Week 2 Flashcards
1
Q
What is ultrasound?
A
a form of mechanical energy consisting of high frequency vibrations (> 20,000 Hz)
2
Q
What is clinical US in PT ranges of ultrasound?
A
from 1-3 MHz
3
Q
The higher the frequency of an ultrasound, the ____ the rate of absorption.
A
Higher (faster heating)
4
Q
The higher frequency of of an ultrasound, the ____ the depth of penetration
A
lesser
5
Q
Ultrasound works on ____ piezoelectric effect
A
reverse
6
Q
What is a piezoelectric effect?
A
Electrical energy (AC current) applied to lead zirconate titanate crystal in sound head which is converted to mechanical energy
7
Q
What are the ultrasound parameters to know for documentation and treatment of a patient?
A
- Intensity—W/cm2
- Frequency—MHz
- Duty cycle—%
- Effective radiating area (ERA)—cm2
- Beam non-uniformity ratio (BNR)
8
Q
The beam of an ultrasound may be absorbed, _____ or ______
A
reflected, or refracted
9
Q
The frequency of an ultrasound determines the _____
A
depth, penetration, and energy absorption
10
Q
Beam reflection in an ultrasound is ____ if the sound is delivered _____ to treatment surface or interface
A
- Less
- Perpendicular
11
Q
Beam refraction occurs as the beam ______
A
travels from one medium to another
12
Q
What is a spatial peak?
A
the highest amplitude in the beam
13
Q
What is a spatial average?
A
the average amplitude of the beam
14
Q
What is beam non-uniformity ratio (BNR)?
A
The ratio of the highest intensity in the field (spatial peak) to the average intensity indicated on the machine (spatial average).
15
Q
BNR is determined by ____
A
material used for piezoelectric
transducer
16
Q
Most BNR machines have ratios between ____ and ____.
A
2: 1
8: 1
17
Q
The lower the ratio of a BNR, the ____
A
better
18
Q
A BNR ratio of ___ is when intensity is set at 1 W/cm2, the spatial peak intensity within the field could be as high as 5 W/cm2.
A
5:1
19
Q
What is an attenuation coefficient?
A
the decrease in energy due to
absorption, reflection, and refraction (absorption accounts for ½ of attenuation)
20
Q
Tissues with more attenuation will show a ____
A
greater temperature rise
21
Q
Attenuation values are higher for tissues with a ____
A
higher collagen content
22
Q
Attenuation increases as frequency of US ____
A
increases
23
Q
Attenuation is ____ related to penetration
A
Inversely
24
Q
Attenuation is best for ____ tissues
A
Collagen rich tissues
25
Attenuation is worst for ____
Fat/Skin/Muscle
26
What is the attenuation of 1 MHz ultrasound to blood?
3%
27
What is the attenuation of 1 MHz ultrasound to fat?
13%
28
What is the attenuation of 1 MHz ultrasound to nerve?
0%
29
What is the attenuation of 1 MHz ultrasound to muscle?
24%
30
What is the attenuation of 1 MHz ultrasound to blood vessels?
32%
31
What is the attenuation of 1 MHz ultrasound to skin?
39%
32
What is the attenuation of 1 MHz ultrasound to tendon?
59%
33
What is the attenuation of 1 MHz ultrasound to cartilage?
68%
34
What is the attenuation of 1 MHz ultrasound to bone?
96%
35
What is the mechanical effects of ultrasound?
* Cavitation, micro-streaming, acoustic streaming
* Increased intracellular calcium
* Promotes cell function
36
The ____ effects of ultrasound happens every time you perform an ultrasound
Mechanical effects
37
What is a duty cycle?
A continuous flow of sound waves
38
The ___ effects of ultrasound is predominantly when performing ultrasound at a 100% duty cycle
Thermal
39
As the duty cycle decreases there will be____ of sound waves
pauses in the transmission of sound waves
40
A decrease in duty cycle will allow the body to ____, therefore leading to ___
- dissipate the heat and prevent an overall buildup of temperature rise in the tissues,
- non-thermal effects of ultrasound
41
The non thermal effects of ultrasound are the _____ effects
mechanical
42
What is acoustic streaming of an ultrasound?
Movement of tissues at the cellular level.
43
Thermal effects of an ultrasound at a 1 deg temperature rise
* Increases metabolism and healing
| * Roughly 13% increase in metabolism for every 1 deg C raise (or up to 2-3 fold increase for 10 deg C rise)
44
Thermal effects of an ultrasound at a 2-3 deg temperature rise
• Decreases pain and muscle spasm
45
Thermal effects of an ultrasound at a 4 deg C or greater temperature rise
Increases extensibility of collagen and scars, and decreases joint
stiffness, a 40-45 degrees C temperature is required for at least 5 minutes
46
Duty cycle is equal to
time on relative to time on + time off
47
When duty cycle is lowered to 20%, there is
Reduced thermal effects as the time off allows heat to dissipate during pulsed US at lower freq.
48
A pulsed sound wave is anything over ____ duty cycle
100%
49
Mechanical effects of a duty cycle occurs at ____
20%
50
At 50% duty cycle, you get more ___ effects, than you get ___ effect. Which is why it has not much clinical use
mechanical effects, than you get thermal effect
51
The selection of frequency determines the ____
depth of penetration which is a result of how much energy is absorbed as sound waves penetrate.
