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Physical agents > Week 2 > Flashcards

Week 2 Flashcards

1
Q

What is ultrasound?

A

a form of mechanical energy consisting of high frequency vibrations (> 20,000 Hz)

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2
Q

What is clinical US in PT ranges of ultrasound?

A

from 1-3 MHz

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3
Q

The higher the frequency of an ultrasound, the ____ the rate of absorption.

A

Higher (faster heating)

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4
Q

The higher frequency of of an ultrasound, the ____ the depth of penetration

A

lesser

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5
Q

Ultrasound works on ____ piezoelectric effect

A

reverse

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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

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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)
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8
Q

The beam of an ultrasound may be absorbed, _____ or ______

A

reflected, or refracted

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9
Q

The frequency of an ultrasound determines the _____

A

depth, penetration, and energy absorption

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10
Q

Beam reflection in an ultrasound is ____ if the sound is delivered _____ to treatment surface or interface

A
  • Less

- Perpendicular

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11
Q

Beam refraction occurs as the beam ______

A

travels from one medium to another

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12
Q

What is a spatial peak?

A

the highest amplitude in the beam

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13
Q

What is a spatial average?

A

the average amplitude of the beam

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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).

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15
Q

BNR is determined by ____

A

material used for piezoelectric

transducer

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16
Q

Most BNR machines have ratios between ____ and ____.

A

2: 1
8: 1

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17
Q

The lower the ratio of a BNR, the ____

A

better

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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

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19
Q

What is an attenuation coefficient?

A

the decrease in energy due to

absorption, reflection, and refraction (absorption accounts for ½ of attenuation)

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20
Q

Tissues with more attenuation will show a ____

A

greater temperature rise

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21
Q

Attenuation values are higher for tissues with a ____

A

higher collagen content

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22
Q

Attenuation increases as frequency of US ____

A

increases

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23
Q

Attenuation is ____ related to penetration

A

Inversely

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24
Q

Attenuation is best for ____ tissues

A

Collagen rich tissues

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25
Q

Attenuation is worst for ____

A

Fat/Skin/Muscle

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26
Q

What is the attenuation of 1 MHz ultrasound to blood?

A

3%

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27
Q

What is the attenuation of 1 MHz ultrasound to fat?

A

13%

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28
Q

What is the attenuation of 1 MHz ultrasound to nerve?

A

0%

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29
Q

What is the attenuation of 1 MHz ultrasound to muscle?

A

24%

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30
Q

What is the attenuation of 1 MHz ultrasound to blood vessels?

A

32%

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31
Q

What is the attenuation of 1 MHz ultrasound to skin?

A

39%

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32
Q

What is the attenuation of 1 MHz ultrasound to tendon?

A

59%

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33
Q

What is the attenuation of 1 MHz ultrasound to cartilage?

A

68%

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34
Q

What is the attenuation of 1 MHz ultrasound to bone?

A

96%

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35
Q

What is the mechanical effects of ultrasound?

A
  • Cavitation, micro-streaming, acoustic streaming
  • Increased intracellular calcium
  • Promotes cell function
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36
Q

The ____ effects of ultrasound happens every time you perform an ultrasound

A

Mechanical effects

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37
Q

What is a duty cycle?

A

A continuous flow of sound waves

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38
Q

The ___ effects of ultrasound is predominantly when performing ultrasound at a 100% duty cycle

39
Q

As the duty cycle decreases there will be____ of sound waves

A

pauses in the transmission of sound waves

40
Q

A decrease in duty cycle will allow the body to ____, therefore leading to ___

A
  • dissipate the heat and prevent an overall buildup of temperature rise in the tissues,
  • non-thermal effects of ultrasound
41
Q

The non thermal effects of ultrasound are the _____ effects

A

mechanical

42
Q

What is acoustic streaming of an ultrasound?

A

Movement of tissues at the cellular level.

43
Q

Thermal effects of an ultrasound at a 1 deg temperature rise

A
  • 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
Q

Thermal effects of an ultrasound at a 2-3 deg temperature rise

A

• Decreases pain and muscle spasm

45
Q

Thermal effects of an ultrasound at a 4 deg C or greater temperature rise

A

Increases extensibility of collagen and scars, and decreases joint
stiffness, a 40-45 degrees C temperature is required for at least 5 minutes

46
Q

Duty cycle is equal to

A

time on relative to time on + time off

47
Q

When duty cycle is lowered to 20%, there is

A

Reduced thermal effects as the time off allows heat to dissipate during pulsed US at lower freq.

