Ultrasound Flashcards
What type of waves are sound waves?
Longitudinal
pressure waves
(i.e. not transverse)
What frequency is ultrasound classed as?
> 20 kHz
What frequency is medical ultrasound classed as?
2 – 15 MHz
Another term used for probes in ultrasound machines?
Transducers
4 main components used in ultrasound machine?
Monitor
Probes/transducers
Pulse controls and computer
Ultrasound coupling gel
Purpose of ultrasound coupling gel?
Improves energy transfer between probe and patient
What is the name of crystals in the probe face?
piezoelectric crystals
What causes the crystals in the probe face to oscillate?
Oscillating current is applied to the crystals which causes them to change shape, and oscillate/vibrate
What is the purpose of making the crystals in the probe face vibrate?
This generates mechanical vibrations at probe face (2-15 MHz ‘Ultrasound’) which can then be transmitted through the patient when placed on the skin surface.
Name 3 ways ultrasound artefacts can be caused?
- Reflections at angles
- Scatter
- Refraction
How do ultrasound probes generate images? (basic)
Ultrasound vibrations are transmitted into the patient.
Either transmitted or reflected through tissue.
The sound that relfects and reaches the transducer face causes a vibration in the crystal.
This vibration is converted into and electrical signal -> image on screen.
Speed = distance/time to determine how far from surface.
Name for scanning heart with ultrasound?
echocardiogram
Can you create 3D/4D images using ultrasound.
Yes its possible, but not common (?)
Describe the doppler effect.
Waves in the direction of the motion of the source will get bunched up together. Waves moving away from source essentially get spread out.
Different frequencies.
Name 2 medical uses of ultrasound dopplers
Pulse-doppler examination
Colour flow doppler
