Describing Pulsed Waves

Question 1

Five parameters that are needed to describe pulsed waves…

Answer 1

pulse duration
pulse repetition period
pulse repetition frequency
duty factor
spatial pulse length

Question 2

type of sound waves that can create anatomic images

Answer 2

pulsed waves

Question 3

Pulse Duration
Units?
Typical values?
Determined by?
Adjustable?

Answer 3

units of time
0.3 - 2 microseconds
sound source
no

Question 4

actual time from start of a pulse to end of that pulse

Answer 4

pulse duration

Question 5

formula for pulse duration

Answer 5

#cycles x period
or
# cycles / frequency

Question 6

Are short / long duration pulses more desirable for imaging?

Answer 6

short, they create more accurate images

Question 7

distance a pulse occupies in space from start to the end of a pulse

Answer 7

spatial pulse length

Question 8

Spatial Pulse Length
Units?
Typical values?
Determined by?
Adjustable?

Answer 8

distance
0.1 - 1 mm
source and medium
no

Question 9

What is the difference between pulse duration and spatial pulse length?

Answer 9

PD - time

SPL - distance

Question 10

Pulse Repetition Period
Units?
Typical values?
Determined by?
Adjustable?

Answer 10

units of time
100 microseconds to 1 millisecond
sound source
yes (we can change the depth)

Question 11

how is PRP and depth related

Answer 11

directly related

Question 12

what are the two components of PRP?

which one can the sonographer change?

Answer 12

transmit time / receive time

we can change the receive time

Question 13

With deep imaging, what happens to the length of the sound wave?
Shallow?

Answer 13

gets longer

shorter

Question 14

Pulse Repetition Frequency
Units?
Typical values?
Determined by?
Adjustable?

Answer 14

hertz
1000 to 10,000 hertz
sound source
yes

Question 15

number of pulses that an ultrasound system transmits into the body per second

Answer 15

PRF

Question 16

how is PRF related to depth of view

Answer 16

inversely related

Question 17

What is the relationship between PRP and PRF

Answer 17

inverse reciprocals

Question 18

Duty Factor
Units?
Typical values?
Determined by?
Adjustable?

Answer 18

no units, %
0.2% to 0.5%
for a continuous wave, DF is 1, or 100%, because it is always transmitting
sound source
yes

Question 19

percentage or fraction of time that the ultrasound system transmits a pulse

Answer 19

duty factor

Question 20

How is duty factor calculated?

Answer 20

PD / PRP

x 100

Question 21

Max value for duty factor

Answer 21

1, or 100%

Question 22

How does the monographer alter the DF?

Answer 22

when they alter the imaging depth

Question 23

When adjusting the imaging depth, the system alters what?

Answer 23

PRP, PRF, DF