An apparatus for extracorporeal lithotripsy includes a shock wave source which generates shock waves converging in focus a zone, within which a calculus to be disintegrated is disposed. The shock wave source can be selectively driven to generate high-intensity shock waves for disintegrating the calculus, and for generating low-intensity shock waves for imaging purposes. A pressure sensor is disposed between the focus zone and the shock wave source to register the reflections of the low-intensity shock waves. The pressure sensor has a sensor surface which is substantially coextensive with the cross-sectional area of the shock waves in the region of the pressure sensor, and is connected to a reception circuit which constructs an image of the calculus during the course of treatment based on the signals from the pressure sensor. An acoustic deflection stage is disposed between the pressure sensor and the focus zone and deflects the low-intensity shock waves to generate a sector scan which covers the focus zone of the high-intensity shock waves. The reception circuit can be operated for producing B-images.
A pressure pulse source, of the type suitable for generating shockwaves, has a positive lens for focusing the pressure pulses onto a focal zone. The positive lens has an acoustic exit face which has a shape, in a focusing zone, for focusing the pressure pulses and a shape, in at least one measurement zone, which deviates from the shape in the focusing zone. A pressure sensor containing a piezoelectric polymer foil is disposed at the measurement zone. The pressure sensor, or a number of such pressure sensors, generate signals which are used to monitor the pressure pulses emerging from the positive lens, such as by acquiring their peak value.
A lithotripter having a shockwave generator having a cavity filled with water, further having an ultrasonic, locating transducer mounted by means of a holding device which includes metallic inner and outer shells each having a large acoustic impedance as compared with water and an acoustically attenuating layer interposed between the two shells; the shells are spaced from each other so that the shockwaves will be eliminated by interference.
In a shock wave generating apparatus, phase shifts contained in echo signals reflected from a calculus are corrected in order to clearly judge whether or not such a calculus is actually present at a focal point or a near region. The shock wave generating apparatus includes: a shock wave producing unit constructed of at least two transducer elements, for producing shock wave pulses used to disintegrate an object located near a focal point of said shock wave producing unit within a biological body under medical examination upon receipt of first drive pulses having first energy levels, and also for producing ultrasonic pulses used to obtain echo pulses reflected from said object near the focal point, as echo signals, upon receipt of second drive pulses having second energy levels lower than said first energy levels of the first drive pulses; an analog type phase-shift correcting unit for correcting phase shifts contained in the echo signals reflected from the object near the focal point by making respective phases of the echo signals coincident with each other as to a time domain of the analog echo signals, thereby obtaining an analog phase-corrected echo signal; a peak detecting unit for detecting a peak value of the analog phase-corrected echo signal; and a controlling unit for controlling the shock wave producing unit based on the peak value of the analog phase-corrected echo signal to determine whether or not the shock wave pulses are produced in order to destroy the object near the focal point.
A generator for acoustic waves has a source of acoustic waves with which acoustic waves can be introduced into an acoustic propagation medium and a liquid lens having a variable focal length which is arranged in the acoustic propagation medium, the liquid lens having two lens walls and a lens liquid situated therebetween. At least one of the lens walls is deformable for the purpose of varying the focal length. The liquid lens has a central opening, so that the lens walls have an outer and an inner edge, and the outer edge of the deformable lens wall is fixed and the inner edge is displaceable in the direction of the center axis of the liquid lens for the purpose of varying the focal length.
An electromagnetic induction type lithotrity apparatus, having a shock-wave source utilizing electromagnetic induction to generate a shock-wave, and focusing means to focus the shock-wave at a predetermined position, for focusing and irradiating the shock-wave toward a stone in the body of a patient which is located at the predetermined position, thereby pulverizing the stone. The apparatus comprising a drive section (sending section) for driving the shock-wave source by a voltage lower than that for generating the shock-wave so as to send a low-pressure wave lower in pressure than the shock-wave to the inside of the body, an echo receiving section, including a piezoelectric film arranged in front of the shock-wave source, for receiving a low-pressure echo reflected from the body, an echo detecting section for detecting the intensity of an echo, among the echoes received by the echo receiving section, reflected by a focal zone of the shock-wave, and a control section for comparing the intensity of the echo detected by the echo detecting section with a predetermined value, sending a predetermined signal to the drive section (sending section) based on the comparison result, switching the drive voltage of the shock-wave source to a high voltage sufficient for lithotrity, and generating a signal for driving the shock-wave source.
