Describing Pulsed Waves Flashcards
Five parameters that are needed to describe pulsed waves…
pulse duration pulse repetition period pulse repetition frequency duty factor spatial pulse length
type of sound waves that can create anatomic images
pulsed waves
Pulse Duration Units? Typical values? Determined by? Adjustable?
units of time
0.3 - 2 microseconds
sound source
no
actual time from start of a pulse to end of that pulse
pulse duration
formula for pulse duration
#cycles x period or # cycles / frequency
Are short / long duration pulses more desirable for imaging?
short, they create more accurate images
distance a pulse occupies in space from start to the end of a pulse
spatial pulse length
Spatial Pulse Length Units? Typical values? Determined by? Adjustable?
distance
0.1 - 1 mm
source and medium
no
What is the difference between pulse duration and spatial pulse length?
PD - time
SPL - distance
Pulse Repetition Period Units? Typical values? Determined by? Adjustable?
units of time
100 microseconds to 1 millisecond
sound source
yes (we can change the depth)
how is PRP and depth related
directly related
what are the two components of PRP?
which one can the sonographer change?
transmit time / receive time
we can change the receive time
With deep imaging, what happens to the length of the sound wave?
Shallow?
gets longer
shorter
Pulse Repetition Frequency Units? Typical values? Determined by? Adjustable?
hertz
1000 to 10,000 hertz
sound source
yes
number of pulses that an ultrasound system transmits into the body per second
PRF
how is PRF related to depth of view
inversely related
What is the relationship between PRP and PRF
inverse reciprocals
Duty Factor Units? Typical values? Determined by? Adjustable?
no units, % 0.2% to 0.5% for a continuous wave, DF is 1, or 100%, because it is always transmitting sound source yes
percentage or fraction of time that the ultrasound system transmits a pulse
duty factor
How is duty factor calculated?
PD / PRP
x 100
Max value for duty factor
1, or 100%
How does the monographer alter the DF?
when they alter the imaging depth
When adjusting the imaging depth, the system alters what?
PRP, PRF, DF
