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Electrotherapy Quiz > Ultrasound > Flashcards

Ultrasound Flashcards

1
Q

Define ultrasound

A

Sound traveling through a medium at frequencies above the upper-limit frequency of human audibility

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2
Q

What is the upper (max) limit of the human auditory range

A

20 kilohertz (20,000 Hz)

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3
Q

Define sound

A

A form of mechanical acoustic energy, or pressure waves, that propagates through vibration in the air and in other media such as water and soft biologic tissues.

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4
Q

What is meant by therapeutic ultrasound

A

Use of mechanical acoustic energy for treating variety of soft tissue pathologies, including bone fractures and dermal wounds

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5
Q

List some uses of ultrasound

A
  • diagnosis
  • destruction of tissue
  • therapeutic agent
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6
Q

Diagnostic ultrasound can be used for

A

Imaging :
-internal structures
- fetus during pregnancy

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7
Q

Ultrasound therapy is classified into 3 categories; what are they

A
  • CUS
  • LIPUS
  • MIST therapy
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8
Q

Conventional ultrasound (CUS)

A
  • oldest and most conventional type of therapeutic ultrasound
  • delivered at low and high frequencies and intensities
  • continuous or pulsed
  • application method : dynamic + contact or non contact
  • common coupling agents : aquasonic gel and tap water
  • used for its thermo-mechanical effects on tendon, ligament, and muscle disorders
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9
Q

What is the oldest and most conventional therapeutic type of ultrasound

A

Conventional ultrasound CUS

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10
Q

Method of application for CUS

A

Dynamic
Contact or no contact

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11
Q

Common coupling agents for CUS

A

Aquasonic gel and tap water

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12
Q

CUS is used for its ______________ effects.

A

Thermo-mechanical effects

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13
Q

What does LIPUS stand for

A

Low-intensity pulsed ultrasound

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14
Q

Low-intensity pulsed ultrasound (LIPUS)

A
  • ultrasonic energy
  • delivered at MEDIUM frequency (1-1.5 MHz)
  • delivered at LOW intensity (0.03 W/cm2)
  • application method: stationary with contact
  • PULSED
  • coupling medium : ultrasonic gel
  • used for its MECHANICAL effect on fresh and slow-to-heal bone fractures
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15
Q

Which therapeutic ultrasound is ideal for fresh and slow-to-heal bone fractures?

A

LIPUS

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16
Q

Which therapeutic ultrasound is applied using stationary applicator ?

A

LIPUS

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17
Q

LIPUS is used for its ____________ effect.

A

Mechanical

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18
Q

Conventional US induces thermal and mechanical effects in pathological soft tissues especially those that are rich in ______________.

A

Proteins

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19
Q

Examples of tissues rich in protein

A
  • tendons
  • ligaments
  • muscles
  • joint capsules
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20
Q

Noncontact low-frequency ultrasound (NCLFUS) is also known as _______________.

A

MIST Therapy System

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21
Q

Noncontact low-frequency ultrasound (NCLFUS)

A
  • most recent therapeutic ultrasound
  • delivered at LOWER frequency (40kHz)
  • delivered at LOWER intensity (0.5 W/cm2)
  • PULSED
  • application technique: dynamic + noncontact
  • coupling medium: sterile saline water
  • promotes dermal wound healing through its mechanical cleansing, debridement, and antibacterial effects
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22
Q

Which therapeutic ultrasound heals dermal wounds through its mechanical cleansing , debridement, and antibacterial effects?

A

NCLFUS (MIST)

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23
Q

Between LIPUS and CUS, which is delivered at a lower intensity?

A

LIPUS

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24
Q

What is the most widely used EPA

A

Conventional US

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25
Q

What type of waves are sound waves ?

A

Longitudinal waves

(NOT TRANSVERSE)

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26
Q

Sound waves consist of areas of _________ and ____________.

A

Compression
Rarefactiion

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27
Q

What happen to particles of materials when exposed to sound waves?

A

Oscillate about a fixed point

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28
Q

True or false
When exposed to sound waves, particles move with the wave itself .

A

False!

