1. The document provides login information and questions for an online ultrasound education site. 2. It includes 10 multiple choice questions about ultrasound physics and imaging. The questions cover topics like beam divergence, aliasing, attenuation in soft tissue, and resolution. 3. Detailed explanations are provided for each answer selection, covering concepts such as the Nyquist limit, absorption, backscatter, and how stiffness and density affect sound speed.

1. MCQs US (1)
Dr. Kamal Sayed MSc US UAA
OK

2. •
ESP US EDDUCATION SITE
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www.esp-inc.com
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Click on this : X-Zone
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and scroll to the bottom of the page
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enter the ‘Email’ and “password’ in the login to X-zone box
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and you will have access.

3. •
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MCQ site
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https://esp-inc.com
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1ST & last name
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Kamal eldirawi
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email
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kamalsono@hotmail.com
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user name
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kamalsono
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pw
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Kamal@341950
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https://esp-inc.com/x-zone/course/view.php?id=37

4. •
1. What would you do to decrease far field divergence?
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a) use a smaller transducer
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b) use a lower frequency transducer
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c) increase the compression
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d) use a higher frequency transducer
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e) reduce the far field gain

5. •
d) Use a higher frequency transducer.
Less divergent beams are created with :
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@ Higher frequency transducers
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@ and larger diameter crystals.
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This improves lateral
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resolution in the far field.

6. •
2. What would you do to decrease aliasing?
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Slect one answer
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a) image by decreasing the nyquist limit
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b) image with a higher frequency transducer
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c) use pulsed rather than CW Doppler
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d) image in a view with a shallower depth
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e) decrease the gain

7. •
d) image in a view with a shallower depth.
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@ This increases the PRF
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@ and the Nyquist limit.
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Aliasing is less likely with a higher Nyquist.

8. •
3. A patient is evaluated with a TEE for possible severe mitral
regurgitation.
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Which color Doppler setting will decrease the jet area
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on TEE from the initial image?
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a) Lower the pulse repetition frequency
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b) increase the Nyquist limit
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c) increasing the Doppler gain
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d) increase compression
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e) decrease the reject

9. •
b) increase the nyquist limit.
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@ Increasing the Nyquist limit will make the system less
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sensitive to low velocities.
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@ Since the edges of a jet are low velocities, the jet will
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appear smaller.
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NOTE: This is the converse of a 2006 question about
visualizing low velocity flow (ASD flow).
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@ To increase the sensitivity to low flow, use a lower PRF.
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@ To decrease the sensitivity to low, use a higher PRF.

10. •
4. What is the wavelength of 2 MHz sound in soft tissue?
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a) 1.54 mm b) 0.75 mm c) 0.75 cm d) 0.75 m e) 0.77 s
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e)
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Wavelength is usually denoted by the Greek letter lambda (λ);
it is equal to the wave speed (v) of a wave train in a medium
divided by its frequency (f) : λ = v/f.
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1.54/2 = 0,77 s

11. •
5. What is the most common form of attenuation in soft
tissue?
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a) reflection b) refraction c) transmission d) attenuation
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e) absorption
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e) Absorption.
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Of these choices, the primary component of attenation is
absorption.
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This is due to the fact that US can be transmitted through soft tissue, but
is mostly reflected when it comes into contact with more dense material
such as bone. Any us that is not reflected will be absorbed by the body.
Doctors also use US to monitor blood flow and destroy kidney stones.

12. •
6. A patient is having aliasing trying to acquire the data with a
velocity of 1.8 m/s.
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To get rid of the aliasing you would :
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a) use a higher frequency probe
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b) lower the PRF
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c) increase the gain
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d) use more wall filterattenuation
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e) use baseline shift
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13. •
e) Baseline shift is the best of all choices.
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In PWD (spectral & CFD)
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@ the velocity peak is cut off at the peak of the scale,
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@ and the peak is displayed at the bottom of the scale, often
overlapping with the rest of the curve.
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# The artifact can be quickly remedied by lowering the
baseline (if display of flow away from the transducer is not
required), or increasing the PRF.

14. Aliasing definition
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Aliasing is a phenomenon inherent to Doppler modalities
which utilize intermittent sampling in which an insufficient
sampling rate results in an inability to record direction and
velocity accurately. ..
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Unlike CWD, PWD & CFD modalities alternate between rapid
emission of ultrasound waves (at a rate termed the pulse
repetition frequency “PRF”) and reception of incident
ultrasound waves.
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The time an ultrasound wave travels, given a constant speed
in soft tissue (c = 1540 meters/second) will correspond to the
distance traveled.

