Non-Ionizing Radiation

Question 1

What are the four types of lasers?

Answer 1

1. Solid state (e.g., ruby)
2. Gas (e.g., He, Ar, CO2)
3. Dye (e.g., tunable dye)
4. Semiconductor (e.g., gallium arsenide)

Question 2

What is the wavelength for an ultraviolet laser?

Answer 2

0.18 µm – 0.40 µm

Question 3

What is the wavelength for UV-C?

Answer 3

0.10 µm – 0.28 µm

Question 4

What is the wavelength for UV-B?

Answer 4

0.28 µm – 0.315 µm

Question 5

What is the wavelength for UV-A?

Answer 5

0.315 µm – 0.40 µm

Question 6

What is the wavelength for a visible laser?

Answer 6

0.40 µm – 0.78 µm

Question 7

What is the wavelength for a near infrared laser?

Answer 7

0.78 µm – 1.40 µm

Question 8

What is the wavelength for a far infrared laser?

Answer 8

1.40 µm – 30.00 µm

Question 9

Laser Hazards

0.40 µm – 1.40 µm (visible and near-IR)

Class II – IV

Answer 9

• A focusing effect through the lens increases the effective power by a factor of 100,000.
• Retina damage
• Skin burns

Question 10

Laser Hazards

0. 315 µm – 0.40 µm (UV-A)
1. 40 µm – 3.00 µm (mid-IR)

Class II – IV

Answer 10

• Acute exposure ⇒ “Welder’s flash” or “snow blindness”
• Chronic exposure ⇒ Heat absorption at the lens causes cataracts.
• Skin burns
• UV is carcinogenic

Question 11

Laser Hazards

0. 10 µm – 0.315 µm (UV-C/B)
1. 00 µm – 10.00 µm (far IR)

Class II – IV

Answer 11

• Temporary cornea “flash blindness” lasts for a few days.
• Skin burns
• UV is carcinogenic

Question 12

What are all of the classes of lasers from least to most dangerous?

Answer 12

I Least dangerous

IIA

II

IIIA

IIIB

IV Most dangerous

Question 13

What class of laser is a fire hazard?

Answer 13

IV

Question 14

What classes of laser have direct ocular hazards?

Answer 14

IIA Only after 1,000 seconds

II Only after 0.25 seconds

IIIA

IIIB

IV

Question 15

What are some beam hazards associated with lasers?

Answer 15

• Thermal damage (burn) ⇒ Tissues are heated to the point where denaturation of protein occurs.
• Photochemical ⇒ Light triggers chemical reactions in tissue.
• Explosions ⇒ Rapid rise in temperature in tissue can cause rapid boiling and subsequent shockwaves to surrounding tissue.

Question 16

Laser Hazards
(non-Beam Viewing)

What different categories are there for these laser hazards?

Answer 16

1. Combustion
2. Ignition
3. Electrical
4. Vaporization

Question 17

Laser Hazards
(non-Beam Viewing)

Combustion

1. Description
2. Safety Precautions

Answer 17

1. Anesthetic and endotracheal tube fires caused by penetration by a direct or stray laser beam.
2. Moistened cotton around the tubes or reflective tape.

Question 18

Laser Hazards
(non-Beam Viewing)

Ignition

1. Description
2. Safety Precautions

Answer 18

1. Inadvertent laser beam exposure to paper drapes, gauze sponges, wooden tongue bales.
2. Positive footswitch activation, aiming guides, and moist drapings

Question 19

Laser Hazards
(non-Beam Viewing)

Electrical

1. Description
2. Safety Precautions

Answer 19

1. High voltages of the equipment
2. No wearing of metallic objects, know resuscitation procedures, don’t work with wet equipment.

Question 20

Laser Hazards
(non-Beam Viewing)

Vaporization

1. Description
2. Safety Precautions

Answer 20

1. Lasers create large quantities of smoke that can be noxious or contain tumor cells.
2. Air evacuation / suction systems can be installed to adapt to current ventilation systems.

