Device for the ultrasonic localization of concrements.

p0001The invention relates to an apparatus for spatial ultrasound locating concrements according to the preamble of the main claim.

p0002To remove the body of a Leb located ewesens concretions such as kidney or gallstones, called Lithotripsy be used by which these concretions are smashed without contact by means of focused ultrasonic shock waves. The use of ultrasonic shock waves surgery or insertion of probes into the patient's body and the infection risk associated can be avoided.

p0003To prevent healthy tissue is damaged in the area of ​​the calculus, the calculus to be destroyed must be positioned as exactly as possible in the focus of the shock wave. The required for exact positioning spatial localization of the calculus can for example be carried out by X-ray or ultrasound.

p0004An important advantage of ultrasound locating the to-be-crushed calculus can be seen in the fact that at the same time information about the conditions for sound propagation of the shock wave can be obtained with the positioning when the sonicated by ultrasonic shockwave field in the body of the living being by the ultrasonic waves used for detection is detected.

p0005From DE-PS 27 22 252, for example, devices for spatial ultrasound locating concretions are known in which the term of from one ultrasonic transmitter emitted and reflected or scattered at the concretion pulses for locating the concretion is taken. In an embodiment of a coupling device that contains the shock wave source and can be placed on the body surface of a patient, an ultrasonic transmitter and an ultrasonic receiver are arranged, whose axes of rotation in the focus of the ultrasonic shock wave at an angle of 30 ° in the wall to cut. Instead of using a separate ultrasonic transmitter, an arrangement is provided in which the operated with reduced intensity shockwave source itself is used as an ultrasonic transmitter for locating the concretion. means arranged in the wall of the coupling device pressure sensors are then received emanating from the concretion scattered pulses and determined from the transit time differences, the position of the calculus. In another embodiment, a pivotable ultrasonic transducer is provided which generated in a containing the focus of the ultrasonic shock wave level is a sectional view after the B-picture method.

p0006With regard to a safe and easy positioning of the stone in focus the ultrasonic shock wave is of the known devices for ultrasound locating the working according to the B-picture process device compared to operating according to the A-frame process means the advantage that the two-dimensional B-mode image on the one hand gives a vivid impression of the geometrical relationships in the environment of the calculus and interpret the other hand is more secure than a one-dimensional a-scan.

p0007However echographic B-mode processes have the disadvantage that only average levels of a body can be represented, which thus substantially duri FEN perpendicular to the body axis and parallel to the propagation direction of the ultrasonic sound waves. The user is thus for the positioning of the focus or the concretion before image information from an unusual setting for sharpness and little suitable object plane. So for example, corresponds with the known device a in the image compared to the focus shifted laterally concretion of defocus that the propagation direction of the ultrasonic shock wave can respect consist of both a lateral as well as from an axial offset.

p0008Another disadvantage of the known device is also seen in the fact that the contingent by the width of beam used for scanning lateral resolution of an echographic layplan particular is unsatisfactory and difficult an accurate axial positioning and positioning of the stone in focus the ultrasonic shock wave.

p0009From "Acoustical Holography Vol. 5, Plenum Publ.Corp., New York 1973, Ed. PSGreen, pages 493-503, an ultrasonic imaging device for diagnostic purposes is known, which operates on the principle of an optical image thrower. This as an ultrasonic camera described device allows the display body section images which are perpendicular to the sagitallen sectional planes of the ultrasound echography. for this purpose, the under examination body with ultrasound is "lit" and either the scattered by the body transmitted or scattered by the body the reflected ultrasound waves by means of a lens system on a displayed image plane, and converted by an arranged there-linear receive array into electrical signals. with the aid of two in the beam path is arranged and counter-rotating prisms, the image produced by the lens system is deflected sinusoidal, so that the measured at the linear receive array receive signals developed a two-dimensional image can be. The thus achieved image frequency is about 15 Hz, so that already can speak of a real-time image display. However, a higher frame rate is no longer possible, since the required for this higher rotational frequency of the prisms would lead to turbulence within the sound-carrying liquid and a disturbance of the sound propagation and a reduction in image quality. The depth of the section plane shown by the ultrasound camera results in accordance with the laws of geometrical optics of the imaging properties of the acoustic imaging devices used, the image size of the receive array and the position of the body relative to the then specified focus range in the object space.

p0010An ultrasound transmission camera with a higher frame rate without moving parts is made possible with a simplified structure of the imaging device, for example, in "Acoustical Imaging, Vol. 15, Plenum Publ. Corp., New York, 1987, Ed. HWJones, pages 213 to 225˝ disclosed. There is a two-dimensional receiver matrix of 29 x is an ultrasonic receiver instead of a linear receive array 128 transducer elements provided. the present at the individual transducer elements electrical signals are read in sequence and combined to form a two-dimensional image whose frame rate about 25 Hz. the ultrasound-sensitive area of ​​the receiving matrix is ​​formed from a thin PVDF foil which is pressed against a matrix-type electrode assembly. a further development of such a reception matrix is ​​also known for example from U.S. Patent No. 4,742,494.

