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Cranial ultrasound is a technique for scanning the brain using high-frequency sound waves. It is used almost exclusively in babies because their fontanelle (the soft spot on the skull) provides an "acoustic window". A different form of ultrasound-based brain scanning, transcranial Doppler, can be used in any age group.
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 is applied using a transducer or applicator that is in direct contact with the patient's skin. Gel is used on all surfaces of the head to reduce friction and assist transmission of the ultrasonic waves. Therapeutic ultrasound in physical therapy is alternating compression and rarefaction of sound waves with a frequency of 0.7 to 3.3 ...
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.
One possible way is the use of an implantable transcranial Doppler device "operatively connected to a drug delivery system". [7] Battery-powered, it would use an RF link to a portable computer running a spectral analysis routine together with input from an oximeter (monitoring the degree of blood oxygenation, which a stroke might impair) to ...
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This method of medical ultrasound therapy can be used for various types of pain relief and physical therapy. In physics, the term "ultrasound" [1] applies to all acoustic energy with a frequency above the audible range of human hearing. The audible range of sound is 20 hertz – 20 kilohertz. Ultrasound frequency is greater than 20 kilohertz.
Traditional obstetric sonograms are done by placing a transducer on the abdomen of the pregnant woman. One variant, transvaginal sonography, is done with a probe placed in the woman's vagina. Transvaginal scans usually provide clearer pictures during early pregnancy and in obese women.