SPI Review Flashcards
(288 cards)
1
Q
what is the effect of the medium upon the sound wave called
A
acoustic propagation properties
2
Q
what are the 3 acoustic variables
A
Pressure, density, distance
3
Q
what are the units of density
A
KG/cm^3
4
Q
period is determined by the
A
sound source only
5
Q
period is the
A
time it takes a wave to vibrate a single cycle
6
Q
frequency is determined by the
A
source only
7
Q
what is the frequency of ultrasound
A
greater than 20 thousand hertz
8
Q
period and frequency relationship?
A
inverse
9
Q
what are the 3 bigness parameters
A
amplitude, intensity, power
10
Q
all the bigness parameters are determined by the
A
sound source
11
Q
power has units of
A
watts
12
Q
power =
A
amplitude squared
13
Q
units of intensity
A
W/cm^2
14
Q
wavelength is determined by
A
the sound source and the medium
15
Q
is the wavelength adjustable
A
no
16
Q
what is the relationship between wavelength and frequency
A
inversely
17
Q
speed of sound fastest to slowest
A
solids, liquids, gas
18
Q
what two characteristics affect the speed of sound
A
stiffness and density
19
Q
what other terms describe stiffness
A
bulk modulus, elasticity, compressability
20
Q
units of pulse duration
A
microseconds
21
Q
pulse duration is determined by
A
sound source only
22
Q
pulse length is determined by
A
source and the medium
23
Q
is pulse length adjustable
A
no
24
Q
is pulse duration adjustable
A
no
25
PRP relationship to the period
unrelated
26
PRP is determined by the
depth and source
27
PRP and depth are
directly related
28
PRF is determined by
sound source only
29
PRF and depth are
inversely related
30
PRF and frequency are
unrelated
31
duty factor and depth are
inversely related
32
depth affects the
PRF,PRF and duty factor
33
the diffrent measurments of intensity are important in the study of
bioeffects
34
which intensity is most relevant in respect to tissue heating
SPTA
35
what is the units for all intensities
W/CM^2
36
what intensity has the highest value what has the lowest
highest= SPTP lowest=SATA
37
when intesity is half we have lost
3 decibels
38
what determines attenuation
path length, frequency
39
frequency and attenuation are
directly related
40
what 3 processes contribute to attenuation
reflection, scattering,absorption
41
diffuse reflection is also called
backscatter
42
sound back to the transducer organized and disorganized
organized = specular disorganized = diffuse/backscatter
43
sound in all directions organized and disorganized
organized = rayleigh scatter disorganized = scattering
44
half-value layer thickness is also known as
penetration depth, depth of penetration, half boundary layer
45
thin half value =
high frequency/ high attenuation rate
46
impedance uses units of
rayls or Z
47
normal incidence is also called
Perpendicular
Orthogonal
Righ angle
Ninty degrees
48
reflection will only occur if media on either side have
different impedences
49
how can we predict reflection with oblique incidence
we cannot
50
refraction is
transmission with a bend
51
refraction only occurs if
there is oblique incidence and difference propagation speeds with the two media
52
time of flight is directly related to
the depth
53
in 1 second sound can travel how many Cm
77,000 cm
54
the matching layer and gel help
increase the efficiency of sound transfer between the PZT and the skin
55
decreasing order of impedence
PZT>matching layer>gel>skin
56
the matching layer is how thick compared to the wavelength
1/4 wavelegth thick
57
the active element is how thick compared to the wavelength
1/2 the wavelength thick
58
what are the 3 consequences of using the backing material
decreased sensitivity, wide bandwidth, low Q factor
59
long pulses degrade what resolution
axial resolution
60
what is polarization
exposing PZT to electrical field while being heated
61
the temperature when the PZT is polarized is called
Currie point
62
how do we sterilize our transducers
we cannot apply heat to them so only disinfection is possible
63
relationship between PZT thickness and frequency
inversely related
64
at the starting point, the beam width is
the same as the transducer diameter
65
the focus is the point where the beam is
the narrowest
66
the width of the sound beam at the focus is
1/2 the diameter
67
focal length is also called the
focal depth or near zone length
68
the focal zone is from where to where
transducer to the focus
69
what happens to the beam in the far zone
it diverges
70
at a depth of two near zone lengths, how wide is the beam
same as the active element
71
with a fixed-focus transducer what two factors determine focal depth
transducer diameter, frequency of the sound
72
a larger diameter makes what kind of focus
deeper
73
relationship of transducer diameter and focal depth
directly related
74
higher frequency makes what kind of focus
deeper focus
75
smaller diameter crystals create beams that diverge more or less
more divergence
76
crystal diameter and beam divergence relationship
inversely related
77
larger diameter crystals improve what resolution in the far field
lateral
78
frequency and beam divergence relationship
inverse
79
