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Ultrasound is defined by the American National Standards Institute as "sound at frequencies greater than 20 kHz". In air at atmospheric pressure, ultrasonic waves have wavelengths of 1.9 cm or less. Ultrasound can be generated at very high frequencies; ultrasound is used for sonochemistry at frequencies up to multiple hundreds of kilohertz.
Medical ultrasound includes diagnostic techniques (mainly imaging techniques) using ultrasound, as well as therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as tendons, muscles, joints, blood vessels, and internal organs, to measure some characteristics (e.g., distances and velocities) or to generate an informative audible sound.
Ultrasound image showing the liver, gallbladder and common bile duct. Medical ultrasound uses high frequency broadband sound waves in the megahertz range that are reflected by tissue to varying degrees to produce (up to 3D) images. This is commonly associated with imaging the fetus in pregnant women. Uses of ultrasound are much broader, however.
Isoechoic – the same echogenicity as another tissue; Transvaginal ultrasonography – Ultrasound is performed through the vagina; Transabdominal ultrasonography – Ultrasound is performed across the abdominal wall or through the abdominal cavity; In normal state, each body tissue type, such as liver, spleen or kidney, has a unique ...
Doppler ultrasonography is medical ultrasonography that employs the Doppler effect to perform imaging of the movement of tissues and body fluids (usually blood), [1] [2] and their relative velocity to the probe. By calculating the frequency shift of a particular sample volume, for example, flow in an artery or a jet of blood flow over a heart ...
Diagnostic medical sonography (DMS), a branch of diagnostic medical imaging, is the use of imaging by medical ultrasound for medical diagnosis. DMS uses non-ionizing ultrasound to produce 2D and 3D images of the body. In Canada, the credentialing for diagnostic medical sonography is the Canadian Association of Registered Ultrasound Professionals.
Ultrasound computer tomographs use ultrasound waves to create images. In the first measurement step, a defined ultrasound wave is generated with typically Piezoelectric ultrasound transducers, transmitted in direction of the measurement object and received with other or the same ultrasound transducers. While traversing and interacting with the ...
Abdominal ultrasound can be used to diagnose abnormalities in various internal organs, such as the kidneys, [1] liver, gallbladder, pancreas, spleen and abdominal aorta.If Doppler ultrasonography is added, the blood flow inside blood vessels can be evaluated as well (for example, to look for renal artery stenosis).