Kremkau Chapter 4 Key Terms Flashcards
compression
reduction in difference between small and large amplitudes. region of high density and pressure in a compressional wave.
scan line
a line produced on a display that represents ultrasonic echoes returning from the body. a sonographic image is composed f many scan lines
shear wave
transverse wave
stress
a force per unit area applied to a material that compresses or stretches it
postprocessing
image processing done after storage in the memory
contrast resolution
ability of a gray scale display to distinguish between echoes of slightly different intensities.
picture archiving and communications systems
the system provides means for electronically communicating images and associated information to work stations and devices external to the sonographic instrument, the examining room, and even the building in which the scanning is done. PACS
bandpass filter
passes a range of frequencies (its bandwidth) and rejects those above and below the acceptance bandwidth.
channel
a single 1 or 2 way path for transmitting electric signals, in distinction to other parallel paths; an independent transmission delay line and transducer element path
analog to digital converter
a device that converts voltage amplitude to a number. ADC
temporal resolution
ability to distinguish closely spaced events in time; improves with increased frame rate
real time display
a display that, with a sufficient frame rate, appears to image moving structures or a changing scan plane continuously
compensation
equalization of received echo amplitude differences caused by different attenuations for different reflector depths. aka TGC DGC
persistence
averaging sequential planes together.
detection
conversion of voltage pulses from radio frequency to video form.
a mode
mode of operation in which the display presents echo amplitude versus depth
elastography
imaging tissue stiffness by tracking movement under mechanical stress
cine loop
sequential display of all the frames stored in memory at a controllable frame rate.
refresh rate
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
young’s modulus
a measure of the hardness of a material. it is the ratio of the applied stress to the resulting strain in a material subjected to the stress.
amplifier
a device that accomplishes amplification
analog
related to a procedure or system in which data are represented by proportional, continuously variable, physical quantities
scanning
the sweeping of a sound beam through the anatomy to produce an image.
signal
information bearing voltages in an electric circuit
TGC
equalization of echo amplitude differences caused by different attenuations for different reflector depths.
frame rate
number of frames of echo information stored each second
signal processor
an electronic device that manipulates electric signals in preparation for appropriate presentation of information contained in them
digital
related to a procedure or system in which data are represented by numeric digits
freeze frame
constant display of one of the frames in memory
frame
a single image produced by one complete scan of the sound beam
lateral gain control
gain controls that enable different gain values to be applied laterally across an image to compensate for differing attenuation values in different anatomic regions
bit
binary digit; one or zero
gain
ratio (dB) of amplifier output to input electric power
real time
imaging with a rapid frame sequence display
dynamic range
ration (dB) of largest to smallest power that a system can handle; ratio of the largest to smallest intensity of echoes encountered
panoramic imaging
the extension of the field of view beyond the normal limits of a transducer scan plane
b mode
mode of operation in which the display presents a spot of appropriate brightness for each echo received by the transducer
gray scale
range of brightness between white and black
pixel
picture element; the unit into which imaging information is divided for storage and display in a digital instrument
digital to analog converter
a device that converts a number to a proportional voltage amplitude. DAC
strain
the increase or decrease of the length of a segment of a material, subjected to a stress, divided by its original length
image memory
the part of the image processor where echo information is stored in image format
preprocessing
signal and image processing accomplished before storage in the memory
b scan
a b mode image that represents an anatomic cross section through the scanning plane.
coded excitation
a sophisticated form of transmission in which the driving voltage pulses have intrapulse variations in amplitude, frequency, and or phase.
bistable
having two possible states.
display
a device that presents a visual image derived from voltages received from an image processor
image processor
an electronic device that manipulates and prepares images for visual presentation
depth gain compensation
same as compensation. aka DGC
volume imaging
3D imaging
flat panel display
a backlighted rectangular matrix of thousands of liquid crystal display elements.
spatial compounding
averaging of frames that view the anatomy from different angles
m mode
a b mode presentation of changing reflector position( motion) versus time
demodulation
detection
radio frequency
voltages representing echoes in cyclic form
amplification
the process by which small voltages are increased to larger ones
