VOCAB Flashcards
1
Q
Absorption
A
The conversion of sound energy to heat
2
Q
Acoustic speckle
A
the interference pattern caused by scatterers that produces the granular appearance of tissue on an image
3
Q
Acoustic variables
A
the changes that occur within a medium as a result of sound traveling through that medium
4
Q
amplitude
A
the maximum or minimum deviation of an acoustic variable from the average value of that variable; the strength of the reflector
5
Q
attenuation
A
a decrease in the amplitude and intensity of the sound beam as sound travels through tissue
6
Q
attenuation coefficient
A
the rate at which sound is attenuated per unit depth
7
Q
axial resolution
A
the ability to accurately identify reflectors that are arranged parallel to the U/S beam
8
Q
backscatter
A
scattered sound waves that make their way back to the transducer and produce an image on the display
9
Q
beam uniformity ratio
A
the ratio of the center intensity to the average spatial intensity; also referred to as the SP/SA factor or beam uniformity coefficient
10
Q
capacitive micromachined U/S transducers
A
technology used to create comparable transducer technology to piezoelectric materials
11
Q
compression
A
an area in the sound wave of high pressure and density
12
Q
continuous wave
A
sound that is continuously transmitted
13
Q
damping
A
the process of reducing the number of cycles of each pulse in order to improve axial resolution
14
Q
decibels
A
a unit that establishes a relationship or comparison between two values of power; intensity or amplitude
15
Q
density
A
mass per unit volume
16
Q
directly related / directly proportional
A
relationship that implies that if one variable decreases, the other also decreases or if variable increases, the other also increases
17
Q
distance
A
how far apart objects are; may also be referred to as vibration or displacement
18
Q
duty factor
A
the percentage of time that sound is actually being produced
19
Q
elasticity / stiffness
A
the ability of an object to resist compression and relates to the hardness of a medium
20
Q
frequency
A
the number of cycles per second
21
Q
half-intensity depth / half-value layer thickness
A
the depth at which sound has lost half of its intensity
22
Q
hertz
A
a unit of frequency
23
Q
hydrophone
A
a device used to measure the output intensity of the transducer
24
Q
impedance
A
the resistance to the propagation of sound through a medium
25
inertia
Newton's principle that states that an object at rest stays at rest and an object in motion stays in motion, unless acted on by an outside force
26
intensity
the power of the wave divided by the area over which it is spread; the energy per unit area
27
intensity reflection coefficient
the percentage of sound reflected at an interface
28
intensity transmission coefficient
the percentage of sound transmitted at an interface
29
interface
the dividing line between two different media
30
inversely related / inversely proportional
relationship that implies that if one variable decreases the other increases or if one variable increases, the other decreases
31
longitudinal waves
waves in which the molecules of the medium vibrate back and forth in the same direction that the waves are traveling
32
medium
any form of matter; solid, liquid or gas
33
nonspecular reflectors
reflectors that are smaller than the wavelength of the incident beam
34
normal incidence
angle of incidence is 90 degrees to the interface
35
oblique incidence
angle of incidence is less than or greater than 90 degrees to the interface
36
parameter
a measurable quantity
37
particle motion
the movement of molecules due to propagating sound energy
38
path length
distance to the reflector
39
period
the time it takes for one cycle to occur
40
piezoelectric materials / element / crystal
a material that generates electricity when pressure is applied to it, and one that changes shape when electricity is applied to it
41
power
the rate at which work is performed or energy is transmitted
42
pressure
force per unit area or the concentration of force
43
propagate
to transmit through a medium
44
propagation speed
the speed at which a sound wave travels through a medium
45
pulse duration
the time during which the sound is actually being transmitted / "on" time
46
pulse repetition frequency
the number of pulses of sound produced in 1 second
47
pulse repetition period
the time taken for a pulse to occur
48
pulsed wave
sound that is sent out in pulses
49
rarefaction
an area in the sound wave of low pressure and density
50
rate
the fixed quantity owed as the sound beam travels through tissue (related to attenuation)
51
Rayleigh scatterers
small scattering reflectors
52
reflection
