SPI Review Flashcards

1
Q

what is the effect of the medium upon the sound wave called

A

acoustic propagation properties

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2
Q

what are the 3 acoustic variables

A

Pressure, density, distance

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3
Q

what are the units of density

A

KG/cm^3

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4
Q

period is determined by the

A

sound source only

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5
Q

period is the

A

time it takes a wave to vibrate a single cycle

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6
Q

frequency is determined by the

A

source only

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7
Q

what is the frequency of ultrasound

A

greater than 20 thousand hertz

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8
Q

period and frequency relationship?

A

inverse

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9
Q

what are the 3 bigness parameters

A

amplitude, intensity, power

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10
Q

all the bigness parameters are determined by the

A

sound source

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11
Q

power has units of

A

watts

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12
Q

power =

A

amplitude squared

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13
Q

units of intensity

A

W/cm^2

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14
Q

wavelength is determined by

A

the sound source and the medium

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15
Q

is the wavelength adjustable

A

no

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16
Q

what is the relationship between wavelength and frequency

A

inversely

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17
Q

speed of sound fastest to slowest

A

solids, liquids, gas

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18
Q

what two characteristics affect the speed of sound

A

stiffness and density

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19
Q

what other terms describe stiffness

A

bulk modulus, elasticity, compressability

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20
Q

units of pulse duration

A

microseconds

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21
Q

pulse duration is determined by

A

sound source only

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22
Q

pulse length is determined by

A

source and the medium

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23
Q

is pulse length adjustable

A

no

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24
Q

is pulse duration adjustable

A

no

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25
Q

PRP relationship to the period

A

unrelated

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26
Q

PRP is determined by the

A

depth and source

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27
Q

PRP and depth are

A

directly related

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28
Q

PRF is determined by

A

sound source only

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29
Q

PRF and depth are

A

inversely related

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30
Q

PRF and frequency are

A

unrelated

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31
Q

duty factor and depth are

A

inversely related

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32
Q

depth affects the

A

PRF,PRF and duty factor

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33
Q

the diffrent measurments of intensity are important in the study of

A

bioeffects

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34
Q

which intensity is most relevant in respect to tissue heating

A

SPTA

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35
Q

what is the units for all intensities

A

W/CM^2

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36
Q

what intensity has the highest value what has the lowest

A

highest= SPTP lowest=SATA

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37
Q

when intesity is half we have lost

A

3 decibels

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38
Q

what determines attenuation

A

path length, frequency

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39
Q

frequency and attenuation are

A

directly related

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40
Q

what 3 processes contribute to attenuation

A

reflection, scattering,absorption

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41
Q

diffuse reflection is also called

A

backscatter

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42
Q

sound back to the transducer organized and disorganized

A

organized = specular disorganized = diffuse/backscatter

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43
Q

sound in all directions organized and disorganized

A

organized = rayleigh scatter disorganized = scattering

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44
Q

half-value layer thickness is also known as

A

penetration depth, depth of penetration, half boundary layer

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45
Q

thin half value =

A

high frequency/ high attenuation rate

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46
Q

impedance uses units of

A

rayls or Z

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47
Q

normal incidence is also called

A

Perpendicular
Orthogonal
Righ angle
Ninty degrees

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48
Q

reflection will only occur if media on either side have

A

different impedences

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49
Q

how can we predict reflection with oblique incidence

A

we cannot

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50
Q

refraction is

A

transmission with a bend

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51
Q

refraction only occurs if

A

there is oblique incidence and difference propagation speeds with the two media

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52
Q

time of flight is directly related to

A

the depth

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53
Q

in 1 second sound can travel how many Cm

A

77,000 cm

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54
Q

the matching layer and gel help

A

increase the efficiency of sound transfer between the PZT and the skin