p0011The invention is now based on the object to provide a device for ultrasound locating located in the body of a living concretions, which enables easy and accurate positioning of the stone in focus of an ultrasonic shock wave.

p0012Said object is achieved with the characterizing features of the main claim.

p0013With a device for ultrasound locating that works on the principle of operating in reflection ultrasonic camera, the user is provided with a locating device available that during the positioning of the stone in focus the ultrasonic shock wave, a real-time image of an outside of the sagittal plane lying sectional plane of the body generated with the aid of which the precise positioning is facilitated. In particular, a sectional plane of the body can be selected, which runs parallel to the focal plane of the ultrasonic shock wave. The user is thus an image information before from a particularly geeignten to adjust the focus of the lithotripter object plane. The imaging conditions of the ultrasonic camera are adjusted so that an area of ​​the subject area is in focus, including the focus of the ultrasonic shock wave, so that the focus is firmly assigned to a predetermined image area on a monitor, for example, the image center. To the viewer, the smashing to calculus appears here only sharp and when it actually is in the center and the focus of the ultrasonic shock wave. Each actual axial misalignment outside the range of the depth of field can be seen as a blur on the monitor screen. Due to the imaging principle used in the ultrasonic camera the resolution in each lateral direction is equal within the section plane. In addition, since a plastic for the viewer real-time image with a high lateral resolution can be generated with an ultrasonic camera, the exact positioning of the calculus is considerably easier in the focus of the ultrasonic shock wave.

p0014Further advantageous embodiments of the invention will be apparent according to the dependent claims.

p0015To further explain the invention reference is made to the drawing, in which<ul><li>Figure 1 the inventive device for ultrasound locating illustrated and in their</li><li>Figures 2, 3 and 4 further advantageous embodiments of the invention are shown schematically.</li></ul>

p0016According to Figure 1 is located in the body 2 of an organism a concretion 4 which is to be destroyed by means of an ultrasonic shock wave. 8 This ultrasonic shock wave 8 generated by a in the figure is not shown focused shock wave transmitter of a lithotripter. Locating the concretion 4 is effected with a driven in reflection ultrasonic camera, an ultrasonic transmitter 6 for the continuous or pulsed sonication of the focus F of the ultrasonic shock wave 8 containing space area of ​​the body 2 with ultrasonic waves 7, an imaging device 10, and an ultrasonic receivers 20 includes, arranged in an image plane 30 of the imaging device 10th The ultrasonic receiver 20 includes a plurality of transducer elements 22 and for signal evaluation having a control and evaluation device 24 is connected, which outputs the received at the ultrasonic receiver 20, sound pressure distribution as an image on the screen of a monitor 26th The ultrasonic receiver 20 includes, in an advantageous embodiment of the invention, a plurality of transducer elements 22 which are arranged in the form of a matrix. A particularly suitable transducer arrangement is known for example from U.S. Patent No. 4,742,494. Shock wave transmitter and ultrasonic camera are, for example, in a not shown in the figure coupling device that is filled with a sound-carrying liquid and is placed on an elastic rubber bellows on the surface of the body. 2 In an advantageous embodiment of the invention a sealed with a PVDF film opening in the wall of the coupling device at the location of the ultrasonic receiver 20 is provided, is pressed, an electrode matrix in analogy with the device known from DE-OS 36 28 705 to the outside becomes.

p0017The imaging device 10 in the example of the figure from an acoustic beam splitter 14, for example a plane-parallel thin plate made of polystyrene PS, and an acoustic lens 16, also preferably made of polystyrene PS, which reflected by the body 2 ultrasonic waves 9 onto the receiving surface of the ultrasonic receiver 20 maps. The beam splitter 14 is preferably disposed at an angle of 45 ° relative to the central axis 80 of the ultrasonic shock wave 8 in the beam path of the ultrasonic shock wave 8, so that the beam path within the ultrasonic camera with the beam path of the ultrasonic shock wave 8 at least in the body 2 is crossed. This entanglement also structures can be detected in the ultrasound locating that lie between the surface of the body 2 and the focus F of the ultrasonic shock wave 8 and a disturbing influence on the propagation of the ultrasonic shock waves 8 could exercise. The beam splitter 14 is arranged at least during positioning in the beam path of the ultrasonic shock wave. 8 During the bombardment of the calculus 4 with the ultrasonic shock wave 8 it is removed in a preferred embodiment of the beam path. According to the example of the figure, preferably a pivotable about a pivot axis 12 beam splitter 14 is provided for this purpose. If the level of the figure to the beam path of the ultrasonic shock wave offset 8 arranged ultrasonic transmitter 6 can to locate instead of a beam splitter 14 and an acoustically opaque mirror, for example a metal plate, are pivoted or pushed into the beam path of the ultrasonic shock wave. 8