the echo; the portion of the sound that returns from an interface
53
refraction
the change in the direction of the transmitted sound beam that occurs with oblique incidence angles and dissimilar propagation speeds
54
scattering
the phenomenon that occurs when sound waves are dispersed into different directions because of the small reflector size compared with the incident wavelength
55
Snell's law
law used to describe the angle of transmission at an interface based on the angle of incidence and the propagation speeds of the two media
56
sound
a traveling variation in pressure
57
spatial pulse length
the length of a pulse
58
specular reflections
reflections that occur when the sound impinges upon a large, smooth reflector at a 90 degree angle
59
stiffness
the ability of an object to resist compression and relates to the hardness of a medium
60
total attenuation
the total amount of sound in dB that has been attenuated at a given depth
61
transverse waves
type of wave in which the molecules in a medium vibrate at 90 degrees to the direction of travel
62
ultrasound
sound waves of frequencies exceeding the range of human hearing
63
wavelength
the length of a single cycle of sound
64
aperture
the diameter of the piezoelectric element producing the beam
65
array
the transducer with multiple active elements
66
automatic scanning
same as real-time ultrasound
67
axial resolution
the ability to accurately identify reflectors that are arranged parallel to the ultrasound beam
68
backing material
the damping material of the transducer assembly, which reduces the number of cycles produced in a pulse
69
bandwidth
the range of frequencies present within the beam
70
curved sequenced array
the transducer commonly referred to as a curvilinear or convex probe
71
damping
the process of reducing the number of cycles of each pulse in order to improve axial resolution
72
damping material
same as backing material; the part of the transducer assembly that reduces the number of cycles produced in a pulse
73
depth ambiguity
the inability to determine the depth of the reflector if the pulses are sent out too fast for them to be timed
74
destructive interference
occurs when out of phase waves meet; the amplitude of the resultant wave is smaller than either of the original waves
75
divergence
spreading of the beam that occurs in the far zone
76
element
the piezoelectric part of the transducer assembly that produces sound
77
elevational plane / slice thickness plane
the third dimension of the beam
78
elevational resolution
the resolution in the third dimension of the beam; slice thickness plane
79
far zone / Fraunhofer zone
the diverging part of the beam distal to the focal point
80
focal point
the area of the beam with the smallest beam diameter
81
footprint
the portion of the transducer that is in contact with the patient's skin
82
four-dimensional ultrasound
three-dimensional ultrasound in real time
83
frame
one complete ultrasound range
84
frame rate
the number of frames per second
85
frequency
the number of cycles per second
86
Huygen's principle
states that waves are the result of the interference of many wavelets produced at the face of the transducer
87
in-phase
waves whose peaks and troughs overlap
88
lateral resolution
the ability to accurately identify reflectors that are arranged perpendicular to the ultrasound beam
89
lead zirconate titanate
the man-made ceramic of which many transducer elements are made (PZT)
90
linear sequenced array
the transducer commonly referred to as the linear probe or transducer
91
matching layer
the component of the transducer that is used to step down the impedence from that of the element to that of the patient's skin
92
matrix array transducer
transducer that acquires real-time volumes using up to 10,000 elements, compared to the 128 to 512 elements used in standard 1D array transducers
93
mechanical scanheads
transducers with a motor for steering the beam
94
near zone / Fresnel zone
the part of the beam between the element and the focal point
95
near-zone length
the length of the region from the transducer face to the focal point
96
out of phase
waves that are 180 degrees opposite each other; the peak of one wave overlaps the trough of the other and vice versa
97
phased array
the transducer that uses phasing, or small time differences to steer and focus the beam
98
phasing
the method of focusing and/or steering the beam by applying electrical impulses to the piezoelectric elements with small time differences between shocks
99
piezoelectric
the ability to convert pressure into electricity and electricity into pressure
100
quality factor / Q - factor
a measure of beam purity; the operating frequency of the transducer divided by the bandwidth
