USS lectures Flashcards
How does USS work
high frequency sound waves
what is the pulse echo principle
it is when the US wave is produced then is reflected back from body then echo is detected and image is generated
the transducer
contains a piezo-electric crystal
what is the piezo-electric effect
electrical energy is converted into US then it echoes then US converted to electrical then to picture
High frequency transducers
high resoloution but low depth, look at superficial vessels and muscles
low frequency transducers
penetrate deeper but lower resoloution - abdominal and obstetric
what happens to sound waves in the body
reflected
scattered
absorbed
acoustic impedance
air to bone
low to high impedance
soft tissue have similar values usually
strength of reflection
the bigger the difference between Z1 and Z2 the stronger the reflection
calcium
it is a strong reflector
vessels in US
black anechoic (poor US absorption
Bones in US
white hyperechoic (high absorption)
soft tissue in US
grey Isoechoic
Nerves in US
Honey comb - hypoechoic/hyperechoic
muscles/tendons in US
gray/white
isoechoic with white strands
two main components of US machines
transducer and base unit
getting started with US
patient details
select transducer - high or low frequency
choose preset MSK, etc
start with high depth and go down
handle transducer with care vexpensive
clean
disinfect
Acoustic Enhancement (Flaring)
some beems keep traveling while others get absorbed thus provide a weird image
