Ultrasound Flashcards
How fast does ultrasound propagate through soft tissue?
a. 343 m/sec
b. 1,540 m/sec
c. 3,051 m/sec
d. 4,892 m/sec
B. 1,540 m/sec
_____ forms the peak of the sound wave.
Compression (a region of high pressure)
______ forms the trough of the sound wave.
rarefaction (a region of low pressure)
A sound is simply a ______ that travels in a longitudinal wave.
pressure wave ( a form of mechanical energy)
Frequency is a measure of _______
pitch.
Frequency tells us how many
cycles occur in a given period of time
________ is the distance between two identical points on adjacent cycles.
Wavelength
______ frequencies produce shorter wavelengths, and _____ frequencies produce longer wavelengths
higher; lower
______ represents the sound’s loudness
Amplitude
Sound propagates through _____ at 343 m/sec and ____ at 3,000-5,000 m/sec
air; bone
Frequency is expressed in
hertz or cycles per second
When no medium is present (such as in a vacuum or outer space), there can
be no sound
Which concept BEST explains why lead zirconate titanate is commonly used in ultrasound transducers?
a. echolocation
b. doppler effect
c. Snell’s law
d. Piezoelectric effect
D. Piezoelectric effect
What is echolocation?
the use of sound and echoes to determine where objects are located in space.
A piezoelectric material can transduce
electric energy to mechanical energy and vice versa
The piezoelectrical material used by modern ultrasound transducers is called
lead zirconate titanate
What is the primary determinant of the vertical placement of each illuminated pixel on the ultrasound monitor?
a. time delay
b. resolution
c. acoustic impedance
d. doppler effect
A. time delay
the vertical placement of each dot is determined by how long it takes for the echo to return to the transducer (time delay)
The horizontal placement of each dot is determined by
the particular crystal that receives the returning echo
The vertical placement of each dot is determined by
how long it takes for the echo to return to the transducer (time delay)
The ultrasound transducer emits ultrasound waves into the body at a fixed rate, and then it listens
for echoes between each pulse- a process that repeats many times each second
______ produces high amplitude echos
Hyperechoic