101
range resolution
the ability to determine how far away a reflector is so it can be displayed on the screen; without range resolution there is depth ambiguity
102
real time
live ultrasound; also known as automatic scanning
103
resonate
to alternatively expand and contract
104
scan lines
created when one or more pulses of sound return from the tissue containing information related to the depth and amplitude of the reflectors
105
section thickness plane / slice thickness plane
the third dimension of the beam
106
sensitivity
the ability of a system to display low-level or weak echoes
107
spatial pulse length
the length of the pulse
108
spatial resolution
the ability of the system to distinguish between closely spaced objects; refers to axial, lateral, contrast, and elevational resolution
109
three-dimensional ultrasound
allows the user to see width, height, and depth; may also be referred to as volume scanning
110
temporal resolution / frame rate
ability to display moving structures in real time
111
transducer
any device that converts one form of energy into another; may also refer to the part of the ultrasound machine that produces sound
112
tungsten
component of the backing material
113
wavefront
the leading edge of a wave which is perpendicular to the direction of the propagating wave; formed as a result of Huygen's principle
114
wavelet
a small wave created as a result of Huygen's principle
115
13 us rule
the rule that states that it takes 13 micro-seconds for sound to travel 1 centimeter in soft tissue
116
acoustic speckle
the interference pattern caused by scatterers that produces the granular appearance of tissue on a sonographic image
117
A mode
amplitude mode; the height of the spike on the image is related to the strength (amplitude) of the echo generated by the reflector
118
ALARA
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
119
amplification
the part of the receiver that increases or decreases the received echoes equally, regardless of depth
120
amplitude (strength)
the maximum or minimum deviation of an acoustic variable from the average value of that variable; the strength of the reflector
121
analog to digital (A to D converter)
the part of the digital scan converter that converts the analog signals from the receiver to binary for processing by the computer
122
anechoic
without echoes or black
123
apodization
the technique that varies the voltage to the individual elements to reduce grating lobes
124
artifacts
echoes on the screen that are not representative of actual anatomy; or reflectors in the body that are not displayed on the screen
125
B flow imaging
a non-Doppler technology that offers real time imaging of blood flow while scanning in grayscale
126
B mode
brightness mode; the brightness of the dots is proportional to the strength of the echo generated by the reflector
127
beam former
the part of the machine that shapes and steers the beam on the transmit end
128
binary system
the digital language of zeroes and ones
129
bistable
black and white image
130
bit
the smallest unit of memory in a digital device
131
byte
8 bits of memory
132
cathode ray tube (CRT)
display that uses an electron gun to produce a stream of electrons toward a phosphor-coated screen
133
coded excitation
a way of processing the pulse to improve contrast resolution and reduce speckle
134
comet tail
a type of reverberation artifact caused by small reflectors (surgical clips)
135
compensation / time - gain compensation
the function of the receiver that changes the brightness of the echo amplitudes to compensate for attenuation with depth
136
compression
the function of the receiver that decreases the range of signal ampitudes present within the
137
contrast resolution
the ability to differentiate one shade of gray from another
138
demodulation
the function of the receiver that makes the signal easier to process by performing rectification and smoothing
139
digital-to-analog (D to A) converter
part of the digital scan converter that converts the binary signals from computer memory to analog for display and storage
140
dynamic range
the series of echo amplitudes present within the signal
141
edge shadowing
refraction artifact caused by the curved surface of the reflector
142
electrical interference
arc-like bands that occur when the machine is too close to an unshielded electrical device
143
enhancement
an artifact caused by sound passing through an area of lower attenuation
144
fill-in interpolation / pixel interpolation
places grayscale pixels where there is no signal information based on adjacent scan lines
145
frame
one complete ultrasound image
146
frequency compounding
