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Fall 2014 study > definitions > Flashcards

definitions Flashcards

1
Q

a type of wave that carries energy , not matter from place to place

A

Sound

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2
Q

the effects of the medium upon the sound wave

A

acoustic propagation properties

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3
Q

the effects of the sound wave upon the biologic tissues

A

biological effects

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4
Q

acoustic variables

A

Pressure, density, distance

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5
Q

concentration of force within an area, Force/area

Units= Pascals (Pa)

A

Pressure

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6
Q

concentration of mass within a volume

Units= Kg/cm^3

A

Density

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7
Q

measure of particles in motion

Units=cm, feet, miles

A

Distance

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8
Q

particles move in a perpendicular direction (right angle) to the direction of the sound wave

A

Transverse waves

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9
Q

particles move in the same direction as the wave

A

Longitudinal wave

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10
Q

regions of higher density and pressure

A

compressions

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11
Q

regions of lower density and pressure

A

rarefractions

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12
Q

inform us of which waves are sound waves

A

acoustic variables

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13
Q

describe the features of a particular sound wave

A

acoustic parameters

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14
Q

the time required to complete a single cycle

can also be described as the time from the start of a cycle to the start of the next cycle

A

period

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15
Q

number of certain events that occur in a particular time duration

A

Frequency

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16
Q

waves with frequencies exceeding 20,000Hz (20KHz)

This frequency is so high that the sound is not audible

A

Ultrasound

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17
Q

infrasound

A

sound with frequencies less than 20Hz

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18
Q

audible sound

A

heard by man, frequencies between 20Hz and 20,000Hz

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19
Q

the difference between the average value and the maximum value of an acoustic variable. The variation of an acoustic variable

A

amplitude

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20
Q

the concentration of energy in a sound beam

the beams power divided by the beam’s cross-sectional area

A

Intensity

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21
Q

the rate that work is performed, or the rate of energy transfer

A

power

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22
Q

the length or distance of a single cycle

A

wavelength

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23
Q

the rate that sound travels through a medium.

Also called velocity and speed

A

Propagation speed

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24
Q

opposites of stiffness

A

compressibility and elasticity

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25
Q

same as stiffness

A

Bulk modulus

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26
Q

a collection of cycles that travel together

A

a pulse

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27
Q

the time from the start of a pulse to the end of that pulse

the actual time that the pulse is on

A

Pulse duration

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28
Q

the length or distance that an entire pulse occupies in space

The distance from the start to the end of one pulse

A

Spatial pulse length

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29
Q

the time from the start of one pulse to the start of the next pulse

It includes one pulse duration and one “listening time”

A

Pulse repetition period

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30
Q

the number of pulses created by the system in one second

A

Pulse repetition frequency

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31
Q

the percentage or fraction of time that the system transmits sound

A

Duty factor

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32
Q

the concentration of the power in a beam

A

intensity

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33
Q

a logarithmic scale
a relative scale
a comparison, therefore, two intensities are needed to calculate decibels

A

Decibels

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34
Q

the decrease in intensity, power and amplitude of a sound wave as it travels

This is unrelated to speed

A

attenuation

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35
Q

the amount of attenuation per centimeter

*a way to report attenuation without dealing with distance

A

attenuation coefficient

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36
Q

transmission with a bend

a change in direction as sound transmits from one medium to another

A

refraction

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37
Q

any device that converts one form of energy into another

A

transducer

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38
Q

when PZT is heated above this temperature (approximately 360C degrees or 680F degrees), it loses its piezoelectric properties, ( the PZT is depolarized)

A

Curie temperature / Currie point

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39
Q

the complete destruction of all living microorganisms by means of exposure to heat, chemical

A

sterilization

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40
Q

the application of a chemical agent to reduce or eliminate infectious organisms on an object, such as a transducer

A

disinfection

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41
Q

the piezoelectric crystal, also called the ceramic, PZT, or crystal
1/2 wavelength thick

A

Active element

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42
Q

the range of frequencies

A

bandwidth

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43
Q

a unitless number representing the extent of damping

A

Quality factor

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44
Q

the location where the beam reaches its minimum diameter

A

Focus or focal point

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45
Q

the distance from the transducer face to the focus. also called focal length or near zone length

A

focal depth

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46
Q

the region or zone in between the transducer and the focus

*sound beams converge here

A

Near zone (Fresnel zone)

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47
Q

the region or zone deeper than the focus, beyond the near field

*sound beams diverge here

A

Far zone (Fraunhofer zone)

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48
Q

the region surrounding the focus where the beam is “sort of narrow” and the picture is relatively good

A

Focal zone

49
Q

V-shaped wave, also called a Huygen’s wavelet

A

Diffraction

50
Q

explains the hourglass shape of an imaging transducer’s sound beam

A

Huygen’s principle

51
Q

the ability to image accurately

A

Resolution

52
Q

the ability to distinguish two structures that are close to each other front to back, parallel to, or along the beams main axis

A

axial resolution

53
Q

the minimum distance that two structures are separated by side-to-side or perpendicular to the sound beam that produces two distinct echoes

A

Lateral resolution

54
Q

a collection of active elements in a single transducer

A

array

55
Q

a single slab of PZT cut into separate pieces called elements

A

element

56
Q

combination of electronic circuitry, the wire and the element

A

channel

57
Q

a collection or elements in a line

  1. linear switched (sequential) array
  2. linear phased array
A

Linear array

58
Q

a group of ringed elements (bull’s eye) with a common center

A

annular array

59
Q

elements arranged in an arc

  1. convex switched (sequential) array
  2. convex phased array
A

convex, curved, or curvilinear array

60
Q

adjustable, or multifocus; achieved electronically

A

Phased arrays

61
Q

creates electronic patterns. Delays are approximately 10 nanoseconds

A

beam former

62
Q

phase delays during reception can be applied to the electrical signals from the transducer to the US system.

