Ultrasound scan

Unlike x rays an ultrasound scan does not use any radiation. it is therefore thought to be completely safe.

A ultrasound 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.