Device for shock wave treatment

Device for chock wave treatment

Applicant: Richard Wolf GmbH

7134 Knittlingen

Pforzheimer Strasse 32

Device for shock wave treatment

The invention concerns a device for shock wave treatment with a shock wave transducer having a delay path, filled with a coupling medium which is enclosed by a membrane, which is placed on the patient ' and having an X-ray device for locating the concrement or tissue to be destroyed by the shock waves, the X-ray source having a tube which can be filled with a loss-free medium, for example a gas, arranged within the delay path and sealed against the coupling medium.

A known device of this type has two location finding devices, one ultrasonic location finding device and one Xray location finding device which penetrate the hemispherical body of the shock wave transducer and extend into the delay path of the same. Within the delay path the X-ray location finding device has a tube which is closed off at its end facing the membrane. The tube and balloon are sealed against the coupling medium of the delay path and can be filled with a gas, for example air, so as to cause as little absorption as possible to the X-rays used for location finding. During operation, the tube and balloon are filled with gas in such a way that the balloon comes to rest against the inside of the membrane and thus indirectly against the body of the person to be treated, which results in the liquid coupling medium situated within the delay path and which strongly absorbs the Xrays, from being almost completely displaced from the X-ray path.

This measure considerably improves the location finding by X-rays, as the x-rays passing through the gas part are subjected to considerably less absorption than would be the case with a liquid coupling medium. The drawback,. however, is that the tube because of its length, which is necessary for efficient X-ray location finding, fades out a relatively large part of the sonic field of the shock wave transducer, such fading out is also caused by the balloon, so that shortening the tube whilst correspondingly enlarging the balloon does not represent an improvement, at least not from the fading out point of view, because for Xray location finding the balloon must be expanded to such an extent that it can no longer adapt to the X-ray cone and fade out a relatively large part of the sonic field. It has been shown that such fading out 6f the sonic field can affect the efficiency of the shock wave therapy.

Fadeout occurs to an even greater extent in the case of the balloon known from DE 38 40 077 Al, where not only the free end of the tube, but the entire tube, is replaced by a balloon. In such a design, provision is therefore also made for the balloon to be completely emptied during the shock wave treatment. Moreover, no treatment is possible under X-ray monitoring.

DE 35 03 702 A2 mentions a coupling device for shock waves which surrounds the patient in a ring shape. The coupling medium is present in a flexible ring-shaped receptacle. An X-ray generator is arranged with its tube such that it can be moved in the direction of the axis, with the cladding of the receptacle being made to bulge out to a greater or lesser extent by the Xray generator, depending on position. The device described there has a shock wave tube as transducer, so that the essehtially large extension of the X-ray location device, since it lies next to the shock wave transducer, does not occur here. Such an arrangement, in which the Xray location device does not lie in the immediate vicinity of the transducer s delay path, has the drawback that shock waves and X-rays follow different routes, which can have the disadvantage that obstacles present on the transducer's delay path during X-ray location may possibly not be recognized or not be adequately recognized. Moreover, in the design shown there, the entire X-ray generator is displaced, which leads to different lateral amplification. In addition, in this design, the X-rays always pass through the coupling medium for a not inconsiderable portion of their route, which constitutes a disadvantage because of the medium's high attenuation level.

US 4,798,196 relating to shroud for coupling kidney stone disintegrator to human body does not refer at all to any location device.

a It is therefore the object of the invention to develop especially the X-ray location finder of a device according to the preamble of claim 1 in such a way that both the shock wave therapy as well as the X-ray location finding can be carried out under optimum conditions without causing mutual interference.

This object is achieved in that! the X-ray tube is constructed within the delay path to be variable in length in the axial direction. This makes it possible during shock wave therapy to reduce the length of the X-ray tube, in accordance with the demands made upon it, to such an extent that the sonic field of the shock wave transducer is not reduced or reduced only slightly. The shortening of the Xray tube does allow further use of the X-ray location finding device, but with the limitation that the resolution of the X-ray image is reduced as a result of the liquid coupling medium being situated in the way of the X-ray path. If a higher resolution is required, the length of the X-ray tube has to be increased in the direction of the membrane in order to displace the liquid coupling medium. By changing the length of the X-ray tube the invention succeeds in optimising both the X-ray location finding as well as the shock wave therapy.