15. •
PWD and CFD operate on this presumption
(emission/reception ) ;
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when a location of interest is designated, the ultrasound
machine will only record returning echoes during an interval
that corresponds to the time necessary for wave egress and
return along a linear path.
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If Doppler shifts occur at a frequency exceeding the maximum
pulse interval (1/pulse repetition frequency) detected phase
shifts will be calculated based on incorrect assumptions.

16. Facors causing aliasing
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The Nyquist limit defines the frequency at which aliasing and
range ambiguity will occur, and is equal to the PRF/2.
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Factors causing aliasing such as :
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1- higher velocities of target structures (vessles).
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2- and increasing depth of the region of interest insonated;
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will result in aliasing and consequent range ambiguity.
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3- use of higher frequency transducers
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4- inappropriate angle of insonation
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5- large sampling volume

17. •
Clinical use of aliasing
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1) Echocardiography
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A specific use for aliasing in echocardiography is the
calculation of the effective regurgitation orifice area (EROA) in
the assessment of valvular regurgitation, most commonly
involving the mitral valve.
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With color Doppler interrogation of a mitral regurgitant jet, a
hemispheric flow convergence forms surface area tapering to
form the vena contracta before entering the left atrium.

18. •
2) Pulsed wave Doppler
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In case of spectral Doppler :
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@ the velocity peak is cut off at the peak of the scale,
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@ and the peak is displayed at the bottom of the scale, often
overlapping with the rest of the curve.
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# The artifact can be quickly remedied by lowering the
baseline (if display of flow away from the transducer is not
required), or increasing the PRF.

19. •
3- Color flow Doppler
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# In color Doppler aliasing is encountered as red to blue hues
immediately adjacent to each other in a vessel, which is –
(unlike in case of true flow reversal) - not separated by a
black region of no flow.
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# The artifact immediately disappears if : the upper margin of
the velocity scale is increased above the peak flow velocity.
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Color aliasing is useful for detecting foci of increased flow (e.g.
stenosis, arteriovenous fistula).
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Note that aliasing does not occur with power
Doppler, as it does not display velocity

20. •
7. The major source of ultrasound information used to create
a two-dimensional image is:
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a) specular reflections/ b) raleigh scattering/ c) scattering/
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d) backscatter
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d) backscatter is the best answer:
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Backscatter (diffuse) and specular reflections redirect sound
energy back towards the TXR.
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Since backscatter redirects energy in many directions, the
sound wave is more likely to be received by the TXR & used to
creat an image.
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21. •
8. The speed of US in soft tissue is closest to:
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a) 1540 km/sec/ b) 1.54 km/msec/ c) 1500 m/s/
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d) 1540 mm/sec
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BE CAREFUL WITH UNITS
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Choice C correct answer
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Sound travels approximately one mile per second in soft
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Tissue (1450 meter/sec) .
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This is best approximated by 1,500 m/s, .

22. •
9. Which of the following creates point spread artifact?
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a) pulse width / b) pulse duration / c) pulse length /
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d) pulse repetition frequency
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Choice a is the best answer
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This artifact occurs when two reflectors are perpendicular to
the beam's main axis create one reflection on the image. It is
also called point spread artifact.
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Lateral resolution is determined by beam width.
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Point spread artifact is another term of describing suboptimal
lateral resolution.
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23. •
10.Which of the following forms of resolution varies within
the depth of a single frame?
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a) axial / b) contrast / c) lateral /d) harmonic
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Choice C is the best answer
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Lateral resolution is determined by beam width.
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Since beam diameter (or width) changes with depth ;
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, so too does lateral resolution.

24. •
11. As a result of ______________ the propagation speed
increases.
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a) increasing stiffness and increasing density
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b) increasing stiffness and decreasing density
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c) decreasing stiffness and increasing density
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d) decreasing stiffness and decreasing density
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The unit of stiffness is Newtons per meter.
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Stiffness is applied to tension or compression.
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25. •
Choice B is the best answer
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Sound waves propagate at a higher velocity in stiffer media.
They also propagate
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faster in media that are less dense. This is why sound travels
rapidly in bone.
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Bone is quite stiff and has a relatively low density.
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Stiffness is the extent to which an object resists deformation
in response to an applied force. The complementary concept
is flexibility or pliability: the more flexible an object is, the
less stiff it is.