higher frequency has more or less divergence
less
80
v shapes waves are known as
spherical waves,diffraction patterns, Huygens wavelets
81
axial resolution uses the mnemonic
LARRD
82
Axial resolution is also known as
Longitudinal
Axial
Radial
Range
Depth
83
Axial resolution is determined by
the spatial pulse length
84
How is a shorter pulse created
less ringing, higher frequency
85
lateral resolution is determined by the
width of the sound beam
86
the mnemonic for lateral resolution is
LATA
87
Lateral resolution is also known as
Lateral
Angular
Transverse
Azimuthal
88
lateral resolution is best at what portion of the sound beam
the focus, the narrowest portion
89
what resolution is better for clinical imaging
Axial resolution
90
lateral resolution only improves the what field
far feild
91
fixed focusing is also called
mechanical or conventional
92
the X-axis of amplitude mode represent
Depth
93
the Y-axis of amplitude mode represents
amplitude
94
the X-axis of brightness mode represents
Depth
95
the Y- axis of brightness mode reresents
Nothing there is no Y axis in B-mode
96
What axis represents Amplitude in B-mode
Z-axis
97
the X-axis in M mode represents
Time
98
the Y- axis in M mode represents
Depth
99
mechanical transducers contain what type of element
singular, disc-shaped
100
what image shape does a mechanical transducer create
fan or sector-shaped
101
what type of steering/focusing does a mechanical transducer use
mechanical steering/ focusing
102
what are the 3 types of array transducers
linear,annular,convex
103
how many crystals does a liner phase have
100-300
104
what image shape does the linear phased create?
fan or sector
105
what type of steering/focusing does a linear phased have
electronic
106
what happens when a crystal gets damaged in a mechanical transducer
the entire image is lost
107
what happens when a crystal is damaged in a linear phased array
erratic beam steering/ focusing
108
how many elements are fired in a linear phased to create a single sound pulse
all
109
the beam former is
what creates the different electrical patterns to steer/focus the beam
110
if the spike pattern is in a straight line that means the beam is
unfocused
111
a servere curve of the sound beam means the focus is
shallower
112
annular phased array has what kind of steering
mechanical steering
113
what happens when a crystal is damaged in a annular phased array
horizontal band of drop out
113
the linear sequential has how many crystals
120 to 250
114
the linear sequential array is also called
linear switched array
114
what is the image shape of the convex transducer
blunted sector
114
what shape is the image of a linear phased array
rectangular
114
what happens when a crystal is damaged in a linear sequential
the image portion below the damaged crystal is lost
114
when the beam is steered on the linear sequential what happens to the image
it turns into a parallelogram
114
the curvilinear transducer is also called
convex, curved
115
how many crystal does the curved transducer have
120 to 250
115
what happens when a crystal is damaged in the curved transducer
only the portion below the dame is lost
115
how many crystals are fired in the convex transducer
some but not all
116
how many crystals are fired in the vector array
some but not all simultaneously
117
what image shape does the vector array make
trapezoidal
118
slice thickness is also called
elevational resolution
119
side lobes are created by
single element transducers
120
lateral resolution is degraded by
side lobes
121
what is apodization
the process to get rid of grating lobes by using electrical signals
122
dynamic aperture is also called
variable aperture
123
what is variable aperture
a technique used to make a sound beam narrow over a greater range of depth
124
dynamic aperture improves what resolution
lateral
125
what is the frame rate determined by
speed in the medium and depth
126
what is the relationship between frame rate and temporal resolution
directly related
127
what two system settings determine the frame rate
imaging depth and number of pulses
128
multi focus does what to temporal resolution
decreases temporal resolution and frame rate
129
what does line density improve
spatial resolution
130
What does line density degrade
temporal resolution and frame rate
131
what are the two major functions of the ultrasound system
prep/transmission and reception
132
what does the pulser do
determines the amplitude,PRP and PRF by exciting the crystals
133
what happens when pulser voltage is low
the entire image will be dark
134
What two measurements are used to standardize output
thermal and mechanical index
135
what is the most common way to increase signal-to-noise ratio
output power
136
what does the switch do
protects the receiver components from powerful transmission signals and directs electrical signals from the transducer
137
order of 5 receiver operations
amplification
compensation
compression
demodulation
reject
138
what is amplification also known as
receiver gain
139
what happens during receiver gain
electronic signals are made equally larger
140
