PTA145-Unit2-Ultrasound Flashcards
what is the frequency of the sound waves in Ultrasound?
above the range of human hearing; above 20,000 Hz
why is a transmission medium required?
because it is sound
where does the sound go? name 4 things
- absorption
- penetration
- reflection
- refraction
describe Absorption
- how much sound energy is taken into the tissue.
- the denser the medium, the more quickly the energy is absorbed
described Penetration
- how far the sound waves will travel within the tissue
- how deep the sound waves will travel
- penetration is much less when absorption is quick
describe Reflection
- when the sounds are bounced back towards the source
- energy lost. doesn’t hit tissue
describe Refraction
- when the sound waves cross the barrier and some of the energy is directed away from the target
what kind of wave is US?
- longitudinal (bungee jumper)
longitudinal waves travel better through ___
solid, liquid. (not gas)
3 things about How Sound Travels
- it’s energy that travels
- molecules are jostled until the energy runs out
- a transmission medium is required
name 6 properties of US transmission
- sinusoidal waveform
- wavelength
- frequency
- amplitude
- rarefaction
- compression
what is rarefaction?
- low particle density along the path of the wave
- the stretched out spring
what is compression?
- high particle density along the path of the wave
- the scrunched up spring
why are rarefaction and compression important?
these cause the disturbance in the tissues, producing the thermal or non-thermal effect
Name the 2 main parts of US equipment
- generator
- transducer (applicator) (sound head)
