Ultrasound imaging (sonography) uses high-frequency sound waves to view soft tissues such as muscles and internal organs. Because ultrasound images are captured in real-time, they can show movement of the body's internal organs as well as blood flowing through blood vessels. In an ultrasound exam, a hand-held transducer is placed against the skin. The transducer sends out high frequency sound waves that reflect off of body structures. The returning sound waves, or echoes, are displayed as an image on a monitor. The image is based on the frequency and strength (amplitude) of the sound signal and the time it takes to return from the patient to the transducer. Unlike with an x-ray, there is no ionizing radiation exposure with this test.
- FDA. Medical Imaging: Ultrasound. Page Last Updated: 06/06/2012. http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/MedicalImaging/ucm115357.htm