Chapter 3 Flashcards
With standard ultrasonic imaging, what happens to the period of a wave as it propagates?
What determines the period of an ultrasound wave?
The transducer
Which of the following units are appropriate to describe the period of an acoustic wave?
A. Minutes
B. Microseconds
C. Meters
D. mm/us
E. Cubic centimeters
Minutes and microseconds
T or F
The sonographer has the ability to alter the period of an ultrasound wave that is produced by a basic transducer.
False
What term describes the number of cycles that an acoustic variable completes in a second?
Frequency
What is the range of frequencies emitted by transducers used in ultrasonic imaging?
1 to 3 MHz
What establishes the frequency of an ultrasound wave?
The transducer
T or F
With standard ultrasound pulses, the frequency of the ultrasound wave changes significantly as the wave propagates through the body.
When a sonographer increases the maximum imaging depth during an exam, what happens to the frequency?
Infrasound is defined as a sound with a frequency of:
Less than 20 Hz
T or F
Waves in the ultrasound range behave in the same general manner as sound waves that are audible
What is characteristics of acoustic waves with frequencies exceeding 20,000 Hz when compared with waves having frequencies of less than 20,000 Hz?
They attenuate more when traveling in soft tissue
T or F
If the periods of two waves are the same, then the frequencies of the waves must also be the same.
Compared to sound waves, A and B. The frequency of a wave A is 1/3 that of wave B. How does the period of wave A compare with the period of wave B?
The reciprocal of period is:
Frequency
What determines the initial amplitude of an ultrasound wave?
The transducer
As an ultrasound wave travels through the body, it’s amplitude usually:
Decreases
The power of an ultrasound wave can be reported with which of the following units?
Watts
Typically, as an ultrasound wave travels through soft tissue, the power of the wave:
Decreases
Mathematically, when a number is squared, the number is multiplied by:
Itself
The final amplitude of an acoustic wave is reduced to one-half of its original value. The final power is _________ the original power.
The amplitude of an acoustic wave decreases from 27 pascals to 9 pascals. If the initial power was 27 watts, what is the waves final power?
