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CORE studying > Davies Test Questions > Flashcards

Davies Test Questions Flashcards

1
Q

What is the time it takes for one pulse to occur known as?

A

Pulse Duration

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2
Q

When you change the transmit frequency, what is altered?

A

Number of cycles per second

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3
Q

What is the speed of sound defined as?

A

Speed at which the sound waves propagate through the medium

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4
Q

What does Snell’s Law describe?

A

The angle of sound transmission at an interface between media having different propagation speeds.

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5
Q

What interaction of ultrasound and tissue is primarily responsible for imaging the internal structure of organs?

A

Scattering

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6
Q

If the number of cycles in a pulse is increased but the wavelength remains the same, what happens to the PD?

A

Pulse duration is increased

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7
Q

Refraction is a bending of the sound beam that results in which misregistration?

A

Lateral registration

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8
Q

The rate of sound attenuation is lowest in what?

A

Water

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9
Q

Which of the following increases as frequency increases?

A. Absorption
B. Scattering
C. Attenuation
D. A and C only
E. All of the Above

A

E. All of the Above

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10
Q

What does ultrasound propagation velocity depend on?

A

Density and compressibility

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11
Q

The length of space over which one cycle occurs is known as what?

A

wavelength

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12
Q

Axial resolution is determined mostly by what?

A

Pulse Duration

The shorter the pulse, the better the axial resolution

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13
Q

According o Snell’s law, the angle of transmission is related to the incident beam angle and what?

A

The relative speeds of sound in the two media

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14
Q

A longitudinal wave is characterized by what?

A

Particle motion occurring in the same direction as propagation

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15
Q

What is another term for nonspecular reflection?

A

Scattering

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16
Q

Relative measurement of intensity based on a logarithmic scale is expressed in which unit?

A

Decibels

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17
Q

When you adjust the pulse repetition frequency, what are you changing?

A

The number of pulses per second

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18
Q

The maximum cyclical change in a quantity is known as?

A

Amplitude

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19
Q

As a general observation about media in diagnostic sonography, sound propagates faster in materials with greater what?

A

Stiffness

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20
Q

What array transducer fires all of the elements for each acoustic scan line, using small time delays to steer the beam?

A

Phased array

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21
Q

What type of resolution is most affected by Pulse Duration?

A

Axial (Axial resolution is determined by SPL, SPL and PD are DIRECTLY related)

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22
Q

The inability to clearly demonstrate small cystic structures comes with a transducer with poor resolution of what? (Lateral, axial, elevational?)

A

Elevational

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23
Q

What is another name for axial resolution?

A

Range resolution

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24
Q

What is associated with a low-Q transducer?

A

Wide bandwidth, multifrequency selection, diagnostic PW ultrasound, loss of most energy in a first few vibrations - good axial resolution, so a short pulse length

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25
Q

Varying the excitation voltage to each element in the group used to form the US pulse is called what?

A

Apodization

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26
Q

What is parallel processing?

A

A method used to improve frame rates with multizone electronic focusing

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27
Q

Which transducer should be selected to produce the narrowest slice thickness throughout the imaging plane?

A

1.5D multirow array

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28
Q

What can you do to improve contrast resolution in the ultrasound image?

A

Use a 2D or matrix array transducer

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29
Q

What does dynamic receive focusing use and do?

A

It uses time delays before echo signals from array elements are combined; results in constructive interference of the waves and produces a higher amplitude and more focused signal

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30
Q

Multiple matching layers on a transducer face result in an increased what?

A

Bandwidth

31
Q

You think you see a calc on B-mode, but posterior acoustic shadow is not present. What is the best optimization for your system to demonstrate the shadow going to be?

A

Increase transducer frequency

32
Q

What is the purpose of curving the transducer elements or applying a lens over the elements?

A

Provides focusing in the out-of-plane direction (elevational)

33
Q

You are imaging a 3D dataset that has anisotropic resolution. What does this mean?

A

Unequal resolution is present between imaging planes

34
Q

The term Signal to Noise Ratio denotes what?