p0018The focal length of the acoustic lens 16 and the image distance of the ultrasonic receiver 20 are selected so that the focus range B of the ultrasonic camera is set to a subject plane 32 containing the focus F of the ultrasonic shock wave. 8 Due to the finite lateral resolution of the ultrasonic receiver 20, which is in all lateral directions about 2 mm, and, based on the geometric dimensions of the imaging device 10, already no longer negligible sound wavelength, not just an object plane 32 is in focus, the would result in analogy to the laws of geometrical optics, but a focus range B, the depth of about 10 mm, depending on the wavelength of the ultrasonic waves transmitted by the ultrasonic transmitter 6 7 to 20 mm. The lying within this field range B environment of each point P, which is located on the object plane 32 and of which a scattered or reflected ultrasonic wave emanates 9 is thus sharply imaged on ultrasound receiver 20th

p0019In the preferred embodiment according to the figure, the central axis 80 of the ultrasonic shock wave 8 coincides with the running in the object space between the body and the beam splitter imaging axis 15 of the imaging device 10 so that the object plane 32 is perpendicular to the central axis 80th The sectional image displayed on the monitor 26 of the body 2 corresponds to a sectional plane of the body, the direction of propagation of the ultrasonic shock wave 8 is perpendicular, so that each actual lateral misalignment of the calculus 4 in the focal plane of a given by the magnification of the imaging device 10 lateral displacement of the further sharply imaged calculus on the screen of the monitor 26 corresponds. Positioning a out of focus F concretion 4 'can then take place in the familiar from optics in focus adjustment manner in the example to the next by a relative axial displacement of the body 2' and rigidly connected to the lithotripter ultrasonic camera to your monitor 26 is a sharp image of the calculus 4 generated 'that then. by lateral displacements that appear directly as also lateral displacements on the monitor, in the example of the marked center of the monitor 26 corresponding focal zone of the ultrasonic shock wave is guided 8 In addition, it is ensured by the arrangement according to the figure that the radiation emanating from the object plane 32 ultrasonic wave 9, the same region of space in the body 2 crosses as the ultrasonic shock wave. 8

p0020According to Figure 2, an embodiment is provided in which the ultrasonic transmitter and the shock-wave transmitter used to generate the ultrasonic shock wave 8 used for ultrasound locating is formed by a common, for example, piezoelectric ultrasonic transmitter 61 for locating ultrasonic waves 7 produced in cw mode, the intensity relative to the intensity of the ultrasonic shock wave 8 is reduced. In this arrangement, only a small area of ​​the image plane is in contrast to the arrangement of Figure 1 also in locating illuminated 30 associated object plane 32, the lateral extension of a but also focus close enough to the concretion 4 sharp in the center of the ultrasonic receiver 20 map. The fact that the position of the focus of the ultrasonic wave 7 with respect to the position of the focus of the ultrasonic shock wave 8 can be moved axially, is irrelevant, since the set of field of the ultrasonic camera is independent of the focus of the ultrasonic wave. 7

p0021In a planar ultrasonic transmitter 61 of the acoustic beam splitter 14 during the ultrasonic location is preferably located between the ultrasonic transmitter 61 and to focus the ultrasonic shock wave 8 serving lens 18 so that these together with a lens 17 of the imaging device 10 the ultrasound camera. This arrangement has the advantage that it simultaneously enables monitoring the position of the focus F of the ultrasonic shock wave. 8 When operating the lithotripter example, it may occur namely that a shift of the ultrasonic transmitter 61 or the lens 18 is caused to their holders through the mechanical stresses caused by the ultrasonic shock waves. Such misalignment may result in that the focal point of the ultrasonic shock wave 8 is outside the original focus. However, since the ultrasonic transmitter 61 and the lens 18 are part of the ultrasound camera, this results in that, in the ultrasound locating the illuminated region of space is no longer imaged on the receiving surface of the ultrasonic receiver 20 is symmetrical about the center thereof. The viewer can thus already noted in the ultrasound locating a misalignment of the focus of the lithotripter and if necessary, take action to correct the focal position.

p0022This is also possible in an arrangement according to Figure 3, in which the focused ultrasonic shock wave 8 generated by a dome-shaped ultrasonic transmitter 62 so that a lens for focusing the ultrasonic shock wave 8 is no longer required.

p0023In the arrangement of Figure 4, an ultrasonic transmitter 64 is provided for the ultrasonic camera, which is arranged in a central region of a surrounding shock wave transmitter 63rd In the example of the figure, the ultrasonic transmitter 64 is inserted in a central bore of a dome-shaped shock wave transmitter 63rd This arrangement has the advantage that as the embodiment according to Figure 1 for receiving the ultrasonic image a large area of ​​the subject area is illuminated and the associated greater pictured on the monitor section plane of the body 2 to search for the concretion is facilitated. This arrangement also an almost complete overlap of sonicated by ultrasonic wave 7 area is achieved with the sonicated of the ultrasonic shock wave 8 territory and structures that could interfere with the propagation of the ultrasonic shock wave 8 are safer detected.

p0024As common ultrasonic transmitter for the lithotripter and the ultrasonic camera are also suitable ring- or matrix-shaped transducer arrays such as are disclosed for example in U.S. Patent No. 4,526,168 and in which the individual transducer elements of the transducer array and focusing the ultrasonic shock wave are driven separately and phase delay. For the ultrasound locating it is sufficient if only a few of the transducer elements, for example, only a single central transducer element used to sound the body. 2