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intro. > Ch. 1 - Foundations of Sonography > Flashcards

Ch. 1 - Foundations of Sonography Flashcards

1
Q

Change in the direction of propogation of a sound wave transmitted across an interface where the speed of sound varies

A

refraction

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2
Q

Angle at which a sound beam strikes the interface between two types of tissue

A

angle of incidence

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3
Q

Power per unit area

A

intensity

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4
Q

Special material in the transducer that has the ability to convert electric impulses into sound waves

A

crystal

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5
Q

Propagation of energy that moves back and forth or vibrates at a steady rate

A

wave

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6
Q

Any device that converts energy from one form to another

A

transducer

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7
Q

Number of cycles per second that a periodic event or function undergoes

A

frequency

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8
Q

Measure of a material’s resistance to the propagation of sound; expressed as the product of acoustic velocity of the medium and density of the medium

A

acoustic impedance

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9
Q

Generation of electric signals as the result of an incident sound beam on a material that has piezoelectric properties

A

piezoelectric effect

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10
Q

Region over which the effective width of the sound beam is within some measure of its width at the focal distance

A

focal zone

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11
Q

Reduction in amplitude and intensity of a sound wave as it propagates through a medium

A

attenuation

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12
Q

Passive force in opposition to another, active force; occurs when tissue exerts pressure against the flow

A

resistance

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13
Q

Surface forming the boundary between media having different properties

A

interface

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14
Q

Region of increased particle density

A

compression

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15
Q

Distance over which a wave repeats itself during one period of oscillation

A

wavelength

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16
Q

Refers to the minimum distance between two structures positioned along the axis of the beam where both structures can be visualized as separate objects

A

axial resolution

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17
Q

Rate of energy flow over the entire beam of sound

A

power

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18
Q

Unit used to quantitatively express the ratio of two amplitudes or intensities

A

decibel (dB)

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19
Q

1,000,000 Hz

A

megahertz (MHz)

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20
Q

Ability of the transducer to distinguish between two structures adjacent to one another

A

resolution

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21
Q

Time interval required for generating the transmitted pulse

A

pulse duration

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22
Q

Sequence of events occurring at regular intervals

A

cycle

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23
Q

Speed of the ultrasound wave; determined by tissue density

A

velocity

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24
Q

Minimum distance between two objects at which they still can be displayed as separate objects

A

lateral resolution

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25
Q

Unit for frequency; equal to 1 cycle per second

A

hertz (Hz)

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26
Q

Field closest to the transducer during formation of the sound beam

A

Fresnel zone

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27
Q

Angle of incidence at which the sound beam strikes the interface

A

angle of reflection

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28
Q

1000 Hz

A

kilohertz (kHz)

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29
Q

Field farthest from the transducer during formation of the sound beam

A

Fraunhofer zone

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30
Q

Thickness of the section in a patient that contributes to echo signals on any one image

A

slice thickness

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31
Q

Sound transmitted and received intermittently with one transducer

A

pulsed wave (PW) Doppler

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32
Q

Ability to compensate for attenuation of the transmittal beam as the sound wave travels through tissue in the body

A

time gain compensation (TGC)

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33
Q

Change in frequency of a reflected wave; caused by motion between the reflector and the transducer’s beam

A

Doppler shift

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34
Q

One transducer continuously transmits sound, and one continuously receives sound; used in high-velocity flow patterns

A

continuous wave (CW) Doppler

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35
Q

Normal pattern of vessel flow; flow in the center of the vessel is faster than it is at the edges

A

laminar

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36
Q

Rate at which images are updated on the display; dependent on transducer frequency and depth selection

A

frame rate

37
Q

Analysis of the entire frequency spectrum

A

spectral analysis

38
Q

Technical artifact that occurs when the frequency change is so great that it exceeds the sampling view and pulse repetition frequency

A

aliasing

39
Q

In pulse-echo instruments, it is the number of pulses launched per second by the transducer

A

pulse repetition frequency (PRF)

40
Q

Ability of the system to accurately depict motion

A

temporal resolution

41
Q

Ratio of the largest to the smallest signals that an instrument or a component of an instrument can respond to without distortion

A

dynamic range

42
Q

In pulsed Doppler, the Doppler signal must be sampled at least twice for each cycle in the wave if Doppler frequencies are to be detected accurately

A

Nyquist sampling limit

43
Q

Strength of the ultrasound wave measured in decibels

A

amplitude

44
Q

Measure of strength of the ultrasound signal

A

gain

45
Q

Echo fill-in of the spectral window that is proportional to the severity of stenosis

A

spectral broadening

46
Q

Ultrasound instrumentation that allows the image to be displayed many times per second to achieve a “real-time” image of anatomic structures and their motion patterns

A

real time

47
Q

B-mode scanning technique that permits the brightness of the B-mode dots to be displayed in various shades of gray to represent different echo amplitudes

A

gray scale

48
Q

Amount of change in the returning frequency compared with the trasmitting frequency when the sound wave hits a moving target such as blood in an artery

A

frequency shift

49
Q

Sample site from which the signal is obtained with pulsed Doppler

A

gate

50
Q

Angle that the reflector path makes with the ultrasound beam; the most accurate velocity is recorded when the beam is parallel to flow

A

Doppler angle

51
Q

Acoustics is the study of _______________, _______________, and _______________ sound waves.