This provides focusing at many depths during reception

A

Dynamic receive focusing

63
Q

the production of a motion picture

A

Real time imaging

64
Q

the ability to accurately locate moving structures at any particular instant in time

A

Temporal resolution

65
Q

communicates with all of the individual components of the ultrasound system

organizes and times their functions, so as to operate as a single integrated systems

A

Master synchronizer

66
Q

converts electrical into acoustic energy during transmission and acoustic into electrical during reception

A

transducer

67
Q

Controls the electrical signals sent to the active elements for sound pulse generation

determines the pulse repetition period, PRF, and pulse amplitude

creates the firing pattern for phased array systems
(called the beam former)

A

Pulser

68
Q

the electronics associated with processing the electronic signal production by the transducer during reception and producing a picture on a display device

A

Reciever

69
Q

the device associated with the presentation of processed data for interpretation

> > monitor, audio speakers, a paper record

A

Display

70
Q

any number of devices and “media” that are used to permanently archive the US data

> > computer memory, hard drive, (NAS, network attached storage)

A

Storage

71
Q

increases the strength o f all electronic signals in the receiver prior to further processing

A

Amplification

72
Q

used to create image of uniform brigthness from top to bottom

A

compensation

73
Q

reducing the total number of signals, from the smallest to the largest

A

compression

74
Q

changes the signal’s form to one more suitable for display

A

demodulation

75
Q

Displays low level echoes only when they are clinically meaningful. Very low level echoes are not always important.; eliminates Low-level noise in our images

A

Reject

76
Q

also called “micro-bubbles”
have different acoustic fingerprint than blood or tissue,
create strong reflections

A

contrast agents

77
Q

affects brightness by adjusting the strength of the sound waves sent to the body from the transducer. affects patient exposure

A

output power

78
Q

affects the brightness by changing the amplification of the electronic signals after returning to the receiver

A

Receiver gain

79
Q

creates ultrasound scans from sound reflections at twice the transmitted frequency

A

harmonic imaging

80
Q

the frequency of the transmitted sound wave

A

fundamental frequency

81
Q

twice the transmitted frequency also called the second harmonic

A

harmonic frequency

82
Q

changes the data format from penetrations (spokes) to horizontal lines of a display . Made gray scale displays possible

A

Scan converters

83
Q

a microprocessor digitizes images. This converts the image into numbers which are stored in memory. The numbers can be processed and then retranslated for display as an image

A

Digital scan converter

84
Q

the smallest element of a digital picture

A

pixel

85
Q

the more pixel per inch, the more detail in the image, spatial or detail resolution

A

Pixel density

86
Q

the smallest amount of digital storage

A

Bit

87
Q

a group of bits,

a series of zeroes and ones

A

binary number

88
Q

a group of 8 bits, 2__________ equal a word

A

byte

89
Q

manipulating the data before storage in the scan converter, it carrot be reversed or “undone”

A

preprocessing

90
Q

related to the ability of humans to see the gray scale differences in anatomic structures. Lowers the high level echoes and boosts the low level echoes.

A

log compression

91
Q

manipulating the data after it has been stored in the scan converter memory but prior to display . increases versatility of the display process.
can be undone

A

Postprocessing

92
Q

images can be improved by filling in gaps between lines

is pre-processing

A

Fill-in interpolation

93
Q

Scan lines are steered by the transducer in different directions or views, so structures are interrogated by multiple pulses from several different angles

A

Spatial compounding

94
Q

a form of electronic receive focusing

A

dynamic aperture

95
Q

creates an element of realism to a 3-D or 4-D image

A

rendering

96
Q

the ratio of the largest to the smallest signal strength that each component processes, the number of choices indicated the number of gray shades on an image

A

Dynamic range

97
Q

Picture Archiving and Communications System

A

PACS

98
Q

Digital Imaging and Communications in Medicine

Provides standards or guidelines for imaging networks

A

DICOM

99
Q

Network storage devices

high storage capacity disc drives, economical, used in PACS systems

A

NAS (Network Attached Storage)

100
Q

the movement of a fluid from one location to another

A

flow

101
Q

Fluid moving at a constant speed or velocity

A

steady flow

102
Q

blood moves with a variable velocity

A

pulsatile and phasic flows

103
Q

flow streamlines are layered, aligned and parallel

plug or parabolic patterns

A

laminar flow

104
Q

chaotic flow in many directions and speeds

A

turbulent flow

105
Q

a unitless number indicating whether flow is laminar or turbulent

A

Reynold’s number

106
Q

Blood flows when the total fluid energy at one location differs from the total fluid energy at another location

A

energy gradient

107
Q

Motion energy, associated with an objects speed and mass

A

Kinetic energy

108
Q

a form of potential or stored energy that has the ability to perform work

A

Pressure energy

109
Q

the conversion of other forms of energy into heat

A

friction

110
Q

describes the thickness of a fluid

A

viscosity

111
Q

relates to the tendency of a fluid to resist changes in its velocity

A

inertia

112
Q

a narrowing or irregularity in a lumen

A

stenosis

113
Q

equals the weight of blood pressing on the vessel from heart level to the point of measurement

A

hydrostatic pressure

114
Q

a change or variation in the frequency of sound as a result of motion between the sound source and the receiver (a moving interface)

A

Doppler shift
or
Doppler frequency

115
Q

extracts the Doppler frequency from the transducer frequency and is preformed by a demodulator.

A

Demodulation

116
Q

magnitude only

A

speed

117
Q

magnitude and direction

A

velocity

118
Q

the Doppler frequency at which aliasing occurs, equal to half the PRF

A

Nyquist frequency

Fall 2014 study (9 decks)

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