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AN SPI (QUIZLET) > SPI > Flashcards

SPI Flashcards

1
Q

What is a wave?

A

A cyclical transfer of energy

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2
Q

What kind of wave is a sound wave?

A

A mechanical longitudinal wave

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3
Q

What are the types of interference?

A

Constructive, destructive, partial

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4
Q

What is the classification for diagnostic ultrasound?

A

2 mhz to 15 mhz

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5
Q

What is the propagation speed in tissue?

A

1540 mhz, 1.54 m/sec (154,000 cm/sec)

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6
Q

A longitudinal wave propagates by a series of ______ and ________ back and forth in the same direction as the wave propagates.

A

Compression, rarefaction

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7
Q

What are the acoustic variables of wave propagation?

A

Pressure, density, temperature, partical motion

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8
Q

What is the equation for the frequency of the wave?

A

f = 1/p

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9
Q

Frequency and period are determined by what?

A

The source

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10
Q

What is the propagation velocity equation?

A

Square root of: Bulk modulus / Density

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11
Q

If the density increases, what happens to the Bulk modulus and propagation velocity?

A

The Bulk modulus increases and the propagation increases.

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12
Q

If the density of the medium decreases, what happens to the Bulk modulus and propagation velocity?

A

The Bulk modulus decreases and the propagation decreases.

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13
Q

Stiffness is the same as what?

A

Bulk modulus

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14
Q

Stiffness and compressability are ______ related.

A

Inversely

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15
Q

What is the equation for the wavelength?

A

Wavelength = c / f

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16
Q

What is the amplitude?

A

Maximum variation of a variable from its mean.

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17
Q

What are the equations for the amplitude?

A

Max - min, Mean - min, Max - min / 2

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18
Q

Power is proportional to the amplitude _______

A

Amplitude squared

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19
Q

What is the definition of intensity?

A

I = Power / Area

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20
Q

The top Diagnostics frequencies are limited by what?

A

Penetration

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21
Q

Low frequencies are limited by what?

A

Resolution

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22
Q

3 dB factor of ?

A

2

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23
Q

10 dB factor of ?

A

10

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24
Q

What is attenuation?

A

The conversion of sound into heat.

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25
Q

What are the factors of attenuation?

A

Absorption, reflection, refraction

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26
Q

What are the key factors of absorption?

A

It is the dominant form of attenuation and it increases exponentially with increasing frequency.

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27
Q

What are the two types of reflection?

A

Acoustic and geometric

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28
Q

What are the kinds of geometric reflectors?

A

Specular reflectors, scatterers, Rayleigh scattering

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29
Q

What causes refraction?

A

Different propagation speeds, oblique angles of incidence

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30
Q

What causes lateral displacement?

A

Refraction, the machine is not aware that refraction occurs.

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31
Q

What is total internal reflection caused by?

A

Critical angle

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32
Q

What is the attenuation rate in soft tissue?

A

0.5

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33
Q

What is the attenuation coefficient of soft tissue?

A

1 / 2 fo

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34
Q

What is the equation for conservation of energy?

A

Reflection % + Transmission % = 100 %

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35
Q

Describe anechoic

A

No echogenicity

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36
Q

Describe hypoechoic

A

Low echogenicity

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37
Q

Describe hyperechoic

A

High echogenicity

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38
Q

Describe calcified

A

Strongly echogenic, usually w/acoustic shadowing

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39
Q

Type of reflection that occurs at an interface depends on what?

A

The size of the wavelength compared to the size of the surface geometry.

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40
Q

Acoustic impedance is measured in what?

A

Rayls

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41
Q

How is pulsed wave created?

A

The pulser is turned on and off.

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42
Q

What is the range resolution equation?

A

SPL / 2

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43
Q

Explain the wave parameter period

A

The time it takes for one cycle to occur ( p = 1 /f ) measured in seconds and is determined by the source.

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44
Q

Explain the wave parameter pulse duration

A

The time for one pulse to occur, PD = P # Cycles, measured in seconds and is determined by the source.

