P4 - Ultrasound Flashcards
What is sound produced by?
All sound is produced by vibrating particles that form a wave.
What is wavelength?
Wavelength is the distance occupied by one complete wave.
What is ultrasound?
Ultrasound is a longitudinal wave, the vibrations of the particles are along the direction of the wave.
What is a compression?
Squashed together air particles.
What is a rarefaction?
Spread out air particles.
Why is sound not heard in space?
Longitudinal waves cannot travel through a vacuum.
What is frequency?
Frequency is the number of complete waves in a second.
What does a high frequency mean?
- the higher the pitch
- the smaller the wavelength
Why can you not hear ultrasound waves?
Their sound is of a higher frequency than humans can hear.
What is a transverse wave?
The vibrations of the particles are at right angles to the direction of the wave.
What are the uses of ultrasound?
- to check the condition of a foetus
- to investigate heart and liver problems
- to look for tumours in the body
- to measure the speed of blood flow in vessels when a blockage of a vein is suspected
What are the advantages of ultrasound?
- differentiates between soft tissues better than x rays
- does not damage living cells
How does a body scan work?
1) ultrasound is sent into the patients body
2) at each boundary between different tissues or organs some ultrasound is reflected and the rest is transmitted
3) the returning echoes are recorded and used to build up an image of the internal structure
What does the proportion of ultrasound reflected at each interface depend on?
- the densities of the adjoining tissues
- the speed of sound in the adjoining tissues
