Three-dimensional Ultrasound

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After taking a cross-sectional image, the emitting surface of the transducer moves or turns in a direction perpendicular to the segment. By placing the data obtained this way in a three dimensional block, further processing and plotting can be performed.
The realization of the two mechanical motions is difficult, so usually at least one of the motions is substituted with the electronic control of several crystals.
The fact that the collection of the three dimensional data can take several seconds is a serious problem, because the area being examined may move. The newest ultrasound devices do not operate based on the traditional A-scan, but they simultaneously emit ultrasound in a zone that contains several lines from several crystals, and the reflected signal is also detected by several crystals. The data are processed with the aid of mathematical methods based on the wave theory, and the degree of reflexivity is determined in every point of the zone in this way as well (zone sonography). By increasing the size of the zones and making use of the possibility of parallel processing, the time needed to produce a segment can be radically reduced; thus, the three-dimensional examination of rapidly moving organs (e.g. the heart) is made possible.