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45
Q

Explain the wave parameter pulse repetition period

A

The time it takes between repeating pulses, 13 msec x depth, is measured in seconds, determined by the source.

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46
Q

Explain the wave parameter pulse repetition frequency

A

1 / PRP, reciprocal of PRP (measured in Hz)

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47
Q

Explain the wave parameter wavelength

A

The physical distance on the cycle takes up, measured in meters, wavelength = c / f , determined by both the medium and the source.

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48
Q

Explain the wave parameter spatial pulse length

A

The physical dimension the pulse occupies in space, SPL = wavelength # of cycles, (measured in meters) determined by the source and the medium.

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49
Q

What is frame time?

A

The time it takes to create one frame, it is measured in seconds and is determined by the source.

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50
Q

What is frame rate?

A

Inverse frame time, fr = 1 / ft (measured in Hz) the amount of time it takes to make one line

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51
Q

What is bandwidth?

A

The range of frequencies at which a single transducer can operate.

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52
Q

What is fractional bandwidth?

A

Bandwidth / operation frequency

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53
Q

What is a factor in regards to the bandwidth?

A

1 / Fbw

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54
Q

What are the other names for range resolution?

A

LARRD - Longitudinal, Axial, Range, Radial, Depth

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55
Q

For better resolution a ________ number means better resolution.

A

Smaller number

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56
Q

What is duty factor?

A

The percent of time the machine is doing work, PD / PRP

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57
Q

What does the backing layer do?

A

It is used to shorten the SPL improving the range resolution.

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58
Q

What is the difference between non scanned and scanned is what?

A

Scanned transmits the beams in different directions.

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59
Q

What does color doppler do to resolution?

A

It worsens the resolution because of the color packet.

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60
Q

What is the amplitude?

A

It is the “loudness” Max - min, Mean - min, Max - min / 2

61
Q

Relationship between power and amplitude

A

Power = amp (power of 2)

62
Q

What is the intensity equation?

A

I = power / area

63
Q

What unit is intensity measured in?

A

Watts

64
Q

What is a transducer?

A

Any device which converts energy from one form to another.

65
Q

What adds in changing focus?

A

Curved elements, lens and electric focusing

66
Q

What is sequencing?

A

Turning on groups of elements over time.

67
Q

What is phasing?

A

Time delay to echo element used for steering.

68
Q

Explain mechanical steering

A

Wobbling done with a motor to move the transducer head to steer the beam.

69
Q

What is the zone from the transducer to the focal zone, what happens to the beam between those two points?

A

The near zone (Fresnel zone), convergence

70
Q

What is the zone from the focal zone and beyond? What happens to the beam after the focal point?

A

The far zone (Fraunafer zone), divergence

71
Q

What is the area called when the diameter is halved?

A

The natural focus / focal point

72
Q

What does increasing the diameter crystal do to the beam?

A

Makes the focal zone bigger and deeper.

73
Q

What does the thickness of the beam affect?

A

The operating frequency

74
Q

What is the equation for operation frequency?

A

Propagation speed / 2 thickness of crystal

75
Q

What does the lens do?

A

Helps focus the beam in the elevation plane.

76
Q

What does the matching layer do?

A

It decreases the acoustic impedance between the transducer and skin

77
Q

What does the PZT crystal do?

A

Converts voltage into an acoustic wave and back to voltage.

78
Q

What does the backing layer do?

A

It shortens the SPL improving range resolution.

79
Q

What does the pulser do? Is it pre-processing or post-processing?

A

Sends energy out of the system to the transducer, pre-processing.

80
Q

What does the A/D converter do? Is it pre or post processing?

A

It converts the analog signal to digital (A mode) pre-processing.

81
Q

What does the receiver do and is it pre or post processing?

A

It receives the digital information and the image can be adjusted, pre-processing.

82
Q

What is the scan converter and is it pre or post processing?

