1462147 Ultrasonic inspection devices AKADEMIET FOR DE TEKNISKE VIDENSKABER SVEJSECENTRALEN 26 Nov 1974 [27 Nov 1973] 51182/74 Heading GIG [Also in Divisions AS and H4] Apparatus for pulse-echo ultrasonic exploration of a biological object comprises a housing 22 with an aperture 24 for passing an elongated biopsy needle and stiletto 30 through it, a first Piezoelectric element 12 within the housing and operating as both pulse transmitter and echo receiver, and a second Piezo-electric element 40 mounted at the end of the stiletto for receiving ultrasonic energy from the first element 12 to determine the precise depth of penetration of the end of the stiletto in the object. In use of the apparatus described, ceramic element 12 is connected to conventional circuitry and a CRT to give a B-scan display of the object interior and so identify a location at which the needle with the stiletto in it are to be inserted. After the insertion the displayed signals from element 40 at the stiletto end enable the penetration depth to be monitored. A 2Hz brightness modulation of the element 40 signals distinguishes them from the element 12 echo signals. Needle 30 may be used to extract an amniotic fluid sample after withdrawal of the stiletto. A damping backing 18 for element 12 comprises a tungsten-loaded plastics resin.
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