pre amplification happens where
within the transducer
141
compression is also known as
dynamic range or log compression
142
what are the two processes of demodulation
rectification and smoothing
143
what does rectification do
turns negatives voltage into positives
144
can you adjust demodulation
no
145
high contrast results in what kind of image
bistable
146
storage of information in the scan converter is called what
writing
147
what kind of number am I if I have unlimited choice
continuous values
analog
148
what scan converter has excellent spatial resolution
analong
149
what is a pixel
the smallest building block of a digital picture
150
higher pixel density improves what resolution
spatial
151
higher pixel density is achieved with
smaller pixels, more pixels per inch
152
what is a byte
a group of 8 bits
153
a bit is
the smallest amount of computer memory
154
if you have more bits you have more
shades of gray
155
1 bit is how many shades of grey
2
156
what are the things that happen during preprocessing
compensation
compression
write magnification
compounding
157
true or false: spatial resolution changes during read magnification
false
158
coded excitation occurs where
in the pulser
159
what is spatial compounding
using info from different image angles to produce a single image
160
compound imaging reduces what artifacts
speckle and shadowing
161
what are the downsides to spatial compounding
reduced temporal resolution and frame rate
162
frequency compounding reduces what artifacts
noise and speckle
163
temporal compounding is also known as
persistence or temporal averaging
164
true or false temporal resolution works best with slow-moving objects
true
165
what does PACS stand for
picture archive and communication systems
166
what does DICOM stand for
digital imaging and computers in medicine
167
what is dicom
a set of rules that allow imaging systems to share information
168
what is dynamic range
the extent a signal can vary and still maintain accuracy
169
dynamic range is measured in
Decibels
170
what is harmonic imaging
twice the fundamental frequency
171
what are the two types of harmonics
tissue and contrast
172
true or false: harmonics only happen at a superficial depth
false harmonics do not happen at all in superficial depth
173
harmonics increase what
signal to noise ratio
174
true or false: weak sound beams do not create harmonics
true
175
harmonics are primarily created where
along the beam's main axis
176
what is the disadvantage of pule inversion harmonics
lower temporal resolution/ frame rate
177
contrast harmonics are created during
reflection
178
what creates better harmonics high or low frequency
lower frequency
179
what does the MI need to be to create harmonics what is the best MI
0.1 and above.... above 1 is the best
180
flow is also called
volume flow rate
181
what are the three basic forms of blood flow
pulsatile, phasic, steady
182
pulsatile flow appears in what circulation
arterial or cardiac contraction
183
phasic flow appears in what circulation
venous
184
what are the two types of laminar flow
plug flow and parabolic
185
velocity is highest in the lumen with which flow
parabolic flow
186
what does the Reynold number predict
whether flow is laminar or turbulent
187
turbulent flow coverts
flow energy into sound and vibration
188
the sound associated with turbulent flow is called
murmur or a bruit
189
in a stenosis where is the pressure lowest
narrowest portion of the stenosis
190
where is the velocity the highest in a stenosis
the narrowest part of the stenosis
191
pressure gradient increases when
flow increases or resistance increases
192
during normal function veins have what kind of pressure
low
193
supine means
flat on your back
194
when standing hydrostatic pressure is
zero at heart level only
195
when lying down hydrostatic pressure is
zero everywhere and is the true circulatory pressure
196
what is the hydrostatic pressure standing up from the ankles to the head
ankle:100
knees:75
waist:50
chest:0
top of head: -30
197
during inspiration the diaphragm moves
downward, increasing venous return to the heart
198
during expiration the diaphragm moves
upward increasing venous flow from the legs
199
Doppler shift is also called
the doppler frequency
200
what is demodulation
extracting the low Doppler frequency
200
The Doppler shift is
a low frequency that rides on top of the transducer frequency
201
when the blood cells are moving toward the transducer the Doppler shift is
positive
202
velocity is defined as
magnitude and direction
203
The Doppler shift is directly related to the
velocity
204
The x-axis of the Doppler spectrum represents
time
205
the Y-axis of the Doppler spectrum represent
velocity
206
you never want your angle to be what degree
90
207
you always want your angle to be
0 or 180
208
a 60-degree angle means the velocity measurement is
half
209
flow above the baseline means
towards the ransducer
210
continuous wave transducer requires how many crystals
two
211
what are the disandvanges of CW
the exact location cannot be determined (range ambiguity)
212
anatomic imaging and doppler is called
