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Therapeutic Modalities > Ultrasound > Flashcards

Ultrasound Flashcards

1
Q

What is ultrasound?

A

Inaudible acoustical energy caused by acoustic vibrations with high frequency

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2
Q

What does ultrasound produce?

A

Thermal and non thermal effects

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3
Q

What are the parts of the basic flow chart algorithm?

A
  • Electrical output
  • Mechanical vibration
  • Acoustic soundwave
  • Absorbed in the tissues
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4
Q

What is ionizing radiation?

A

Radiation of sufficient energy to dissociate atoms or molecules into electrically charged atoms or radicals in the irradiated material

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5
Q

What is diagnostic ultrasounds?

A

A method of obtaining images from inside the human body through the use of high frequency sound waves

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6
Q

What is ultrasound imaging also known as?

A

Sonography

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7
Q

What is the difference between acoustical and electromagnetic energy?

A

Acoustical:

  • Requires a medium to be transported
  • Does not travel through a vacuum
  • Travels most efficiently through dense tissue
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8
Q

What is the energy output for high frequency?

A

75,000-3.3 million Hz (.75-3.3 MHz)

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9
Q

What is the piezoelectric effect?

A

The ability of certain materials like crystals, somer ceramics and bone to generate an electric potential in response to applied mechanical stress

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10
Q

What are different types of piezoelectric crystals used?

A
  • Quartz
  • Lead zirconate or titanate
  • Barium titanate
  • Nickel cobalt
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11
Q

How does the crystal convert electrical energy to sound energy?

A

Through mechanical deformation

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12
Q

What is crystal deformation?

A

When an alternating current is passed through a crystal it will expand and compress

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13
Q

What is the reverse piezoelectric effect?

A

Occurs when an alternating electrical current passes through the crystal causing the crystal to contract and expand creating an acoustical sound wave

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14
Q

What is the effective radiating area (ERA)?

A

The total surface area of the sound head which emits acoustic energy

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15
Q

What are the typical sound head sizes?

A
  • 2.5 cm
  • 5 cm
  • 10 cm
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16
Q

What is the beam non-uniformity ratio (BNR)?

A

Indicates the amount of variability in intensity within the beam

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17
Q

What is the ratio of the BNR?

A

The highest intensity found in the beam relative to the average intensity of the transducer

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18
Q

What is the ideal BNR and what is the typical BNR?

A

Ideal: 1:1
Typical: 6:1

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19
Q

How does the BNR affect the intensity?

A

The lower the BNR the more even the intensity

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20
Q

What frequency do most generators produce?

A

1.0 or 3.0 MHz

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21
Q

What is the depth of penetration dependent on?

A

The frequency

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22
Q

What depth is 1 MHz absorbed at?

A

3-5 cm

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23
Q

What depth is 3 MHz absorbed at?

A

1-2 cm

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24
Q

What occurs in the near field?

A

Distribution of energy is non uniform due to the manner in which waves are generated and differences in acoustic pressure

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25
Q

What is the point of maximum acoustic intensity?

A

Waves are indistinguishable and basically arrive simultaneously

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26
Q

What occurs in the far field?

A

Energy is more evenly distributed and the beam becomes more divergent

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27
Q

How does absorption increase?

A

As the frequency is increased

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28
Q

What happens with penetration and absorption in tissues high in water content?

A

Decreased absorption, energy penetrates easily

29
Q

What happens with penetration and absorption in adipose tissue?

A

Decreased absorption, energy penetrates easily to deeper tissues

30
Q

What happens with penetration and absorption in tissues high in protein content?

A

Increased energy absorption

31
Q

What happens with penetration and absorption in peripheral nerves?

A

Energy is absorbed 2X that of muscle

32
Q

What are the different ways the intensity of the sound wave can be decreased?

A
  • Reflected
  • Refracted
  • Absorbed
33
Q

What is a longitudinal wave?

A

The molecular displacement is in the direction of wave propagation.
There are regions go high and low molecular density (compression and rarefaction) as the wave travels through alternating regions

34
Q

What can longitudinal waves travel through?

A

Liquids and solids (soft tissue)

35
Q

What is a transverse wave?

A

Displacement is perpendicular to direction of propagation

36
Q

What can transverse waves travel through?

A

Solids (bone) and it rebounds when it hits

37
Q

What is rarefaction?

A

The lessening in the density of something

38
Q

What are standing waves (hot spots)?

A

When an ultrasound wave hits the interface between two tissues of different acoustic impedance a reflection of a percentage of the waves will occur.

39
Q

What can occur in standing waves?

A

Achieve peak intensity and pressure which can create increased pain and tissue destruction through excess NRG and gas bubble formation

40
Q

What is power?

A

The total amount of ultrasound NRG in the beam and is expressed in watts

41
Q

What is intensity?

