15 Radiation & Lasers

Question 1

Electromagnetic Radiation (EMR)

Answer 1

Refers to the waves or their photons (particles) from an electromagnetic field

• Radio waves
• Microwaves
• Infrared light
• Visible light
• UV light
• X rays
• Gamma rays

Question 2

Electromagnetic Field

Answer 2

Force field that consists both electric and magnetic components resulting from the motion an electric charge and containing a definite amount electromagnetic energy

Question 3

Inductance

Answer 3

Electrons flow around wire induce magnetic field around the wire
Wire coiled repeatedly around an iron core

Question 4

Electromagnetic

Answer 4

Expresses dual nature electricity and magnetism
Electric current + magnetic waves
Changing magnetic waves = electric current

Question 5

Wavelength λ

Answer 5

Trough to trough

Peak to peak

Question 6

Frequency

Answer 6

Number oscillations

Shorter wavelength = higher frequency & stronger energy

Question 7

Reflected

Answer 7

Reflects directly back to source

Question 8

Refracted

Answer 8

Reflects indirectly

Question 9

Diffracted

Answer 9

Reflects indirectly at lower frequency

Question 10

Absorbed

Answer 10

Light not reflected

Question 11

Radiation

Answer 11

Energy emission
Non-ionizing (visible, UV or infrared light, radio waves, microwaves)
Ionizing (beta, gamma, or X-rays)

Question 12

Average Natural Radiation

Answer 12

300mrem

Question 13

Beta Particle Radiation

Answer 13

Neutrons are excessive → convert to proton and electron
Electron ejected at high speed
Travels only few meters in air before being absorbed
Shielding w/ radiation-absorbing material necessary

Question 14

Alpha Particle Radiation

Answer 14

2 protons & 2 neutron are ejected as 1 particle
Heavy & slow
Travel only few cm in air before energy expended

Question 15

Gamma Radiation

Answer 15

Nucleus in excited state emits “energy packet” known as photon
Number protons & neutrons are not altered but instead the nucleus moves from higher to lower energy state
Travel long distances & shielding best achieved w/ lead

Question 16

X-ray Radiation

Answer 16

Less energy than gamma rays & less penetrating

Require less shielding

Question 17

Ionizing Radiation

Answer 17

Radiation w/ enough energy to remove tightly bound electrons from atom orbit
Causes atom to become charged or ionized
Alpha, beta, gamma, & X-rays (UV)

Question 18

Radiation Units

Answer 18

Absorbed dose - amount energy deposited per unit mass (grays Gy or milligray mGy)
Equivalent dose - absorbed dose multiplied by converting factors based on biological radiation effects (sieverts Sv or millisieverts mSv)
Amount ionizing radiation required to produce the same biological effect as one RAD high-penetration X-rays
RAD radiation absorbed dose
Milliroentgen mrem

Question 19

C-arms

Answer 19

Portable X-ray machine that are used in ORs & ICUs
X-ray beam directed toward the patient and tube
Stand at least 6ft away to minimize exposure

Question 20

X-ray Safety

Answer 20

Distance from source
Barriers (shielding)
Exposure time

Question 21

Radiation intensity INVERSELY proportional to _____

Answer 21

Distance from the source
Intensity = 1/d^2
6ft away = 0.5mm lead shielding

Question 22

LASER

Answer 22

Light
Amplification
Stimulated
Emission
Radiation

Light emitted when electrons jump from more distant orbitals to orbitals closer to the nucleus

Question 23

LASER Physics

Answer 23

Monochromatic
Coherent
Collimated - light has minimal dispersion yielding narrow light band

• Generate intense light beams
• Send beams efficiently & accurately through lenses
• Deliver intense energy to small target site

Question 24

Photochemical

Answer 24

UV <400nm & visible wavelengths <500nm

Photo absorption excites molecules & react to form unwanted chemical products cause erythema & vesiculation

Question 25

Thermal

Answer 25

Occurs at all wavelengths
Tissue heated via laser energy absorption
Thermal effects depend on energy rate & absorption to dissipation

Question 26

Continuous Wave

Answer 26

Output expressed in power terms (energy rate)
Watts
Produces beams that are constant & power delivered to tissue does not vary

Question 27

Pulsed Lasers

Answer 27

Output expressed in energy terms per pulse
Joules
Produces beams in small bursts controlled by the user
Power levels are more intense than maximum power levels generated by continuous wave lasers

Question 28

Q-Switched Mode Lasers

Answer 28

Both continuous & pulsed wave mode

Question 29

Clinical Laser Uses

Answer 29

Coagulation
Cutting
Vaporization

Question 30

Laser Safety

Answer 30

Airway fire risk
Bleeding
Pneumothorax
Tissue damage & edema
ETT cuff failure
Laser injury
Surgical smoke inhlalation

Question 31

Maximum Permissible Exposure

Answer 31

MPE
Determines level eye/skin protection needed
Eye protection important d/t lens multiplies power density at the retina
Retina - photoreceptors location (neurons sensitive to light)

Question 32

Optimal Density

Answer 32

OD indicates inverse amount light transmitted through material
Wear eye protection whenever operational conditions have potential eye hazards
Eyewear labeled w/ rated wavelength & OD
Ensure sufficient OD at correct laser wavelength
OD = 5
10^-5 or 0.001%

Question 33

Laser Classifications

Answer 33

Class 1 - no beam hazard
Class 2 - no realistic hazard
Class 3a - CAUTION label normally no eye hazard w/in 0.25sec
DANGER label potentially exceed MPE in 0.25sec remains low hazard
Class 3b - hazardous to view directly or specular reflection normally no diffuse reflection or skin hazard
Class 4 - hazard to view beam or specular or diffuse reflection also skin & fire hazard

*Most healthcare laser systems are class 4

Question 34

Reflections

Answer 34

Specular (mirror-like) more hazardous than diffuse reflections
Keep shiny surfaces away from field to prevent specular reflections
Utilize blackened, anodized, or matte finish to minimize specular reflections