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55
Q

decreasing order of impedence

A

PZT>matching layer>gel>skin

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56
Q

the matching layer is how thick compared to the wavelength

A

1/4 wavelegth thick

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57
Q

the active element is how thick compared to the wavelength

A

1/2 the wavelength thick

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58
Q

what are the 3 consequences of using the backing material

A

decreased sensitivity, wide bandwidth, low Q factor

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59
Q

long pulses degrade what resolution

A

axial resolution

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60
Q

what is polarization

A

exposing PZT to electrical field while being heated

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61
Q

the temperature when the PZT is polarized is called

A

Currie point

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62
Q

how do we sterilize our transducers

A

we cannot apply heat to them so only disinfection is possible

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63
Q

relationship between PZT thickness and frequency

A

inversely related

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64
Q

at the starting point, the beam width is

A

the same as the transducer diameter

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65
Q

the focus is the point where the beam is

A

the narrowest

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66
Q

the width of the sound beam at the focus is

A

1/2 the diameter

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67
Q

focal length is also called the

A

focal depth or near zone length

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68
Q

the focal zone is from where to where

A

transducer to the focus

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69
Q

what happens to the beam in the far zone

A

it diverges

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70
Q

at a depth of two near zone lengths, how wide is the beam

A

same as the active element

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71
Q

with a fixed-focus transducer what two factors determine focal depth

A

transducer diameter, frequency of the sound

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72
Q

a larger diameter makes what kind of focus

A

deeper

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73
Q

relationship of transducer diameter and focal depth

A

directly related

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74
Q

higher frequency makes what kind of focus

A

deeper focus

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75
Q

smaller diameter crystals create beams that diverge more or less

A

more divergence

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76
Q

crystal diameter and beam divergence relationship

A

inversely related

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77
Q

larger diameter crystals improve what resolution in the far field

A

lateral

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78
Q

frequency and beam divergence relationship

A

inverse

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79
Q

higher frequency has more or less divergence

A

less

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80
Q

v shapes waves are known as

A

spherical waves,diffraction patterns, Huygens wavelets

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81
Q

axial resolution uses the mnemonic

A

LARRD

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82
Q

Axial resolution is also known as

A

Longitudinal
Axial
Radial
Range
Depth

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83
Q

Axial resolution is determined by

A

the spatial pulse length

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84
Q

How is a shorter pulse created

A

less ringing, higher frequency

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85
Q

lateral resolution is determined by the

A

width of the sound beam

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86
Q

the mnemonic for lateral resolution is

A

LATA

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87
Q

Lateral resolution is also known as

A

Lateral
Angular
Transverse
Azimuthal

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88
Q

lateral resolution is best at what portion of the sound beam

A

the focus, the narrowest portion

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89
Q

what resolution is better for clinical imaging

A

Axial resolution

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90
Q

lateral resolution only improves the what field

A

far feild

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91
Q

fixed focusing is also called

A

mechanical or conventional

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92
Q

the X-axis of amplitude mode represent

A

Depth

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93
Q

the Y-axis of amplitude mode represents

A

amplitude

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94
Q

the X-axis of brightness mode represents

A

Depth

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95
Q

the Y- axis of brightness mode reresents

A

Nothing there is no Y axis in B-mode

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96
Q

What axis represents Amplitude in B-mode

A

Z-axis

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97
Q

the X-axis in M mode represents

A

Time

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98
Q

the Y- axis in M mode represents

A

Depth

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99
Q

mechanical transducers contain what type of element

A

singular, disc-shaped

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100
Q

what image shape does a mechanical transducer create

A

fan or sector-shaped

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101
Q

what type of steering/focusing does a mechanical transducer use

A

mechanical steering/ focusing

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102
Q

what are the 3 types of array transducers

A

linear,annular,convex

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103
Q

how many crystals does a liner phase have

A

100-300

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104
Q

what image shape does the linear phased create?

