Chapter 8 Flashcards
True or False. Any time a vessel is without color, the first thing to do is check the angle between flow and sound.
True
True or False: For color to appear in the vessel, an angle of 90 degrees must be created between the direction of flow and the direction of the sound beam.
False
True or False: When the color gain is set to an inappropriately low level, all color will disappear in the image
True
List potential causes of artifact in diagnostic imaging.
Violation of Assumption, Equipment Malfunction, Physics of Ultrasound, and Operator Error
Six distinct, equally spaced reflections appear on an image at ever increasing depths. What type of artifact is this?
Reverberation
What type of situation will commonly produce reverberation artifact?
When the medium has a very high propagation speed or from a resonance, or vibration, of a small structure such as a gas bubble.
Where are shadowing artifacts commonly seen on an acoustic scan?
In the Tissue above the shadow (deep reflecting surfaces)
How is shadowing artifact expressed?
They express as the same color as the background
What causes enhancement artifact?
Appear beneath tissues with abnormally low attenuation
When enhancement occurs, where does it appear on the image?
Hyperechoic regions are brighter and the same color as the foreground (echoes) of the image.
Opposite of shadowing artifact
What process causes mirror image artifact?
Created when sound reflects off a strong reflector and is redirected toward a second structure. This is what causes the “replica”
Where is a mirror image artifact located?
Located deeper than the real structure
What type of artifact is created by sound moving through a medium with a propagation speed less than soft tissue?
It produces, Speed Error
While imaging a test object, an ultrasound system displays one image 1.8 cm deeper than another. Upon measuring the test object, it is found that it is actually 2.0 cm deeper. What conclusion can be drawn from this?
That there is a range error artifact
What causes side lobe artifact?
Lobes created by a mechanical transducer are known as side lobes
Grating lobes are most common with which type of transducer technology?
Array transducers
True or false? Grating lobes are attributed only to array transducers.
True
What assumption is violated when a refracted sound wave is processed?
Sound travels in a straight line, is invalid
With standard diagnostic imaging instrumentation, which has the higher numerical value?
A. axial resolution
B. lateral resolution
C. elevational resolution
D. No answer text provided.
D
Axial resolution artifacts are due to which of the following?
A. multiple reflections
B. beam width
C. attenuation
D. pulse length
D
The lateral resolution of four ultrasound systems appear below. Which will produce the finest quality picture?
A. 2 cm
B. 4 mm
C. 6 mm
D. 8 hm
B
True or false? All artifacts are errors in imaging that do not represent the true anatomy of the imaged organ. Therefore, they are all undesirable and should be eliminated if possible.
False
In diagnostic imaging, how does multipath artifact affect the image?
The transmit path length differs from the return path length which often results in subtle, nonspecific changes that cannot be specifically identified on the image.
Which artifact is not related to the unexpected reflection of an acoustic wave?
A. multipath
B. comet tail
C. reverberation
D. lateral resolution
D
