Physics 111 Chapter 4 Flashcards

1
Q

The rule that states that it takes 13 ms for sound to travel 1 cm in soft tissue

A

13 ms rule

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2
Q

Amplitude mode; the height of the spike on the image is related to the strength (amplitude) of the echo generated by the reflector

A

A-Mode

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3
Q

As low as reasonably achievable; the principle that states one should always use the lowest power and shortest scanning time possible to reduce potential exposure to the patient

A

ALARA

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4
Q

The part of the receiver that increases or decreases the received echoes equally, regardless of depth.

A

Amplification

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5
Q

The maximum or minimum deviation of an acoustic variable from the average value of that variable; the strength of the reflector.

A

Amplitude

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6
Q

The part of the digital scan converter that converts the analog signals from the receiver to binary for processing by the computer

A

Analog-to-digital (A-to-D) converter

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7
Q

Without echoes or black

A

Anechoic

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8
Q

The technique that varies the voltage to the individual elements to reduce grating lobes

A

Apodization

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9
Q

Echoes on the screen that are not representative of actual anatomy, or reflectors in the body that are not displayed on the screen

A

Artifacts

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10
Q

Brightness mode; the brightness of the dots is proportional to the strength of the echo generated by the reflector

A

B-Mode

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11
Q

The instrument that shapes and steers the beam on the transmit end

A

Beam Former

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12
Q

The digital language of zeroes and ones

A

Binary

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13
Q

Black and white image

A

Bistable

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14
Q

The smallest unit of memory in a digital device

A

Bit

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15
Q

Eight bits of memory

A

Byte

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16
Q

Display that uses an electron gun to produce a stream of electrons toward a phosphor-coated screen

A

Cathode ray tube (CRT)

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17
Q

A way of processing the pulse to improve contrast resolution and reduce speckle

A

Coded excitation

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18
Q

A type of reverberation artifact caused by small reflectors

A

Comet tail

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19
Q

The function of the receiver that changes the brightness of the echo amplitudes to compensate for attenuation with depth

A

Compensation

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20
Q

The function of the receiver that decreases the range of signal amplitudes present with the machines receiver; opposite of dynamic range

A

Compression

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21
Q

The ability to differentiate one shade of gray from another

A

Contrast resolution

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22
Q

The function of the receiver that makes the signal easier to process by performing rectification and smoothing

A

Demodulation

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23
Q

Part of the digital scan converter that converts the binary signals from computer memory to analog for display and storage

A

Digital-to-analog (D to A) converter

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24
Q

The series of echo amplitudes present within the signal

A

Dynamic range

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25
Q

Refraction artifact caused by the curved surface of the reflector

A

Edge shadowing

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26
Q

Arc-like bands that occur when the machine is too close to an unshielded electrical device

A

Electrical interference

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27
Q

An artifact caused by sound passing through an area of lower attenuation

A

Enhancement

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28
Q

One half of a frame on the display

A

Field

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29
Q

Places pixels where there is no signal information based on adjacent scan lines

A

Fill-in interpolation

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30
Q

One complete ultrasound image

A

Frame

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31
Q

Averages the frequencies across the image to improve contrast resolution and reduce speckel

A

Frequency compounding

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32
Q

The operating or resonating frequency emitted by the transducer

A

Fundamental frequency

33
Q

An artifact caused by extraneous sound not along primary beam path; occurs with arrays; reduced or eliminated by apodization, subdicing and tissue harmonics

A

Grating lobes

34
Q

Displayed echoes that are relatively brighter than the surrounding tissue; may also be referred to as echogenic

A

Hyperechoic

35
Q

Displayed echoes that are relatively darker than the surrounding tissue

A

Hypoechoic

36
Q

Display that uses the twisting and untwisting of liquid crystals in front of a light source

A

Liquid crystal display (LCD)

37
Q

Motion mode; used to display motion of the reflectors

A

M-Mode

38
Q

The timing component of the ultrasound machine that notes how long it takes for signals to return from reflectors

A

Master synchronizer

39
Q

An artifact caused by sound bouncing off of a strong reflector and causing a structure to appear on both sides of the reflector

