Ultrasound and Laser Therapy

Question 1

What is Ultrasound?

Answer 1

Sound wave with frequencies above the range of human hearing

Question 2

Ultrasound uses:

Answer 2

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

Question 3

Ultrasound Variables

Answer 3

• Size of sound head
• Frequency
• Intensity

Question 4

Sound Head characteristics

Answer 4

• 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

Question 5

Sound Head - Beam Non-Uniformity Ratio

Answer 5

• Some parts of crystal may emit more energy than others

- Move sound head at all times

Question 6

Frequency

Answer 6

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

Question 7

What is the Frequency for therapeutic ultrasound?

Answer 7

0.75-3 MHz

Question 8

What are the high frequency sound waves created with?

Answer 8

Piezoelectric crystals

Question 9

Piezoelectric effect

Answer 9

Transforms mechanical energy to electrical energy (cigarette lighter)

Question 10

Crystals and materials that have piezo properties? (8)

Answer 10

• Quartz
• Sucrose
• Topaz
• Bone
• Tendon
• Silk
• Enamel
• Synthetic crystals

Question 11

The more dense the tissue the ________

Answer 11

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

Question 12

More dense tissues absorb more energy therefore ________ the penetration

Answer 12

decreasing

Question 13

Why do higher frequencies decrease penetration?

Answer 13

Molecules vibrate faster, requiring more energy to overcome friction

Question 14

What type of frequency will allow for deeper penetration?

Answer 14

Low - due to less friction

Question 15

What frequency treats superficial tissue?

Answer 15

3MHz

Question 16

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

Answer 16

1MHz

Question 17

What is Attenuation?

Answer 17

As beam passes through tissue, loses energy

Question 18

What is Intensity in Ultrasound?

Answer 18

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

Question 19

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

Answer 19

Intensity = 1W/cm2

Question 20

Spatial Average Temporal Peak Intensity

Answer 20

Highest intensity delivered w/n the ERA during a pulse

Question 21

Intensity - Pulsed

Answer 21

• Interrupted periodically

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

Question 22

What is Duty Cycle?

Answer 22

% time that it is on

Question 23

Intensity - definition

Answer 23

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

Question 24

General Thermal Effects (6)

Answer 24

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

Question 25

Thermal Mechanisms - Muscle @ 3 MHz

Answer 25

Intensity: 0.5-1.5 Time: 5-10 minutes

Question 26

Thermal Mechanisms - Muscle @ 1 MHz

Answer 26

Intensity: 1.0-2.0 Time: 5-10

Question 27

Thermal Mechanisms - Connective Tissue @ 3 MHz

Answer 27

Intensity: 0.5-1.0 Time: 2-10

Question 28

Thermal Mechanisms - Connective Tissue @ 1 MHz

Answer 28

Intensity: 0.5-1.5 Time: 2-10

Question 29

Non-Thermal? Effects (4)

Answer 29

- Increase cell membrane permeability - Increase histamine release - Increase macrophage activity - Enhance wound contraction

Question 30

Contraindications for Ultrasound

Answer 30

**Do NOT go over growth plates in children

Question 31

How fast should you move the sound head?

Answer 31

4cm/sec

Question 32

What does LASER stand for?

Answer 32

Light Amplification of Stimulated Emissions of Radiation

Question 33

What is Coherence?

Answer 33

same wavelength and in phase

Question 34

What is monochromacity?

Answer 34

Same color (same as wavelength)

Question 35

What is Collimation?

Answer 35

In parallel (minimal divergence)

Question 36

How does a Laser work?

Answer 36

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

Question 37

4 Types of Lasers

Answer 37

- Crystal lasers - Gas lasers - Diode lasers - Liquid lasers

Question 38

High Power Laser

Answer 38

Surgical laser produces heat and can cut tissue | -Tissue destruction

Question 39

Low Power Laser

Answer 39

Tissue healing

Question 40

Class 1 Laser

Answer 40

Cannot emit laser radiation at known hazard levels invisible

Question 41

Class 1A Laser

Answer 41

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

Question 42

Class 2 Laser

Answer 42

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

Question 43

Class 3A Laser

Answer 43

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

Question 44

Class 3B Laser

Answer 44

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

Question 45

Class 4 Laser

Answer 45

- High-power lasers - hazardous to view under any condition | - Potential fire and skin hazard

Question 46

What does the depth of penetration depend on?

Answer 46

Types of Laser (wavelength) | -Longer wavelengths have greater penetration

Question 47

How deep can Infrared lasers penetrate?

Answer 47

Up to 13 cm

Question 48

What is a Joule?

Answer 48

- 1W/sec | - Energy density J/cm2 (average power)

Question 49

Will you have more energy with pulsed or continuous?

Answer 49

Continuous

Question 50

Dosage depends on:

Answer 50

- Power - output of the laser - Exposure time - Power Density - Energy Density - Dose Tissue

Question 51

Dose Tissue equation

Answer 51

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

Question 52

Treatment time equation

Answer 52

TA = (Energy/Power) x Area

Question 53

Laser dosage for acute conditions?

Answer 53

0.05 to 0.5 J/cm2

Question 54

Laser dosage for chronic conditions?

Answer 54

0.5 to 3.0 J/cm2

Question 55

Laser: Clinical Applications

Answer 55

- Largely unknown - Pain - Wound Healing/Scar - Immunological response - Connective tissue stimulation (bone)

Question 56

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

Answer 56

- Absorbed - Reflected - Transmitted - Refracted