Pulsed Echo Instrumentation Flashcards
anything not properly indicative of anatomy or motion imaged
artifact
group of bits
binary number
binary digit; smallest amount of computer memory
bit
group of 8 bits of computer memory
byte
imaging display ehere the strength of the electron beam determines the brightness
cathode ray tube (CRT)
an independent signal path consisting of a transducer element, delay, and other electronic components
channel
storage of the last several real time frames
cine loop
a series of pulses and gaps allowing multiple focal zones and harmonic frequencies
code excitation
a series of closely spaced reverberation echoes behind a strong reflector
comet tail
the ratio of the largest to smallest amplitude that the ultrasound system can handle
dynamic range
loss in intensity from bending of the sound beam at a curved surface
edge shadowing
the increase in reflection amplitude from structures that lie behind a weakly attenuating structure
enhancement
displayed image of the returning echoes
feild of view
a complete scan of the ultrasound beam; individual image composed of multiple scan lines
frame
the number of complete scans (images) displayed per second
frame rate
holding and displaying one frame of the real time sequence
freeze frame
ration of amplifier output to input of electric power
gain
secondary sound beams produced by a multielement transducer
grating lobes
number of scan lines per fram; scan line density
line density
denotes the rows and colums of pixels in a digital image
matrix
storage of echo information
memory
an artifactual gray scale, color flow, or doppler signal appearing on the opposite side of a strong reflector
mirror image
the path toward and away from a reflector are different
multipath
disturbance that reduces the clarity of the signal
noise
the minimum number oof samples required to avoid aliasing; doppler shift frequency above which aliasing occurs
nyquist limit
an expanded immage display beyond the normal limits of the transducer
panoramic image
picture element; smalles portion of a digital image
pixel
number of picture elements per inch
pixel density
assigning a brightness value to a missing pixel
pixel interpolation
a harmonic imaging technique using two pulses per scan line where the second pulse is an inverse of the first one
pulse inversion
the number of voltage pulses sent to the transducer each second
pulse rep frequency
time from the beginning of one pulse to the start of the next
pulse rep period
allows access of stored data in an unsystematic order
random access memory (RAM)
produced when echoes are placed too superficially because a second pulse was emitted before all reflections have returned from the first pulse
range ambiguity
stored data that cannot be modified
read only memory (ROM)
two dimensional imaging of the motion of moving structures
real time imaging
portion of the sound reflected from the boundary of a medium
reflection
change of sound direction on passing from one medium to another
refraction
multiple reflections between a structure and the transducer or within a structure
reverberation
redirection of sound in several directions on encountering a rough surface
scattering
reduction of reflective amplitude from reflectors that lie behind a strongly reflecting or attenuating structure
shadowing
comparision of meaningful information in an image (signal) to the amount of signal disturbance (noise)
signal to noise ratio
averging of frames that view anatomy from different angles
spatial compounding
large, flat, smooth surface
specular
the smallest distinguishable part of a 3 dimensional image
voxel
A-mode
amplitude mode
1-d
displays amplitude on y-axis and distance on x-axis
B-mode
brightness mode
2D imaging
y axis = increasing depth
x axis = side to side or superior to inferior aspects of body
the stronger the reflection the brighter the pixel
M-Mode
motion mode
1d
y axis = reflector depth
x axis = time
