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66 Cards in this Set

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(assumption 6), the intensity of a reflection is related to the characteristics of the tissue, is invalid that causes_____?
enhancement artifact
the opposite of the shallowing___?
enhancement artifact
enhancement artifact in clinic provides____?
diagnostic information
enhancement is unrelated to__?
the speed of sound travel in a medium
characteristics of enhancement artifact?
1. hyperechoic (appears the same as the foreground color)
2. too little attenuation
3. abnormally low attention
focal enhancement artifact____?
side-to-side image that appear brighter than tissue at other depth
focal enhancement artifact also called___?
focal banding
the most prominent at the focus is at____?
banding
characteristics of focal enhancement?
1. a hyperechoic side-to-side region(the same foreground color)
2. the result of increase intensity at the focus
sound reflect off of a strong reflector, and is redirected toward a second structure causes_____?
mirror image artifact
(assumption 1), sound travels in a straight line, and (assumption 2) sound travels directly to a reflector and back to the transducer, are invalid that cause______?
mirror image artifact
____is placed deeper that the real structure?
mirror artifact
_____always located along a straight line between the transducer and the artifact?
the mirror
mirror image artifact appear____?
in color Doppler
characteristics of mirror image?
1. a second copy of a true reflector
2. the copy appear deeper than the true reflector
3. bright reflector the mirror lies on a straightline between artifact and transducer
mirror image artifact that appear on a spectral Doppler display is called____?
crosstalk artifact
if sound wave propagates with a speed higher than the speed of soft tissue (1.54km/s), then create____?
speed error artifact
speed errors appear as____?
step-off, structure are split or cut
if medium's speed is faster than speed in soft tissue, then____?
1. sound travels faster than ultrasound system
2. pulses return fast
3. go return time is too short
4. reflector is close to transducer
5. reflector is shallow on image
6. distance underestimated (too small)
if medium's speed is slower than speed in soft tissue, then_____?
1. sound travel slower than ultrasound system
2. pulse return slow
3. go-return time too long
4. reflector far from transducer
5. reflector too deep
6. distance overestimated
propagation speed errors also called____?
range error artifact or range ambiguity artifact
(assumption 3), sound travels at a speed of exactly 1,540m/s, is invalid that cause____?
speed error artifact
characteristics of speed error?
1. correct number or reflector
2. improper depth
3. appear as a step off
sound is transmitted in a direction other than along the beam's main axis, cause___?
lobe artifacts
lobe artifact degrade____?
lateral resolution
lopes are____than the primary beam and do not create____?
weaker...reflection
if strong reflector in the path of the lobe, then creating____?
reflection
(assumption 2), reflections arise from structures located along the beam's main axis, is invalid, then creates____?
lobes artifacts
characteristics of lobe artifact?
1. a second copy of the true reflector
2. the artifact and the true reflector are side by side at the same depth
lobes created by a single crystal transducer (a mechanical probe) are called___?
side lobes
lobes created by array transducers are called___?
grating lobes
dividing each PZT element into small piece called subdicing that reduces____?
grating lobes
apodization reduces____?
grating lobes
if a sound pulse changes direction during transmission, then creates___?
refraction artifact
a sound wave strike a boundary obliquely and with different propagation speed, it occurs___?
refraction
_____degrades lateral resolution?
refraction artifact
(assumption 1), sound travels in a straight line , is invalid that causes___?
refraction artifact
characteristics of refraction artifact?
1. a second copy of the reflector
2. the copy is side by side or the same depth
the image is neither___nor____?
thin...uniform thickness
_____is the dimension of the beam perpendicular to the imaging plane?
slide thickness artifact
____determined by the thickness of the imaging plane?
elevational resolution
(assumption 5), the imaging plane is extremely thin, is invalid that cause
slice thickness artifact
_____lies outside of the imaging plane?
the true reflector
______fills in hollow structure such as cysts?
slice thickness
if the beam dimension is greater than the reflector size, then appear____?
slice thickness artifact
____reduced with thinner imaging planes by 1 and half dimensional array transducer?
slice thickness artifact
if beam is wider than the distance between two reflectors that located side by side or perpendicular to the beam, then cause_____?
lateral resolution artifact
lateral resolution artifact display a small____?
reflector as a wide rather than a narrow dot
lateral resolution artifact is least at____?
the focus
if a long pulse strike two closely spaced structure, then causes___?
axial resolution artifact
_____creates one reflection on the image from 2 closely spaced reflectors?
axial resolution artifact
if sound pulses glance off a second structure on the way to or from the primary reflector, then cause___?
multipath artifact
the transmit path length____from the return path length
differ
(assumption 2), a pulse travels directly to a structure and then back to the transducer, is invalid that causes___?
multipath artifact
if sound beam strikes_____, some of reflected sound directed away from transducer
a curved or oblique reflector
the ability to precisely position a moving structure is called____?
temporal resolution
temporal resolution determined by___?
frame rate, best with high frame rate
_____related to the overall detail in an image?
spatial resolution artifact
spatial resolution artifact determined by____?
sound beam's spacing or line density
Analog display (TV), spatial resolution is determined by____?
TV scan lines per frame
in the digital, spatial resolution is related to____?
pixel density
high pixel density creates___?
good spatial resolution
low pixel density creates___?
bad spatial resolution
____appears as small amplitude echoes and result from electrical interference, signal process?
noise
____,a form of noise, arises from small amplitude sound waves interfering with each other?
speckle
_____high tech solution for reducing an image's noise?
harmonic imaging