A

Converts A mode imaging into a picture B mode using gray scale compression mapping. Gain and compression are done post-processing.

83
Q

The storage and monitor receive the same image unless you do what?

A

Change the monitor settings

84
Q

What is read zoom and what is another name for it?

A

Blows up the picture, has poor resolution and is also called non acoustic zoom.

85
Q

What is write zoom and what is another name for it?

A

Pre-processing area zoomed, better resolution and is also called acoustic zoom.

86
Q

What is the doppler effect?

A

An apparent change in frequency due to a change in wavelength that is caused by motion.

87
Q

If motion is moving towards the transducer, what happens to frequency, wavelength and pitch?

A

Frequency increases, wavelength decreases and pitch increases.

88
Q

If motion is moving away from the transducer, what happens to frequency, wavelength and pitch?

A

Frequency decreases, wavelength increases and pitch decreases.

89
Q

The faster the motion the ______ the doppler shift.

A

Greater

90
Q

How are the doppler effect and the propagation speed related?

A

Inversely related

91
Q

What does mixing to baseband do?

A

It is a mathematical process that takes the received frequency and subtracts out the frequency sent in to get the shift.

92
Q

How do wall filters work?

A

They only let high frequencies go through giving them the name high pass filters, reducing noise.

93
Q

What is FFT?

A

Fast fournier transform, mathematical process necessary to separate the collection of shifts into frequency bits.

94
Q

When does aliasing occur?

A

When the Nyquist criteria is broken, PRF / 2

95
Q

What is variance?

A

Anything that is outside the mean velocity (bar next to color bar)

96
Q

What is a normal color packet size range?

A

3 - 12 pulses per line

97
Q

What is autocorrelation?

A

Detects mean velocities, direction of shifts and variance

98
Q

What kind of doppler shift has arrows kissing?

A

Positive shift

99
Q

What kind of doppler shift has arrows in the same direction?

A

Negative shift

100
Q

How do you get rid of aliasing?

A

Increase PRF, change baseline, HPRF, lower the op frequency, increase the doppler angle (not gain!)

101
Q

What is refraction? What assumption is broken?

A

Lateral displacement of a structure within an image caused by a high acoustic impedance mismatch / AB is “transmitted wave travels along a straight line path from the transducer to the objection and back.”

102
Q

What is reverberation? What assumption is broken?

A

Unwanted structures repeated the same distance apart caused by sound bouncing between multiple structures / AB is that each reflector contributes to a single echo which integrates along a single scan line.

103
Q

What are the two types of reverberation?

A

Ring down (cause by air filled structures), comet tail (cause by metallic structures).

104
Q

What is multipath? What assumption is broken?

A

Structures appear deeper than reality because of elongated path length / AB is that each reflector contributes to a single echo which integrates along a single scan line.

105
Q

What are grating lobes and what assumption is broken?

A

Lateral displacement caused by energy outside of the main beam / the assumption broken is that all detected echoes originate from the axis of the main beam.

106
Q

What is speed error and what assumption is broken?

A

Structures drawn at an incorrect depth / the assumption broken is that the U/S wave travels at a rate of 1540 m/sec in tissue.

107
Q

What is range ambiguity and what assumption is broken?

A

Result of reflected data from the previous acoustic transmit adding to the

108
Q

What is range ambiguity and what assumption is broken?

A

Result of reflected data from the previous acoustic transmit adding to the reflection of the current acoustic line / AB all received echoes are derived from the most recent pulse.

109
Q

What is mirroring and what assumption is broken?

A

Artificial structures symmetrical to the actual structure on the other side of a specular reflector / AB the transmitted wave travels along a straight line, all detected echoes originate from the axis of the main beam.

110
Q

What is shadowing and what assumption is broken?

A

The dark portion under an object caused by excessive reflection, absorption or refraction / AB are that the attenuation of sound is uniformed along a path and that the amplitude of the echo is derived from the object scanned alone.

111
Q

What is speckle and what assumption is broken?