averages the frequencies across the image to improve contrast resolution and reduce speckle
147
fundamental frequency
the operating or resonating frequency emitted by the transducer
148
grating lobes
an artifact caused by extraneous sound that is not located along primary beam path; occurs with arrays; reduced or eliminated by apodization, subdicing, and tissue harmonics
149
harmonics / native tissue harmonic imaging
harmonic signal produced by the patient's tissue and that is a multiple of the fundamental frequency
150
hyperechoic / echogenic
displayed echoes that are relatively brighter than the surrounding tissue
151
hypoechoic
displayed echoes that are relatively darker than the surrounding tissue
152
liquid crystal display (LCD)
display that uses the twisting and untwisting of liquid crystals in front of a light source
153
M mode
motion mode, used to display motion of the reflectors
154
master synchronizer
the timing component of the ultrasound machine that notes how long it takes for signals to return from reflectors
155
mirror image artifact
an artifact caused by the sound bouncing off strong reflectors and causing a structure to appear on both sides of the reflector
156
multipath
an artifact caused by the beam bouncing off several reflectors before returning to the transducer
157
noise
low-level echoes on the display that do not contribute useful diagnostic information
158
output
output power; strength of the sound entering the patient
159
overall gain
receiver function that increases or decreases all of the echo amplitudes equally
160
picture archiving and communication system (PACS)
a type of display and storage device commonly used in sonography and other imaging modalities
161
pixel (picture element)
the smallest component of 2D digital image
162
preamplification
occurs at the receiver to the relatively weak signal coming from the transducer; ultimately the signal has to be increased so the rest of the receiver can analyze it
163
preprocessing
occurs in the A to D converter; the image must be live
164
propagation speed errors
artifact that occurs because the actual propagation speed of the tissue is greater than or less than 1540 meters per second, the machine places the reflector at the wrong location on the display
165
postprocessing
occurs in the D to A converter; the image must be frozen
166
pulse inversion technology
harmonic technology in which the fundamental frequency is flipped 180 degrees and transmitted, which cancels out the fundamental frequency via destructive interference, leaving only the harmonic signal
167
pulser
part of the beam former that controls the amount of energy in the pulse
168
range equation
equation used to calculate the distance to the reflector; in soft tissue, d = 0.77t where d is depth of the reflector and t represents the round-trip time of the pulse
169
read zoom
the type of magnification performed in the D to A converter (post processing) that magnifies the image by enlarging the pixels
170
receiver / signal processor
the component of the machine that processes the signals coming back from the patient
171
rectification
the part of the receiver that inverts the negative voltages to positives
172
rejection
function of the receiver that is used to reduce image noise; sets a threshold below which the signal will not be displayed
173
reverberation
an artifact caused by the beam bouncing between 2 strong reflectors
174
ring down
an artifact caused by vibration of air bubbles
175
scan converter
the part of the U/S machine that processes the signals from the receiver; consists of the A to D converter, computer memory, and D to A converter
176
scan line
created when one or more pulses of sound return from the tissue containing information related to the depth and amplitude of the reflectors
177
shadowing
an artifact caused by the failure of sound to pass through a strong attenuator
178
side lobes
an artifact caused by extraneous sound that is not found along the primary beam path; occurs with single-element transducers
179
slice thickness artifact / elevational plane artifact
artifact that occurs as a result of the beam not being razor thin; thus, unintended echoes may appear in the image as the beam slices through structures adjacent to intended reflectors
180
smoothing
part of the demodulation component of the receiver; an envelope is wrapped around the signal to eliminate the humps
181
spatial compounding
technique that eliminates edge shadowing because the object is imaged at different angles
182
speckle reduction
algorithm used in signal processing to reduce the amount of acoustic speckle
183
specular reflectors
large, flat, smooth boundaries that cause reflection
184
subdicing