They oscillate about a fixed point

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29
Q

Relationship between molecular vibration and heat

A

Increase in molecular vibration = increase in heat generation

(More oscillation = more heat)

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30
Q

Therapeutic ultrasound is produced at a frequency of ________ to _____ MHz

A

0.7 - 3.3 MHz

(But on machines its usually 1-3 MHz)

NOTE: increases depth of absorption by 2-5 cm

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31
Q

How does therapeutic ultrasound transmit energy?

A

By compressing and rarefying materials

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32
Q

What happens to intensity as it travels deeper in the tissue

A

Decrease

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33
Q

True or false
Ultrasound is inaudible

A

True

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34
Q

How is the ultrasonic beam energy formed ?

A

High frequency electric current is applied to the surface of a piezoelectric material (crystal) called a transducer , causing mechanical deformation of this transducer, leading to cycles of expansion and contraction that produce compressions and rarefactions of the beam.

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35
Q

What is a transducer

A

A piezoelectric material or crystal that is usually a fragile quartz. This crystal when exposed to an electrical current can expand or contract; thus, producing compressions and rarefactions.

IT CONVERTS ELECTRICAL ENERGY INTO ACOUSTIC ENERGY

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36
Q

Expansion of the transducer causes __________.

A

Compression

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37
Q

Contraction of the transducer causes ___________.

A

Rarefaction

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38
Q

Ultrasound waves created by repeated cycles of micro-expansion and micro-contraction of the transducer have what shape ?

A

Sinusoidal shape

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39
Q

What happens during the expansion phase of the transducer

A
  • high pressure in soft tissues
  • molecules closer together
  • compressions
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40
Q

What happens during the contraction phase of the transducer ?

A
  • low pressure in soft tissues
  • molecules further apart
  • rarefaction
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41
Q

Compression and rarefaction and compression and rarefaction again and again cause …

A

heat due to oscillation

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42
Q

The applicator is made out of 2 parts :

A
  1. Transducer
  2. Sound head (metal plate/ faceplate)
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43
Q

How thick is the transducer ?

A

2-3 mm

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44
Q

Purpose of the transducer

A

Converts electrical energy into acoustic energy

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45
Q

What is the purpose of the sound head on the applicator

A

Transfers acoustic energy from transducer to soft tissues through a medium

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46
Q

Describe the near field

A
  • closest to the transducer
  • less divergent
  • more focused beam

AKA : Fresnel zone

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47
Q

Describe far field

A
  • immediately follows near field
  • more divergent
  • less focused beam

AKA: Fraunhofer zone

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48
Q

Which field is referred to as the Fresnel zone

A

Near field

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49
Q

Which field is referred to as Fraunhofer zone

A

Far field

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50
Q

Two types of delivery modes

A

Continuous mode
Pulsed mode

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51
Q

Define continuous mode

A

Uninterrupted (continuous) flow of acoustic energy during the whole treatment duration

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52
Q

Is continuous mode thermal or athermal

A

Thermal

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53
Q

Is continuous used for acute or chronic conditions

A

Chronic

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54
Q

What is pulsed mode

A

Acoustic energy that is periodically interrupted (rhythmic flow) where ultrasound is delivered for a given duration (ON time) followed by a period of no delivery (OFF time)

55
Q

Is pulsed used mainly for acute or chronic conditions

A

Acute

56
Q

Does pulsed mode produce a thermal or athermal effect

A

Athermal

But high intensity may produce a slight thermal effect

57
Q

What is duty cycle

A

Period of time, measured in percentage, during which acoustic energy is delivered

58
Q

How to calculate duty cycle

A

ON-time / (ON-time + OFF-time) x 100

59
Q

What is the duty cycle for continuous mode

A

100%

60
Q

What is the most commonly used duty cycle for pulsed mode

A

20%

61
Q

What does it mean to have an on and off ratio of 1:4

A

The time during which US is delivered ON is four times shorter than the time value during which it is OFF

62
Q

What is meant by pulse frequency

A

The number of compressions and rarefactions or the number of wave cycles completed each second

63
Q

How to calculate pulse frequency

A

f= 1 / (ON time + OFF time)

64
Q

Which frequency is suitable for superficial heating

A

3 MHz

65
Q

Which frequency is suitable for deep heating

A

1 MHz

66
Q

Relationship between wavelength and frequency

A

Inversely proportional

67
Q

Which heating involves higher frequency and lower wavelength according to this picture?

