Physics Final Kremkau Vocabulary Flashcards
Mode of operation in which the display presents echo amplitude versus depth (used in opthamology)
A mode
conversion of sound to heat
absorption
having to do with sound
acoustic
pressure, density, and particle vibration; sound wave quantities that vary in space and time
acoustic variables
as low as reasonably achievable. The principle that is prudent to obtain diagnostic information with the least amount possible of energy exposure to the patient
ALARA
Improper doppler-shift information from a pulsed spectral-Doppler or color-Doppler instrument when the true Doppler shift exceeds one-half the pulse repetition frequency
aliasing
the process by which small voltages are increased to larger ones
amplification
a device that accomplishes amplification
amplifier
maximum variation of an acoustic variable or voltage
amplitude
related to a procedure or system in which data are represented by proportional, continuously variable, physical quantities
analog
a device that converts voltage amplitude to a number. Abbreviated ADC
analog to digital converter
echo free
anechoic
size of a transducer element (for a single element transducer) or group of elements (for an array)
aperture
nonuniform driving of elements in an array to reduce grating lobes
apodization
a transducer assembly containing several piezoelectric elements
array
decrease in amplitude and intensity with distance as a wave travels through a medium
attenuation
attenuation per centimeter of wave travel
attenuation coefficient
A rapid technique, used in most Color-Doppler instruments, to obtain mean Doppler-shift frequency
autocorrelation
in the direction of the transducer axis (sound travel direction)
axial
the minimum reflector separation along the sound path that is required to produce separate echoes
axial resolution
Mode of operation in which the display presents a spot of appropriate brightness for each echo received by the transducer
B mode
a B-mode image that represents an anatomic cross section through the scanning plane
B scan
sound scattered back in the direction from which it originally came
backscatter
range of frequencies contained in an ultrasound pulse; range of frequencies within which a material, device, or system can operate
bandwidth
movement of the zero Doppler-shift frequency or zero flow speed line up or down on a spectral display
baseline shift
region containing continuous wave sound; region through which a sound pulse propagates
beam
the part of an instrument that accomplishes electronic beam scanning, apodization, steering, focusing, and aperture with arrays
beam former
pressure reduction in a region of high-flow speed
Bernoulli effect
indicating Doppler instruments capable of distinguishing between positive and negative Doppler shifts (approaching and receding flow)
bidirectional
having two possible states
bistable
binary digit; one or zero
bit
production and dynamics of bubbles in sound
cavitation
a single one- or two-way path for transmitting electric signals, in distinction from other parellel paths; an independent transmission delay line and transducer element path; an independent reception transducer element, amplifier, analong-to-digital converter, and delay line path
channel
sequential display of all the frames stored in memory at a controllable frame rate
cine loop
noise in the Doppler signal that generally is caused by high-amplitude, Doppler-shifted echoes from the heart or vessel walls
clutter
capacative micromachined ultrasonic transducer that contains miniature elements that are comprised of two electrically conducting layers facing each other; one of which is fixed and the other of which is a flexible membrane
CMUT
a sophisticated form of transmission in which the driving voltage pulses have intrapulse variations in amplitude, frequency, and/or phase.
coded excitation
the presentation of two-dimensional, real-time Doppler-shift information in color superimposed on a real-time, gray-scale, anatomic, cross-sectional image. Flow directions toward and away from the transducer are presented as different colors on the display
color-Doppler display
a series of closely spaced reverberation echoes
comet tail
equalization of received echo amplitude differences caused by different attenuations for different reflector depths; also called depth gain compensation or time gain compensation
compensation
distensibility; nonrigid stretchability of vessels
compliance
combination of a piezoelectric ceramic and a nonpiezoelectric polymer
composite
reduction in differences between small and large amplitudes. Region of high density and pressure in a compressional wave
compression
combination of positive or negative pressures
constructive interference
a wave in which cycles repeat indefinitely; not pulsed. Abbreviated CW
continuous wave
A Doppler device or procedure that uses continuous wave ultrasound
continuous wave doppler
a suspension of bubbles or particles introduced into circulation to enhance the contrast between anatomic structures, thereby improving their imaging
contrast agen
ability of a gray-scale display to distinguish between echoes of slightly different intensities
contrast resolution
curved linear array
convex array
the cosine of angle A is the length of side b divided by the length of side c. abbreviated cos
cosine
a gel used to provide a good sound path between a transducer and the skin by eliminating the air between the two
coupling medium
the Reynolds number above which turbulence occurs
critical Reynolds number
leakage of strong signals in one direction channel of a Doppler receiver into the other channel; can produce the spectral-Doppler mirror-image artifact
cross-talk
element
crystal
temperature at which an element material loses its piezoelectric properties
curie point
one complete variation of an acoustic variable
cycle
material attached to the rear face of a transducer element to reduce pulse duration; the process of pulse duration reduction
damping
unit of power or intensity ratio; the number of decibels is 10 times the logarithm (to the base of 10) of the power or intensity ratio. Abbreviated dB.
