History Review Flashcards
What is sound?
A travelling vibration that is received by a receiver.
What is frequency?
Cycles per second
What is the frequency of infra sound and give an example of something that uses it.
0-20 Hertz
Whale calls
What is the frequency of audible sound and what is it?
20Hz - 20 kHz
Any sound we can hear.
What is the frequency of ultrasound and what is an example of something that uses it?
Above 20,000 Hertz
UT, remote controls, NDT
If something has a frequency of zero?
It has no sound
What frequency does DMS use and what is the intensity?
Low intensity, 1-30 Megahertz
What frequency does therapeutic ultrasound use and what is the intensity?
20kHz - 1 MHz, high intensity.
How does high intensity ultrasound effect tissue?
Heats it up.
What is the difference between high frequency and low frequency in ultrasound?
High frequencies cannot travel (the waves get weaker faster) but they give good resolution in pictures.
Low frequencies can travel (penetrate deep) but give a lower resolution (worse picture)
Ex. Car stereo, the bass (low frequency) can be heard a distance from the car but the treble cannot
Who discovered the piezoelectric effect?
The Currie brothers
What is the piezoelectric effect?
When pressure (an electrical current) is applied to crystals it causes a vibration (sound waves) to enter the body
What is the reverse piezoelectric effect?
The sound waves bounce off of structures in the body and reflect back into the transducer, these echoes are then converted into an image
Who was the first person to have the idea to use ultrasound inside the body and what was his background?
Tom Park
He worked in the military (sonar used for iceberg and submarine detection)
What is A-mode?
Amplitude ultrasound (graph mode) Represented on a graph when sound bounces off of structures.
Who was the first person to use an ultrasound for medical purposes? What was it and what mode was used?
Karl Dussik
A-mode scanning was used to see a brain tumour.