A

The relative amplitude of the signal compared to the amplitude of the noise

35
Q

What does increasing the threshold do to weak signals?

A

Reduces the display of weak signals

36
Q

What is the typical value for the duty factor in diagnostic imaging?

A

0.1-1%

37
Q

What does the range equation describe?

A

The relationship between round-trip pulse time and distance to the reflector

38
Q

What is a disadvantage of a water-path scanner?

A

Bubbles in the fluid can inhibit sound transmission into the body

39
Q

The range equation is used to determine what?

A

Reflector depth

40
Q

What information is present in the M-mode display?

A

Time, motion pattern, and amplitude

41
Q

What is another name for image memory?

A

Digital scan converter

42
Q

Pulse repetition period is the inverse of what?

A

Pulse repetition frequency

43
Q

What is a typical frame rate for B-mode real-time imaging?

A

10-50 Hz

44
Q

When you increase the scanning depth, which of the following is automatically decreased by the system to avoid range ambiguity?

A

PRF

45
Q

What is the order in which the signal travels in the ultrasound system?

A

Transducer, receiver, scan converter, display

46
Q

What is echo ranging?

A

A physical concept that allows us to determine the location of an interface by measuring the elapsed time between the transmitted pulsed ultrasound wave and the detected echo from that interface.

47
Q

What provides a thinner beam and improved contrast resolution?

A

Tissue Harmonic Imaging

48
Q

What is the purpose of the preamplification of the incoming signal that occurs in the transducer assembly?

A

To INCREASE echo voltages before noise is induced through the cable

49
Q

When changing the transmit frequency, what is altered?

A

Number of cycles per second

50
Q

The algebraic summation of waves leading to patterns of minima and maxima is called?

A

Interference

51
Q

Another term for nonspecular reflection is?

A

Scattering

52
Q

What factor determines the frequency of the sound wave for PULSED wave ultrasound?

A

Transmitter Frequency

53
Q

The speed is sound is defined as the…?

A

Speed at which the sound wave propagates through the medium

54
Q

When you perform a Doppler exam, the frequency of the transmitted signal is determined by what?

A

The frequency of the electrical signal applied to the transducer

55
Q

Acoustic impedance increases with what 2 things?

A

Increased tissue density & increased propagation speed

56
Q

When you adjust PRF, you are changing what?

A

The number of pulses per second

57
Q

Which of the following would increase the spatial pulse length?

A

Increased numbers of cycles per pulse

58
Q

What is constructive interference?

A

Sound waves are in phase and resulting amplitude is increased

59
Q

Interference patterns of reflected waves causes what?

A

Acoustic Speckle

60
Q

Another name for axial resolution is?

A

Range resolution

61
Q

What aspect of the Doppler spectrum is colour-encoded with colour Doppler?

A

Frequency Shift

62
Q

What is the name of the control that sets the gray-scale brightness at which colour will be displayed instead of gray-scale at a pixel location?

A

Priority

63
Q

What two controls affect the spatial resolution of the colour image?

A

Frequency and line density

64
Q

The most numerous cells are in the blood are in the?

A

Erythrocytes

65
Q

The Reynolds number increases with increasing…?

A

Flow speed, vessel diameter, blood density, blood flow viscosity

65
Q

What is the continuity rule?

A

The fact that the volumetric flow rate must be the same proximal, at, and distal to a stenosis

66
Q

What is the Bernoulli effect?

A

Pressure reduction in a region of high-flow speed.

66
Q

What is Poisueille’s law?

A

The dependence of volume flow rate on pressure, vessel length and radius, and viscosity.

67
Q

When you encounter high velocities within a vessel, what best describes the Doppler frequency shift?

A

Frequency shift is increased

68
Q

Volume flow = cross section area x (what?)

A

Mean velocity

69
Q

Transducers should NOT be cleaned with:

A

Ultraviolet, autoclave, gas

70
Q

What is strain relief of a transducer?

A

The portion of the transducer that protects the insertion of the cable into the transducer housing. Prone to wear and tear.

71
Q
A

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