A

fan or sector

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105
Q

what type of steering/focusing does a linear phased have

A

electronic

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106
Q

what happens when a crystal gets damaged in a mechanical transducer

A

the entire image is lost

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107
Q

what happens when a crystal is damaged in a linear phased array

A

erratic beam steering/ focusing

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108
Q

how many elements are fired in a linear phased to create a single sound pulse

A

all

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109
Q

the beam former is

A

what creates the different electrical patterns to steer/focus the beam

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110
Q

if the spike pattern is in a straight line that means the beam is

A

unfocused

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111
Q

a servere curve of the sound beam means the focus is

A

shallower

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112
Q

annular phased array has what kind of steering

A

mechanical steering

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113
Q

what happens when a crystal is damaged in a annular phased array

A

horizontal band of drop out

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113
Q

the linear sequential has how many crystals

A

120 to 250

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114
Q

the linear sequential array is also called

A

linear switched array

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114
Q

what is the image shape of the convex transducer

A

blunted sector

114
Q

what shape is the image of a linear phased array

A

rectangular

114
Q

what happens when a crystal is damaged in a linear sequential

A

the image portion below the damaged crystal is lost

114
Q

when the beam is steered on the linear sequential what happens to the image

A

it turns into a parallelogram

114
Q

the curvilinear transducer is also called

A

convex, curved

115
Q

how many crystal does the curved transducer have

A

120 to 250

115
Q

what happens when a crystal is damaged in the curved transducer

A

only the portion below the dame is lost

115
Q

how many crystals are fired in the convex transducer

A

some but not all

116
Q

how many crystals are fired in the vector array

A

some but not all simultaneously

117
Q

what image shape does the vector array make

A

trapezoidal

118
Q

slice thickness is also called

A

elevational resolution

119
Q

side lobes are created by

A

single element transducers

120
Q

lateral resolution is degraded by

A

side lobes

121
Q

what is apodization

A

the process to get rid of grating lobes by using electrical signals

122
Q

dynamic aperture is also called

A

variable aperture

123
Q

what is variable aperture

A

a technique used to make a sound beam narrow over a greater range of depth

124
Q

dynamic aperture improves what resolution

A

lateral

125
Q

what is the frame rate determined by

A

speed in the medium and depth

126
Q

what is the relationship between frame rate and temporal resolution

A

directly related

127
Q

what two system settings determine the frame rate

A

imaging depth and number of pulses

128
Q

multi focus does what to temporal resolution

A

decreases temporal resolution and frame rate

129
Q

what does line density improve

A

spatial resolution

130
Q

What does line density degrade

A

temporal resolution and frame rate

131
Q

what are the two major functions of the ultrasound system

A

prep/transmission and reception

132
Q

what does the pulser do

A

determines the amplitude,PRP and PRF by exciting the crystals

133
Q

what happens when pulser voltage is low

A

the entire image will be dark

134
Q

What two measurements are used to standardize output

A

thermal and mechanical index

135
Q

what is the most common way to increase signal-to-noise ratio

A

output power

136
Q

what does the switch do

A

protects the receiver components from powerful transmission signals and directs electrical signals from the transducer