A

The rate at which energy is being delivered per unit area

42
Q

What is spatial average intensity?

A

Intensity of the beam average over the area of the transducer

43
Q

What is the usual rage for intensity?

A

0.1 - 3.0 W/cm2

44
Q

What is the recommendation for intensity?

A

The lowest intensity at the highest frequency which transmits energy to a specific tissue to achieve a desired therapeutic effect

45
Q

What are the thermal effects of ultrasound?

A
  • Increased collagen extensibility
  • Increased blood flow
  • Decreased pain
  • Reduction of muscle spams
  • Decreased joint stiffness
  • Reduction of chronic inflammation
46
Q

For thermal effects to occur how much does the temperature need to rise and for how long?

A

Temp raised 40-50 degrees for a minimum of 5 minutes

47
Q

What occur during mild, moderate and vigorous heating?

A
  • Mild: increase of 1 degree C, accelerators metabolic rate in tissue
  • Moderate: increase of 1-2 degrees C, reduces pain, muscle spams, chronic inflammation, increases blood flow
  • Vigorous: increase of 3-4 degrees C, viscoelastic properties of collagen
48
Q

What are the non-thermal effects of ultrasound?

A
  • Increased fibroblastic activity
  • Increased protein synthesis
  • Tissue regeneration
  • Reduction of edema
  • Bone healing
  • Pain modulation
49
Q

What is micro-streaming?

A

Unidirectional flow of fluid and tissue components along the cell membrane interface resulting in mechanical pressure waves in an ultrasonic field

50
Q

What does micro-streaming do?

A

Alters cell membrane permeability to sodium and calcium ions important in the healing process

51
Q

What does the movement if air bubbles within the interstitial tissue do?

A

Enhances the permeability of cell membranes, increasing diffusion rates

52
Q

What is cavitation?

A

The formation of gas filled bubbles that expand and compress due to pressure changes in fluid

53
Q

What is stable cavitation?

A

Results in an increased fluid flow around these bubbles. The resultant movement of interstitial fluids in essence promotes acoustical streaming

54
Q

What is unstable cavitation?

A

Results in violent large excursions in bubble volume with collapse, creating increased pressure and temperatures that can cause tissue damage

55
Q

What does cavitation and streaming do during the inflammatory stage?

A

Increases transport of calcium across cell membrane releasing histamine which stimulates leukocytes to ‘clean-up’, leading to the stimulation of fibroblasts to produce collagen

56
Q

What are some application considerations?

A
  • Size of the area being treated
  • What are you trying to accomplish
  • Intensity of treatment
  • Treatment area should be no larger than 2-3 times the size of the ERA
  • If you decrease intensity then you should increase treatment duration
57
Q

What are some different coupling mediums that can be used?

A
  • Gel
  • Water
  • Mineral oil
  • Distilled water
  • Glycerin
  • Analgesic creams
58
Q

What should you consider when getting started?

A
  • Apply to clean skin
  • If too hairy, consider shaving
  • Use appropriate conducting medium
  • Select appropriate sound head size/frequency
  • Ensure sound head is in contact with the skin before turing machine on
  • Adjust intensity
  • Move sound head (2.5 cm per second)
59
Q

What are some different ultrasound techniques?

A
  • Direct contact
  • Immersion
  • Bladder
60
Q

How/when is the immersion technique used?

A
  • When treating irregular surfaces
  • Use a plastic, ceramic or rubber basin
  • Can us tap water as a culling medium
  • Transducer should not be in contact with the skin
  • Wipe air bubbles away
61
Q

How/when is the bladder technique used?

A
  • Treating irregular surfaces
  • Uses a balloon filled with water
  • Coat both sides of the balloon with gel
62
Q

What should the patient be told to pay attention for?

A
  • Heat
  • Aching
  • Burning
63
Q

If the patient says something doesn’t feel right what should be done?

A
  • Switch to pulse mode
  • Decrease intensity
  • Discontinue treatment
64
Q

What is the continuous mode?

A

The transmission on NRG is on throughout the treatment and the intensity remains constant

65
Q

What is the pulsed mode?

A

The transmission of ultrasound is pulsed on and off, the intensity is interrupted therefore the average intensity of output is low over time

66
Q

What is the duty cycle?

A

The percentage of on:off time (20%, 50%)

67
Q

What are some contraindication for ultrasound?

A
  • Acute injury
  • Over bone
  • Over exposed spinal cord
  • Over the eyes
  • Over the carotid artery
  • Pregnancy/pelvic area during menstruation
  • Active infection
  • Fracture site
  • Cancer/tumours
  • Decrease skin sensation
68
Q

What is phonophoresis?

A

Ultrasound used to drive topical application of selected medication into the tissues

Therapeutic Modalities (5 decks)

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