decibel
detection
demodulation
mass divided by volume
density
combination of positiver and negative pressures
destructive interference
the ability to image fine detail and to distinguish closely spaced reflectors
detail resolution
conversion of voltage pulses from radio frequency to video form
detection
related to a procedure or system in which data are represented by numeric digits
digital
a device that converts a number to a proportional voltage amplitude. Abbreviated DAC.
digital-to-analog converter
a thin, flat, circular object
disk
a device that presents a visual image derived from voltages received from an image processor
display
flow that cannot be described by straight, parallel streamlines
disturbed flow
the angle between the sound beam and the flow direction
Doppler angle
a change in frequency caused by reflector motion
Doppler effect
the mathematical description of the relationship between the Doppler shift, frequency, Doppler angle, propagation speed, and reflector speed
Doppler equation
color-doppler display in which colors are assigned according to the strength (amplitude, power, intensity, energy) of the Doppler-shifted echoes
Doppler-power display
reflected frequency minus incident frequency; the change in frequency caused by motion
Doppler shift
the range of frequencies present in Doppler-shifted echoes
Doppler spectrum
an ultrasound instrument that combines gray-scale sonography with pulsed Doppler and, possibly, continuous wave Doppler
duplex instrument
fraction of time that pulsed ultrasound is on
duty factor
aperture that increases with increasing focal length (to maintain constant focal width)
dynamic aperture
continuously variable reception focusing that follows the increasing depth of the transmitted pulse as it travels
dynamic focusing
ratio (in decibels) of largest to smallest power that a system can handle; ratio of the largest to smallest intensity of echoes encountered
dynamic range
reflection
echo
regions of circular flow patterns present in turbulence
eddies
imaging tissue stiffness by tracking movement under mechanical stress
elastography
the piezoelectric component of a transducer assembly
element
the detail resolution in the direction perpendicular to the scan plane. It is equal to the section thickness and is the source of section thickness artifact
elevational resolution
capability of doing work
energy
increase in echo amplitude from reflectors that lie behind a weakly attenuating structure
enhancement
number of pulses used to generate one color-Doppler image scan line
ensemble length
the region of a sound beam in which the beam diameter increases as the distance from the transducer increases
far zone
digital computer implementation of the Fourier transform
fast Fourier transform
an electric circuit that passes frequencies within a defined range
filter
a backlighted rectangular matrix of thousands of liquid-crystal display elements
flat-panel display
to move in a stream; volume flow rate
flow
a material that flows and conforms to the shape of its container;a gas or liquid
fluid
distance from a focused transducer to the center of a focal region or to the location of the spatial peak intensity
focal length
region of minimum beam diameter and area
focal region
length of the focal region
focal zone
the concentration of the sound beam into a smaller beam area than would exist otherwise
focus
a mathematical technique for obtaining a Doppler frequency spectrum
Fourier transform
bandwidth divided by operating frequency
fractional bandwidth
a single image produced by one complete scan of the sound bream
frame
number of frames of echo information stored each second
frame rate
far zone
Fraunhofer zone
constant display of one of the frames in memory
freeze
number of cycles per second
frequency
the range of Doppler-shift frequencies present in the returning echoes
frequency spectrum
near zone
fresnel zone
the primary frequency in a collection of frequencies that can include odd and even harmonics and subharmonics
fundamental frequency
ratio (in decibels) of amplifier output to input electric power
gain
a device that allows only echoes from a selected depth (arrival time) to pass
gate
an electronic device that rapidly performs calculations to accelerate the creation of images
graphics processing unit (GPU)
additional weaker beams of sound traveling out in directions different from the primary beam as a result of the multielement structure of transducer arrays
grating lobes
range of brightness (gray levels) between white and black
gray scale
frequencies that are even and odd multiples of another, commonly called fundamental or operating frequency
harmonics
unit of frequency, one cycle per second; unit of pulse repetition frequency, one pulse per second
hertz
the color perceived based on the frequency of light
hue
a small transducer element mounted on the end of a narrow tube; a piezoelectric membrane with small metallic electrodes
hydrophone
having relatively weak echoes. Opposite of hyperechoic (having relatively strong echoes)
hypoechoic
a reproduction, representation, or imitation of the physical form of a person or a thing
image
the portion of a system operating on Principle 2 that acquires the echo information from the signal processor, performs the retrospective, virtual-beam computations and sends the results to the display.
