Ultrasound unit for generation of a thin emitted beam

摘要

A 2-dimensional array (9) having a number of elementary ultrasonic transducers (10) is controlled by a control device (11) in such a way that a sound field is produced which corresponds to the focussing tube (5b) of a single large ultrasonic transducer (1). The data needed for control, that is, phase relation and emission level, of each individual elementary ultrasonic transducer (10) are calculated or determined experimentally. Thus, a long, sharp ultrasonic beam (5b) is generated directly on the 2-dimensional array (9); this avoids the disadvantages of a broad near field (5a). High scanning rates with high resolution can be achieved. By the omission of a broad near field (5a) the ultrasound unit can be made relatively narrow. For examinations a short distance under the skin it can be applied directly onto the body surface of a patient. A preferred field of application is transmission-based ultrasonic computed tomography. <IMAGE>