VOCAB Flashcards
Absorption
The conversion of sound energy to heat
Acoustic speckle
the interference pattern caused by scatterers that produces the granular appearance of tissue on an image
Acoustic variables
the changes that occur within a medium as a result of sound traveling through that medium
amplitude
the maximum or minimum deviation of an acoustic variable from the average value of that variable; the strength of the reflector
attenuation
a decrease in the amplitude and intensity of the sound beam as sound travels through tissue
attenuation coefficient
the rate at which sound is attenuated per unit depth
axial resolution
the ability to accurately identify reflectors that are arranged parallel to the U/S beam
backscatter
scattered sound waves that make their way back to the transducer and produce an image on the display
beam uniformity ratio
the ratio of the center intensity to the average spatial intensity; also referred to as the SP/SA factor or beam uniformity coefficient
capacitive micromachined U/S transducers
technology used to create comparable transducer technology to piezoelectric materials
compression
an area in the sound wave of high pressure and density
continuous wave
sound that is continuously transmitted
damping
the process of reducing the number of cycles of each pulse in order to improve axial resolution
decibels
a unit that establishes a relationship or comparison between two values of power; intensity or amplitude
density
mass per unit volume
directly related / directly proportional
relationship that implies that if one variable decreases, the other also decreases or if variable increases, the other also increases
distance
how far apart objects are; may also be referred to as vibration or displacement
duty factor
the percentage of time that sound is actually being produced
elasticity / stiffness
the ability of an object to resist compression and relates to the hardness of a medium
frequency
the number of cycles per second
half-intensity depth / half-value layer thickness
the depth at which sound has lost half of its intensity
hertz
a unit of frequency
hydrophone
a device used to measure the output intensity of the transducer
impedance
the resistance to the propagation of sound through a medium
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
intensity
the power of the wave divided by the area over which it is spread; the energy per unit area
intensity reflection coefficient
the percentage of sound reflected at an interface
intensity transmission coefficient
the percentage of sound transmitted at an interface
interface
the dividing line between two different media
inversely related / inversely proportional
relationship that implies that if one variable decreases the other increases or if one variable increases, the other decreases
longitudinal waves
waves in which the molecules of the medium vibrate back and forth in the same direction that the waves are traveling
medium
any form of matter; solid, liquid or gas
nonspecular reflectors
reflectors that are smaller than the wavelength of the incident beam
normal incidence
angle of incidence is 90 degrees to the interface
oblique incidence
angle of incidence is less than or greater than 90 degrees to the interface
parameter
a measurable quantity
particle motion
the movement of molecules due to propagating sound energy
path length
distance to the reflector
period
the time it takes for one cycle to occur
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
power
the rate at which work is performed or energy is transmitted
pressure
force per unit area or the concentration of force
propagate
to transmit through a medium
propagation speed
the speed at which a sound wave travels through a medium
pulse duration
the time during which the sound is actually being transmitted / “on” time
pulse repetition frequency
the number of pulses of sound produced in 1 second
pulse repetition period
the time taken for a pulse to occur
pulsed wave
sound that is sent out in pulses
rarefaction
an area in the sound wave of low pressure and density
rate
the fixed quantity owed as the sound beam travels through tissue (related to attenuation)
Rayleigh scatterers
small scattering reflectors
reflection
the echo; the portion of the sound that returns from an interface
refraction
the change in the direction of the transmitted sound beam that occurs with oblique incidence angles and dissimilar propagation speeds
scattering
the phenomenon that occurs when sound waves are dispersed into different directions because of the small reflector size compared with the incident wavelength
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
sound
a traveling variation in pressure
spatial pulse length
the length of a pulse
specular reflections
reflections that occur when the sound impinges upon a large, smooth reflector at a 90 degree angle
stiffness
the ability of an object to resist compression and relates to the hardness of a medium
total attenuation
the total amount of sound in dB that has been attenuated at a given depth
transverse waves
type of wave in which the molecules in a medium vibrate at 90 degrees to the direction of travel
ultrasound
sound waves of frequencies exceeding the range of human hearing
