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PHYS3 Artifacts

artifacts classified as Propagation, Attenuation, or and/or Doppler

Artifact:Group(s)Correct by:
Axial resolution Propagation ↑ frequency
Lateral resolution Propagation ↑ frequency
Section thickness Propagation ↓ gain and/or TGC OR ↑ z axis (3rd dimension) focus
Acoustic Speckle Propagation ↓ gain or ↓ frequency
Reverberation Propagation multiple matching layers
Refraction Propagation change angulation of transducer
Multipath Propagation change angulation of transducer
Mirror image Propagation / Doppler change angulation of transducer
Side lobe Propagation inherent within the transducer ↓ gain
Grating lobe Propagation inherent within the transducer ↓ gain
Comet tail Propagation inherent within the tissue
Ring-down Propagation inherent within the tissue
Speed error Propagation inherent within the tissue
Range ambiguity Propagation / Doppler PROPAGATION: ↓ PRF (↑PRP) by ↑ imaging depth DOPPLER: Need to ↑ PRF to decrease aliasing, but this can cause range ambiguity artifact
Main bang Propagation • Multiple matching layers • Electronic focusing • ↑ Frequency • ↓ Near gain • Stand-off pad
Shadowing Attenuation / Doppler inherent within the tissue
Enhancement Attenuation inherent within the tissue
Refraction (edge) shadowing Attenuation inherent within the tissue • Change angulation of transducer so it is perpendicular to anatomy
Focal enhancement Attenuation inherent within the transducer • ↓ gain in mid field (or wherever the focal zone is – use TGC to adjust)
Aliasing Doppler • Adjust baseline • Adjust scale • ↑ PRF • ↑ Doppler angle (only if bad to begin with – must remain between 45° and 60°) • ↓ transducer frequency • ↓ sample volume depth • Use CW Doppler
Speckle (noise) Doppler ↓ gain
Doppler angle effects Doppler use “angle correct” control or change Doppler angle
Clutter Doppler ↑ wall filter
Created by: lefut on 2007-03-31



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