69. ULTRASOUNDS: PULSED WAVES Flashcards
1
Q
- What is the speed of sound in Soft Tissue?
A
- 1540 m / s
2
Q
- What characteristics determine the Speed of Sound of the medium?
A
- the density of the medium
- the stiffness of the medium
3
Q
- What is Stiffness?
A
- this is the ability of an object to resist compression
4
Q
- What is Density?
A
- this is the relative weight of the material
5
Q
- What does an increase in Stiffness result in?
A
- it increases the speed of sound of the medium
6
Q
- What does an increase in Density result in?
A
- it decreases the speed
7
Q
- What do Continuous Wave sounds fail to do in Diagnostic Ultrasounds?
A
- they fail to create Anatomic Images
8
Q
- What do Imaging systems produce?
A
- they produce short bursts (pulses) of acoustic energy
- these create a picture of anatomy
9
Q
- Define the Pulse of an Ultrasound?
A
- it is the collection of cycles that travel together
10
Q
- What two components do Pulsed Ultrasounds have?
A
- Transmitting
- this is considered on time
- Receiving
- this is considered off time
11
Q
- What are the 5 parameters that describe Pulsed Sounds completely?
A
- Pulse Duration
- Spatial Pulse Length
- Pulse Repetition Period
- Pulse Repetition Frequency
- Duty Factor
12
Q
- How do we calculate the Duty Factor?
A
13
Q
- Label this image.
A
- Pulse Duration (µs)
- this could also be the Spatial Pulse Length (mm)
- Pulse Repetition Period (µs)
- Transmit time of the sound waves
- Receive time of the echoes
14
Q
- What is the depth of view?
A
- this describes the maximum distance into the body
- that an ultrasound system is imaging
15
Q
- What indicated depth in an Ultrasound?
A
- the markers along the edge of the image
16
Q
- What is the Pulse Repetition Period directly related to?
A
- Imaging depth
17
Q
- What does this image show?
A
- this shows Deep Imaging
- the structure that is being images is far inside the body
18
Q
- What does this image show?
A
- this shows Shallow Imaging
- there is a shorter Pulse Repetition period
- the structure being images is closer to the surface
19
Q
- What are 4 characteristics of Shallow Imaging?
A
- Less listening
- Shorter Pulse Repetition Period
- Higher Period Repetition Frequency
- Higher Duty Factor
20
Q
- What are the 4 characteristics of Deep Imaging?
A
- More listening
- Longer Pulse Repetition Period
- Lower Period Repetition Frequency
- Lower Duty Factor
21
Q
- Fill in the following questions regarding the
Pulse Duration:
21.1. It is adjustable?
21.2. What are the units?
21.3. What is it determined by?
21.4. What are the typical values?
A
(21.1) No
(21.2) µsec (Time)
(21.3) Source
(21.4) 0.5 to 3.0 µs
22
Q
- Fill in the following questions regarding the
Pulse Repetition Period:
22.1. It is adjustable?
22.2. What are the units?
22.3. What is it determined by?
22.4. What are the typical values?
A
(22.1) Yes
(22.2) msec (Time)
(22.3) Source
(22.4) 0.1 to 1.0 ms
23
Q
- Fill in the following questions regarding the
Pulse Repetition Frequency:
23.1. It is adjustable?
23.2. What are the units?
23.3. What is it determined by?
23.4. What are the typical values?
A
(23.1) Yes
(23.2) Hz per sec
(23.3) Source
(23.4) 1 to 10 kHz
24
Q
- Fill in the following questions regarding the
Spatial Pulse Length:
24.1. It is adjustable?
24.2. What are the units?
24.3. What is it determined by?
24.4. What are the typical values?
A
(24.1) No
(24.2) mm (distance)
(24.3) Source and Medium
(24.4) 0.1 to 1.0 mm
25
25. Fill in the following questions regarding the
Duty Factor:
25.1. It is adjustable?
25.2. What are the units?
25.3. What is it determined by?
25.4. What are the typical values?
(25.1) Yes
(25.2) none
(25.3) Source
(25.4) 0.2% to 0.5%