Further advantageous embodiments of the invention are characterised by the features disclosed in the subordinate claims.

Advantageously, the change in the length of the X-ray tube is achieved by a telescopic construction. The tube length can thus be continuously changed. The advantageous embodiment of the X-ray tube also has the big advantage that no constructional alterations are necessary to the Xray source itself, which means that for example generically similar devices of older construction can be adapted without problems.

Advantageously, the X-ray tube consists of telescoping, concentric tubular sections whose diameters are chosen to correspond with the X-ray beam enlarging towards the membrane.

By applying an overpressure or underpressure the length of the X-ray tube can be varied in an advantageous manner. Through this it is possible on the one hand to achieve a continuous change in length of the tube and on the other hand complicated mechanical drive means in the area of the delay path can be omitted. The change in length through the overpressure and underpressure of the X-ray tube in the direction towards the membrane which seals off the hemispherical body, also means there is no problem in discharging the coupling medium displaced by the tube in the delay path or of reintroducing this again into the delay path when the tube length is shortened. An equalising reservoir divided into two chambers is provided for this, in which one of the chambers is connected through pipes to the delay path and the other chamber is connected to the inside of the tube which is sealed by an elastic membrane or the like. Such an equalising system is described in the

German Patent Application P 39 34 105.4, which is expressly referred to here.

In a particularly advantageous manner the X-ray tube according to the invention is fitted with an inflatable balloon which extends inside the X-ray tube along the wall of the tube and is secured air-tightly against the inner wall of the tube in a simple manner, for example by means of a clamping ring. The change in length of the tube can thus be effected through this balloon by applying to it an overpressure or underpressure. By using a balloon it is possible to dispense with additional sealing of the tube with respect to the coupling medium situated inside the delay path, especially with the necessary and expensive sealing of the individual telescopic tubular sections. The balloon may thus be of relatively thin construction, especially in the region of the wall of the tube, as it is supported by the tube wall over its entire circumference.

In order to change the length of the tube, apart from being secured at the end of the tube near the hemispherical body, the balloon must additionally be fixed to the free end of the tube, for example by means of a clamping ring.

The invention is now explained in more detail with the aid of an embodiment example shown in the drawings which exemplifies further advantageous embodiments of the invention. These show:

Fig. 1 a part of the X-ray location finding device integrated in the cup-shaped body of a shock wave transducer with an X-ray tube according to the invention,

Fig. 2 the schematic representation of the cup-shaped body of a shock wave transducer in section, with the X-ray tube in the first end position,

Fig. 3 the cup-shaped body of the shock wave transducer according to Fig. 2 with a partly telescopically extended

X-ray tube,

Fig. 4 the cup-shaped body of the shock wave transducer according to Fig. 2 with the X-ray tube in the second end position.

The generic device only partly shown in the drawings in a known manner represents a shock wave transducer 1 with a focusing cup-shaped body 2 with an adjacent delay path filled with a liquid coupling medium 3 and sealed to the outside by a membrane 4 shown in the Figs. 2 to 4.

For carrying out a shock wave treatment it is necessary to locate the concrement 24 or tissue to be treated and to bring it into the focal point of the cup-shaped body 2. For this purpose two location finding devices are provided, one X-ray location finding device 5 and one ultrasonic location finding device 6 which penetrate the cup-shaped body 2 or are fixed to it and extend into the delay path.

The object of the present invention is the development of the X-ray location finding device 5, which is why the ultrasonic location finding device is not described in any detail. Other location finding devices may if necessary be provided, and the ultrasonic location finding device 6 is of course not absolutely necessary.