dividing the piezoelectric elements into very small pieces to reduce grating lobes
185
transmit / receive switch
ensures the electrical signals travel in the correct direction
186
voxel (volume element)
the smallest component of a 3D image
187
write zoom
the type of magnification performed in the A to D converter (pre processing) that magnifies the image by redrawing it before it is stored in memory
188
x - axis
the plane that is perpendicular to the beam path
189
y - axis
the plane that is parallel to the beam path
190
z - axis
the brightness (amplitude) of the dots on the display
191
aliasing
the wraparound of the spectral or color Doppler display that occurs when the frequency shift exceeds the Nyquist limit; occurs only with pulsed-wave Doppler
192
angle correction
the tool used to inform the machine what the flow angle is so that velocities can be accurately calculated
193
auto correlation
the color Doppler processing technique that assesses pixels as stationary or in motion
194
BART
the acronym used to describe color Doppler scale "blue away, red toward"
195
baseline
the operator adjustable dividing line between positive frequency shifts and negative frequency shifts on spectral and color Doppler
196
Bernoulli's principle
the principle that describes the inverse relationship between velocity and pressure
197
bidirectional Doppler
the Doppler deice that can detect positive and negative Doppler shifts
198
boundary layer
the stationary layer of blood cells immediately adjacent to the vessel wall
199
brightness
the term describing the intensity or luminance of the color Doppler display
200
calf muscle pump
the muscles in the calf that upon contraction propel venous blood toward the heart
201
capacitance
the ability of veins to store blood
202
clutter
acoustic noise in the color and/or spectral Doppler signal
203
collateral blood vessels
accessory vessels that connect portions of the same blood vessel together
204
color Doppler imaging
Doppler shift information presented as a color hue superimposed over the grayscale image
205
color priority
the setting for color Doppler that allows the operator to select frequency shift threshold; it determines whether color pixels should be displayed preferentially over grayscale pixels
206
continuity equation
the equation that describes the change in velocity as the area changes in order to maintain the volume of blood flow
207
continuous wave Doppler
Doppler device that uses continuous wave U/S transmission; a device that consists of two elements, one element is used by the system to constantly transmit sound and the other is used to constantly receive sound
208
critical stenosis
the point at which a stenosis is hemodynamically significant within a pressure drop distal to the stenosis
209
depth ambiguity
the inability to determine the depth of the reflector if the pulses are sent out too fast for them to be timed
210
diastole
the relaxation of the heart following contraction
211
Doppler effect
the change in the frequency of the received signal related to motion of reflector
212
Doppler equation
the equation that explains the relationship of the Doppler frequency shift to the frequency of the transducer; the velocity of the blood, the angle to blood flow and the propagation speed
213
duplex
real-time 2D imaging combined with the spectral Doppler display
214
effective resistance
the sum of the individual resistances when multiple vessels are connected in series
215
energy gradient
the difference in energy between 2 points
216
ensemble length / packet size
the number of pulses per scan line in color Doppler
217
extrinsic pressure
pressure applied to the outside of an object
218
fast Fourier transform
a mathematical process used for analyzing and processing the Doppler signal to produce the spectral waveform
219
flash artifact
a motion artifact caused by the movement of tissue when using power doppler
220
flow
the volume of blood per unit time; typically measured in liter per minute or mililiter per second; represented by the symbol Q
221
frequency shift
the difference between the transmitted and received frequencies
222
friction
a form of resistance caused by 2 materials rubbing against each other; thereby converting energy to heat
223
hemodynamics
the study of blood flow through the blood vessels of the body
224
hue
a term used to describe displayed colors
225
hydrostatic pressure
describes the relationship between gravity, density of the blood, and distance between an artery's reference point
226
aliasing
the wraparound of the spectral or color Doppler display that occurs when the frequency shift exceeds the Nyquist limit; occurs only with pulsed-wave Doppler
227
angle correction
