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N927 Chem/Physics > 15 Radiation & Lasers > Flashcards

15 Radiation & Lasers Flashcards

1
Q

Electromagnetic Radiation (EMR)

A

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
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2
Q

Electromagnetic Field

A

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

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3
Q

Inductance

A

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

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4
Q

Electromagnetic

A

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

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5
Q

Wavelength λ

A

Trough to trough

Peak to peak

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6
Q

Frequency

A

Number oscillations

Shorter wavelength = higher frequency & stronger energy

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7
Q

Reflected

A

Reflects directly back to source

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8
Q

Refracted

A

Reflects indirectly

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9
Q

Diffracted

A

Reflects indirectly at lower frequency

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10
Q

Absorbed

A

Light not reflected

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11
Q

Radiation

A

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

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12
Q

Average Natural Radiation

A

300mrem

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13
Q

Beta Particle Radiation

A

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

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14
Q

Alpha Particle Radiation

A

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

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15
Q

Gamma Radiation

A

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

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16
Q

X-ray Radiation

A

Less energy than gamma rays & less penetrating

Require less shielding

17
Q

Ionizing Radiation

A

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)

18
Q

Radiation Units

A

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

19
Q

C-arms

A

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

20
Q

X-ray Safety

A

Distance from source
Barriers (shielding)
Exposure time

21
Q

Radiation intensity INVERSELY proportional to _____

A

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

22
Q

LASER

A 
Light
Amplification
Stimulated
Emission
Radiation

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

23
Q

LASER Physics

A

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
24
Q

Photochemical

A

UV <400nm & visible wavelengths <500nm

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

25
Q

Thermal

A

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

26
Q

Continuous Wave

A

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

27
Q

Pulsed Lasers

A

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

28
Q

Q-Switched Mode Lasers

A

Both continuous & pulsed wave mode

29
Q

Clinical Laser Uses

A

Coagulation
Cutting
Vaporization

30
Q

Laser Safety

A 
Airway fire risk
Bleeding
Pneumothorax
Tissue damage & edema
ETT cuff failure
Laser injury
Surgical smoke inhlalation
31
Q

Maximum Permissible Exposure

A

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)

32
Q

Optimal Density

A

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%

33
Q

Laser Classifications

A

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

34
Q

Reflections

A

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

N927 Chem/Physics (12 decks)

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