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All modern ultrasound scanners use pulsed Doppler to measure velocity. Pulsed wave instruments transmit and receive series of pulses. The frequency shift of each pulse is ignored, however the relative phase changes of the pulses are used to obtain the frequency shift (since frequency is the rate of change of phase).
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.
Doppler echocardiography is a procedure that uses Doppler ultrasonography to examine the heart. [1] An echocardiogram uses high frequency sound waves to create an image of the heart while the use of Doppler technology allows determination of the speed and direction of blood flow by utilizing the Doppler effect.
Functional ultrasound imaging (fUS) is a medical ultrasound imaging technique for detecting or measuring changes in neural activities or metabolism, such as brain activity loci, typically through measuring hemodynamic (blood flow) changes. It is an extension of Doppler ultrasonography.
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.
In medicine, Esophageal Doppler or Oesophageal Doppler uses a small ultrasound probe inserted into the esophagus through the nose or mouth to measure blood velocity in the descending aorta. It is minimally invasive (does not break the skin) and is used to derive hemodynamic parameters such as stroke volume (SV) and cardiac output (CO). A ...
Schematic view of a flow sensor. An ultrasonic flow meter is a type of flow meter that measures the velocity of a fluid with ultrasound to calculate volume flow. Using ultrasonic transducers, the flow meter can measure the average velocity along the path of an emitted beam of ultrasound, by averaging the difference in measured transit time between the pulses of ultrasound propagating into and ...
Echocardiography, also known as cardiac ultrasound, is the use of ultrasound to examine the heart. It is a type of medical imaging , using standard ultrasound or Doppler ultrasound . [ 1 ] The visual image formed using this technique is called an echocardiogram , a cardiac echo , or simply an echo .