duplex imaging
213
true or false: CW transducers use backing material
false
214
CW transducers have what bandwith
narrow
215
what are the disadvantages of PW
inaccurate measurement of high velocity
216
true or false: aliasing can happen with CW
false
217
the Nyquist limit is
the highest doppler frequency/ velocity
218
what are the two ways to avoid aliasing
increase the nyquist limit or reduce the doppler shift
219
deeper sampler volumes have
a low PRF and low nyquist limit
220
true of false: higher frequencies create more aliasing
true
221
what are the 5 techniques to avoid aliasing
adjust scale
shallower view
lower frequency transducer
baseline shift
use CW
222
grey shades on the doppler are related to
number of blood cells
223
Color Doppler reports what type of velocity
average or mean velocity
224
Spectral Doppler reports what type of velocity
peak velocity
225
variance mode shows what type of flow
turbulent and laminar
226
the left and right side of variance mode shows what type of flow
left is laminar
right is turbulent
227
what is an ensemble
multiple pulses on the color doppler
228
what are the disadvantages of packets
lower frame rate and temporal resolution
229
power mode is
non directional
230
power doppler is also called
energy mode or color angio
231
what are the advantages of using power mode
increased sensitivity to slow flow
unaffected by the angle
no aliasing
232
what are the disadvantages of energy mode
no velocity measurement
lower frame rate
susceptible to motion
233
on spectral doppler low-frequency doppler shifts are called
clutter
234
wall filter is also called
low pass filter
235
what is cross-talk
a special form of mirroring, the doppler spectrum is shown above and below the baseline
236
cross-talk results from
the doppler gain is set too high
angle is near 90
237
what is spectral analysis
a tool that breaks complex signals down
238
what are the two methods of spectral analysis
fast Fourier transform
autocorrelation
239
true or false FFT can only be used for PW
false FFT can be used for CW and PW
240
what is spectral broadening?
a range of velocity shown by the spectral window being filled
241
autocorrelation is only used with
color doppler
242
what happens when the color gain is set too high
color confetti
243
what happens when the color gain is set too low
color disappears
244
what is isoechoic
structures with equal brightness
245
how does the artifact reverb appear
resembles a latter, multiples equally spaced
246
what causes reverb artifact
bouncing of the soundwave between 2 strong reflectors
247
comet tail artifact is caused by what 2 things
very high propagation speeds or gas bubbles
248
why does shadowing appear
attenuation is higher in the structures above
249
shadowing is not related to what
the speed of sound in a medium
250
focal banding is also called
focal enhancement
251
with the mirror artifact the artifact is located where
deeper than the real structure
252
speed error artifact is also called
range error artifact
253
what is a refraction artifact
when a sound pulse changes direction during transmission
254
refraction occurs when
a sound wave strikes a boundary obliquely
255
doppler phantoms contains what 3 things
vibrating string, moving belt, flow fantom
255
the structures in refraction artifact appear
side by side
256
sensitivity refers to
the system's ability to display low level echos
257
what are the two forms of sensitivity
normal and maximum
258
what 3 things are adjusted to establish normal sensitivity
output power, amplification, TGC
259
what kind of dead zone do higher frequency transducers have
thinner
260
what does a deep dead zone indicate
detached backing, cracked crystal, longer pulse duration
261
where does the hydrophone measure
a specific location within the sound beam
262
the hydrophone is also called
micro probe
263
what is a schlieren
a shadowing system that has to do with acousto optics
264
what are the 3 devices that measure output of the transducer
calorimeter
thermocouple
liquid crystal
265
calorimeter measures
the total power of the beam
266
thermocouple measures
power at a specific location in the sound beam
267
what is dosimetry
measuring characteristics of an ultrasound beam to its potential for bioeffects
268
what are the two approaches to studying bioeffects
mechanical and empirical
269
what does the mechanical approach search for
a relationship between cause and effect
270
what does the empirical approach search for
a relationship between exposure and response
271
what are the two bio-effect mechanisms
thermal and cavitation
272
what is radiation force
sheer stressors and streaming of fluids
273
what is cavitation
interaction of sound waves on with gasbubbles in tissues
274
what are the two forms of cavitation
stable and transient
275
microstreaming and sheer stressors happen during what type of cavitation
stable
276
transient cavitation is also called
normal or inertial
277
what are the violent effects of transient cavitation
colossal temps and enormous pressures
278
what is sensitivity vs specificity
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
