Module 5 Physics Flashcards
What causes the double aorta appearance?
refraction from the linea alba
How can we minimize reverb?
- decreasing gain superficially
- harmonics
- SC
What is gas reverb?
vibration of fluid trapped along gas bubbles - continuous sound wave back to tx
aka as ring down
this is not normal when in organs that don’t normally produce gas
Normal in GI tract - dirty shadow
What is comet tail artifact
a form of reverb (like ring down) but in a small reflective structure with NO absorption
banding appearance
What is apodization
varying the strength of voltage across the aperature - can be helpful for grating lobe artifact - decrease voltage in peripheral
How can you fix the range ambiguity artifact?
increase the depth and lower the PRF
What is the mirror artifact?
a fake structure symmetrical to an actual structure across a mirroring structure
What image feature decreases refraction/edge shadow?
SC
What creates speckle artifact?
scattering and wave interference
Frequency and speckle artifact relationship
increase freq = shorter wavelength = finer speckle
decrease freq = longer wavelength = coarse speckle
How can we decrease specke?
increase freq, SC, RTAF, frequency compounding, coded harmonics
How cna you change the angle to eliminate aliasing in SD?
actually increasing the angle (but keeping below 60 deg) to decrease DSF value
Ghost artifact in CD
vessel with flow duplicated on opposite side of strong reflector
What can cause electronic cross talk in SD?
overgaining, superficial scanning, angle close to 90 deg
Causes of artifical SB?
overgaining or perpindicular angles
