Extracoporeal ultrasonic lithotripter with a variable focus

A therapeutical apparatus includes a measuring apparatus including a probe which generates an X-ray or ultrasonic wave in order to detect the location of a target to be treated such as calculi situated within the kidney, liver, biliary ducts. A therapeutical energy generator generates a shock wave of sufficient energy for purposes of therapy externally of the physical body and focuses it upon the target. Structure is provided for causing a displacement of the generator and the measuring apparatus around the surface of a patient. Structure is provided to activate the generator.