Lasers

Question 1

Electromagnetic radiation is composed of what 2 types of fields?

Answer 1

electric and magnetic that are perpendicular to one another

Question 2

Electromagnetic radiation with a lower frequency has a ____ wavelength

Answer 2

longer

Question 3

Electromagnetic radiation with a higher frequency has a ____ wavelength

Answer 3

shorter

Question 4

What is low frequency EM radiation used for?

Answer 4

therapeutic medical applications

Question 5

What is high frequency EM radiation used for?

Answer 5

imaging or tissue destruction

Question 6

Which type of EM radiation is ionizing and which is not?

Answer 6

high frequency EM radiation is ionizing therefore it can break molecular bonds to form ions
low frequency EM radiation is not ionizing therefore it cannot break molecular bonds or produce ions

Question 7

What does the intensity of the EM radiation directly proportional to?

Answer 7

The energy of the output from the source

the greater the energy output from the source the greater the intensity

Question 8

When is the intensity of the EM radiation greatest?

Answer 8

When the…

• energy output is high
• radiation source is close to the patient
• beam is perpendicular to the surface of the skin

Question 9

What 3 things determine the effect of the EM radiation?

Answer 9

• Frequency
• Wavelength range of the radiation
• Intensity of the radiation

Question 10

What is the effect of IR radiation?

Answer 10

it produces superficial heating

Question 11

What are the effects of UV radiation?

Answer 11

it produces erythema, tanning, and epidermal hyperplasia

Question 12

What are the effects of shortwave and microwave radiation?

Answer 12

They heat deep tissues, decrease pain, decrease edema, and facilitate tissue healing

Question 13

What are the effects of low-intensity laser therapy?

Answer 13

promotes tissue healing, controls pain and inflammation

Question 14

What are the non-thermal effects of EM radiation?

Answer 14

It cause changes at the cellular level by:

 - Altering cell membrane function and permeability
 - Altering intracellular organelle function
 - Binding of chemical to the cell membrane to trigger complex sequences of cellular reactions
 - Causing proteins to undergo conformational changes to promote active transport and ATP use

Question 15

LASER stands for what?

Answer 15

Light Amplification by Stimulated Emission of Radiation

Question 16

When are hot and cold lasers used?

Answer 16

Hot lasers heat and destroy tissue

Cold laser is used clinically

Question 17

Lasers produce ____ light of a ____ wavelength

Answer 17

coherent

single

Question 18

3 types of diodes

Answer 18

• Light-emitting diode (LEDs)
• Supraluminous diode (SLDs)
• Laser diodes

Question 19

2 sources of light

Which is the most commonly used for therapeutic reasons?

Answer 19

Light can be produced by emission from a gas-filled glass tube or a photodiode
Today, therapeutic light sources generally use photodiodes instead of glass tubes

Question 20

A laser (photo)diode produces light that has what 3 characteristics?

Answer 20

• Monochromatic
• Coherent
• Directional

Question 21

Are LEDs and SLDs Monochromatic, Coherent, and Directional?

Answer 21

LEDs 
     - Not coherent
     - Not monochromatic
     - Not directional, spreads widely
SLDs
     - Not coherent
     - Almost monochromatic
     - Deliver energy to a wider area than laser but a smaller area than LEDs

Question 22

Which wave characteristic affects the depth of penetration?

Answer 22

wavelength

Question 23

What is the optimal depth of penetration of a wave?

Answer 23

600-1300 nm

Question 24

Longer wavelength, lower frequency penetrates _____ than shorter wavelength, higher frequency waves

Answer 24

deeper

Question 25

How deep does IR penetrate into soft tissue?

Answer 25

2-4 cm

Question 26

How deep does red light penetrate into soft tissue?

Answer 26

only a few millimeters

*better for treating superficial tissues

Question 27

What is power?

Answer 27

the rate of energy flow

Question 28

Most laser diodes used for therapy have a power between _-__ mW

Answer 28

5-500

Question 29

What does energy equal?

Answer 29

= Power (W) x Time (s)

Question 30

The energy density is aka what?

Answer 30

the treatment dose

Question 31

How do laser and light effect a target cell?

Answer 31

They directly effect of photons on intracellular chromophores (the light-absorbing part of a molecule)

Question 32

What are high power (hot) lasers used for?

Answer 32

Surgical cutting and coagulation
Ophthalmologic  (LASIK)
Dermatologic
Oncologic 
Vascular

Question 33

What are low-level (cold) lasers used for?

Answer 33

Therapy

 - Treatment of tendon or ligament injury
 - Arthritis
 - Lymphedema 
 - Soft-tissue healing
 - Bone healing
 - Neurological conditions
 - Pain management

Question 34

Contraindications for Lasers

Answer 34

Malignancy
Direct irradiation of the eyes
Within 4-6  months of radiotherapy
Hemorrhaging regions
Over thyroid or other endocrine glands

Question 35

Precautions for Lasers

Answer 35

Low back or abdomen during pregnancy
Epiphyseal plates in children
Impaired sensation
Impaired mentation
Photophobia
Abnormally high sensitivity to light
Pretreatment with one or more photosensitizers

Question 36

Adverse effects of lasers and light

Answer 36

Transient tingling
Mild erythema
Skin rash
Burning sensation
Adverse effects from irradiation of the eyes

Question 37

Laser wavelength

Answer 37

500-1100 nm

Question 38

Near-IR wavelength

Answer 38

700-1100 nm

Question 39

Clinically what power class is used?

Answer 39

3B (5-500 mW)

Question 40

3 Laser Treatment Techniques

Answer 40

Gridding – imaginary grid with 1 cm squares
Scanning – no contact between laser tip and the skin
Wanding – uses oscillatory technique over a grid area