Fundamentals of Ultrasound pgs 1-21 Flashcards
Define amplitude
Peak pressure of a wave. It is measured in decibels (dB), this can describe the volume of audible sound or the strength of the echo in US.
What is hyperechoic?
Strong returning echos that translate into bright or white areas on the screen.
What is hypoechoic?
Weak returning echoes translate into dark gray or black areas. Also called anechoic.
What is “gray scale”?
Range of echo strength
Define velocity
The speed of the wave.
How does an US machine calculate distance/depth?
It measures the time it takes for an emitted US beam to be reflected back to the source.
Define frequency
The number of times per second the wave is repeated. One hertz (Hz) is equal to one wave cycle per second. Diagnostic US frequencies typically range from 2-12 MHz.
Describe lower resolution waves.
They conserve energy. Although they do not create pictures of equally high resolution, they are able to penetrate deeper into tissue.
Define wavelength
The distance the wave travels in a single cycle.
Wavelength is inversely related to frequency.
velocity = frequency x wavelength
High frequency _____ wavelength, and lower frequency _____wavelength.
decreases; increases
Define attenuation
The progressive weakening of a sound wave as it travels through a medium.
What factors contribute to attenuation?
The density of the medium, the number of interfaces encountered, and the wavelength of the sound.
