Lecture 15: Principles of ultrasound Flashcards
What are the directions for cranial and caudal in ultrasound
cranial is left, caudal is right
when holding ultrasound probe, do you want to approach at perpendicular angle or 45 degree angle and why
perpendicular angle- sound goes in, hits something and bounces right back to probe giving best image
Any other angle- sound bounces away and not back to probe so get bad image
what is the m/sec for air
331
what is m/sec for fat
1450
what is m/sec for water
1500
what is m/sec for average ST
1540 (baseline value)
what is m/sec for liver
1549
what is m/sec for kidney
1570
what is m/sec for bone
4080
Why does ultrasound have hard time telling difference between bone and air
M/sec so different from each other (air-331) (bone-4080) and they are also far from baseline ST value 1540 that both just appear white
what is ultrasound power
how much sound is coming out of the probe
if you decrease power what happens to image
becomes darker
does increasing gain make things brighter and darker and at the surface or deeper tissues
brighter in more superficial tissues because more sound is located near the top
what is time gain compensator
changes sound at different depths
what is a focal spot good and bad for
good for looking at a specific site, bad because you lose detail where focal spot isn’t
if you have a hard time seeing deep what should you adjust first
focal spot
identify the types of probes 1-3
- Phased array
- Curvilinear
- Linear array
which probe is good for cardiac procedures, good for motion
phased array
which probe provides the best resolution but not a wide view. Good for tendons and small animals
linear array
which probe is good for the abdomen, large field of view but loss of resolution
curvilinear
what are MHz
Frequency of sound produced from probe
generally MHz ranges from __-__ for ultrasound probes
1-18MHz
the higher the MHz= better __, but decreased __
resolution, penetration
what is penetration for a 1MHz probe
30cm