A

The result of varying degrees of constructive and destructive interference of sound waves caused by a low operating frequency / AB is that attenuation of sound is uniform over a scan line.

112
Q

What are the kinds of doppler artifact?

A

Aliasing, range ambiguity, spectral mirroring, spectral broadening, blossoming, color bleeding and wall filter saturation.

113
Q

What is bioeffect?

A

An undesired change in tissue as a result of interaction with the insonating beam.

114
Q

What are the two types of bioeffects?

A

Thermal and mechanical

115
Q

What is thermal bioeffect?

A

Temperature, time related (related to temporal averaging, duty factor, scan time, non scanned)

116
Q

What are 3 thermal indices?

A

TIS (Thermal index in soft tissue), TIB (Thermal index of bone), TIC (Thermal index of cranial bone)

117
Q

What is a mechanical bioeffect?

A

Related to cavitation, scanned

118
Q

What are the two types of mechanical bioeffects?

A

Stable and transient / inertial cavitation

119
Q

What kind of cavitation causes the microbubbles to not burst?

A

Stable cavitation

120
Q

What kind of cavitation causes the microbubble to implode causing damage to the tissue around it?

A

Inertial / transient

121
Q

What is mechanical index?

A

Risk of cavitation

122
Q

What is the mechanical index equation?

A

Peak rarefaction / op frequency

123
Q

What is the eqation for intenity?

A

Power / Area

124
Q

Which common intensity has the most intensity?

A

SPTP, Spatial Peak Temporal Peak

125
Q

Which of the common intensities is a common mechanical intensity?

A

SPPA, Spatial Peak Pulse Average

126
Q

Which of the common intensities is a common thermal intensity?

A

SPTA, Spatial Peak Temporal Average

127
Q

Which of the common intensities is the smallest intensity?

A

SATA, Spatial Average Temporal Average

128
Q

What is the max unfocused intensity?

A

100 mw/cm squared

129
Q

What is the max focused intensity?

A

1 w/cm squared

130
Q

Duty factor in relation to bioeffect.

A

PD/PRP = TA / PA

131
Q

What is B.U.F.?

A

Beam uniformity factor, a measure of how the beam intensity uniformity over space.

132
Q

What is the B.U.F. equation?

A

SP / SA

133
Q

What is a hydrophone?

A

Routinely used to make power measurement in a water bath.

134
Q

What does contrast do?

A

Increases the acoustic impedance mismatch within the blood as a result of the high compressability and low density of the gas.

135
Q

What is harmonics?

A

The transducer sends at one frequency and receives at one twice the frequency.

136
Q

What kind of transducer is needed to use harmonics?

A

Broadband transducer

137
Q

What are the two types of harmonics?

A

Tissue and contrast

138
Q

What part of the beam has the strongest harmonic response?

A

The mid field

139
Q

What does harmonics do to grating lobes?

A

Reduces them

140
Q

What is the object used to test equipment?

A

Phantoms

141
Q

What are the components of a doppler flow phantom?

A

Imaging face, a medium, flow conduit, pump, reservoir, blood mimicking fluid

142
Q

What are doppler flow phantoms used for?

A

For directional discrimination, flow velocity, sensitivity, maximum penetration or location of flow.

143
Q

What are doppler string phantoms?

A

String around a pully with the transducer over the moving string helps test.

144
Q

What are the string phantoms to test?

A

Peak velocity, spectral broadening, gate depth accuracy

145
Q

What is a vibrating plate doppler phantom? What does it test?

A

Plate vibrates and test sensitivity

146
Q

Imaging phantom tests what?

A

Detail resolution (axial, lateral an elevation) sensitivity, contrast resolution, the dead zone and dimensional measurement accuracy.

147
Q

What is Q & A testing?

A

The statistical measurement used to determine the quality of a test compared to the gold standard.

148
Q

How do you calculate accuracy?

A

TP + TN / ALL

149
Q

Define power.

A

The rate at which energy is transferred.

AN SPI (QUIZLET) (1 decks)

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