Health encyclopaedia - Alphabetical Topic List
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Ultrasound scan
Ultrasound scanning has become increasingly important as a way of scanning without using any radiation such as X-rays. Because it does not use radiation, it is thought to be completely safe.
It uses very high frequency sound waves to create an image of part of the body. The frequency of the sound waves is around ten million cycles per second (10MHz) which means that the human ear is not able to hear them.
Ultrasound scanning uses similar principles to the sonar systems used to detect submarines. When the sound waves are directed at part of the body, different density tissue reflects it in different ways. These reflected waves are translated into an image by a computer.
Ultrasound of even higher intensity can cause tissue warming and is sometimes used for treatment purposes by physiotherapists.