wavelength
the length of a single cycle of sound
aperture
the diameter of the piezoelectric element producing the beam
array
the transducer with multiple active elements
automatic scanning
same as real-time ultrasound
axial resolution
the ability to accurately identify reflectors that are arranged parallel to the ultrasound beam
backing material
the damping material of the transducer assembly, which reduces the number of cycles produced in a pulse
bandwidth
the range of frequencies present within the beam
curved sequenced array
the transducer commonly referred to as a curvilinear or convex probe
damping
the process of reducing the number of cycles of each pulse in order to improve axial resolution
damping material
same as backing material; the part of the transducer assembly that reduces the number of cycles produced in a pulse
depth ambiguity
the inability to determine the depth of the reflector if the pulses are sent out too fast for them to be timed
destructive interference
occurs when out of phase waves meet; the amplitude of the resultant wave is smaller than either of the original waves
divergence
spreading of the beam that occurs in the far zone
element
the piezoelectric part of the transducer assembly that produces sound
elevational plane / slice thickness plane
the third dimension of the beam
elevational resolution
the resolution in the third dimension of the beam; slice thickness plane
far zone / Fraunhofer zone
the diverging part of the beam distal to the focal point
focal point
the area of the beam with the smallest beam diameter
footprint
the portion of the transducer that is in contact with the patient’s skin
four-dimensional ultrasound
three-dimensional ultrasound in real time
frame
one complete ultrasound range
frame rate
the number of frames per second
frequency
the number of cycles per second
Huygen’s principle
states that waves are the result of the interference of many wavelets produced at the face of the transducer
in-phase
waves whose peaks and troughs overlap
lateral resolution
the ability to accurately identify reflectors that are arranged perpendicular to the ultrasound beam
lead zirconate titanate
the man-made ceramic of which many transducer elements are made (PZT)
linear sequenced array
the transducer commonly referred to as the linear probe or transducer
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
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
mechanical scanheads
transducers with a motor for steering the beam
near zone / Fresnel zone
the part of the beam between the element and the focal point
near-zone length
the length of the region from the transducer face to the focal point
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
phased array
the transducer that uses phasing, or small time differences to steer and focus the beam
phasing
the method of focusing and/or steering the beam by applying electrical impulses to the piezoelectric elements with small time differences between shocks
piezoelectric
the ability to convert pressure into electricity and electricity into pressure
quality factor / Q - factor
a measure of beam purity; the operating frequency of the transducer divided by the bandwidth
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
real time
live ultrasound; also known as automatic scanning
resonate
to alternatively expand and contract
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
section thickness plane / slice thickness plane
the third dimension of the beam
sensitivity
the ability of a system to display low-level or weak echoes
spatial pulse length
the length of the pulse
spatial resolution
the ability of the system to distinguish between closely spaced objects; refers to axial, lateral, contrast, and elevational resolution
three-dimensional ultrasound
allows the user to see width, height, and depth; may also be referred to as volume scanning
temporal resolution / frame rate
ability to display moving structures in real time
transducer
any device that converts one form of energy into another; may also refer to the part of the ultrasound machine that produces sound
tungsten
component of the backing material
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
wavelet
a small wave created as a result of Huygen’s principle
13 us rule
the rule that states that it takes 13 micro-seconds for sound to travel 1 centimeter in soft tissue
acoustic speckle
the interference pattern caused by scatterers that produces the granular appearance of tissue on a sonographic image
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
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
amplification
the part of the receiver that increases or decreases the received echoes equally, regardless of depth
amplitude (strength)
the maximum or minimum deviation of an acoustic variable from the average value of that variable; the strength of the reflector
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
anechoic
without echoes or black
apodization
the technique that varies the voltage to the individual elements to reduce grating lobes
artifacts
echoes on the screen that are not representative of actual anatomy; or reflectors in the body that are not displayed on the screen