137
Q

order of 5 receiver operations

A

amplification
compensation
compression
demodulation
reject

138
Q

what is amplification also known as

A

receiver gain

139
Q

what happens during receiver gain

A

electronic signals are made equally larger

140
Q

pre amplification happens where

A

within the transducer

141
Q

compression is also known as

A

dynamic range or log compression

142
Q

what are the two processes of demodulation

A

rectification and smoothing

143
Q

what does rectification do

A

turns negatives voltage into positives

144
Q

can you adjust demodulation

A

no

145
Q

high contrast results in what kind of image

A

bistable

146
Q

storage of information in the scan converter is called what

A

writing

147
Q

what kind of number am I if I have unlimited choice
continuous values

A

analog

148
Q

what scan converter has excellent spatial resolution

A

analong

149
Q

what is a pixel

A

the smallest building block of a digital picture

150
Q

higher pixel density improves what resolution

A

spatial

151
Q

higher pixel density is achieved with

A

smaller pixels, more pixels per inch

152
Q

what is a byte

A

a group of 8 bits

153
Q

a bit is

A

the smallest amount of computer memory

154
Q

if you have more bits you have more

A

shades of gray

155
Q

1 bit is how many shades of grey

A

2

156
Q

what are the things that happen during preprocessing

A

compensation
compression
write magnification
compounding

157
Q

true or false: spatial resolution changes during read magnification

A

false

158
Q

coded excitation occurs where

A

in the pulser

159
Q

what is spatial compounding

A

using info from different image angles to produce a single image

160
Q

compound imaging reduces what artifacts

A

speckle and shadowing

161
Q

what are the downsides to spatial compounding

A

reduced temporal resolution and frame rate

162
Q

frequency compounding reduces what artifacts

A

noise and speckle

163
Q

temporal compounding is also known as

A

persistence or temporal averaging

164
Q

true or false temporal resolution works best with slow-moving objects

A

true

165
Q

what does PACS stand for

A

picture archive and communication systems

166
Q

what does DICOM stand for

A

digital imaging and computers in medicine

167
Q

what is dicom

A

a set of rules that allow imaging systems to share information

168
Q

what is dynamic range

A

the extent a signal can vary and still maintain accuracy

169
Q

dynamic range is measured in

A

Decibels

170
Q

what is harmonic imaging

A

twice the fundamental frequency

171
Q

what are the two types of harmonics

A

tissue and contrast

172
Q

true or false: harmonics only happen at a superficial depth

A

false harmonics do not happen at all in superficial depth

173
Q

harmonics increase what

A

signal to noise ratio

174
Q

true or false: weak sound beams do not create harmonics

A

true

175
Q

harmonics are primarily created where

A

along the beam’s main axis

176
Q

what is the disadvantage of pule inversion harmonics

A

lower temporal resolution/ frame rate

177
Q

contrast harmonics are created during

A

reflection

178
Q

what creates better harmonics high or low frequency

A

lower frequency

179
Q

what does the MI need to be to create harmonics what is the best MI

A

0.1 and above…. above 1 is the best

180
Q

flow is also called

A

volume flow rate

181
Q

what are the three basic forms of blood flow

A

pulsatile, phasic, steady

182
Q

pulsatile flow appears in what circulation

A

arterial or cardiac contraction

183
Q

phasic flow appears in what circulation

A

venous

184
Q

what are the two types of laminar flow

A

plug flow and parabolic

185
Q

velocity is highest in the lumen with which flow

A

parabolic flow

186
Q

what does the Reynold number predict

A

whether flow is laminar or turbulent

187
Q

turbulent flow coverts

A

flow energy into sound and vibration

188
Q

the sound associated with turbulent flow is called

A

murmur or a bruit

189
Q

in a stenosis where is the pressure lowest

A

narrowest portion of the stenosis

190
Q

where is the velocity the highest in a stenosis

A

the narrowest part of the stenosis

191
Q

pressure gradient increases when

A

flow increases or resistance increases

192
Q

during normal function veins have what kind of pressure

A

low

193
Q

supine means

A

flat on your back

194
Q

when standing hydrostatic pressure is

A

zero at heart level only

195
Q

when lying down hydrostatic pressure is

A

zero everywhere and is the true circulatory pressure

196
Q

what is the hydrostatic pressure standing up from the ankles to the head

A

ankle:100
knees:75
waist:50
chest:0
top of head: -30

197
Q

during inspiration the diaphragm moves

A

downward, increasing venous return to the heart

198
Q

during expiration the diaphragm moves

A

upward increasing venous flow from the legs

199
Q

Doppler shift is also called

A

the doppler frequency

200
Q

what is demodulation

A

extracting the low Doppler frequency

200
Q

The Doppler shift is

A

a low frequency that rides on top of the transducer frequency

201
Q

when the blood cells are moving toward the transducer the Doppler shift is

A

positive

202
Q

velocity is defined as

A

magnitude and direction

203
Q

The Doppler shift is directly related to the

A

velocity

204
Q

The x-axis of the Doppler spectrum represents

A

time

205
Q

the Y-axis of the Doppler spectrum represent

A

velocity

206
Q

you never want your angle to be what degree

A

90

207
Q

you always want your angle to be

A

0 or 180

208
Q

a 60-degree angle means the velocity measurement is

A

half

209
Q

flow above the baseline means

A

towards the ransducer

210
Q

continuous wave transducer requires how many crystals

A

two

211
Q

what are the disandvanges of CW

A

the exact location cannot be determined (range ambiguity)