image former
the part of the image processor where echo information is stored in image format
image memory
an electronic device that manipulates and prepares images for visual presentation
image processor
density multiplied by the sound propagation speed
impedance
angle between incident sound direction and a line perpendicular to the boundary of a medium
incidence angle
resistance to acceleration
inertia
an electronic system that electrically drives a transducer, receives returning echoes, and presents them on a visual display as an anatomic image, Doppler spectrum, or color-Doppler presentation
instrument
power divided by area
intensity
reflected intensity divided by incident intensity; the fraction of incident intensity transmitted into the second medium
intensity reflection coefficient
transmitted intensity divided by incident intensity; the fraction of incident intensity transmitted into the second medium
intensity transmission coefficient
combinations of positive and/or negative pressures
interference
one thousand hertz
kilohertz
flow in which fluid layers slide over each other in a smooth, orderly manner, with no mixing between layers
laminar flow
perpendicular to the direction of sound travel
lateral
gain controls that enable different gain values to be applied laterally across an image to compensate for differing attenuation values in different anatomic regions
lateral gain control
minimum reflector separation perpendicular to the sound path that is required to produce separate echoes
lateral resolution
a ceramic piezoelectric material
lead zirconate titanate
a curved material that focuses a sound or light beam
lens
adjectival form of line
linear
array made of rectangular elements arranged in a straight line
linear array
an anatomic image presented in a rectangular format
linear image
linear array operated by applying voltage pulses to all elements, but with small time differences (phasing) to direct ultrasound pulses out in various directions
linear phased array
linear array operated by applying voltage pulses to groups of elements sequentially
linear sequenced array
wave in which the particle motion is parellel tot he direction of wave travel (compressional wave)
longitudinal wave
brightness of a presented hue and saturation
luminance
A B-mode presentation of changing reflector position (motion) versus time (used in echocardiography)
M mode
measure of the resistance of an object to acceleration
mass
material attached to the front face of a transducer element to reduce the reflections at the transducer surface
matching layer
an indicator of nonthermal mechanism activity; equal to the peak rarefactional pressure divided by the square root of the center frequency of the pulse bandwidth
mechanical index
material through which a wave travels
medium
one million hertz
megahertz
an artifactual gray-scale, color flow, or Doppler signal appearing on the opposite side of a strong reflector
mirror image
several reflections produced by a pulse encountering a pair of reflectors; reverberation
multiple reflection
the narrowing of a sound beam that occurs with an unfocused flat transducer element
natural focus
the region of a sound beam in which the beam diameter decreases as the distance from the transducer increases
near zone
sound propagation in which the propagation speed depends on pressure causing the wave shape to change and harmonics to be generated
nonlinear propagation
the Doppler-shift frequency above which aliasing occurs; one-half of the pulse repetition frequency
Nyquist limit
sound direction that is not perpendicular to media boundaries
oblique incidence
preferred frequency of operation of a transducer
operating frequency
in operating principle 1, positional information is determined by knowledge of the direction of the pulse when it enters the patient and by measurment of the time it takes for each echo to return to the transducer. The proper location to present the echo can then be determined from a starting point on the display (usually at the top). With knowledge of the sound speed, the instrument uses the echo arrival time to determine the depth of the structure that produced that echo
Operating Principle 1
Operating principle 2 sends several pulses of ultrasound through the cross section of anatomy to be imaged but does not produce a one-for-one correspondence of pulse and displayed scan line. Instead, all the echo information from throughout the anatomic cross section is collected, and then massive computational processes determine the location and strength of each echo produced at each location in the anatomy. This approach is used in recent, sophisticated instruments and produces improved quality compared with Principle 1.