the tool used to inform the machine what the flow angle is so that velocities can be accurately calculated
228
autocorrelation
the color Doppler processing technique that assesses pixels as stationary or in motion
229
BART
the acronym used to describe color Doppler scale
230
baseline
the operator-adjustable dividing line between positive frequency shifts and negative frequency shifts on spectral and color Doppler
231
Bernouilli's principle
the principle that describes the inverse relationship between velocity and pressure
232
bidirectional Doppler
the Doppler device that can detect positive and negative Doppler shifts
233
boundary layer
the stationary layer of blood cells immediately adjacent to the vessel wall
234
brightness
the term describing the intensity or luminance of the color Doppler display
235
calf muscle pump
the muscles in the calf that, upon contraction, propel venous blood toward the heart
236
capacitance
the ability of veins to store blood
237
clutter
acoustic noise in the color and/or spectral Doppler signal
238
collateral blood vessels
accessory vessels that connect portions of the same blood vessel together
239
color Doppler imaging
Doppler shift information presented as a color hue superimposed over the grayscale image
240
color priority
the setting for color Doppler that allows the operator to select frequency shift threshold; it determines whether color pixels should be displayed preferentially over grayscale pixels
241
continuity equation
the equation that describes the change in velocity as the area changes in order to maintain the volume of blood flow
242
continuous wave Doppler
Doppler device that uses continuous wave U/S transmission; a device that consists of 2 elements, one element is used by the system to constantly transmit sound and the other is used to constantly receive sound
243
critical stenosis
the point at which a stenosis is hemodynamically significant with a pressure drop distal to the stenosis
244
depth ambiguity
the inability to determine the depth of the reflector if the pulses are sent out too fast for them to be timed
245
diastole
the relaxation of the heart following contraction
246
Doppler effect
the change in the frequency of the received signal related to motion of reflector
247
Doppler equation
the equation that explains the relationship of the Doppler frequency shift to the frequency of the transducer, and the propagation speed
248
duplex
real-time 2D imaging combined with the spectral Doppler display
249
effective resistance
the sum of the individual resistances when multiple vessels are connected in series
250
energy gradient
the difference in energy between 2 points
251
ensemble length / packet size
the number of pulses per scan line in color Doppler
252
extrinsic pressure
pressure applied to the outside of an object
253
fast Fourier transform
a mathematical process used for analyzing and processing the Doppler signal to produce the spectral waveform
254
flash artifact
a motion artifact caused by the movement of tissue when using power Doppler
255
flow
the volume of blood per unit time; typically measured in liter per minute or mililiter per second (represented by Q)
256
frequency shift
the difference between the transmitted and received frequencies
257
friction
a form of resistance; caused by 2 materials rubbing against each other, converting energy to heat
258
hydrostatic pressure
describes the relationship between gravity, density of the blood, and distance between an arbitrary reference point
259
inertia
Newton's principle that states that an object at rest stays at rest and an object in motion stays in motion, unless acted on by an outside force
260
innervated
supplied with nerves
261
kinetic energy
the energy form of flowing blood
262
laminar flow
the flow profile represented by blood that travels in nonmixing layers of different velocities, with the fastest flow in the center and the slowest flow near the vessel walls
263
law of conservation of energy
the total amount of energy in a system never changes, although it might be in a different form from which it started
264
luminance
the brightness of the color Doppler image
265
mm Hg
milimeters of mercury
266
noise
low-level echoes on the display that do not contribute useful diagnostic information
267
nondirectional Doppler
Doppler device that cannot differentiate between positive and negative frequency shifts
268
nonhemodynamically significant stenosis
a stenosis that does not necessarily compromise blood flow to organs or structures
269
Nyquist limit
the maximum frequency shift sampled without aliasing; equal to one half the PRF
270
Ohm's Law
a law used in electronics in which flow is equal to the pressure differential divided by resistance
271
