Intended for healthcare professionals

General Practice


BMJ 2000; 321 doi: (Published 22 July 2000) Cite this as: BMJ 2000;321:218
  1. Abi Berger, science editor
  1. BMJ

    Echocardiography uses very high frequency sound waves (ultrasound), which are inaudible to human ears. Sound waves are forms of pressure wave; they can travel through any medium. In echocardiography these waves are generated and detected by means of a piezoelectric crystal contained within a transducer.1 A simple mechanical scanner comprises a single crystal that is oscillated by a small motor, while the newer (“phased array”) systems comprise multiple crystal elements that are pulsed in a rapid and controlled sequence. In cardiac imaging the ultrasound beam arises from a small source and is directed, in a pyramidal sector, across …

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