B flow imaging
a non-Doppler technology that offers real time imaging of blood flow while scanning in grayscale
B mode
brightness mode; the brightness of the dots is proportional to the strength of the echo generated by the reflector
beam former
the part of the machine that shapes and steers the beam on the transmit end
binary system
the digital language of zeroes and ones
bistable
black and white image
bit
the smallest unit of memory in a digital device
byte
8 bits of memory
cathode ray tube (CRT)
display that uses an electron gun to produce a stream of electrons toward a phosphor-coated screen
coded excitation
a way of processing the pulse to improve contrast resolution and reduce speckle
comet tail
a type of reverberation artifact caused by small reflectors (surgical clips)
compensation / time - gain compensation
the function of the receiver that changes the brightness of the echo amplitudes to compensate for attenuation with depth
compression
the function of the receiver that decreases the range of signal ampitudes present within the
contrast resolution
the ability to differentiate one shade of gray from another
demodulation
the function of the receiver that makes the signal easier to process by performing rectification and smoothing
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
dynamic range
the series of echo amplitudes present within the signal
edge shadowing
refraction artifact caused by the curved surface of the reflector
electrical interference
arc-like bands that occur when the machine is too close to an unshielded electrical device
enhancement
an artifact caused by sound passing through an area of lower attenuation
fill-in interpolation / pixel interpolation
places grayscale pixels where there is no signal information based on adjacent scan lines
frame
one complete ultrasound image
frequency compounding
averages the frequencies across the image to improve contrast resolution and reduce speckle
fundamental frequency
the operating or resonating frequency emitted by the transducer
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
harmonics / native tissue harmonic imaging
harmonic signal produced by the patient’s tissue and that is a multiple of the fundamental frequency
hyperechoic / echogenic
displayed echoes that are relatively brighter than the surrounding tissue
hypoechoic
displayed echoes that are relatively darker than the surrounding tissue
liquid crystal display (LCD)
display that uses the twisting and untwisting of liquid crystals in front of a light source
M mode
motion mode, used to display motion of the reflectors
master synchronizer
the timing component of the ultrasound machine that notes how long it takes for signals to return from reflectors
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
multipath
an artifact caused by the beam bouncing off several reflectors before returning to the transducer
noise
low-level echoes on the display that do not contribute useful diagnostic information
output
output power; strength of the sound entering the patient
overall gain
receiver function that increases or decreases all of the echo amplitudes equally
picture archiving and communication system (PACS)
a type of display and storage device commonly used in sonography and other imaging modalities
pixel (picture element)
the smallest component of 2D digital image
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
preprocessing
occurs in the A to D converter; the image must be live
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
postprocessing
occurs in the D to A converter; the image must be frozen
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
pulser
part of the beam former that controls the amount of energy in the pulse
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
read zoom
the type of magnification performed in the D to A converter (post processing) that magnifies the image by enlarging the pixels
receiver / signal processor
the component of the machine that processes the signals coming back from the patient
rectification
the part of the receiver that inverts the negative voltages to positives
rejection
function of the receiver that is used to reduce image noise; sets a threshold below which the signal will not be displayed
reverberation
an artifact caused by the beam bouncing between 2 strong reflectors
ring down
an artifact caused by vibration of air bubbles
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
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
shadowing
an artifact caused by the failure of sound to pass through a strong attenuator
side lobes
an artifact caused by extraneous sound that is not found along the primary beam path; occurs with single-element transducers
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
smoothing
part of the demodulation component of the receiver; an envelope is wrapped around the signal to eliminate the humps
spatial compounding
technique that eliminates edge shadowing because the object is imaged at different angles
speckle reduction
algorithm used in signal processing to reduce the amount of acoustic speckle
specular reflectors
large, flat, smooth boundaries that cause reflection