oscillator
the component of a continuous - wave Doppler device that produces the voltage that drives the transducer
272
persistence
the averaging of color frames in order to display blood flow with a low signal-to-noise ratio
273
phase quadrature
the component of the Doppler device that determines positive opposed to negative frequency shifts and direction of blood flow
274
phasic flow
the characteristic waveform of peripheral veins; flow is determined by respiratory variations as a result of intrathoracic pressure changes
275
phasicity
in arteries, the phasicity describes the shape of the waveform based on the resistiveness of the distal bed (multiphasic/monophasic) in veins, phasicity describes the flow pattern that results from respiratory variation (respiratory phasicity)
276
plug flow
the flow profile represented by blood typically flowing at the same velocity
277
Poiseuille's Law
the law that describes the relationship of resistance, pressure, and flow
278
potential energy
pressure energy created by the beating heart
279
power Doppler / amplitude Doppler
Doppler mode in which the signal is determined by the amplitude (strength) of the shift, not the shift itself, amplitude is directly proportional to the number of red blood cells
280
pressure gradient
the difference between pressures at two points of a blood vessel
281
pulsatility
blood that flows in a pattern representative of the beating heart, with increases and decreases in pressure and blood flow velocity
282
pulsatility index
Doppler measurement used to determine how pulsatile a vessel is over time
283
pulse repetition frequency
the number of pulses of sound produced in 1 second
284
pulsed-wave Doppler
the Doppler technique that uses pulses of sound to obtain Doppler signals from a user-specified depth
285
range gate
the gate placed by the operator in the region where Doppler sampling is desired; used with pulsed-wave Doppler
286
range resolution
the ability to determine the depth of echoes by timing how long it takes for the echoes to go from the transducer to the reflector and back; utilized by pulsed wave devices
287
rayleigh scatterers
very small reflectors (RBC's)
288
resistance
the downstream impedence to flow; determined by vessel length, vessel radius, and viscosity of blood
289
resistive index
Doppler measurement used to quantitate the resistiveness of the distal bed
290
Reynolds number
the formula used to quantitate the presence of turbulence; Reynolds numbers greater than 2000 typically indicate turbulence
291
sample volume
the area within the range gate where the Doppler signals are obtained
292
saturation
the amount of white added to a hue; the more white there is, the less saturated the color
293
scale / PRF (in spectral / color Doppler)
the spectral Doppler / color Doppler tool that controls the number of pulses transmitted per second to obtain the Doppler information;
294
speckle tracking
the method used to obtain the strain information
295
spectral broadening
the filling of the spectral window
296
spectral window
the area underneath the envelope on the spectral display
297
stenosis
pathologic narrowing of a blood vessel
298
strain
the changing of the shape of the muscle as it lengthens and contracts
299
sweep speed
the operator-adjustable spectral Doppler control that increases or decreases the number of heartbeats visualized on spectral display
300
systole
the time period of the cardiac cycle when the heart is contracting
301
tardus parvus
an arterial waveform shape with a delayed peak systolic upstroke that indicates proximal obstruction
302
thrombus
combination of platelets, red blood cells, and fibrin that make up a blood clot
303
tissue Doppler imaging
color DOppler imaging technique used to document wall motion
304
transmural pressure
the difference in pressure inside a vessel compared to the pressure outside of the vessel
305
triplex
the ability to visualize real time grayscale, color Doppler, and spectral Doppler simultaneously
306
tunica adventitia
the outer layer of a blood vessel
307
tunica intima
the inner layer of a blood vessel which is closest to the flowing flood
308
tunia media
the middle, muscular layer of blood vessel
309
turbulent flow
chaotic, disorderly flow of blood
310
variance mode
the color Doppler scale with mean velocities displayed vertically on the scale and turbulence displayed horizontally
311
vasa vasorum
a network of small blood vessels that supply blood to the walls of arteries and veins
312
vasoconstriction
the narrowing of a blood vessel caused by the contraction of the vessel wall
313
vasodilatation
the widening of a blood vessel caused by the relaxation of the vessel wall
314
velocity mode
