15 Radiation & Lasers Flashcards Preview

AS - N927 Chem/Physics > 15 Radiation & Lasers > Flashcards

Flashcards in 15 Radiation & Lasers Deck (34)
Loading flashcards...
1

Electromagnetic Radiation (EMR)

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

2

Electromagnetic Field

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

3

Inductance

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

4

Electromagnetic

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

5

Wavelength λ

Trough to trough
Peak to peak

6

Frequency

Number oscillations
Shorter wavelength = higher frequency & stronger energy

7

Reflected

Reflects directly back to source

8

Refracted

Reflects indirectly

9

Diffracted

Reflects indirectly at lower frequency

10

Absorbed

Light not reflected

11

Radiation

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

12

Average Natural Radiation

300mrem

13

Beta Particle Radiation

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

14

Alpha Particle Radiation

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

15

Gamma Radiation

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

16

X-ray Radiation

Less energy than gamma rays & less penetrating
Require less shielding

17

Ionizing Radiation

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

Radiation Units

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

C-arms

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

X-ray Safety

Distance from source
Barriers (shielding)
Exposure time

21

Radiation intensity INVERSELY proportional to _____

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

22

LASER

Light
Amplification
Stimulated
Emission
Radiation

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

23

LASER Physics

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

Photochemical

UV <400nm & visible wavelengths <500nm
Photo absorption excites molecules & react to form unwanted chemical products cause erythema & vesiculation

25

Thermal

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

26

Continuous Wave

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

27

Pulsed Lasers

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-Switched Mode Lasers

Both continuous & pulsed wave mode

29

Clinical Laser Uses

Coagulation
Cutting
Vaporization

30

Laser Safety

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