A

Superficial heating :
- higher frequency
- lower wavelength

Deep heating :
- lower frequency
- higher wavelength

68
Q

What is the effective radiating area ERA?

A

Total area of the surface of the transducer that actually produces the sound wave

69
Q

Unit of ERA

A

cm2

70
Q

The ERA is ___% smaller than the transducer faceplate area

A

10%

71
Q

True or false
The ERA is 10% bigger than transducer faceplate ?

A

False

(Smaller)

72
Q

Relationship between treating area and ERA

A

The larger the treating area the larger the ERA

(NOTE: the ERA and treating area have a ratio of 1:3)

73
Q

What is intensity

A

The amount of acoustic power (measured in Watts W) per unit area of the transducer ERA (measured in cm2) used to deliver this energy to tissue

74
Q

How to calculate intensity

A

Acoustic power (W) / ERA (cm2)

75
Q

Unit of intensity

A

(W/cm2)

76
Q

What terms are used to describe intensity ?

A

Spatial
Temporal

77
Q

What is meant by beam non uniformity ratio (BNR)

A

Amount of variability of intensity within the ultrasound beam

78
Q

True or false
The higher the quality of the crystal (transducer) = the better the beam

A

True

79
Q

Physiological THERMAL effects of therapeutic ultrasound

A
80
Q

Athermal (mechanical) therapeutic effects

A
  • acceleration of healing process
  • wound healing
  • acceleration of bone growth
81
Q

Physiological ATHERMAL effects of therapeutic ultrasound

A
82
Q

What two things occur during athermal ultrasound that promote therapeutic effects

A

Stable cavitation
Acoustic microstreaming

83
Q

What is meant by acoustic cavitation

A

Formation of empty spaces or cavities resulting from the formation of micro bubbles which expand and contracts under the influence of acoustic radiation

84
Q

What are the two types of acoustic cavitations

A

Stable (good)
Unstable (bad)

85
Q

Describe stable cavitation and microstreaming

A

Occurs when the bubbles begin to pulsate, meaning it compresses during high pressure and expand during low pressure waves.

This triggers MOLECULAR MOVEMENT as molecules come closer together during compression and further apart during rarefaction

This movement of the fluid is called MICROSTREAMING

Microstreaming causes movement and transfer of intracellular and extracellular ions affecting cellular membrane permeability

86
Q

Describe unstable cavitation

A

Occurs when the bubbles, subjected to strong cycles of compression and expansion, collapse or implode, releasing very high temperature and pressure changes in their surrounding

87
Q

How to prevent unstable cavitations

A

With dynamic application technique (constantly moving the head)

88
Q

Define acoustic microstreaming

A

The Unidirectional movement of fluids along the boundaries of cell membrane resulting from stable cavitation

89
Q

True or false
Stable cavitation leads to microstreaming

A

True

90
Q

Indications of ultrasound therapy

A

Inflammatory conditions (acute, subacute, chronic)

Swelling and effusion

Pain relief

Soft tissue healing and repair

Wound management

Bony fracture management

91
Q

Ultrasound is a mechanical wave in which energy is transmitted by _____________.

A

Vibration

92
Q

What is meant by absorption

A

Conversion of mechanical energy into heat

93
Q

In what tissue is absorption rate the highest

A

Tissue with high protein content

94
Q

In what tissue is absorption rate the lowest

A

High water content tissue

95
Q

Get a good look at this slide, containing tissue with the highest and lowest rates of absorption

A
96
Q

What is reflection

A

The amount of energy transmitted determined by the acoustic impedance of the two materials on either side of interface

(From my understanding its basically the amount of acoustic waves reflected and not absorbed)

97
Q

Reflection and absorption at soft tissues such as bony interface

A

35 % reflection
65 % absorption

98
Q

Reflection and absorption of skin interface with medium

A

0.1% reflection
99.9% absorption

99
Q

Reflection and absorption of skin interface at air (without coupling medium)

A

100% reflection
0 % absorption

100
Q

What is meant by refraction

A

Ultrasound energy enters the tissue at an angle and transmitted at a different angle

101
Q

What is meant by standing wave “HOT SPOT”

A

We have some of the waves are reflected correct?

The reflected energy can combine with new transmitted energy, causing the intensity of the energy to INCREASE.

This can cause tissue damage

Can be avoided by moving head throughout treatment

102
Q

What happens to intensity in the case of a standing wave “hot spots”?

