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WorksheetsUS Physics 16-21
Total questions: 40
Worksheet time: 24mins
A signal with a 120 decibel dynamic range is compressed by 40 decibels. What is the dynamic range of the compressed signal?
40 decibels
120 decibels
3 decibels
80 decibels
Using pulse inversion harmonics, an image is created with 4 MHz sound. What is the resonant frequency of the transducer?
4 MHz
8 MHz
2 MHz
Can not be determined
Why do contrast agents reflect sound?
Different propagation speed
Impedance of the agent is low
Different speed of sound than soft tissue
Impedance of the agent is different than that of soft tissue
When an individual inhales, the diaphragm __________ and venous return to the heart ____________ .
descends; increases
descends;
decreases
ascends;
increases
ascends; decreases
Which of the following flow patterns is associated with cardiac contraction?
Pulsatile
Phasic
Spontaneous
Continuous
The arterial blood pressure of a standing individual is 100 mmHg at the level of the heart. What is the measured blood pressure at the subject's ankle?
100 mmHg
220 mmHg
0 mmHg
90 mmHg
The Doppler Effect is observed as a change in ___________ and has units of ___________.
amplitude; watts
power; watts
frequency; per second
wavelength; millimeters
What is the resulting change in Pressure and Kinetic energy through a stenosis?
Pressure Inc
Kinetic Dec
Pressure Inc
Kinetic Inc
Pressure Dec
Kinetic Inc
Pressure Dec
Kinetic Inc
What is the range of Doppler shifts commonly measured in clinical exams?
-10 kHz to 1 MHz
-0.5 MHz to 0.5 MHz
-0.02 MHz to 0.02 MHz
None of the Above
What information does the Doppler shift furnish concerning the blood cells that produce it?
velocity
speed
frequency
density
Blood moving at a velocity of 2 m/s creates a Doppler frequency of 3000 Hz. What will the Doppler shift be if the velocity increases to 4 m/s?
3000 Hz
2 Hz
1500 Hz
6000 Hz
Two identical exams are performed using 2.5 MHz and 5 MHz transducers. Which exam will measure the highest Doppler shift?
2.5 MHz exam
5 MHz exam
neither
cannot be determined
Two identical exams are performed using 2.5 MHz and 5 MHz transducers. Which exam will measure the highest velocities?
2.5 MHz exam
5 MHz exam
neither
cannot be determined
What is true of the Doppler shift when the sound beam is normally incident to the velocity of the RBCs?
it is at maximum
it is at half of maximum
it is absent
it is at minimum
Which of the following is not true regarding use of continuous wave (CW) Doppler?
A minimum of 2 PZT crystals are in the transducer.
Problems with aliasing significantly limit its clinical utility.
Frequencies measured at the transducer are produced from many different locations along the beam
The duty cycle is 100%.
The appearance of negative velocities in a pulsed Doppler display always indicates that red blood cells are moving away from the transducer.
True
False
The higher the pulse repetition frequency of a Doppler exam, the more likely aliasing will occur.
True
False
Which choice relates to the presence of gray shades in a Doppler spectrum?
velocity
frequency shift
amplitude of the echo
laminar flow
During a pulsed Doppler exam, aliasing is observed. All of the following may eliminate aliasing except:
selection of another imaging view that provides a greater pulse repetition period
selection of another transducer with a lower frequency
selection of another imaging view with a shallower sample volume
use of a continuous wave system
Color flow Doppler imaging incorporates pulsed Doppler principles and provides range resolution.
True
False
Color flow Doppler exams tend to have higher temporal resolution than traditional 2D, real-time imaging.
True
False
Absence of color on a color Doppler image always indicates a region of no blood flow.
True
False
Velocity mode and variance mode color Doppler will produce identical images when blood flow patterns are laminar.
True
False
What is the current method of processing color Doppler signals?
Fast Fourier Transform
Bernoulli's Principle
Fast Fourier Correlation
Autocorrelation
Starting from the same point, the sound source is moving towards the west at 12 mph and the receiver is moving toward the west at 10mph. The Doppler shift is _____.
Positive
Negative
Absent
Unable to be determined
An 8 MHz transducer with a pulse repetition frequency of 5000 Hz is imaging to a depth of 7cm. What is the Nyquist frequency?
4 MHz
3.5 Hz
2.2 kHz
2.5 dB
Which situation will commonly produce reverberation artifact?
two masses that lie perpendicular to the sound beam's main axis
two weak reflectors that lie close to each other along the axis of the beam
two strong reflectors that lie along the main axis of the beam
a single highly reflective mass
Which of the following is not a potential cause of artifact in diagnostic imaging?
operator error
equipment malfunction
patient motion
ultrasound physics
none of the above
What is the most likely cause of ring down artifact?
refraction
reflection
reabsorption
inversion
How is shadowing artifact expressed?
positioning structures too deep on this image
locating structures in improper lateral position
placing reflections in multiple locations
reflectors being absent on the image
Which of these produces shadowing?
reverberation
multipath
reflection
attenuation
Unexpected low attenuation results in which of the artifacts listed below?
refraction
attenuation
enhancement
shadowing
If an ultrasound pulse travels through a large mass in the body at a speed of 1.2 mm/microsec, what happens to the position of all echoes produced from reflectors shallower than the mass?
they are placed in too shallow a location on the image
they are placed in too deep a location on the image
they are likely to be placed at the correct depth
Which artifact results in improper side-by-side positioning of reflectors?
multipath
comet tail
refraction
reverberation
How does slice thickness artifact commonly express itself?
fill in of cystic structures
improper brightness of reflectors
absence of reflectors
strong linear echoes
With depth resolution, _______.
too many reflectors appear on the image
reflectors are placed too deep on the image
reflectors appear too shallow on the image
too few reflectors appear on the image
Axial resolution artifacts are due to which of the following?
multiple reflectors
spatial pulse length
beam width
attenuation
What assumption is violated when a refracted sound wave is processed?
waves travel directly to and from a reflector
sound travels at an average speed of 1.54mm/microsec
sound travels in a straight line
the acoustic imaging plane is very thin
What is the cause of acoustic speckle?
refraction
interference of tiny acoustic wavelets
attenuation
resonance of particles in the near field
With which of the following pulses would lateral resolution be worst?
10 MHz, 4mm beam diameter, 4 cycles per pulse
4 MHz, 4mm beam diameter, 2 cycles per pulse
7.5 MHz, 8mm beam diameter, 2 cycles per pulse
6 MHz, 2mm beam diameter, 2 cycles per pulse
