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
The propagation speed for sound is lowest in which of the following biologic tissues?
a) fat
b) blood
c) muscle
d) bone
e) liver
fat
As a general observation about media in diagnostic sonography, sound propagates faster in materials with greater:
a) compressibility
b) acoustic impedance
c) stiffness
d) refractive index
e) all of the above
Stifness
An echo from which one of the following sound reflectors is most dependent on the angle of incidence?
a) rayleigh scatterer
b) diffuse reflector
c) specular reflector
d) acoustic scatterer
e) nonspecular reflector
specular reflector
As you perform a sonographic exam, you switch from a 3.5 MHz transducer to a 7.0 MHz transducer to image a superficial structure. Compared to the 3.5 MHz transducer, what will the 7.0 MHz attenuation rate and wavelength be?
a) double the attenuation rate, one-half the wavelength
b) double the attenuation rate, double the wavelength
c) one-fourth the attenuation, one-half the wavelength
d) one-half the attenuation rate, double the wavelength
e) one-half the attenuation rate, one-fourth the wavelength
A
During production of a sonogram, you image the following structures. Which is the MOST attenuating?
a) blood
b) bile
c) soft tissue
d) calcification
e) muscle
D
What can you do to enhance the visibility of a specular reflector?
a) scan with the lowest possible frequency
b) scan with oblique incidence
c) scan with perpendicular incidence
d) increase the distance to the reflector
e) scan with an incident angle of 45 degrees
c
If sound waves of 3 MHz, 5MHz, and 10 MHz are transmitted through the same section of anatomy, reflections from which frequency would reach the transducer first?
a) 3 MHz
b) 5 MHz
c) 10 MHz
d) reflections from all three frequencies would have nearly identical transit times
e) it is not possible to predict which will arrive first
d
What would you do if the image does not show adequate penetration and the far field displays noise instead of tissue?
a) turn on spatial compound imaging
b) move the focal position to a more superficial location
c) use an acoustic standoff pad
d) increase TGC
E) decrease transmit frequency
E
The maximum cyclical change in a quantity is known as:
a) amplitude
b) pressure
c) power
d) intensity
e) decibel
a
If the number of cycles in a pulse is increased but the wavelength remains the same, which of the following is true?
a) the frequency is increased
b) the propagation speed is increased
c) the pulse duration is increased
d) the period is decreased
e) the bulk modulus is decreased
c
Which of the following is most likely also to decrease beam intensity?
a) increasing acoustic output
b) decreasing receiver gain
c) increasing focusing
d) increasing beam area
e) increasing amplitude
d
Which of the following increases as frequency increases?
a) absorption
b) scattering
c) attenuation
d) a and c only
e) all of the above
e
You are imaging with a 5 MHz linear array transducer. What sound parameters slays constant as the beam propagates through the tissue?
a) frequency
b) intensity
c) amplitude
d) wavelength
e) none of the above
e
Choose two benefits of tissue harmonic imaging
a) grating lobe artifacts are reduced and lateral resolution is improved
b) axial and lateral resolutions are improved
c) contrast and axial resolutions are improved
d) penetration is improved and axial resolution is improved
e) penetration is improved and contrast resolution is improved
A
Which of the following would increase the spatial pulse length?
a) increased PRF
b) decreased number of transmit pulses per frame
c) increased number of transmit pulses per second
d) increased number of transmit pulses per line
e) increased number of cycles per pulse
e
Spatial resolution is determined by which of the following? a. the number of bits per pixel b. spatial pulse length c. frame rate d.the number of pixels per inch e beam diameter
d