Ultrasound Flashcards
When acoustical energy is absorbed by tissue what is created?
Thermal energy is created
Are tendons and ligaments dense tissues?
Yes
Compression happens in what type of tissue?
Dense tissue
Rarefraction happens in what type of tissue?
Less dense tissue
What are the principles of acoustic energy?
- Propagation of US waves
- Production of compression and rarefractions
- effect on US on various tissue densities
Is ultrasound more effective at heating dense tissues or less dense tissues?
Dense tissues
What does alternating current cause the crystal in US sound head to do?
Causes the crystal to expand and compress at a fast rate
What is the following a definition of?
Drawing in & drawing out of the shape of crystal
Piezoelectric effect
What is the ERA?
ERA = effective radiating area
Smaller than the actual size of the sound head
What are the frequencies that the ultrasound head can be placed at?
1 MHz, 3 MHz, 3.3 MHz
Frequency and depth of penetration are ____ ____
inversely proportional
Does tissue absorb heat faster at 1 MHz or 3 MHz?
3 MHz
A frequency of 1 MHz will penetrate how deeply?
6 cm deep
A frequency of 3 MHz will penetrate how deeply?
2.5 cm deep
What are the guidelines for intensity?
No guidelines - follow how to pt feels and is responding to treatment
What is the unit of measurement of dosage?
Joules (J)
What mode is this?
US delivered at constant energy level throughout the treatment
Continous
What mode is this?
energy flow cycles on/off
Pulsed
What part of the Pulsed Mode of US is this?
Time energy is flowing?
Pulse duration
What part of the Pulsed Mode of US is this?
‘on’ time (flow) + ‘off’ time (no flow)
Pulse Period