subdicing
dividing the piezoelectric elements into very small pieces to reduce grating lobes
transmit / receive switch
ensures the electrical signals travel in the correct direction
voxel (volume element)
the smallest component of a 3D image
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
x - axis
the plane that is perpendicular to the beam path
y - axis
the plane that is parallel to the beam path
z - axis
the brightness (amplitude) of the dots on the display
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
angle correction
the tool used to inform the machine what the flow angle is so that velocities can be accurately calculated
auto correlation
the color Doppler processing technique that assesses pixels as stationary or in motion
BART
the acronym used to describe color Doppler scale “blue away, red toward”
baseline
the operator adjustable dividing line between positive frequency shifts and negative frequency shifts on spectral and color Doppler
Bernoulli’s principle
the principle that describes the inverse relationship between velocity and pressure
bidirectional Doppler
the Doppler deice that can detect positive and negative Doppler shifts
boundary layer
the stationary layer of blood cells immediately adjacent to the vessel wall
brightness
the term describing the intensity or luminance of the color Doppler display
calf muscle pump
the muscles in the calf that upon contraction propel venous blood toward the heart
capacitance
the ability of veins to store blood
clutter
acoustic noise in the color and/or spectral Doppler signal
collateral blood vessels
accessory vessels that connect portions of the same blood vessel together
color Doppler imaging
Doppler shift information presented as a color hue superimposed over the grayscale image
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
continuity equation
the equation that describes the change in velocity as the area changes in order to maintain the volume of blood flow
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
critical stenosis
the point at which a stenosis is hemodynamically significant within a pressure drop distal to the stenosis
depth ambiguity
the inability to determine the depth of the reflector if the pulses are sent out too fast for them to be timed
diastole
the relaxation of the heart following contraction
Doppler effect
the change in the frequency of the received signal related to motion of reflector
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
duplex
real-time 2D imaging combined with the spectral Doppler display
effective resistance
the sum of the individual resistances when multiple vessels are connected in series
energy gradient
the difference in energy between 2 points
ensemble length / packet size
the number of pulses per scan line in color Doppler
extrinsic pressure
pressure applied to the outside of an object
fast Fourier transform
a mathematical process used for analyzing and processing the Doppler signal to produce the spectral waveform
flash artifact
a motion artifact caused by the movement of tissue when using power doppler
flow
the volume of blood per unit time; typically measured in liter per minute or mililiter per second; represented by the symbol Q
frequency shift
the difference between the transmitted and received frequencies
friction
a form of resistance caused by 2 materials rubbing against each other; thereby converting energy to heat
hemodynamics
the study of blood flow through the blood vessels of the body
hue
a term used to describe displayed colors
hydrostatic pressure
describes the relationship between gravity, density of the blood, and distance between an artery’s reference point
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
angle correction
the tool used to inform the machine what the flow angle is so that velocities can be accurately calculated
autocorrelation
the color Doppler processing technique that assesses pixels as stationary or in motion
BART
the acronym used to describe color Doppler scale
baseline
the operator-adjustable dividing line between positive frequency shifts and negative frequency shifts on spectral and color Doppler
Bernouilli’s principle
the principle that describes the inverse relationship between velocity and pressure
bidirectional Doppler
the Doppler device that can detect positive and negative Doppler shifts
boundary layer
the stationary layer of blood cells immediately adjacent to the vessel wall
brightness
the term describing the intensity or luminance of the color Doppler display
calf muscle pump
the muscles in the calf that, upon contraction, propel venous blood toward the heart
capacitance
the ability of veins to store blood
clutter
acoustic noise in the color and/or spectral Doppler signal
collateral blood vessels
accessory vessels that connect portions of the same blood vessel together
color Doppler imaging
Doppler shift information presented as a color hue superimposed over the grayscale image
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
continuity equation
the equation that describes the change in velocity as the area changes in order to maintain the volume of blood flow
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