Question 21

Radiant Energy

1. Define
2. Symbol
3. Units

Answer 21

Radiant Energy

1. Define ⇒ The energy of electromagnetic and gravitational radiation. It is calculated by integrating radiant flux (or power) with respect to time.
2. Symbol ⇒ Q
3. Units ⇒ Joule (J)

Question 22

Radiant Flux (Power)

1. Define
2. Symbol
3. Units

Answer 22

1. Define ⇒ The radiant energy emitted, reflected, transmitted, or received, per unit time.
2. Symbol ⇒ Φ
3. Units ⇒ Watt (W)

Question 23

Irradiance

1. Define
2. Symbol
3. Units

Answer 23

Irradiance

1. Define ⇒ The radiant flux (power) received by a surface, per unit area.
2. Symbol ⇒ E
3. Units ⇒ Watt cm^-2

Question 24

Radiant Fluence (Exposure)

1. Define
2. Symbol
3. Units

Answer 24

Radiant Fluence (Exposure)

1. Define ⇒ Energy (in Joules) received by a surface, per unit area.
2. Symbol ⇒ H
3. Units ⇒ Joule cm^-2

Question 25

_Radiance_ 1. Define 2. Symbol 3. Units

Answer 25

_Radiance_ 1. Define ⇒ The radiant flux (in watts) emitted, reflected, transmitted, or received by a given surface, per unit area, per unit solid angle. 2. Symbol ⇒ L 3. Units ⇒ Watt cm^-2 sr^-1

Question 26

_Integrated Radiance_ 1. Define 2. Symbol 3. Units

Answer 26

1. Define ⇒ The radiance integrated over time of exposure. 2. Symbol ⇒ L_p 3. Units ⇒ Joule cm^-2 sr^-1

Question 27

What is the pathological effect would you have from the following laser? UV-B (0.28 - 0.315 µm) and UV-C (0.10 - 0.28 µm)

Answer 27

Photokeratitis (inflammation of the cornea, equivalent to sunburn)

Question 28

What is the pathological effect from a laser in the UV-A wavelength range?

Answer 28

Photochemical cataract (clouding of the eye lens)

Question 29

What is the pathological effect from a laser in the visible wavelength range?

Answer 29

Photochemical damage to the retina, retinal burn

Question 30

What is the pathological effect from a laser in the near-IR wavelength range?

Answer 30

Cataract, retinal burn

Question 31

What is the pathological effect from a laser in the IR wavelength range?

Answer 31

Cataract, corneal burn, aqueous flare (dispersion of light)

Question 32

What are the two ranges of gain (G) for energy distribution in a microwave antenna?

Answer 32

G = 1 ⇒ "Unity gain," Isotropic radiator (omnidirectional) G \> 1 ⇒ Energy is focused in a direction

Question 33

What are visible symptoms among personnel chronically exposed to microwaves?

Answer 33

* Increased fatigue * Periodic or constant headaches * Extreme irritability * Sleepiness during work * Decrease in olfactory sensitivity

Question 34

What are clinical signs among personnel chronically exposed to microwaves?

Answer 34

1. Bradycardia 2. Hypotension 3. Hyperthyroid 4. Increase in blood histamine levels

Question 35

_Microwave Hazards (by Frequency)_ **\< 150 MHz** 1. Site of Major Tissue Effect 2. Major Biological Effects

Answer 35

1. None 2. Body absorbs energy in the region from 30 – 100 MHz

Question 36

_Microwave Hazards (by Frequency)_ **150 MHz – 1,200 MHz** 1. Site of Major Tissue Effect 2. Major Biological Effects

Answer 36

1. Lens of the eye 2. Critical wavelength band for eye cataracts

Question 37

_Microwave Hazards (by Frequency)_ **1,000 MHz – 10,000 MHz** 1. Site of Major Tissue Effect 2. Major Biological Effects

Answer 37

1. Lens of the eye 2. Critical wavelength band for eye cataracts

Question 38

_Microwave Hazards (by Frequency)_ **3,000 MHz – 10,000 MHz** 1. Site of Major Tissue Effect 2. Major Biological Effects

Answer 38

1. Top layers of skin, lens of eye 2. Lens of eye particularly susceptible

Question 39

_Microwave Hazards (by Frequency)_ **10,000 MHz** 1. Site of Major Tissue Effect 2. Major Biological Effects

Answer 39

1. Skin 2. Skin heating with sensation of warmth

Question 40

_Microwave Hazards (by Frequency)_ **\> 10,000 MHz** 1. Site of Major Tissue Effect 2. Major Biological Effects

Answer 40

1. Skin 2. Skin surface acts as reflector or absorber with heating effects

Question 41

_Exposure to Static Magnetic Fields_ **Occupational Guideline** Whole working day

Answer 41

* 200 mT * 2,000 G

Question 42

_Exposure to Static Magnetic Fields_ **Occupational Guideline** Ceiling limit

Answer 42

* 2 T * 20,000 G

Question 43

_Exposure to Static Magnetic Fields_ **Occupational Guideline** Extremities

Answer 43

* 5 T * 50,000 G

Question 44

_Exposure to Static Magnetic Fields_ **General Public Guideline** 24 Hours per Day