the color Doppler scale with mean velocities displayed vertically
315
viscous energy
the energy loss caused by friction
316
wall filter / high - pass filter
the operator control that eliminates low frequency, high amplitude signals caused by wall or valve motion
317
Z axis
the brightness/amplitude of the dots on a B-mode display; the brighter the dots of the spectral waveform, the more red blood cells that make up the signal
318
axial resolution
the ability to accurately identify reflectors that are arranged parallel to the U/S beam
319
contrast resolution
the ability to differentiate one shade of gray from another
320
Doppler phantom
the test object used to evaluate the flow direction, the depth capability or penetration of the DOppler beam, and the accuracy of the sample volume location and measured velocity
321
elevational plane / slice -thickness plane
the resolution in the 3rd dimension of the beam
322
horizontal calibration
the ability to place echoes in the proper location horizontally and perpendicular to the sound beam
323
lab accreditation
a voluntary process that acknowledges an organization's competency and credibility according to standards and essentials set forth by a reliable source
324
lateral resolution
the ability to accurately identify reflectors that are arranged perpendicular to the U/S beam
325
preventative maintenance
a methodical way of evaluating equipment's performance on a routine basis to ensure proper and accurate equipment function
326
quality assurance program
a planned program consisting of scheduled equipment testing activities that confirm the correct performance of equipment
327
registration
the ability to place echoes in the correct location
328
sample volume
the area within the range gate where the Doppler signals are obtained
329
sensitivity
the ability of a system to display low-level or weak echoes
330
slice thickness phantom
the test object that evaluates the elevational resolution, or the thickness portion, of the sound beam perpendicular to the imaging plane
331
tissue equivalent phantom
the test object that mimics the acoustic properties of human tissue and is used to ensure proper equipment performance
332
vertical depth
the distance from the transducer
333
acoustic cavitation
the production of bubbles in a liquid medium
334
acoustic radiation force impulse imaging
uses acoustic radiation force to compress the soft tissue and provides a qualitative measurement of stiffness without requiring pressure input from the sonographer
335
ALARA
As Low As Reasonably Achievable / keep patient exposure minimal
336
automatic external defibrillator
a portable device that is used to detect and treat abnormal heart rhythms with electrical defibrillation
337
contrast enhanced U/S (CEUS)
type of imaging in which an U/S contrast agent containing microscopic gas bubbles is used to improve visualization of structures or blood flow
338
diabetes mellitus
a group of metabolic diseases that result from a chronic disorder of carbohydrates metabolism
339
diabetic ketoacidosis
a complication of diabetes that results from the severe lack of insulin
340
elastography
a sonographic technique used to evaluate the stiffness of a mass or tissue
341
ergonomics
the scientific study of creating tools and using equipment effectively in order to help the human body adjust to the work environment
342
fusion imaging / hybrid imaging
technology that provides the ability to view alternate imaging modality (CT / MRI) during real time sonography
343
Health Insurance Portability and Accountability Act
US law which upholds patient confidentiality and requires the use of electronic medical records
344
hyperglycemic hypersmolar nonketotic syndrome
a diabetic syndrome characteristics by excessive urination and dehydration
345
intravascular U/S
the technique that employs a miniature U/S transducer placed on a catheter and inserted into the circulatory system
346
mechanical index
the calculation used to identify the likelihood into the circulatory system
347
nonsocomial infection
a hospital - acquired infection
348
radiation forces
forces exerted by a sound beam on an absorber or reflector that can alter structures
349
shear wave elastography
elastography technique that uses shear wave information to analyze the stiffness of tissue
350
shock
the body's pathologic response to illness, trauma, or severe physiologic or emotional stress
351
strain elastrography
operator dependent type of elastography that measure the change in tissue as a result of compression
352
streaming
when acoustic fields cause motion of fluids
353
thermal index
the calculation used to predict the maximum temperature elevation in tissues as a result of the attenuation of sound
