Richard Wolf Gmbh

Dagobert Schafer

Helmut Wurster

Werner Krauss

Peter Jaggy

There is disclosed an ultrasonic shockwave transducer for use in lithotripsy, hypothermia and like treatments for generating ultrasonic shock waves and transmitting them to a concretion or tissue to be destroyed. The transducer is arranged to focus the energy of the ultrasonic shock waves proportionally onto at least two points disposed on a line disposed about the main axis of, and being spaced from the radiation surface of, the transducer, the line being arbitrarily curved in three dimensions.

Ultrasonic shock-wave transducer

There is disclosed, a piezoelectric transducer for generating focussed ultrasonic shock waves for use in lithotripsy. The ultrasonic shock waves are emitted in pulsed form and can be transmitted by way of a coupling medium to the body of a patient to be treated. The transducer comprises a substantial member of individual piezoelectric transducer elements of ceramic or like material which are connected to the poles of a pulse generator and are fixed to a support in mosaic form and with their sides electrically insulated from one another. The acoustic termination of the transducer elements is essentially free from reflection. An intermediate medium of at least one layer, the acoustic impedance of which lies between that of the ceramic of the transducer element and that of the coupling medium, is provided between the transducer elements and the coupling medium. The thickness d of the layer is chosen in accordance with the relationship d&gt;.tau..sub.k .multidot.c.sub.LA, where .tau..sub.k is the propagation time of sound in the piezoceramic of the transducer elements and c.sub.LA is the sound velocity in the intermediate medium.

Piezoelectric transducer

An ultrasonic transducer for lithotripsy has piezoelectric transducer elements fixed to a backing and connected on the front side to first electrodes and on the rear side to second electrodes which can be connected to an electrical pulse generator. In order to avoid the danger of tissue damage in the focal area, especially for focusing transducers, the electrodes are designed such that an homogeneous field is produced in the front-side part of the transducer elements and a non-homogeneous field is produced in the opposite, rear-side part of the transducer elements. The amplitude of the negative pulse occurring in addition to the positive pressure pulse is thus reduced, the negative pulse being responsible for the danger of this tissue damage. In one way of achieving this effect each transducer element is provided with a pot-shaped electrode which surrounds the rear-side part of the transducer element.

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Bretten, Germany

Dagobert Schafer