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Regarding electrical safety and quality assurance (QA) in ultrasound: a. Electrical safety tests of the ultrasound unit should be performed annually b. QA of the ultrasound unit should be performed semi-annuallyc. The resolution in B-mode imaging may be tested with a string phantom d. Phantoms used for B-mode imaging are usually filled with distilled water e. The power output of the transducer may be measured with a radiation force balance |
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Answer» a. True. b. False. The Royal College of Radiologists recommends in its ‘Standards for Ultrasound Equipment’ that testing should be performed annually or biannually. c. False. Resolution is usually tested using a test object containing a set of filament targets in a tissue-mimicking material phantom. A string phantom is used for testing the velocity in a Doppler mode. d. False. They need to be filled with a material in which the speed of sound (1540 m s-1 ), attenuation (0.5 dB cm-1 MHz-1 ) and density (1050 kg m-3 ) are close to that in a soft tissue. e. True. The ultrasound emitted from a transducer exerts a force proportional to the output power, which can be ‘weighed’ on a special balance. A power of 1 W corresponds to approximately 68 mg. |
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