Part 5 Flashcards
What display method below will help you to demonstrate flow turbulence with color Doppler?
Variance
Color flash artifact is obscuring the anatomy of interest in an exam of the abdominal aorta. What can you do to reduce impact of the flash?
Increase the wall filter
The nyquist limit describes which of the following?
Sampling frequency needed for detecting the Doppler signal unambiguously
Spectral analysis is used to
Determine the distribution and magnitude of frequency shifts in the reflected Doppler signal
Which answer provides the best explanation for the reason that the frame rate decrease when color Doppler is activated?
More pulses are fired on each line of sight
The Doppler frequency shift is in the different between the
Received frequency and the transmitted frequency
You will see aliasing of the Doppler spectrum occurs whenever the frequency shift exceeds
1/2 the PRF
When you measure the width of a point target in a tissue-mimicking phantom, you are evaluating
lateral resolution
String test objects are used to evaluate
Doppler accuracy
What can you test with a Doppler flow phantom?
All of the above (Range- gate accuracy, spectral Doppler velocity accuracy, color Doppler penetration)
Which of the following should be regularly checked as a component of quality control program?
All of the above (system penetration, image uniformity, assurance of electrical safety, distance measurement accuracy)
What is meant by the dead zone in performance testing?
Distance from the transducer to the first identifiable echo
In an ultrasound phantom, the targets typically used for measuring axial resolution are
Closely spaced targets of varying distances
What is the order in which the signal travels in the ultrasound system?
Transducer, receiver scan converter, display
The conversion of an incident pressure wave to an electrical signal is the
PZT effect
Which of the following can not be evaluated with a tissue -equivalent phantom?
temp resolution
What array transducer tries all of the elements for acoustic scan line, using small time delays to steer the beam?
Phased array
Which image technique may increase visualization of the reflections from blood flow on the real-time ultrasound image?
Tissue harmonic imaging
Which of the following helps to improve the axial resolution in a B-mode image?
Increased bandwidth
A type of sonographic imaging that transmits two pulses of opposite phase in rapid succession so they can be cancelled out upon reception is termed
Pulse inversion harmonics
Which of the following best describes the Doppler frequency shift when you encounter high velocities within a vessel?
Frequency shift is increased
What must be known to covert the Doppler shift frequency spectrum into velocities
All of the above (Doppler frequency, angle of incidence, speed of sound in tissue, ultrasound frequency)
Which of the following occurs when you lower the pulse repetition frequency?
The Nyquist limit is decreased
Which of the following human tissues has the highest rate of attenuation of an ultrasound wave?
a) liver
b) fat
c) fluid
d) lung
e) blood vessels
Lung