critical stenosis
the point at which a stenosis is hemodynamically significant with a pressure drop distal to the stenosis
depth ambiguity
the inability to determine the depth of the reflector if the pulses are sent out too fast for them to be timed
diastole
the relaxation of the heart following contraction
Doppler effect
the change in the frequency of the received signal related to motion of reflector
Doppler equation
the equation that explains the relationship of the Doppler frequency shift to the frequency of the transducer, and the propagation speed
duplex
real-time 2D imaging combined with the spectral Doppler display
effective resistance
the sum of the individual resistances when multiple vessels are connected in series
energy gradient
the difference in energy between 2 points
ensemble length / packet size
the number of pulses per scan line in color Doppler
extrinsic pressure
pressure applied to the outside of an object
fast Fourier transform
a mathematical process used for analyzing and processing the Doppler signal to produce the spectral waveform
flash artifact
a motion artifact caused by the movement of tissue when using power Doppler
flow
the volume of blood per unit time; typically measured in liter per minute or mililiter per second (represented by Q)
frequency shift
the difference between the transmitted and received frequencies
friction
a form of resistance; caused by 2 materials rubbing against each other, converting energy to heat
hydrostatic pressure
describes the relationship between gravity, density of the blood, and distance between an arbitrary reference point
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
innervated
supplied with nerves
kinetic energy
the energy form of flowing blood
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
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
luminance
the brightness of the color Doppler image
mm Hg
milimeters of mercury
noise
low-level echoes on the display that do not contribute useful diagnostic information
nondirectional Doppler
Doppler device that cannot differentiate between positive and negative frequency shifts
nonhemodynamically significant stenosis
a stenosis that does not necessarily compromise blood flow to organs or structures
Nyquist limit
the maximum frequency shift sampled without aliasing; equal to one half the PRF
Ohm’s Law
a law used in electronics in which flow is equal to the pressure differential divided by resistance
oscillator
the component of a continuous - wave Doppler device that produces the voltage that drives the transducer
persistence
the averaging of color frames in order to display blood flow with a low signal-to-noise ratio
phase quadrature
the component of the Doppler device that determines positive opposed to negative frequency shifts and direction of blood flow
phasic flow
the characteristic waveform of peripheral veins; flow is determined by respiratory variations as a result of intrathoracic pressure changes
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)
plug flow
the flow profile represented by blood typically flowing at the same velocity
Poiseuille’s Law
the law that describes the relationship of resistance, pressure, and flow
potential energy
pressure energy created by the beating heart
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
pressure gradient
the difference between pressures at two points of a blood vessel
pulsatility
blood that flows in a pattern representative of the beating heart, with increases and decreases in pressure and blood flow velocity
pulsatility index
Doppler measurement used to determine how pulsatile a vessel is over time
pulse repetition frequency
the number of pulses of sound produced in 1 second
pulsed-wave Doppler
the Doppler technique that uses pulses of sound to obtain Doppler signals from a user-specified depth
range gate
the gate placed by the operator in the region where Doppler sampling is desired; used with pulsed-wave Doppler
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
rayleigh scatterers
very small reflectors (RBC’s)
resistance
the downstream impedence to flow; determined by vessel length, vessel radius, and viscosity of blood
resistive index
Doppler measurement used to quantitate the resistiveness of the distal bed
Reynolds number
the formula used to quantitate the presence of turbulence; Reynolds numbers greater than 2000 typically indicate turbulence
sample volume
the area within the range gate where the Doppler signals are obtained
saturation
the amount of white added to a hue; the more white there is, the less saturated the color
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;
speckle tracking
the method used to obtain the strain information
spectral broadening
the filling of the spectral window
spectral window
the area underneath the envelope on the spectral display
stenosis
pathologic narrowing of a blood vessel
strain
the changing of the shape of the muscle as it lengthens and contracts
sweep speed
the operator-adjustable spectral Doppler control that increases or decreases the number of heartbeats visualized on spectral display
systole
the time period of the cardiac cycle when the heart is contracting
tardus parvus
