Basic principles of ultrasonography
In examinations using external energy sources such as X-rays, ultrasound and injected radioactive substances, the information contained in the images is produced by the interaction between the energy and the organ under examination. This interaction can be visualized in two different ways: an image may be formed by the energy which manages to pass through the organ or its parts, or the energy reflected or scattered from portions of the structure under examination may be transferred into images. The two techniques are respectively termed visualization by transmission and visualization by reflection. In the visualization by transmission technique, the energy is propagated through the object, i.e. the biological tissues; the energy, which is not absorbed, scattered or reflected by the tissues, is visualized. Traditional radiology makes use of this technique. The visualization by reflection method uses the energy, which has been scattered back from or reflected by the tissues. In most cases, diagnostic ultraso und currently uses the technique of formation of images by reflection.
KeywordsLateral Resolution Specular Reflection Oblique Incidence Ultrasound Beam Endorectal Ultrasonography
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