Operating Principle 2
the extension of the field of view beyond the normal limits of a transducer scan plane
panoramic imaging
laminar flow with a profile in the shape of a parabola
parabolic flow
imaging depth
penetration
time per cycle
period
geometrically related by 90 degrees
perpendicular
sound direction that is perpendicular to the boundary between media
perpendicular incidence
averaging sequential frames together
persistence
tissue-equivalent device that has characteristics that are representative of tissues
phantom
a description of progress through a cycle; one full cycle is divided into 360 degrees of phase
phase
two signals differing by one-fourth of a cycle
phase quadrature
an array that steers and focuses the beam electronically (with short time delays)
phased array
linear sequenced array with phased focusing added; linear sequenced array with phased steering of pulses to produce a parallelogram-shaped display
phased linear array
the system provides means for electronically communicating images and associated information to workstations and devices external to the sonographic instrument, the examining room, and even the building in whcih the scanning in done
picture archiving and communications system
conversion of pressure to electric voltage
piezoelectricity
picture element; the unit into which imaging information is divided for storage and display in a digital instrument
pixel
flow with all fluid portions traveling with the same flow speed and direction
plug flow
unit of viscosity
poise
the mathematical description of the dependence of volume flow rate on pressure, vessel length and radius, and fluid viscosity
Poiseuille equation
imaging processing done after storage in the memory
postprocessing
rate at which work is done; rate at which energy is transferred
power
signal and image processing accomplished before storage in the memory
preprocessing
force divided by the area in a fluid
pressure
the gray-scale echo strength below which color-Doppler information is shown preferentially on a display
priority
transducer assembly
probe
progession or travel
propagation
speed at which a wave moves through a medium
propagation speed
flow that accelerates and decelerates with each cardiac cycle
pulsatile flow
a description of the relationship between peak systolic and end diastolic flow speeds of Doppler shifts
pulsatility index
a brief excursion of a quantity from its normal value; a few cycles
pulse
interval of time from beginning to the end of a pulse
pulse duration
number of pulses per second
pulse-repetition frequency
interval of time from the beginning of one pulse to the beginning of the next
pulse repetition period
a Doppler device or procedure that uses pulsed-wave ultrasound
pulsed Doppler
ultrasound produced in pulsed form by applying electric pulses or voltages of one or a few cycles to the transducer
pulsed ultrasound
ultrasound imaging in which pulses are reflected and used to produce a display
pulse-echo technique
the force exerted by a sound beam on an absorber or a reflector
radiation force
voltages representing echoes in cyclic form
radio frequency
an artifact produced when echoes are placed too close to the transducer because a second pulse was emitted before they were received from the first pulse
range ambiguity
relationship between round-trip pulse travel time, propagation speed, and distance to a reflector
range equation
selection of the depth from which echoes are accepted based on echo arrival time
range gating
region of low density and pressure in a compressional wave
rarefaction
unit of impedance
rayl
imaging with a rapid frame sequence display
real time
a display that, with a sufficient frame rate, appears to image moving structures or a changing scan plane continuously
real-time display
portion of sound returned from a media boundary; echo
reflection
angle between the reflected sound direction and a line perpendicular to the media boundary
reflection angle
media boundary that produced a reflection; reflecting surface
reflector
change of sound direction on passing from one medium to another
refraction
the number of times each second that information is sent from the image memory to the display. The number of times per second that a computer monitor redraws the information found in the memory
refresh rate
pressure difference divided by volume flow rate for steady flow
resistance
the ability to distinguish echoes in terms of space, time, or strength
resolution
the condition in which a driven mechanical vibration is of a frequency similar to a natural vibration frequency of the structure, yielding maximum response
resonance
operating frequency
resonance frequency
multiple reflection
reverberation
a number that depends on flow speed and viscosity to predict the onset of turbulence
Reynolds number
the anatomic region from which pulsed Doppler echoes are accepted
sample volume
the amount of hue present in a mix with white
saturation
a line produced on a display that represents ultrasonic echoes returning from the body. A sonographic image is composed of many such lines
scan line
transducer assembly
scanhead
the sweeping of a sound beam through the anatomy to produce an image
scanning
an object that scatters sound in many directions because of its small size or fits surface roughness
scatterer
diffusion or redirection of sound in several directions upon encountering a particle suspension or a rough surface
scattering
a geometric figure bounded by two radii and the arc of the circle included between them
sector
an anatomic image presented in a pie slice- shaped format
