Describing Pulsed Waves

Question 1

What are the five parameters used to describe pulsed sound?

Answer 1

1. Pulse duration
2. Pulse repeition period
3. Pulse repeition frequency
4. Duty factor
5. Spatial pulse length

Question 2

What is pulsed sound?

Answer 2

It is a collection of cycles that travel together

Question 3

What are the two components of pulsed ultrasound?

Answer 3

1. Transmit, talking, or “on” time
2. Recieve, listening, or “off” time

Question 4

What is pulse duration?

Answer 4

It is the actual time from start of a pulse to the end of that pulse.

Question 5

What is the unit for pulse duration?

Answer 5

It is reported in units of time.

Question 6

What is pulse duration determined by?

Answer 6

It is determined by the sound source only.

Question 7

Is the pulse duration adjustable?

Answer 7

No.

Question 8

What are the 2 formulas for pulse duration?

Answer 8

1. PD (us)= # of cycles x period (us)
2. PD (us)= # of cycles / frequency (Hz)

Question 9

What is the relationship between pulse duration and the number of cycles in that pulse?

Answer 9

Directly proportional

Question 10

What is the relationship between pulse duration and period?

Answer 10

Directly proportional

Question 11

What is the relationship between pulse duration and frequency?

Answer 11

Inversely proprtional.

Question 12

What characteristics create pulses of long duration?

Answer 12

Many cycles in the pulse or individual cycles with long periods.

Question 13

What characteristics create pulses of short duration?

Answer 13

Few cycles in the pulse or individual cycles with short periods.

Question 14

In clinical imaging, a pulse typically contains how many cycles?

Answer 14

2 to 4 cycles.

Question 15

Which type of pulse is more desirable in diagnostic imaging, and why?

Answer 15

Shorter duration pulses are desirable for imaging because they create images if greater accuracy.

Question 16

What is spatial pulse length?

Answer 16

It is the distance from the start of tge oulse to the end.

Question 17

What is the unit for spatial pulse length?

Answer 17

It has units of distance.

Question 18

What is the spatial pulse length determined by?

Answer 18

It is determined by both sound source and medium.

Question 19

Is the spatial pulse length adjustable?

Answer 19

No.

Question 20

What is the equation of spatial pulse length (mm)?

Answer 20

SPL (mm)=# of cycles X wavelength (mm)

Question 21

What is the relationship between SPL and the number of cycles?

Answer 21

Directly related.

Question 22

Whta is the relationship between SPL and wavelenght?

Answer 22

Directly related

Question 23

What is the relationship between SPL and frequency?

Answer 23

Inversely related

Question 24

What is pulse duration?

Answer 24

It is the time that a pulse is “on”

Question 25

What is SPL?

Answer 25

It is the **distance** of the pulse from end to end.

Question 26

What characteristics create a long SPL?

Answer 26

* Many cycles in the pulse * Cycles with longer wavelength

Question 27

What characteristics create a short SPL?

Answer 27

* Fewer cycles in the pulse * Cycles with shorter wavelengths

Question 28

What is **pulse repetition period?**

Answer 28

It is the time from the start of one pulse to the start of the next pulse.

Question 29

What units is PRP reported in?

Answer 29

Units of time.

Question 30

What is PRP determined by?

Answer 30

Sound source and **imaging depth.**

Question 31

Is the PRP adjustable?

Answer 31

Yes.

Question 32

Which type of pulse is more desirable and why?

Answer 32

Pulses of shorter length because they create more accurate images

Question 33

What is the depth of view?

Answer 33

It describes the maximum distance into the body that an ultrasound system is imaging.

Question 34

How are pulse repetition period and depth of view related?

Answer 34

Directly related. * As depth of view increases, PRP increase * As depth of view decreases, PRP decrease.

Question 35

What is PRF?

Answer 35

It is the number of pulses that an ultrasound system transmits into the body each second.

Question 36

What unit is PRF reported in?

Answer 36

Hz

Question 37

What is PRF determined by?

Answer 37

Sound source and by the maximum imaging depth of the system.

Question 38

Is the PRF adjustable?

Answer 38

Yes; by adjusting the depth of view.

Question 39

What happens to the PRF when the system is imaging shallow?

Answer 39

PRF is higher

Question 40

What happens to the PRF when the system is imaging deep?

Answer 40

PRF is lower.