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MCQ5
1.
An advantage of spatial compound scanning is that it:
a) reduces slice thickness artifact
b) improves lateral resolution
c) increases the frame rate
d) reduces speckle
2.
The period of an ultrasound wave is:
a) the distance occupied by a single cycle of ultrasound
b) the time it takes for a single cycle of ultrasound to occur
c) the time from one transmit pulse to the next
d) the time it takes for a single transmit pulse
3.
Doppler frequency aliasing can be reduced or eliminated by:
a) decreasing the Doppler angle
b) increasing the wall filter cutoff frequency
c) decreasing the PRF
d) decreasing the ultrasound frequency
4.
When the Doppler angle is reduced the Doppler shift:
a) remains unchanged
b) increases or decreases depending on the blood velocity
c) increases
d) decreases
5.
The lateral resolution in an ultrasound image is determined by the:
a) beamwidth
b) slice thickness
c) duty factor
d) pulse duration
6.
Doppler shifted echoes from moving tissues are reduced by:
a) the Nyquist Limit
b) the wall filter
c) quadrature signal detection
d) autocorrelation
7.
The purpose of the backing layer in a probe is to:
a) dampen the resonant vibration of the transducer
b) absorb energy transmitted backwards into the probe
c) absorb energy transmitted backwards and dampen resonant vibration
d) none of these
8.
An ultrasound phantom usually contains tissue mimicking material that matches the following properties of average tissue:
a) propagation speed, attenuation, scattering
b) propagation speed, attenuation, acoustic impedance
c) attenuation, scattering, acoustic impedance
d) propagation speed, scattering, acoustic impedance
9.
The finite width of the ultrasound beam causes:
a) lateral smearing of tissue structures in the image
b) multiple copies of a tissue structure to be displayed lateral to its true position
c) axial smearing of tissue structures
d) displacement of a structure in the image to a location deeper than its true position
10.
In Doppler ultrasound intrinsic spectral broadening is worse when:
a) the Doppler angle is small
b) the ultrasound frequency is low
c) the transducer aperture is large
d) the sample volume depth is large
11.
The purpose of the persistence function in an ultrasound machine is to:
a) improve the visualisation of tissue interfaces
b) increase speckle
c) reduce speckle
d) increase the depth of penetration
12.
Speckle is the grainy appearance in an ultrasound image caused by:
a) the use of low frequencies
b) inappropriate gain settings
c) the summation of echoes from multiple scatterers
d) refraction of the beam
13.
In ultrasound imaging lateral resolution:
a) improves when the transmit pulse duration is reduced
b) varies with depth into the tissues
c) depends on the acoustic impedance of the tissues
d) improves when the PRF is increased
14.
The ratio (S - D)/S (where S and D are the peak systolic and minimum diastolic blood velocities or Doppler shifts respectively) is called the:
a) Pulsatility Index
b) Reverberation Index
c) Resistance Index
d) Systolic-Diastolic Ratio
15.
If the ultrasound propagation speed in the tissues under examination is higher than the value assumed by the machine (1540 m/s) objects will be displayed in the image as being ________________ their true location.
a) at the correct depth but displaced laterally from
b) less deep than
c) deeper than
d) none of these, the image will be unaffected
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