It has been known for a long time that respiratory movements cause considerable displacement of concretions. Thus, if the operator judges it necessary, he/she can use the real time viewing possibility available at all times to control the emission of a pressure wave when, in the course of a respiratory cycle, the concretion returns to the center of the focal point FC, which is usually highlighted by a cross on the echographic image.

The invention furthermore makes it possible to position the image forming means 20 in contact agains the patient's body, which enable the resolution to be improved (it should be noted that in the figure, the position of the table 62 supporting the patient is deliberately incorrect to help understand the drawing showing the body of the patient which is not shown to scale ; normally, this position is considerably shifted away and thus no obstacle can hinder the displacement of means 10, especially along the direction X-X or in the vertical plane).

The apparatus according to the invention can be fitted to any type of pressure wave generator, be it a generator for hydraulic lithotropsy, especially of the type having an ellipsoidal reflector, as shown in figure 1 and 2, or an ultrasonic generator, e.g. having a spherical cup fitted with a mosaic of piezoelectric transducers.

To facilitate the setting into rotation of the image forming means 20 relative to the intermediate element 40, it is possible to adopt the structure described and shown with reference to figure 5 of patent FR-A-2 598 073 from the present assignees.

It is thus clear that many variants and modif cations of the apparatus according to the invention are possible without departing from the scope of the latter. The invention thus comprises all the means forming technical equivalents of the means described, as well as their various combinations.

Claims

CLAIMS 1. An apparatus (10) for real-time tracking and imaging of a concretion (12) in cavities (14) of a mammal, and in particular a human being, to destroy said concretion into fragments that can be evacuated by natural passages using a pressure wave generator (16) directed towards a target-focus (F.C.) put into coincidence with said concretion (12), comprising image forming means (20) capable of forming a real-time image of said concretion (12) for real-time observation of the latter, and coupling means (22) for coupling said image forming means (20) with said pressure wave generator (16), said coupling means (22) being provided in the region of the front edge (18) of said generator from which pressure waves are emitted from said generator (16), wherein said coupling means (22) are comprised of means (24) for displacing said image forming means (20) from one peripheral point (P · 3. Apparatus as claimed in claim 2, wherein said support (26) is comprised of a fixed part (28) and a rotatable part (30) mutually articulated by an articulation axle (32) located substantially perpendicular to the symmetry plane of said generator (16), said symmetry plane of the generator passing substantially along the longitudinal axis (X-X) of said image forming means (20). 4. Apparatus as claimed in any one of claims 1 to 3, wherein said image forming means (20) are unitary with an intermediate element (40) displaceably mounted in translation in a plane that is substantially perpendicular to said articulation axle (32) which preferably coincides with a symmetry plane of said generator (16). 5. Apparatus as claimed in any one of claims 2 to 4, characterized in that said image forming means (20) are rotatably mounted with respect to said support (26). - 14 - 91468/2 C L A I M S :-

1. An apparatus (10) for real time tracking and imaging of a target (12). aimed to be submitted to the effect of pressure waves transmitted by a pressure wave generator (16), said pressure waves being directed towards a target-focus (F.C.) put into coincidence with said target (12), comprising image forming means (20) forming a real time image of said target (12), for real time observation of the latter, and connecting means (22) for connecting said image forming means (20) to said pressure wave, generator (16), said connecting means (22) being located in the vicinity of the front edge (18) of said generator (16) from where the pressure waves are emitted, said image forming means (20) presenting a longitudinal axis (X-X) going through the target-focus (F.C.), characterized in that said connecting means (22) are designed to perform a displacement in translation of the image forming means (20) in a displacement, plane coinciding with a symmetry plane of said generator including said target-focus (F.C.) and said longitudinal axis (X-X) of said image forming means (20).

2. Apparatus according to Claim 1, characterized in that said connecting means (22) comprise, a support (26) linking the image forming means (20) to said pressure wave generator (16).

3. Apparatus according to Claims 1 or 2, characterized in that said connecting means (22) comprise peripheral displacing means (24) for peripherical ly displacing said image forming means (20) from one external peripheral - 15 - 91468/2 point (P.|) of said generator (16) to another peripheral point (P2) of said generator (16); said image forming means (20) being preferably linked to a support . (26) mounted displaceable on said external periphery of said generator (16).

4. Apparatus according to Claims 2 or 3, characterized in that said support (26) comprises a fixed portion (28) and a rotative portion (30) mutually articulated by an articulation axle (32) located substantially perpendicularly to the symmetry plane of said generator (16) passing throug the target focus (F.C.) and through longitudinal axis (X-X) of said image forming means (20).

5. Apparatus according to one of Claims 1 to 4, characterized in that said connecting means (22) comprise an intermediate element (40) displaceably mounted in translation substantially according to said longitudinal axis (X-X) of said image forming means (20).

6. Apparatus according to one of Claims 3 to 5, characterized in that said image forming means (20) are mounted rotatable around said longitudinal axis (X-X).

7. Apparatus according to one of Claims 1 to 6, characterized in that said connecting means (22) comprise an intermediate element (40) comprising a through opening (42) inside which said image forming means are rotatably mounted relatively to said intermediate element (40), thereby enabling a displacement in translation of said image forming means (20) towards the target-focus (F.C.) - 16 - 91468/2 and a displacement in rotation around said longitudinal axis (X-X) .

8. Apparatus according to one of Claims 3 to 7, characterized in that said intermediate element (40) is mounted on said support (26) by a real time coupling system (46), preferably of the monorail type (48).

9. Apparatus according to any one of Claims 2 to 8, characterized in that said support (26) has a shoulder section (34) displaceably mounted on the upper edge (36) of said generator (16).

10. Apparatus according to any one of Claims 4 to 9, characterized in that said fixed portion (28) of said support (26) has a cross-section in the shape of an "L" pressing against said generator (16), preferably one end of said "L" being mounted displaceable on the upper edge (36) of said generator (16) and the other end comprising said articulation axle (32) of said fixed portion (28) relatively to said rotative portion (30).

11. Apparatus according to any one of Claims 1 to 10, characterized in that said connecting means (22) comprise distance measuring means for measuring the distance of displacement in translation of said image forming means (20), such as a scale (54), notably on which is marked the position of the image forming means (20) at which the target-focus (F.C.) appears at the center of the echo-graph image, or preferably also indicating the distance separating the front end (20a) of the image forming means (20) from the target-focus (F.C). - 17 - 91468/2

12. Apparatus according to any one of Claims 1 to 11, characterized in that, in a normal position, the longitudinal axis (X-X) of said image forming means (20) subtends an angle of approximately 45° with respect to the horizontal .

13. Pressure wave generating apparatus for destroying targets such as concretions, and in particular kidney concretions and biliary concretions, said apparatus comprising at least one real time tracking and imaging device as defined in any one of Claims 1 to 12.

14. Generating apparatus according to Claim 13, characterized in that said apparatus comprises an ellipsoidal reflector, said image forming means are preferably selected from the group consiting of an ultrasonic transducer, a B-type scanner and an echograph.

15. An apparatus for real-time tracking and imaging of a target, substantially as described in the specification and drawings and claimed in any one of the previous Claims . For the Applicants, Patent Attorney