an arterial waveform shape with a delayed peak systolic upstroke that indicates proximal obstruction
thrombus
combination of platelets, red blood cells, and fibrin that make up a blood clot
tissue Doppler imaging
color DOppler imaging technique used to document wall motion
transmural pressure
the difference in pressure inside a vessel compared to the pressure outside of the vessel
triplex
the ability to visualize real time grayscale, color Doppler, and spectral Doppler simultaneously
tunica adventitia
the outer layer of a blood vessel
tunica intima
the inner layer of a blood vessel which is closest to the flowing flood
tunia media
the middle, muscular layer of blood vessel
turbulent flow
chaotic, disorderly flow of blood
variance mode
the color Doppler scale with mean velocities displayed vertically on the scale and turbulence displayed horizontally
vasa vasorum
a network of small blood vessels that supply blood to the walls of arteries and veins
vasoconstriction
the narrowing of a blood vessel caused by the contraction of the vessel wall
vasodilatation
the widening of a blood vessel caused by the relaxation of the vessel wall
velocity mode
the color Doppler scale with mean velocities displayed vertically
viscous energy
the energy loss caused by friction
wall filter / high - pass filter
the operator control that eliminates low frequency, high amplitude signals caused by wall or valve motion
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
axial resolution
the ability to accurately identify reflectors that are arranged parallel to the U/S beam
contrast resolution
the ability to differentiate one shade of gray from another
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
elevational plane / slice -thickness plane
the resolution in the 3rd dimension of the beam
horizontal calibration
the ability to place echoes in the proper location horizontally and perpendicular to the sound beam
lab accreditation
a voluntary process that acknowledges an organization’s competency and credibility according to standards and essentials set forth by a reliable source
lateral resolution
the ability to accurately identify reflectors that are arranged perpendicular to the U/S beam
preventative maintenance
a methodical way of evaluating equipment’s performance on a routine basis to ensure proper and accurate equipment function
quality assurance program
a planned program consisting of scheduled equipment testing activities that confirm the correct performance of equipment
registration
the ability to place echoes in the correct location
sample volume
the area within the range gate where the Doppler signals are obtained
sensitivity
the ability of a system to display low-level or weak echoes
slice thickness phantom
the test object that evaluates the elevational resolution, or the thickness portion, of the sound beam perpendicular to the imaging plane
tissue equivalent phantom
the test object that mimics the acoustic properties of human tissue and is used to ensure proper equipment performance
vertical depth
the distance from the transducer
acoustic cavitation
the production of bubbles in a liquid medium
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
ALARA
As Low As Reasonably Achievable / keep patient exposure minimal
automatic external defibrillator
a portable device that is used to detect and treat abnormal heart rhythms with electrical defibrillation
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
diabetes mellitus
a group of metabolic diseases that result from a chronic disorder of carbohydrates metabolism
diabetic ketoacidosis
a complication of diabetes that results from the severe lack of insulin
elastography
a sonographic technique used to evaluate the stiffness of a mass or tissue
ergonomics
the scientific study of creating tools and using equipment effectively in order to help the human body adjust to the work environment
fusion imaging / hybrid imaging
technology that provides the ability to view alternate imaging modality (CT / MRI) during real time sonography
Health Insurance Portability and Accountability Act
US law which upholds patient confidentiality and requires the use of electronic medical records
hyperglycemic hypersmolar nonketotic syndrome
a diabetic syndrome characteristics by excessive urination and dehydration
intravascular U/S
the technique that employs a miniature U/S transducer placed on a catheter and inserted into the circulatory system
mechanical index
the calculation used to identify the likelihood into the circulatory system
nonsocomial infection
a hospital - acquired infection
radiation forces
forces exerted by a sound beam on an absorber or reflector that can alter structures
shear wave elastography
elastography technique that uses shear wave information to analyze the stiffness of tissue
shock
the body’s pathologic response to illness, trauma, or severe physiologic or emotional stress
strain elastrography
operator dependent type of elastography that measure the change in tissue as a result of compression
streaming
when acoustic fields cause motion of fluids
thermal index
the calculation used to predict the maximum temperature elevation in tissues as a result of the attenuation of sound