A

Increases

103
Q

General contraindications of US

A
  1. Impaired mentation
  2. Over infected lesions
  3. Cardiac pacemaker or other electronic devices (implanted or external)
  4. Over thrombosis areas
  5. On CNS tissue (brain and spinal cord after laminectomy)
  6. Malignant areas
  7. Ischemic areas
104
Q

Local contraindications

A
105
Q

Adverse effects of ultrasound

A

Burn
Blood cell stasis

106
Q

Why is burn an adverse reaction

A
107
Q

How does blood cell stasis occur as a side effect

A
108
Q

List some dosimetric parameters

A
  • coupling method
  • delivery mode
  • frequency
  • ERA
  • intensity
  • application duration
  • frequency of treatment
109
Q

How is the ultrasound head properly placed on treated area?

A

90 degrees and parallel to the skin with moderate pressure

110
Q

Two types of delivery modes

A

Continuous mode
Pulsed mode

111
Q

Large duty cycle will __________ the thermal effect and _________ the mechanical effect.

A

Maximize thermal effect
Minimize mechanical effect

112
Q

What is the depth of superficial heating with a frequency of 3MHz

A

2-3 cm depth

113
Q

What is the depth of deep heating with a frequency of 1MHz

A

5 cm depth

114
Q

In terms of sizes, the treated area should be no more than ____________________ than the ERA.

A

3 times greater (max)

115
Q

Stationary application may cause _____________,

A

Hot spot

116
Q

The intensity set for the treatment depends on what

A

Size, depth, nature of treated area, mode, frequency of ultrasound and time of application

Read these numbers below

117
Q

What is the application duration of therapeutic ultrasound

A

5 to 10 minutes

118
Q

What are the different delivery methods of ultrasound

A
  • direct contact application
  • water immersion (water bath application)
  • cushion contact (water bag application)
  • phonophoresis
119
Q

Direct contact application

A
  • contact between the skin and applicator with THIN layer of gel
  • MOST convenient and efficient method
  • move head in SLOW parallel strokes with LIGHT pressure at 90 degrees
  • used to treat flat surfaces
120
Q

Water immersion (water bath application)

A
  • non contact method
  • treated surface area and applicator are immersed in a plastic bath filled with tap water
  • sound head is over and close to the skin (without contact)
121
Q

Why should stainless-steel baths be avoided during water immersion application ?

A

It has a high capacity to reflect ultrasonic waves back to the operator immersed hand during therapy

122
Q

Cushion contact (water bag application)

A
  • soft ultrasonic gel pad is placed between the sound head faceplate and the skin, overlying the treatment area
  • used is treated area cant be immersed in water and irregular and sensitive to pressure
  • a thin layer of ultrasonic gel is required at both faceplate-pad interface and pad-skin interface
123
Q

What are two application techniques

A

Dynamic technique
Stationary technique

124
Q

Dynamic technique can be done by __________ displacement or _____________ displacement

A

Manual
Automatic

125
Q

Why shouldn’t the movement of the applicator be too fast?

A

Because the faster the movement, the less the absorption of the ultrasonic energy into the soft tissue per unit of time

126
Q

What are the parameters that should be documented and recorded

A
127
Q

What is phonophoresis

A

-A technique in which ultrasound is used to enhance delivery of a selected medication into the tissue

  • safe, painless and non invasive technique
  • thermal and athermal mechanisms are used
  • used to decrease pain and inflammation
128
Q

If there is improvement, what do you do to the parameters ?

A

Continue using the same parameters

129
Q

If there is no improvement after 3-4 treatments , what do you do to the parameters ?

A

Change the parameters or discontinue treatment with US

130
Q

Read and understand these points

A

👍🏻

131
Q

Can US be applied along with other agents ?

A

Yes !

132
Q

What other agents can we apply in conjunction with US

A
  • US with hot packs to relieve pain
  • with ice packs to promote soft tissue healing and produce analgesic effect
133
Q

What happens if we do skin cooling BEFORE ultrasound application?

A

Less heating effect in deeper tissues

134
Q

Should Thermotherapy and cryotherapy be applied before or after ultrasound?

A

AFTER

(NِِEVER BEFORE)

Electrotherapy Quiz (3 decks)

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