26. •
A stiff material : @ has a high Young's modulus (a mechanical
property that measures the tensile stiffness of a solid
material.) @ and changes its shape only slightly under elastic
loads (e.g. diamond). ... A stiff material requires high loads to
elastically deform it - not to be confused with a
strong material, which requires high loads to permanently
deform (or break) it.
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The Young's Modulus (or Elastic Modulus) is in essence
the stiffness of a material. In other words, it is how easily it
is bended or stretched.

27. •
Density is a calculation of how much matter is squeezed into a
given amount of space. It is a ratio— the amount of mass per
unit of volume.
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Scientists define density as the mass of a substance per unit
volume.
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28. •
Acoustic impedance (Z) is a physical property of tissue.
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It describes how much resistance an ultrasound beam
encounters as it passes through a tissue.
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Acoustic impedance depends on:
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the density of the tissue (d, in kg/m3)
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the speed of the sound wave (c, in m/s)
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and they are related by:
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Z = d x c
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29. •
Thus , Increased density & increased speed of sound both will
lead to increased impedance
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The ability of an ultrasound wave to transfer from one tissue
type to another depends on the difference in impedance of
the two tissues. If the difference is large, then the sound is
reflected.
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The SI unit for acoustic impedance is the Rayl, kg/(m2s),
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30. •
12. If the frequency of US is increased from 0.77 MHz to 1.54 MHz,
what happens to the wavelength?
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a) doubles / b) halved / c) remains the same /
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d) 4 times greater
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Choice B is the best answer
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Recall that wavelength and frequency are inversely proportional,
Thus, when
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frequency doubles, wavelength is halved.
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31. •
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US wavelength decreases with increasing frequency. –In soft
tissue, the ultrasound wavelength is 0.39 mm at 4 MHz and
0.15 mm at 10 MHz. –
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For sound waves, the relation between velocity (v) measured
in m/s, frequency (f), and wavelength is :
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v = f X λ (m/s).
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In air at atmospheric pressure, ultrasonic waves
have wavelengths of 1.9 cm or less.
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32. •
13. What is the wavelength of 5 MHz sound in soft tissue?
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a) 1.54 mm / b) 0.7 mm / c) 0.5 mm / d) 0.3 mm
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Choice D is the best answer
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The wavelength of sound in soft tissue equals 1.54 mm
divided by the frequency
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For sound waves, the relation between velocity (v) measured
in m/s, frequency (f), and wavelength is :
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v = f X λ (m/s).
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(with units of MHz). 1.54 mm divided by 5 equals 0.3 mm.

33. •
14. An ultrasound system creates a two dimensional image with a
depth of view of 10 cm.
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The echocardiographer then switches
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to m-mode with the same depth of view.
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During both phases, the PRF is maximized.
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How does the PRF during M- mode acquisition compare to that
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during 2-D acquisition?
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a) PRF for m-mode is 1/10th that of 2-D
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b) PRF for m-mode is half that of 2-D
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c) PRF for m-mode is equal to that of 2-D
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d) PRF for m-mode is twice that of 2-D

34. •
Choice C is the best answer
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maximum PRF is determined solely by the depth of view.
Since the depths of view
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in both cases are equal, so too are the PRFs.

35. •
15. Refraction only occurs if there is:
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a) normal incidence & different impedances
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b) indirect intensity & different propagation speeds
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c) oblique incidence & different propagation speeds
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d) oblique frequency & identical impedances
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36. •
Choice C is the best answer
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Refraction is the redirection of a sound wave as it transmits
from one medium to another.
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Refraction depends upon :
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@ the media having different propagation speeds.
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@ speeds and the sound wave striking the boundary between
the media at an oblique angle.
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37. •
16. If the lines per frame is increased while the imaging depth is
unchanged then :
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a) frame rate increases / b) number of shades of gray decreases
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c) the frame rate decreases / d) this cannot happen
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Choice C is the best answer
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When depth remains constant and the number of pulses in each
image increases, more time is required to create each image.
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As a result, the number of frames created each second is
decreased.
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38. •
17. A sonographer adjusts an ultrasound machine to double
the depth of view from 5 cm to 10.
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IF FR remains the same :
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Which of the following also changed ?
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a) increased line density / b) wider sector c) multi-focus
imaging turned on / d) narrower sector
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•
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39. •
choice D is the best answer
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With constant FR , the time required to create a frame must
be be unchanged.
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Increasing imaging depth would increase the time needed to
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make a single image.
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The other action must act to counteract this increase.
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The only choice that decreases the time to make a frame is d)
narrowing the sector
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