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Regarding the properties of ultrasound: a. Ultrasound propagates through tissue as a longitudinal wave b. The velocity of the ultrasound wave is equal to the velocity of the particles of the tissue through which it propagates c. The wavelength of ultrasound in tissue in the range of frequencies used in diagnostic imaging is 1–5 mm d. An ultrasound wave undergoes reflection and refraction but not Rayleigh scattering e. Attenuation of the ultrasound wave by 10 dB corresponds to a tenfold decrease in ultrasound intensity |
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Answer» a. True. This means that local movement of the tissue particles is in the same direction as the wave propagation. b. False. The velocity of the ultrasound wave is independent of the velocity of the particles of the medium. c. False. It ranges from approximately 0.77 mm (at 2 MHz frequency) to 0.1 mm (at 15 MHz frequency). d. False. It undergoes all these processes. Rayleigh scattering occurs when a wave is scattered from small structures with dimensions less than the ultrasound wavelength, such as red blood cells or micro bubbles. e. True. 10 dB (1 Bel) corresponds to a change by one order of magnitude. |
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