/ul"treuh sownd'/, n.1. Physics. sound with a frequency greater than 20,000 Hz, approximately the upper limit of human hearing.2. Med. the application of ultrasonic waves to therapy or diagnostics, as in deep-heat treatment of a joint or imaging of internal structures. Cf. ultrasonography.[1920-25; ULTRA- + SOUND1]
* * *Use of ultrasonic waves to produce images of body structures.The waves travel through tissues and are reflected back where density differs (e.g., the border between a hollow organ's wall and its inside). The reflected echoes are received by an electronic apparatus that measures their intensity level and the position of the tissue reflecting them. The results can be displayed as still images or as a moving picture of the inside of the body. Unlike X rays or other ionizing radiation, ultrasound carries minimal, if any, risk. Most often used during pregnancy to examine the fetus, ultrasound imaging is also used on internal organs, the eye, breast, and major blood vessels. It can often show whether a growth is benign or malignant. See also diagnostic imaging.
* * *also called ultrasonographyin medicine, the use of high-frequency sound (ultrasonic) waves to produce images of structures within the human body. Ultrasonic waves are sound waves that are above the range of sound audible to humans. The ultrasonic waves are produced by the electrical stimulation of a piezoelectric crystal and can be aimed at a specific area of the body. As the waves travel through bodily tissues, they are reflected back at any point where there is a change in tissue density, as, for instance, in the border between two different organs of the body. The reflected echoes are received by an electronic apparatus that determines the intensity level of the echoes and the position of the tissue giving rise to the echoes. The images thus formed can be displayed in static form, or, through the use of rapid multiple sound scans, they can in effect provide a moving picture of the inside of the body.Part of ultrasound's usefulness derives from the fact that the sound waves are less potentially harmful to human tissues than are X rays (X-ray) or other ionizing radiations. Because it is an invasive procedure, theoretical risks to the tissues do exist; however, there are no known examples of tissue damage from conventional ultrasound imaging. Ultrasound is most commonly used to examine fetuses in utero in order to ascertain size, position, or abnormalities. Ultrasound is also used to provide images of the heart, liver, kidneys, gallbladder, breast, eye, and major blood vessels.
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См. также в других словарях:
ultrasound — 1923, from ULTRA (Cf. ultra ) + SOUND (Cf. sound). Cf. ULTRASONIC (Cf. ultrasonic). In reference to ultrasonic techniques of detection or diagnosis it is recorded from 1958 … Etymology dictionary
ultrasound — ► NOUN ▪ sound or other vibrations having an ultrasonic frequency, particularly as used in medical imaging … English terms dictionary
ultrasound — [ul′trə sound΄] n. 1. ultrasonic waves, used in medical and dental diagnosis and therapy, in cleaning and detecting flaws in metal, etc. 2. the use of ultrasonic waves in ultrasonography to form images of interior body organs, as the uterus or… … English World dictionary
Ultrasound — Not to be confused with Supersonic .Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Although this limit varies from person to person, it is approximately 20 kilohertz (20,000 hertz) in healthy,… … Wikipedia
Ultrasound — High frequency sound waves. Ultrasound waves can be bounced off of tissues using special devices. The echoes are then converted into a picture called a sonogram. Ultrasound imaging, referred to as ultrasonography, allows physicians and patients… … Medical dictionary
ultrasound — ultrasonic waves; n. sound waves of high frequency (above 20 kHz), inaudible to the human ear. Ultrasound in the range 2–20 MHz can be used to produce images of the interior of the human body as the waves reflect off structures back to the probe… … The new mediacal dictionary
ultrasound — ul|tra|sound [ ʌltrə,saund ] noun uncount a way of producing an image of an organ inside someone s body using sound waves: Ultrasound was used to show the size of the tumor. a. ultrasound or ultrasound scan a process in which a part of someone s… … Usage of the words and phrases in modern English
ultrasound — UK [ˈʌltrəˌsaʊnd] / US noun [uncountable] medical a) a way of producing an image of an organ inside someone s body using sound waves Ultrasound was used to show the size of the tumour. b) ultrasound or ultrasound scan a process in which a part of … English dictionary
ultrasound — [[t]ʌ̱ltrəsaʊnd[/t]] N UNCOUNT: usu N n Ultrasound is sound waves which travel at such a high frequency that they cannot be heard by humans. Ultrasound is used in medicine to get pictures of the inside of people s bodies. I had an ultrasound scan … English dictionary
ultrasound — noun Date: 1923 1. vibrations of the same physical nature as sound but with frequencies above the range of human hearing 2. the diagnostic or therapeutic use of ultrasound and especially a noninvasive technique involving the formation of a two… … New Collegiate Dictionary