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DMU physics final
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A linear array transducer creates a _____ image
rectangular
contrast agents are
called microbubbles
can be swallowed
strong reflectors of ultrasound
shallow imaging has
higher frame rate
shorter go-return time
superior temporal resolution
when frame rate increases, ____ resolution improves
temporal
harmonic frequency arises from
non-linear behavior
low MI has _____ harmonics
no
high line density improves individual images with images containing more detail. this improves
spatial resolution
a damaged crystal array
displays a single shadow on the overall image
has to be reported
what is the dynamic range of an ultrasound system that can process voltages ranging from 5 volts to 5000 volts
60 dB
with linear phased array transducers, ___ crystals are fired to create each sound pulse
all
high MI causes
bubbles to rupture
strong harmonics
fundamental frequency is
frequency created by the transducer
affects the number of pulses
sector size
line density
number of focal points
dynamic range is measured in
dB
a mechanical transducer has
mechanical steering
frame rate is affected by
speed of sound in the medium
imaging depth
harmonic frequency is
twice the fundamental frequency
the second harmonic frequency
artifacts created by array transducers are called
grating lobes
frame rate and Tframe are ______________ related
inversely
if a transducer transmits a fundamental frequency of 2 MHz the harmonic frequency will be
4 MHz
the main advantage of multiple focal zones is it provides excellent ____ resolution
later
the amount of contrast harmonics produced can be estimated by a number called ---
the mechanical index (MI)
slice thickness resolution is also called
elevational resolution
an amplifier increases a voltage from 5 to 5000 volts. how many decibels of gain is this?
40
imaging depth and number of pulses in each picture
determine frame rate
are controlled by the sonographer
what determines the frame rate on an ultrasound machine
imaging depth
speed of sound in the medium
what increases temporal resolution
narrow sector
single focus
shallow imaging
low line density
contrast harmonics result from
non linear behavior of microbubbles
number of lines per frame and the frame rate determine the
PRF
wide sector image will
inferior temporal resolution
lower frame rate
more pulses per frame
if a sonographer turns off the multi-focus feature, what would happen?
temporal resolution improves
dynamic aperture is a form of
recieve electronic focusing
accomplished by varying the number of crystals being used to recieve the reflected signal coing back from the body
convex transducers have a blunted ____top
fan shaped
annular arrays
use inner crystals for shallow regions
have larger diameter rings that have a deep focal length
use outer crystals to image outer regions
have small diameter rings with a shallow focus that diverges rapidly
phased arrays typically have _____ crystals
100 - 500
linear switched or sequential arrays
rectangular shaped
large transducers with approx 200 crystals or elements arranged in a line that are fired at different times in sequence
have no steering and are fixed focusing
Author
patty.espinoza26@yahoo.com
ID
35656
Card Set
DMU physics final
Description
DMU physics final review
Updated
2010-09-19T06:38:47Z
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