A

Mirror image

40
Q

An artifact caused by the beam bouncing off of several reflectors before returning to the transducer

A

Multipath

41
Q

Principle that pressure waves change in shape as they travel deeper, through in a disproportionate way

A

Nonlinear propagation

42
Q

Waves that are not pure sine waves

A

Nonsinusoidal

43
Q

Output power; strength of sound entering the patient

A

Output

44
Q

Receiver function that increases or decreases all the echo amplitudes equally

A

Overall gain

45
Q

Picture archiving and communication system; a type of display and storage device commonly used in ultrasound and other imaging modalities

A

PACS

46
Q

The smallest component of a 2D digital iamge

A

Pixel (picture element)

47
Q

Occurs in the A to D converter; The image must be live

A

Preprocessing

48
Q

Occurs in the D-to -A converter; the image must be frozen

A

Postprocessing

49
Q

Part of the beam former that controls the amount of energy in the pulse

A

Pulser

50
Q

Equation used to calculate the distance to the reflector; in soft tissue, d=0.77t where “d” is the depth of the reflector and “t” represents the round trip time of the pulse

A

Range equation

51
Q

The type of magnification performed in the D to A converter (postprocessing) that magnifies the image by enlarging the pixels

A

Read zone

52
Q

The component of the machine that processes the signals coming back from the patient

A

Receiver

53
Q

The part of the receiver that inverts the negative voltages to positives

A

Rectification

54
Q

Function of the receiver that is used to reduce image noise; sets a threshold below which the signal will not be displayed

A

Rejection

55
Q

An artifact caused by the beam bouncing between two strong reflectors

A

Reverberation

56
Q

A type of reverberation artifact caused by air

A

Ring down

57
Q

The part of the ultrasound machine that processes the signals from the receiver; consist of the A - to - D converter, computer memory, and D - to - A converter

A

Scan converter

58
Q

Created when one or more pulses of sound return from the tissue containing information related to the depth and amplitude of the reflectors

A

Scan line

59
Q

An artifact caused by the failure of sound to pass through a strong attenuator

A

Shadowing

60
Q

An artifact caused by extraneous sound that is not found along the primary beam path; occurs with single-element transducers

A

Side lobes

61
Q

Part of the demodulation component of the receiver; an “envelope” is wrapped around the signal to eliminate the “humps”

A

Smoothing

62
Q

Algorithm used in signal processing to reduce the amount of acoustic speckle

A

Speckle reduction

63
Q

Dividing the piezoelectric elements into very small pieces to reduce grating lobes

A

Subdicing

64
Q

Harmonic signal produced by the patient and is a multiple of the fundamental frequency; also referred to as native tissue harmonic imaging

A

Tissue harmonics

65
Q

Time gain compensation; Compensation

A

TGC

66
Q

The smallest component of a 3D image

A

Voxel (volume element)

67
Q

The type of magnification performed in the A -to- D converter (postprocessing) that magnifies the image by redrawing it before it is stored in memory

A

Write zoom

68
Q

the plane that is perpendicular to the beam path

A

X-Axis

69
Q

The plane that is parallel to the beam path

A

Y-Axis

70
Q

The brightness, or amplitude, of the dots on the display

A

Z-Axis

71
Q

Having two possible states

A

Bistable

72
Q

Sequential display of all the frames stored in memory at a controllable frame rate

A

Cine loop

73
Q

A sophisticated form of transmission in which the driving voltage pulses have intrapulse variations in amplitude, frequency, and/or phase

A

Coded excitation

74
Q

A single one or two way path for transmitting electric signals, in distribution from other parallel paths; an independent transmission delay line and transducer element path; an independent reception transducer element , amplifier, analog - to - digital converter, and delay line path

A

Channel

75
Q

Conversion of voltage pulses from radio frequency to video form. Also called demodulation , amplitude detection and envelope detection.

A

Detection

76
Q

Imaging tissue stiffness by tracking movement under mechanical stress

A

Elastography

77
Q

A backlighted rectangular matrix of thousands of liquid crystal elements

A

Flat panel display

78
Q

Constant display of one of the frames in memory

A

Freeze