#1
What is the Doppler effect?
A change in frequency or wavelength of a wave in relation to an observer who is moving relative to the wave source.
ExplanationFrequency or wavelength change relative to observer motion.
#2
Which of the following is NOT a factor affecting Doppler ultrasound measurements?
Frequency of the ultrasound beam
ExplanationUltrasound beam frequency does not affect Doppler measurements.
#3
Which of the following is NOT a clinical application of Doppler ultrasound?
Evaluating liver function
ExplanationLiver function evaluation is not a clinical application.
#4
In Doppler ultrasound imaging, what does the color blue typically represent?
Venous blood flow away from the transducer
ExplanationBlue represents venous flow away from the transducer.
#5
What is the principal difference between continuous-wave (CW) Doppler and pulsed-wave (PW) Doppler?
CW Doppler measures blood flow in a continuous stream, while PW Doppler sends and receives ultrasound pulses intermittently.
ExplanationCW Doppler continuously measures flow, while PW Doppler uses intermittent pulses.
#6
What is the primary advantage of color Doppler imaging over spectral Doppler?
Color Doppler can assess blood flow in multiple vessels simultaneously.
ExplanationColor Doppler can assess multiple vessel flows simultaneously.
#7
What is the primary limitation of Doppler ultrasound in assessing blood flow?
Susceptibility to aliasing artifacts
ExplanationAliasing artifacts are a primary limitation.
#8
What is the equation for calculating Doppler shift frequency?
Doppler shift = (Speed of source × Wavelength) / Speed of observer
ExplanationDoppler shift = (Speed × Wavelength) / Observer speed.
#9
What is the Nyquist limit in Doppler ultrasound?
The frequency shift at which aliasing occurs
ExplanationNyquist limit is the aliasing threshold.
#10
What effect does increasing the Doppler angle have on the measured Doppler shift?
Decreases the Doppler shift
ExplanationIncreasing angle reduces measured shift.
#11
What phenomenon causes aliasing artifacts in Doppler ultrasound?
Frequency shift exceeding the Nyquist limit
ExplanationAliasing due to frequency shift beyond Nyquist limit.
#12
What factor primarily determines the frequency shift in Doppler ultrasound?
Velocity of the blood relative to the transducer
ExplanationFrequency shift is primarily determined by blood velocity.