The X-ray location finding device 5 has an X-ray source 7 essentially arranged outside the cup-shaped body 2, the length-adjustable tube 8 of the X-ray source 7 extending into the delay path filled with the coupling medium. The X-ray tube 8 in the embodiment shown consists of three telescoping tube sections 9, 10, and 11 concentrically arranged with respect to each other, forming a telescope system (see Fig. 1). The number of tube sections and their dimensions can be selected to be smaller or larger, depending on the requirement. Inside the X-ray tube 8 formed by the tube sections 9, 10 and 11 there is arranged an elastic balloon 12 for sealing the inside of the X-ray tube against the coupling medium. The open end 12 of the balloon is firmly connected to the X-ray tube 8 by means of a first clamping ring 13 arranged within the tube section 9 near the cup-shaped body, in which the clamping ring 13 presses the surrounding balloon 12 in a gas-tight manner against the inside of the tube section 9.

The balloon 12 which seals the tube 8 in a gas and fluid tight manner is placed over the end of the tube section 11 in a collar-like manner and firmly placed against this by a second clamping ring 14 arranged on the outside of the tube section 11.

Tube section 9 of the X-ray tube 8 is inserted in base 16 and sealed by rubber seals 15, and base 16 is' seated firmly and tightly in the cup-shaped body 2. The cup-shaped body end of the X-ray tube 8 is sealed off tightly against the X-ray source 7 by an X-ray window 17.

Within the base 16 and the tube section 9 is provided a duct 18 which connects the inside of the tube with the pump 23 via the connection 19 and the valves 21 and 22.

The valves 21 and 22 can be connected to the two chambers of an equalising reservoir according to the

EP Patent No. 0,423,534,Bl whose chambers on the one hand are filled with gas and on the other side with the liquid coupling medium 3.

By introducing gas into the X-ray tube 8 its length can be continuously adjusted from the first end position shown in Fig. 2 to the second end position shown in Fig. 4, in which the end of the balloon which seals off the X-ray tube

ר rests against the membrane 4. The introduction of more gas causes the X-rayable balloon 12, which consists for example of latex resting against the inside wall of the X-ray tube 8 and radially supported by the tube sections 9, 10, 11, to be completely unfolded causing the liquid coupling medium to be completely displaced and the balloon to rest against the membrane 4 of the cup-shaped body. By evacuating the balloon 12 via the duct 18 and the pipe 20 it is possible to reduce the X-ray tube 8 to its shortest length.

Figures 2 to 4 show the ultrasonic location finding device 6 and the X-ray location finding device 5 in different operating positions. In the position shown in Fig. 2 both the ultrasonic location finding device 4 as well as the Xray location finding device 5 are moved into a membranefree position in which no fading out of the sonic field or only the slightest possible fading out occurs. This position allows for in-situ X-ray and ultrasonic location finding as well as a particularly efficient shock wave application.

Fig. 3 shows the ultrasonic location finding device 6 in the position close to the membrane in which the length of the X-ray tube 8 of the X-ray location finding device 5 is reduced by approximately half. This position results in an optimum picture quality for the ultrasonic location finding device 6 and an improved picture quality for the X-ray location finding device when compared to the position shown in Fig. 2, whilst the efficiency of the shock wave application is only slightly reduced as a result of the fading out of the sonic field caused by the location finding devices 5 and 6 and it is still acceptable for an effective shock wave treatment.

Fig. 4 shows a position in which both the ultrasonic location finding device 6 as well as the X-ray location finding device 5 rest against the membrane 4. This presents an optimum position for taking a picture of the concrement 24 or tissue within the body of the person to be treated, whereas because of the severe fading-out of the sonic field in this position by the location finding devices 5 and 6 an efficient shock wave treatment is no longer possible.

Through the continuous, longitudinally adjustable X-ray tube 8 the fading out of the sonic field for therapeutic purposes can be minimised and for location finding purposes the resolution of the X-ray device 5 can be optimised. Depending on the particular application, the therapist can freely choose between the respective optima and thus optimise the treatment by locating the concrement 24 or tissue on the one hand, and destroying the concrement 24 by means of shock waves on the other hand.