A

generating, propagating, receiving

52
Q

Ultrasound is defined as sound frequencies beyond the upper limits of human hearing, that is, greater than _______________.

A

20 kHz

53
Q

Name three pioneers who made a significant contribution to ultrasound.

A

Douglass Howry, Hertz and Elder, John Wild

54
Q

The terms _______________, _______________, and _______________ have all been used to describe an imaging technique by which soft tissue structures of the body are visualized by recording the returning reflection of ultrasonic waves directed into the body.

A

diagnostic medical ultrasound, ultrasound, ultrasonography

55
Q

The term that applies to the ultrasound evaluation of cardiac structures is _______________.

A

echocardiography

56
Q

One who performs ultrasound studies and gathers diagnostic data under the direct or indirect supervision of a physician is a _______________.

A

sonographer

57
Q

List the qualities of a good sonographer.

A

Intellectual curiosity, perseverance, ability to conceptualize 2D images into a 3D format, quick/analytical mind, technical aptitude, good physical health, independence/initiative, emotional stability, communication skills, dedication

58
Q

As the ceramic element vibrates, it periodically presses against and pulls away from the adjacent medium with resultant particle _______________ and _______________ in the medium.

A

compression, rarefaction

59
Q

A transducer converts _______________ energy into _______________ energy

A

electrical, mechanical

60
Q

A propagation of energy that moves back and forth or vibrates at a steady rate is a _______________.

A

wave

61
Q

The time required to produce each cycle depends on the _______________ of the transducer.

A

frequency

62
Q

The distance between two peaks over a period of time is the _______________.

A

wavelength

63
Q

Wavelength is inversely related to frequency, which means that the higher the frequency, the _______________ the wavelength.

A

shorter

64
Q

As frequencies become higher, the pulse duration _______________, yielding a decrease in the depth of field.

A

decreases

65
Q

The rate at which energy is transmitted is referred to as the _______________.

A

power

66
Q

Power per unit area is defined as _______________.

A

intensity

67
Q

If you double the power, the intensity _______________.

A

doubles

68
Q

The piezoelectric effect was first described by the _______________ brothers in 1880.

A

Curie

69
Q

Air-filled structures, such as as lungs and stomach, or gas-filled structures, such as bowel, _______________ sound transmission.

A

impede

70
Q

Bone conducts sound at a _______________ speed than soft tissue.

A

faster

71
Q

Normal transmission of sound through soft tissue travels at _______________ m/sec.

A

1540

72
Q

Acoustic impedance is the product of the _______________ in a medium and the density of that medium.

A

velocity of sound

73
Q

The angle of reflection is equal to the _______________.

A

angle of incidence

74
Q

If specular reflectors are aligned _______________ to the direction of the transmitted pulse, they reflect sound directly back to the active crystal elements in the transducer and produce a strong signal.

A

perpendicular

75
Q

The sum of acoustic energy losses resulting from absorption, scattering and reflection is the _______________.

A

attenuation

76
Q

Minimum reflector separation along the sound path required to produce separate echoes is _______________ resolution

A

axial

77
Q

The _______________ resolution is the ability to produce separate echoes perpendicular to the sound path; it is affected by transducer diameter and focusing.

A

lateral

78
Q

Lateral resolution is determined by _______________.

A

beam width

79
Q

_______________ resolution refers to the ability to resolve objects that are the same distance from the transducer but are located perpendicular to the plane of imaging.

A

Azimuthal

80
Q

Identify three criteria that determine the type of transducer selected for a particular examination.

A

examination, size of patient, amount of fatty or muscle tissue

81
Q

The number of pulses launched per second is the _______________.

A

pulse repetition frequency

82
Q

If the gain is set too _______________, artifactual echo noise will be displayed throughout the image.

A

high

83
Q

A one-dimensional image displaying the amplitude strength of returning echo signals along the vertical axis and the time (distance) along the horizontal axis is produced by _______________.

A

amplitude modulation

84
Q

The intensity (amplitude) of an echo attained by varying the brightness of a dot to correspond to echo strength is displayed by the _______________ method.

A

brightness modulation

85
Q

The condition of assigning each level of amplitude a particular shade of gray is referred to as the _______________.

A

gray scale

86
Q

The _______________ displays time along the horizontal axis and depth along the vertical axis to depict movement, especially in cardiac structures.

A

motion mode

87
Q

A dynamic presentation of multiple image frames per second over selected areas of the body is provided by _______________ imaging.

A

real-time

88
Q

With pulsed Doppler, for accurate detection of Doppler frequencies, the Doppler signal must be sampled at least _______________ for each cycle in the wave.

A

twice

89
Q

When the Nyquist limit is exceeded, an artifact called _______________ occurs.

A

aliasing

intro. (2 decks)

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