48
Q

A pulsed sound wave is anything over ____ duty cycle

49
Q

Mechanical effects of a duty cycle occurs at ____

50
Q

At 50% duty cycle, you get more ___ effects, than you get ___ effect. Which is why it has not much clinical use

A

mechanical effects, than you get thermal effect

51
Q

The selection of frequency determines the ____

A

depth of penetration which is a result of how much energy is absorbed as sound waves penetrate.

52
Q

1 MHz provides treatment of tissue up to ___ deep

53
Q

3 MHz provides treatment of tissue up to ___ deep

54
Q

If the goal is to increase the temperature in ultrasound, patient should feel some warmth within ____ minutes

A

2-3 minutes

55
Q

With 1 MHz use intensity roughly

A

1.5 to 2.0 W/cm^2

56
Q

With 3 MHz use intensity roughly

A

0.5 W/cm^2

57
Q

When near bone or metal, the intensity will be _____, because they cause greater tissue heating

58
Q

If non-thermal ultrasound is desired intensities of about _____ have been shown to be beneficial

A

0.5 to 1.0 W/cm2

59
Q

The speed to be used during ultrasounds should be ___ circles

60
Q

The head of the ultrasound should be moved about ____

61
Q

Make sure to keep the ultrasound ___, even before its turned on to prevent a build up of energy

62
Q

Every circle of an ultrasound should overlap the last one by ___

63
Q

Slow speed allows for ___ and is ___ for patients

A

proper heating and is

relaxing for patient

64
Q

Faster speeds decrease the

____

A

amount of energy absorbed by tissues

65
Q

The size of area covered by the ultrasound should be about ____ the size of the ERA in 5-10 minutes

66
Q

What is an ERA?

A

Effective treatment/radiating area

67
Q

What is the average duration of an ultrasound?

A

5-10 minutes

68
Q

Improvement of a condition treated with an ultrasound should be detected within ____, sometimes longer for more chronic problems

A

within 2-3 treatments

69
Q

If progress is not observed, treatment should be

modified, either by ____

A

changing parameters or by

selecting a different intervention

70
Q

If used to increase tissue extensibility in order to

maximize the increase in length produced with stretching, the US must be applied ____

A

directly before, and if possible during the application of stretching.

71
Q

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

A

Similar time

72
Q

For soft tissue shortening what type of effects of ultrasound should be used?

73
Q

For soft tissue shortening what type of duty cycle should be used?

74
Q

What level of ultrasound frequency should be used when the depth of a soft tissue shortening is 1-2cm?

75
Q

What level of ultrasound frequency should be used when the depth of a soft tissue shortening is less than or equal to 5 cm?

76
Q

What level of ultrasound intensity should be used when the depth of a soft tissue shortening is 1-2cm?

A

0.5 W/cm^2

77
Q

What level of ultrasound intensity should be used when the depth of a soft tissue shortening is less than or equal to 5cm?

A

1.5-2.0 W/cm^2

78
Q

For delayed tissue healing prolonged inflammation what type of effects of ultrasound should be used?

A

Nonthermal

79
Q

For delayed tissue healing prolonged inflammation what type of duty cycle should be used?

80
Q

What level of ultrasound frequency should be used when the depth of a delayed tissue healing prolonged inflammation is 1-2cm?

81
Q

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?

82
Q

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

A

0.5 - 1.00 W/cm^2

83
Q

The duration of treatment for any type of ultrasound for any impairment should be ____

A

5-10 mins/2 x ERA

84
Q

What are the indications(things it helps with) for ultrasound?

A
  • 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
Q

What are the contraindications of an ultrasound?

A 
• Malignancy
• Pregnancy
• CNS tissue
• Joint cement
• Plastic
• Pacemaker
• Thrombophlebitis
• Eyes and reproductive
organs
86
Q

Precautions to be taken when doing an ultrasound?

A
  • Acute inflammation
  • Epiphyseal plates
  • Fractures
  • Breast implants
87
Q

What is a reverse piezoelectric effect?

A

An electrical current passes through a crystal inside the transducer causing it to expand and contract which generates the acoustic wave

88
Q

What is a transducer? What is the most common form of a transducer?

A

A medium for transmitting ultrasound into the body tissues.

Gel

89
Q

What are the components that will determine the effect of ultrasound on heating tissues?

A
  • Frequency, intensity, and duty cycle
90
Q

What determines the safety of the use of US?

A

Depth, duty cycle, frequency and intensity

91
Q

Non-thermal effects of US intensity are:

A
  • 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
Q

ERA is defined as…

A

How much the sound head on an US actually deliver sound waves. Usually less

93
Q

How to determine the BNR of the US unit?

A

Consult the user’s manual

Physical agents (7 decks)

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