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Concerning the Q factor of an ultrasound transducer: a. A low Q transducer has a narrow bandwidth b. A heavily damped transducer has a low Q factor c. A low Q transducer can achieve better axial resolution than a high Q transducer of the same frequency d. High Q transducers are preferred for continuous-wave imaging e. Continuous-wave Doppler imaging requires a receiving transducer that is lightly damped |
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Answer» a. False. As the Q factor is the ratio of the resonant frequency to the transducer bandwidth, a low Q value indicates a wide bandwidth. b. True. A heavily damped transducer produces a pulse of short duration. The shorter the pulse, the wider the spectrum of frequencies produced (bandwidth). Therefore, a heavily damped transducer has a low Q factor. c. True. A low Q transducer is highly damped and produces a pulse of short duration and therefore of low spatial pulse length (SPL). The shorter the SPL, the better the axial resolution. d. True. Continuous-wave imaging requires a transducer with high persistence of sound (‘ringing’). Such a transducer needs to be lightly damped, and therefore of a high Q factor. e. True. A high Q transducer has a narrow bandwidth, which is optimal for detection of the relatively small frequency changes caused by the blood flow. |
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