Ultrasound Physics Exam 2 UPDATED ACTUAL QUESTIONS
AND CORRECT Answers
Artifacts False structures on an image that do not have a one-to-one correspondence
to the object being scanned
Refraction Artifact - Ghost Image Artifact Bending of sound
Due to change in propagation speeds
Lateral duplication of structures
To fix: Reposition transducer or use a different plane
Velocity Artifact Due to velocity change within an object
More evident on larger objects with spectral reflectors behind them & silicone
breast implants
Velocity Artifact when speed is less than 1540 m/sec Front wall of object is placed correctly
Back wall of object is placed further away than actual place
Object is measured larger than actual size
Velocity Artifact when speed is greater than 1540 m/sec Front of object will be placed correctly
Back wall of object is placed closer than actual place
Object is measured smaller than actual size
, Edge Artifact/Edge Shadowing Shadowing effect on edges of large, rounded structures
Depends on characteristics of medium
To fix: use spatial compounding and scan from multiple angles
How is Edge Artifact related to loss of intensity? Beam deflection and refraction at the interface
Edge Artifact when V1 > V2 Narrow shadow projection
Ex. Cysts, GB
Edge Artifact when V1 < V2 Wide shadow projection
Ex. Fetal head
Multipath Artifact Sound beam strikes interface at an angle, and is reflected from a second
interface before being reflected back to the transducer
Axial displacement of interface
To fix: scan from a different angle or use spatial compounding
Total Internal Reflection Reflected echo does not make it back to transducer
Missing interfaces - vessels look connected, but are really not
Side Lobe Artifact Extra echoes created by energies that fall outside of main beam
Grating Lobe Artifact Occur when the crystal is diced into smaller elements
Seen with linear and curved transducers
To fix Lobe Artifacts Multiple scanning planes
Apodization
AND CORRECT Answers
Artifacts False structures on an image that do not have a one-to-one correspondence
to the object being scanned
Refraction Artifact - Ghost Image Artifact Bending of sound
Due to change in propagation speeds
Lateral duplication of structures
To fix: Reposition transducer or use a different plane
Velocity Artifact Due to velocity change within an object
More evident on larger objects with spectral reflectors behind them & silicone
breast implants
Velocity Artifact when speed is less than 1540 m/sec Front wall of object is placed correctly
Back wall of object is placed further away than actual place
Object is measured larger than actual size
Velocity Artifact when speed is greater than 1540 m/sec Front of object will be placed correctly
Back wall of object is placed closer than actual place
Object is measured smaller than actual size
, Edge Artifact/Edge Shadowing Shadowing effect on edges of large, rounded structures
Depends on characteristics of medium
To fix: use spatial compounding and scan from multiple angles
How is Edge Artifact related to loss of intensity? Beam deflection and refraction at the interface
Edge Artifact when V1 > V2 Narrow shadow projection
Ex. Cysts, GB
Edge Artifact when V1 < V2 Wide shadow projection
Ex. Fetal head
Multipath Artifact Sound beam strikes interface at an angle, and is reflected from a second
interface before being reflected back to the transducer
Axial displacement of interface
To fix: scan from a different angle or use spatial compounding
Total Internal Reflection Reflected echo does not make it back to transducer
Missing interfaces - vessels look connected, but are really not
Side Lobe Artifact Extra echoes created by energies that fall outside of main beam
Grating Lobe Artifact Occur when the crystal is diced into smaller elements
Seen with linear and curved transducers
To fix Lobe Artifacts Multiple scanning planes
Apodization
