Chapter 21, 22 and 23 Flashcards
Which of the following describes portions of an image that are brighter than the surrounding tissue or tissues that appear brighter than normal?
hyperechoic
What images that not as bright or less bright than normal?
hypoechoic
A structure without echoes, how would you describe that?
anaechoic
A tissue or structure that has a similar echo characteristic throughout, what is it?
homogeneous
Tissue displaying a variety of different echo characteristics
heterogeneous
Artifacts on an image are errors in imaging, which is not considered an error?
?
Equipment malfunction or design physics of ultrasound in operator error, what are those called?
causes of artifacts
Multiple equally spaced parallel lines, what are they?
Reverberation
Which artifact produces an image with an incorrect number of reflectors side by side?
focal enhancement
Artifacts result in the placement of too many echoes on the image except for what?
artifacts with too many echoes: reverberation comet tail enhancement focal enhancement
Lobes created by array transducers are called what?
grating lobes
What methods can be used to eliminate lobe artifacts?
subdicing and apodization
What artifact occurs when the beam is unable to pass through a structure because of the high attenuation?
shadowing
Refractions at the end of a circular structure can cause what artifact?
edge shadow
What artifact occurs when there is too much gain in the focal zone?
focal banding
What standard is best used in a quality assurance program?
objective
An objective standard is best for quality assurance program. These standards are free of personal opinion.
All of the following are characteristics of tissue equivalent phantom except.
density similar to that of soft tissue
The density of the material within a tissue equivalent phantom is not important. The other three characteristics of the phantom must be similar to that of soft tissue.
What form of resolution is evaluated by measuring the width of reflections arising from small, point targets?
lateral resolution
lateral resolution can be evaluated by measuring the width of reflections on the display that are created by point targets in the phantom.
What form of resolution is evaluated by visualizing closely spaced pins that are parallel to the sound beam’s axis?
axial resolution
axial resolution is the smallest distance at which two pins positioned parallel to the sound beam are displayed at two distinct echoes.
At what interval should quality assurance evaluations be performed?
routinely
quality assurance evaluations should be performed routinely
When propagation speed is greater than 1540 m/sec the reflector will be placed to what on the display?
reflectors are located too shallow on the screen
Grading lobes are caused by which type of transducer?
array transducers
What artifact occurs when the medium in which the sound travels has a lower attenuation rate than soft tissue?
reflectors are located too deep on the screen
Which artifact occurs when you see reflectors at incorrect depths?
speed error
What artifact can be cured by lowering the PRF?
temporal resolution artifact
Which of the following artifacts are only found with Doppler?
crosstalk
Two causes for crosstalk
Doppler gain is too high
incident angle is close to 90 degrees
What are errors in imaging?
not real not seen on the image incorrect shape or size incorrect position incorrect brightness
What are causes of artifacts?
violation of assumptions
equipment malfunction or poor design
the physics of ultrasound
operator error
If the path to the reflector is a different length than the returning path, the reflector will be incorrectly positioned. That results in general image debris degradation. What artifact is that?
multipath
What produces shadowing?
high attenuation
Wall filters are used to reject what?
low frequency doppler shifts
slow moving blood cells
Which transducer may have poor elevational resolution?
1 and 1/2 dimensional array transducer
Where does enhancement appear on the image?
below the imaged tissue
Two reflections side by side only one is real. What is the most likely cause of this artifact?
refraction
Which artifacts create one reflection on an image from two closely spaced reflectors?
comet tail
A grainy appearance not directly from tissues created by interference, is what?
speckle
Propagation speed error appears a what?
step-off. split or cut
If a media through which ultrasound travels doesn’t propagate at 1540 then the assumed relationship between time and distance is invalid, what artifact occurs?
speed error
A single solid hyperechoic line parallel to the sound beam, no spaces in the echogenic line is what artifact?
focal enhancement
What term is defined by avoidance of unnecessary risk, harm or needless injury?
nonmaleficence
What provides the bases for informed consent?
autonomy
When can a patient revoke consent?
at any time
What’s the first action when a sonographer enters a patient’s room?
introduce yourself
What is the study between a worker and their environment called?
ergonomics
