The operating principle of the sonar system used by ships provided the basis for one of the most significant inventions in medical science since the invention of the X-Ray machine. Developed in the 1950's, the ultrasound scanner enables doctors to see parts of the body in much more detail than is possible with an X-Ray.
A probe which emits sound waves is pressed against the body. These bounce back from the internal organs in the form of echoes, which are picked up and processed by a computer to form an image on a screen. The ultrasound scanner is most useful when monitoring objects lying in water, or fluid, such as a fetus in a womb. For this reason, patients due to be scanned are sometimes asked to arrive at the hospital with a full bladder. Primarily used for pre-natal observation, it is used to monitor the growth of a fetus as well as detecting abnormalities, such as spina bifida. With modern technology it is even possible to obtain moving pictures of a baby. As well as providing a much more detailed picture than an X-Ray, it can be used much more often without the risk of damage to the baby because there is none of the radiation associated with X-Rays.
As well as being a valuable asset to the maternity wing, the ultrasound scanner is used to take images of other organs, especially the gall bladder, which is difficult to X-Ray because of its position within the body. A further development of the scanner is the ultrasound probe which is used to destroy kidney stones. The probe is inserted into the kidney, complete with an eyepiece to enable the surgeon to see the stones. It is then aimed at the stone and turned on, generating sound waves which destroy the stones by a process of vibration.