Answer 44

* 40 mT * 400 G

Question 45

What tissues have significant energy absorption for the following wavelength laser? (0.78 - 1.40 μm)

Answer 45

Skin, retina, cornea, and lens

Question 46

What tissues have significant energy absorption for the following wavelength laser? Far infrared laser (1.40 - 30.00 μm)

Answer 46

Skin and cornea

Question 47

What tissues have significant energy absorption for the following wavelength laser? UV-B (0.28 - 0.315 μm)

Answer 47

Skin and cornea

Question 48

What tissues have significant energy absorption for the following wavelength laser? Visible laser (0.40 - 0.78 µm)

Answer 48

skin and retina

Question 49

What tissues have significant energy absorption for the following wavelength laser? UV-C (0.315 - 0.40 μm)

Answer 49

skin and lens

Question 50

Identify and justify the anatomical structure of the eye that is most sensitive to damage for the following laser. Far infrared, carbon dioxide laser (10.6 μm)

Answer 50

* Cornea * This wavelength is strongly absorbed by most organic molecules, including those in corneal tissue, located in outer eye structure

Question 51

Identify and justify the anatomical structure of the eye that is most sensitive to damage for the following laser. Visible, gold vapor laser (0.628 μm)

Answer 51

* Retina * This wavelength is transmitted to the retina and largely absorbed in the pigmented retinal epithelium, thereby causing thermal effects and damage

Question 52

Identify and justify the anatomical structure of the eye that is most sensitive to damage for the following laser. UV-A, nitrogen laser (0.337 μm)

Answer 52

* Lens * UV-A radiation has a long wavelength and will be absorbed in the lens, producing photochemical effects, leading to possible cataracts.

Question 53

Identify and justify the anatomical structure of the eye that is most sensitive to damage for the following laser. UV-C, krypton fluoride excimer laser (0.248 μm)

Answer 53

* Cornea * Shorter wavelength UV-C radiation is strongly absorbed superficially in corneal tissues, thereby producing effects such as conjunctivitis and possible corneal clouding

Question 54

Why does MPE vary so drastically across a short spectrum of wavelengths?

Answer 54

MPEs vary significantly between wavelengths of 0.647 μm (red) and 0.530 μm (green) because retinal tissue is the major tissue at risk. The first pathology occurs in the pigmented retinal epithelium (PRE) The damage to the retinal tissue varies with wavelength because * The percentage of light transmitted to the retina and PRE varies with wavelength * The energies of photons and consequent thermal energy produced by absorption vary inversely with wavelength * The efficiency of absorption of photons by melanin the PRE varies somewhat with wavelength

Question 55

What are the effects to the skin of UV-A, UV-B, and UV-C?

Answer 55

_UV-A_ * Reflected to a significant extent * Unless the individual is extremely (unusually) photosensitive, significant skin effects should not occur _UV-B and UV-C_ * At significant exposures, both can be expected to produce erythema, skin tanning, premature skin aging, and possible skin cancer * Melanoma is strongly associated with UV-B exposure

Question 56

_Generic FDA Laser Class Characteristics_ Class I Class II Class III Class IV

Answer 56

Class I ⇒ Not an ocular hazard Class II ⇒ 0.25 second exposure threshold Class III ⇒ Momentary intrabeam viewing is hazardous Class VI ⇒ Can damage skin or eye from diffuse reflection

Question 57

Answer 57

1. Iris 2. Pupil 3. Cornea 4. Lens 5. Retina 6. Sclera 7. Optic nerve

Question 58

Provide an example of ELF electromagnetic radiation

Answer 58

50 – 60 Hz radiation resulting from the generation, propagation, and use of common household, commercial, and industrial alternating current

Question 59

Sketch a spatial graph of a plane, sinusoidal electromagnetic wave.

Answer 59

Question 60

List two sources of electromagnetic radiation in video display terminals. Describe the radiation and normal operating values.

Answer 60

Examples * Flyback transformer * Electron deflection coils The electromagnetic fields from these components are pulsed and produce a wide range of harmonic frequencies. * Electric field strengths at operator locations are typically about 50 V m^-1 * Magnetic field strengths at operator locations are typically about 0.50 A m^-1

Question 61

What biological effect of RF electromagnetic radiation is the primary basis for establishing RF electromagnetic radiation exposure criteria? (NCRP 86)

Answer 61

Thermal effect

Question 62

What is the ANSI recommendation for microwave exposure?

Answer 62

10 mW cm^-2 averaged over 6 minutes