212
Q

anatomic imaging and doppler is called

A

duplex imaging

213
Q

true or false: CW transducers use backing material

A

false

214
Q

CW transducers have what bandwith

A

narrow

215
Q

what are the disadvantages of PW

A

inaccurate measurement of high velocity

216
Q

true or false: aliasing can happen with CW

A

false

217
Q

the Nyquist limit is

A

the highest doppler frequency/ velocity

218
Q

what are the two ways to avoid aliasing

A

increase the nyquist limit or reduce the doppler shift

219
Q

deeper sampler volumes have

A

a low PRF and low nyquist limit

220
Q

true of false: higher frequencies create more aliasing

A

true

221
Q

what are the 5 techniques to avoid aliasing

A

adjust scale
shallower view
lower frequency transducer
baseline shift
use CW

222
Q

grey shades on the doppler are related to

A

number of blood cells

223
Q

Color Doppler reports what type of velocity

A

average or mean velocity

224
Q

Spectral Doppler reports what type of velocity

A

peak velocity

225
Q

variance mode shows what type of flow

A

turbulent and laminar

226
Q

the left and right side of variance mode shows what type of flow

A

left is laminar
right is turbulent

227
Q

what is an ensemble

A

multiple pulses on the color doppler

228
Q

what are the disadvantages of packets

A

lower frame rate and temporal resolution

229
Q

power mode is

A

non directional

230
Q

power doppler is also called

A

energy mode or color angio

231
Q

what are the advantages of using power mode

A

increased sensitivity to slow flow
unaffected by the angle
no aliasing

232
Q

what are the disadvantages of energy mode

A

no velocity measurement
lower frame rate
susceptible to motion

233
Q

on spectral doppler low-frequency doppler shifts are called

A

clutter

234
Q

wall filter is also called

A

low pass filter

235
Q

what is cross-talk

A

a special form of mirroring, the doppler spectrum is shown above and below the baseline

236
Q

cross-talk results from

A

the doppler gain is set too high
angle is near 90

237
Q

what is spectral analysis

A

a tool that breaks complex signals down

238
Q

what are the two methods of spectral analysis

A

fast Fourier transform
autocorrelation

239
Q

true or false FFT can only be used for PW

A

false FFT can be used for CW and PW

240
Q

what is spectral broadening?

A

a range of velocity shown by the spectral window being filled

241
Q

autocorrelation is only used with

A

color doppler

242
Q

what happens when the color gain is set too high

A

color confetti

243
Q

what happens when the color gain is set too low

A

color disappears

244
Q

what is isoechoic

A

structures with equal brightness

245
Q

how does the artifact reverb appear

A

resembles a latter, multiples equally spaced

246
Q

what causes reverb artifact

A

bouncing of the soundwave between 2 strong reflectors

247
Q

comet tail artifact is caused by what 2 things

A

very high propagation speeds or gas bubbles

248
Q

why does shadowing appear

A

attenuation is higher in the structures above

249
Q

shadowing is not related to what

A

the speed of sound in a medium

250
Q

focal banding is also called

A

focal enhancement

251
Q

with the mirror artifact the artifact is located where

A

deeper than the real structure

252
Q

speed error artifact is also called

A

range error artifact

253
Q

what is a refraction artifact

A

when a sound pulse changes direction during transmission

254
Q

refraction occurs when

A

a sound wave strikes a boundary obliquely

255
Q

doppler phantoms contains what 3 things

A

vibrating string, moving belt, flow fantom

255
Q

the structures in refraction artifact appear

A

side by side

256
Q

sensitivity refers to

A

the system’s ability to display low level echos

257
Q

what are the two forms of sensitivity

A

normal and maximum

258
Q

what 3 things are adjusted to establish normal sensitivity

A

output power, amplification, TGC

259
Q

what kind of dead zone do higher frequency transducers have

A

thinner

260
Q

what does a deep dead zone indicate

A

detached backing, cracked crystal, longer pulse duration

261
Q

where does the hydrophone measure

A

a specific location within the sound beam

262
Q

the hydrophone is also called

A

micro probe

263
Q

what is a schlieren

A

a shadowing system that has to do with acousto optics

264
Q

what are the 3 devices that measure output of the transducer

A

calorimeter
thermocouple
liquid crystal

265
Q

calorimeter measures

A

the total power of the beam

266
Q

thermocouple measures

A

power at a specific location in the sound beam

267
Q

what is dosimetry

A

measuring characteristics of an ultrasound beam to its potential for bioeffects

268
Q

what are the two approaches to studying bioeffects

A

mechanical and empirical

269
Q

what does the mechanical approach search for

A

a relationship between cause and effect

270
Q

what does the empirical approach search for

A

a relationship between exposure and response

271
Q

what are the two bio-effect mechanisms

A

thermal and cavitation

272
Q

what is radiation force

A

sheer stressors and streaming of fluids

273
Q

what is cavitation

A

interaction of sound waves on with gasbubbles in tissues

274
Q

what are the two forms of cavitation

A

stable and transient

275
Q

microstreaming and sheer stressors happen during what type of cavitation

A

stable

276
Q

transient cavitation is also called

A

normal or inertial

277
Q

what are the violent effects of transient cavitation

A

colossal temps and enormous pressures

278
Q

what is sensitivity vs specificity

A

sensitivity is the ability of a test to identify people with a disease
specificity is the ability of a test to identify people without the disease