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PTRS 705 - PT Interventions 2 > Ultrasound and Laser Therapy > Flashcards

Ultrasound and Laser Therapy Flashcards

1
Q

What is Ultrasound?

A

Sound wave with frequencies above the range of human hearing

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2
Q

Ultrasound uses:

A
  • Diagnostic test (fetal)
  • Anti-cancer treatment to eradicate cancer tumors
  • Heating and healing soft tissues, reducing pain, and restoring function (therapeutic)
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3
Q

Ultrasound Variables

A
  • Size of sound head
  • Frequency
  • Intensity
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4
Q

Sound Head characteristics

A
  • Head size: 2cm2, 5 (most common), 10
  • Effective Radiating Area (ERA) - size of transducer that is producing the vibration
  • Crystal will be slightly smaller than circumference of surface area
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5
Q

Sound Head - Beam Non-Uniformity Ratio

A
  • Some parts of crystal may emit more energy than others

- Move sound head at all times

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6
Q

Frequency

A
  • Frequency and shape of the wave are directly related
  • Frequency and depth of penetration are inversely related
  • Measured in Hz (Hertz) = 1 cycle/sec
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7
Q

What is the Frequency for therapeutic ultrasound?

A

0.75-3 MHz

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8
Q

What are the high frequency sound waves created with?

A

Piezoelectric crystals

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9
Q

Piezoelectric effect

A

Transforms mechanical energy to electrical energy (cigarette lighter)

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10
Q

Crystals and materials that have piezo properties? (8)

A
  • Quartz
  • Sucrose
  • Topaz
  • Bone
  • Tendon
  • Silk
  • Enamel
  • Synthetic crystals
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11
Q

The more dense the tissue the ________

A

closer together the molecules are and faster the energy will be transmitted

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12
Q

More dense tissues absorb more energy therefore ________ the penetration

A

decreasing

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13
Q

Why do higher frequencies decrease penetration?

A

Molecules vibrate faster, requiring more energy to overcome friction

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14
Q

What type of frequency will allow for deeper penetration?

A

Low - due to less friction

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15
Q

What frequency treats superficial tissue?

A

3MHz

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16
Q

What frequency penetrates to tissues b/w 2-5cm deep?

A

1MHz

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17
Q

What is Attenuation?

A

As beam passes through tissue, loses energy

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18
Q

What is Intensity in Ultrasound?

A

The amount of energy contained in the ultrasound beam - in Watts

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19
Q

Example problem - Intensity: Power = 2 W and sound head is 2cm2

A

Intensity = 1W/cm2

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20
Q

Spatial Average Temporal Peak Intensity

A

Highest intensity delivered w/n the ERA during a pulse

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21
Q

Intensity - Pulsed

A
  • Interrupted periodically

- If on for 2 ms, then off for 2ms = 50% duty cycle

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22
Q

What is Duty Cycle?

A

% time that it is on

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23
Q

Intensity - definition

A

To provide the lowest intensity of ultrasound energy at the highest frequency that will transmit the energy to a specific tissue and achieve the desired therapeutic effect

24
Q

General Thermal Effects (6)

A
  • Reduce muscle spasm and guarding
  • Modulate perception of pain
  • Increase nerve conduction velocity
  • Increase blood flow
  • Increase enzyme activity
  • Increase extensibility of collagen fibers
25
Q

Thermal Mechanisms - Muscle @ 3 MHz

A

Intensity: 0.5-1.5
Time: 5-10 minutes

26
Q

Thermal Mechanisms - Muscle @ 1 MHz

A

Intensity: 1.0-2.0
Time: 5-10

27
Q

Thermal Mechanisms - Connective Tissue @ 3 MHz

A

Intensity: 0.5-1.0
Time: 2-10

28
Q

Thermal Mechanisms - Connective Tissue @ 1 MHz

A

Intensity: 0.5-1.5
Time: 2-10

29
Q

Non-Thermal? Effects (4)

A
  • Increase cell membrane permeability
  • Increase histamine release
  • Increase macrophage activity
  • Enhance wound contraction
30
Q

Contraindications for Ultrasound

A

**Do NOT go over growth plates in children

31
Q

How fast should you move the sound head?

A

4cm/sec

32
Q

What does LASER stand for?

A

Light Amplification of Stimulated Emissions of Radiation

33
Q

What is Coherence?

A

same wavelength and in phase

34
Q

What is monochromacity?

A

Same color (same as wavelength)

35
Q

What is Collimation?

A

In parallel (minimal divergence)

36
Q

How does a Laser work?

A
  1. Activate electrons
  2. Inversion to an excited state
  3. Emission of a photon
  4. Stimulated emission - the striking of an electron by a photon
  5. Amplification - repeated stimulated emission
  6. Maximum capacity is reached, then photons are released for a light beam
37
Q

4 Types of Lasers

A
  • Crystal lasers
  • Gas lasers
  • Diode lasers
  • Liquid lasers
38
Q

High Power Laser

A

Surgical laser produces heat and can cut tissue

-Tissue destruction

39
Q

Low Power Laser

A

Tissue healing

40
Q

Class 1 Laser

A

Cannot emit laser radiation at known hazard levels invisible

41
Q

Class 1A Laser

A

Lasers that are “not intended for viewing”, such as a supermarket laser scanner

42
Q

Class 2 Laser

A

Low-power visible lasers that emit above Class 1 levels but not above 1 mW. The concept is that the human aversion reaction to bright light will protect a person

43
Q

Class 3A Laser

A
  • Intermediate -power lasers (1-5 mW)
  • hazardous only for intrabeam viewing
  • pen-like lasers
44
Q

Class 3B Laser

A
  • Moderate-power lasers
  • 5-500 mW
  • Can damage the retina
  • Protective eyewear needed for clinician and client
45
Q

Class 4 Laser

A
  • High-power lasers - hazardous to view under any condition

- Potential fire and skin hazard

46
Q

What does the depth of penetration depend on?

A

Types of Laser (wavelength)

-Longer wavelengths have greater penetration

47
Q

How deep can Infrared lasers penetrate?

A

Up to 13 cm

48
Q

What is a Joule?

A
  • 1W/sec

- Energy density J/cm2 (average power)

49
Q

Will you have more energy with pulsed or continuous?

A

Continuous

50
Q

Dosage depends on:

A
  • Power - output of the laser
  • Exposure time
  • Power Density
  • Energy Density
  • Dose Tissue
51
Q

Dose Tissue equation

A

Dose Tissue = Sum of Dose per Diode X number of applications (Joules)

52
Q

Treatment time equation

A

TA = (Energy/Power) x Area

53
Q

Laser dosage for acute conditions?

A

0.05 to 0.5 J/cm2

54
Q

Laser dosage for chronic conditions?

A

0.5 to 3.0 J/cm2

55
Q

Laser: Clinical Applications

A
  • Largely unknown
  • Pain
  • Wound Healing/Scar
  • Immunological response
  • Connective tissue stimulation (bone)
56
Q

What happens to light when it hits an object? (4)

A
  • Absorbed
  • Reflected
  • Transmitted
  • Refracted

PTRS 705 - PT Interventions 2 (4 decks)

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