Ultrasound is an imaging technique that uses high frequency sound wave and echoes. There are different kinds of ultrasound they are two-dimensional image, 3D ultrasound imagining, and Doppler ultrasound.
Doppler ultrasound is based on the Doppler effect. (Doppler effect is whenever relative motion exists between a source of sound and a listener and the frequency of the sound heard by the listener sounds different compared to the frequency when there is no motion.) The frequency of the echoes depend on how the object reflecting the ultrasound waves is moving. If it is a high frequency then it is moving toward the probe and if it is a lower frequency it is moving away from the probe. How much the frequency changes depends on how fast the object is moving. TO calculate how fast and object is moving, Doppler ultrasounds measure the change in frequency of the echoes. Doppler ultrasound is used to measure the rate of blood flow through the heart and major arteries.
In 3D ultrasound imaging the 3D ultrasound machine takes many two-dimensional images and puts them together to get a 3D image. 3D-ultrasound imaging is used to get a better look at organs.
Ultrasound is used in obstetrics, gynecology, cardiology, and cancer detection. Ultrasound’s main advantage is that it can be used without using radiation. It can also be done quicker than X-rays or other radiographic techniques.
There are some concerns about the safety of ultrasound. There are a few reports of low birth weight babies being born to mothers who had many ultrasound examinations during pregnancy. There are two possibilities with ultrasound and they are…
1. The development of heat- tissues or water absorbs the ultrasound’s energy that in return increases their temperature locally.
2. The formation of bubbles- when the liquefied gases come out of the solution due to local heat caused by the ultrasound’s energy.
Yet, there is no substance ill effect of ultrasound documented in the studies in either humans or animals. Ultrasound should be only used when necessary.
1 How ultrasound works. Freudenrich, Craig c., Ph.D. 1/6/03.
2 Doppler effect. May 8, 1995. 1/6/03. http://csgrad.cs.vt.edu/~chin/doppler.html.