Physics Quiz 4 Flashcards
Shadowing and enhancement are descriptions of __________ artifacts
Attenuation
Which artifact displaces structures in the axial plane?
Speed error
What is an example of a structure that would likely demonstrate acoustic enhancement?
Gallbladder
T/F
Artifacts are distorted portions of the image that have to be corrected
False
T/F
External influences can also produce artifacts
True
T/F The intensity of the returning Doppler shift echoes is affected by the flow speed
False
What factor would most likely cause the following:
2 objects lying close together in the axial plane but are displayed as one
Large spatial pulse length
Array transducers use apodization to help eliminate which kind of artifact?
Grading lobes
Which artifact(s) result(s) in reflectors with incorrect image amplitude?
Shadowing, focal banding, enhancement
(All artifacts will cause incorrect amplitude)
Color can change in a vessel due to…
Vessel contour, increase in flow speed, & change in Doppler signal.
(All of these will cause a change)
T/F
Aliasing happens with spectral Doppler but not color Doppler
False
T/F
Power Doppler does not rely on the velocity of the reflector and is not angle dependent.
True
T/F
If you are interrogating a vesssel at 90 degrees the color in the vessel will be diminished or black.
True
How would you fix color blossoming?
Turn the gain down
For mirror artifact to happen you must have:
Highly reflective surface
Spectral Doppler crosstalk occurs when:
The angle is too close to 90°
Refraction is a change in the ultrasound beam…
Direction
What is the technique where multiple sound beams are emitted from the transducer from different angles to create one image?
Compound imaging
What are three of the listed mechanisms of artifact production?
- Viewer assumptions
- Operator error
- Equipment malfunction
(Note: NOT “patient body habitus”)
Spectral broadening will cause which change in a spectral analysis tracing?
Vertical thickening
What are three factors that would cause the presence of false sludge/debris in a cystic mass?
- Reverberation artifact
- Side lobe artifact
- Scanning at high gain
(Note: Speed of sound artifact would NOT cause this false presence)
What is the term used for color Doppler that is seen at areas of stationary objects?
Ghosting
The far side of a mass is at a depth of 12 cm, but is displayed on the image at a depth of 10 cm. What is the most likely cause of this error?
Propagation speed of the medium is GREATER than 1540 m/s
How would you fix the image if you are seeing two celiac axis on the same image?
Change windows
T/F
Crosstalk on spectral Doppler will display both arterial and venous waveform
False
The “ghost vessel” will always be the one displayed __________ on the image
Posterior
*** Written
What are the 6 assumptions of ultrasound imaging systems?
- Assumes that all sound travels directly from the body to the machine and back in a straight line without changing direction
- Assumes that the Imaging plane is thin or the slice of tissue being imaged is very thin
- Assumes that sound always travels at 1540m/sec
- Assumes that sound will always travel to a reflector and back to the transducer
- Assumes that the intensity of the sounds reflection will accurately tell the machine how strong the tissues echo is.
- Assumes that sound bounces back from the center of the beam to create a clear image.