sector image
ability of an imaging system to detect weak echoes
sensitivity
reduction in echo amplitude from reflectors that lie behind a strongly reflecting or attenuating structure
shadowing
weaker beams of sound traveling out from a single element in directions different from those of the primary beam
side lobes
information-bearing voltages in an electric circuit; an acoustic, visual, electric, or other conveyance of information. The physical representation of a message or information
signal
an electronic device that manipulates electric signals in preparation for appropriate presentation of information contained in them
signal processor
thickness of the scanned tissue volume perpendicular to the scan plane
slice thickness
medical two-dimensional, cross-sectional, and three-dimensional anatomic and flow imaging using ultrasound
sonography
traveling wave of acoustic variables
sound
the region of a medium that contains virtually all of the sound produced by a transducer
sound beam
an emitter of ultrasound; transdcuer
source
averaging of frames that view the anatomy from different angles
spatial compounding
length of space over which a pulse occurs
spatial pulse length
the granular appearance of images and spectral displays that is caused by the interference of echoes from the distribution of scatterers in tissue
speckle
separation of frequencies in a Doppler signal for display as a Doppler spectrum; the application of the Fourier transform to determine the frequency components present in a Doppler signal
spectral analysis
the widening of the Doppler-shift spectrum; that is, the increase in the range of Doppler-shift frequencies present that occurs because of a broadened range flow velocities encountered by the sound beam. This occurs for disturbed and turbulent flow
spectral broadening
the presentation of Doppler-information in a quantitative form of Doppler shift versus time. Visual display of a Doppler spectrum
spectral-Doppler display
a device that derives a frequency spectrum from a complex signal
spectrum analyzer
reflection from a large, flat, smooth boundary
specular reflection
propagation speed that is different from the assumed value
speed error
narrowing of a vessel lumen
stenosis
property of a medium; applied pressure divided by the fractional volume change produced by the pressure
stiffness
the increase or decreaseof the length of a segment of a material, subjected to a stress, divided by its original length
strain
a line representing the path of a motion of a particle of fluid
streamline
nonspecific term referring hear to amplitude or intensity
strength
a force per unit area applied to a material that compresses or stretches it
stress
ability to distinguish closely spaced events in time; improves with increased frame rate
temporal resolution
a device without tissue-like properties that is designed to measure some characteristic of an imaging system
test object
an indicator of thermal mechanism activity (estimated temperature rise); a value equal to transducer acoustic output power divided by the estimated power required to raise tissue temperature by 1 degree celcius
thermal index
equalization of echo amplitude differences caused by different attenuations for different reflector depths
time gain compensation
a device that converts energy from one form to antoher
transducer
transducer element(s) with damping and matching materials assembled in a case
transducer assembly
angle between the transmitted sound direction and a line perpendicular to the media boundary
transmission angle
a sound wave in which the particle motion is perpedicular to the direction of wave travel, also called a shear wave
transverse wave
random, chaotic, multidirectional flow of a fluid with mixing between layers; flow that is not laminar
turbulence
sound having a frequency greater than what humans can hear, that is, greater than 20 kHz
ultrasound
a device that converts electric energy to ultrasound energy, and vice versa
ultrasound transducer
square of standard deviation; one of the outputs of the autocorrelation process; a measure of spectral broadening
variance
linear sequenced array that emits pulses from different starting points and (by phasing) in different directions
vector array
an imaginary beam that describes the result of retrospective, computed beam forming. The virtual beam can be imagined in transmission or reception form
virtual beam
an imaginary reception beam that can be thought of as determine the echo produced at each pixel location in the image
virtual reception beam
an imaginary laser-thin transmitted ultrasound beam that can be thought of as producing the excellent detail resolution throughout the image that is accomplished with retrospective, computed beam forming
virtual transmission beam
resistance of a fluid to flow
viscosity
three-dimensional imaging
volume imaging
volume of fluid passing a point per unit of time
volumetric flow rate
an electric filter that passes frequencies above a set level and eliminates strong, low-frequency Doppler shifts from pulsating heart or vessel walls or tissue motion
wall filter
traveling variation of one or more quantities
wave
length of space over which a cycle occurs
wavelength
an anechoic region appearing beneath echo frequencies presented on a Doppler spectral display
window
a measure of the hardness (stiffness) of a material. It is the ratio of the applied stress to the resulting strain in a material subjected to the stress
Young’s modulus
an analog detector that yields mean Doppler shift as a function of time
zero-crossing detector