52
1 MHz provides treatment of tissue up to ___ deep
5 cm
53
3 MHz provides treatment of tissue up to ___ deep
1-2 cm
54
If the goal is to increase the temperature in ultrasound, patient should feel some warmth within ____ minutes
2-3 minutes
55
With 1 MHz use intensity roughly
1.5 to 2.0 W/cm^2
56
With 3 MHz use intensity roughly
0.5 W/cm^2
57
When near bone or metal, the intensity will be _____, because they cause greater tissue heating
decreased
58
If non-thermal ultrasound is desired intensities of about _____ have been shown to be beneficial
0.5 to 1.0 W/cm2
59
The speed to be used during ultrasounds should be ___ circles
Slow
60
The head of the ultrasound should be moved about ____
1 cm/sec
61
Make sure to keep the ultrasound ___, even before its turned on to prevent a build up of energy
moving
62
Every circle of an ultrasound should overlap the last one by ___
1/2
63
Slow speed allows for ___ and is ___ for patients
proper heating and is
| relaxing for patient
64
Faster speeds decrease the
| ____
amount of energy absorbed by tissues
65
The size of area covered by the ultrasound should be about ____ the size of the ERA in 5-10 minutes
2-3 times
66
What is an ERA?
Effective treatment/radiating area
67
What is the average duration of an ultrasound?
5-10 minutes
68
Improvement of a condition treated with an ultrasound should be detected within ____, sometimes longer for more chronic problems
within 2-3 treatments
69
If progress is not observed, treatment should be
| modified, either by ____
changing parameters or by
| selecting a different intervention
70
If used to increase tissue extensibility in order to
| maximize the increase in length produced with stretching, the US must be applied ____
directly before, and if possible during the application of stretching.
71
If not used for extensibility, ultrasound should be performed at a ____ time during each treatment (in relation to other interventions) to allow accurate assessment of its effectiveness
Similar time
72
For soft tissue shortening what type of effects of ultrasound should be used?
Thermal
73
For soft tissue shortening what type of duty cycle should be used?
100%
74
What level of ultrasound frequency should be used when the depth of a soft tissue shortening is 1-2cm?
3 MHz
75
What level of ultrasound frequency should be used when the depth of a soft tissue shortening is less than or equal to 5 cm?
1 MHz
76
What level of ultrasound intensity should be used when the depth of a soft tissue shortening is 1-2cm?
0.5 W/cm^2
77
What level of ultrasound intensity should be used when the depth of a soft tissue shortening is less than or equal to 5cm?
1.5-2.0 W/cm^2
78
For delayed tissue healing prolonged inflammation what type of effects of ultrasound should be used?
Nonthermal
79
For delayed tissue healing prolonged inflammation what type of duty cycle should be used?
20%
80
What level of ultrasound frequency should be used when the depth of a delayed tissue healing prolonged inflammation is 1-2cm?
3 MHz
81
What level of ultrasound frequency should be used when the depth of a delayed tissue healing prolonged inflammation is less than or equal to 5cm?
1 MHz
82
What level of ultrasound intensity should be used when the depth of a delayed tissue healing prolonged inflammation is 1-2 or less than or equal to 5cm
0.5 - 1.00 W/cm^2
83
The duration of treatment for any type of ultrasound for any impairment should be ____
5-10 mins/2 x ERA
84
What are the indications(things it helps with) for ultrasound?
* Soft tissue shortening
* Pain control
* Dermal ulcers
* Tendon and Ligament injuries
* Resorption of calcium deposits
* Bone fractures
* Carpal tunnel syndrome
* Phonophoresis (medication added to ultrasound waves to increase medicine penetration)
* Patient values???
85
What are the contraindications of an ultrasound?
```
• Malignancy
• Pregnancy
• CNS tissue
• Joint cement
• Plastic
• Pacemaker
• Thrombophlebitis
• Eyes and reproductive
organs
```
86
Precautions to be taken when doing an ultrasound?
* Acute inflammation
* Epiphyseal plates
* Fractures
* Breast implants
87
What is a reverse piezoelectric effect?
An electrical current passes through a crystal inside the transducer causing it to expand and contract which generates the acoustic wave
88
What is a transducer? What is the most common form of a transducer?
A medium for transmitting ultrasound into the body tissues.
Gel
89
What are the components that will determine the effect of ultrasound on heating tissues?
- Frequency, intensity, and duty cycle
90
What determines the safety of the use of US?
Depth, duty cycle, frequency and intensity
91
Non-thermal effects of US intensity are:
- Increase intracellular calcium
- Increase skin and cell membrane permeability
- Increase mast cell degranulation
- Release histamine
- Promote macrophage activity
- Increase rate of protein synthesis by fibroblast and tendon cells
- Stimulate proteoglycan synthesis by chondrocytes
- Activate satellite cells in muscle which inhibits muscle atrophy
92
ERA is defined as...
How much the sound head on an US actually deliver sound waves. Usually less
93
How to determine the BNR of the US unit?
Consult the user's manual
