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Chapter 1 Hagen Ansert > Ch. 1 Foundations of Sonography > Flashcards

Ch. 1 Foundations of Sonography Flashcards

1
Q

Change in the direction of propagation 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 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 boundry 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

Decible (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

22
Q

Sequence of events occurring at regular intervals

A

Cycle

23
Q

Speed of ultrasound wave; determined by tissue density

A

Velocity

24
Q

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

A

Lateral resolution

25
Q

Unit for frequency; equal to 1 cycle per second

A

Hertz (Hz)

26
Q

Field closest to the transducer during formation of the sound beam

A

Fresnel zone

27
Q

Angle of incidence at which the sound beams strike the interface

A

Angle of reflection

28
Q

1000 Hz

A

Kilohertz (KHz)

29
Q

Field farthest from the transducer during formation of the sound beam

A

Fraunhofer zone

30
Q

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

A

Slice thickness

31
Q

Sound transmitted and received intermittently with one transducer

A

Pulse wave (PW) Doppler

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)

33
Q

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

A

Doppler shift

34
Q

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

A

Continuous wave (CW) Doppler

35
Q

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

A

Laminar

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 smallest signals that an instrument of a component of an instrument can respond to without distortion

A

Dynamic range

42
Q

In pulse 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 ultrasound wave measured in decibels

A

Amplitude

44
Q

Measure of strength of the ultrasound signal

A

Gain

45
Q

Echo fil-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 time per second to achieve a “real time” image of anatomic structures and ther motion pattern

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 transmitting 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

Chapter 1 Hagen Ansert (3 decks)

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