Ionizing Radiation Flashcards
(125 cards)
1
Q
What is radiation?
A
Energy in the form of rays (waves) or corpuscles (particles) that emanate from a source
2
Q
Describe background radiation
A
cosmos produces radiation & sun emits radiation, but only small amount reaches the earth
3
Q
What happens to most of the energy produced by the cosmos?
A
energy lost when passing though the atmosphere
4
Q
Is life still exposed to cosmic radiation?
A
yes
5
Q
Where is cosmic radiation exposure the strongest?
A
at the poles and high elevations
6
Q
What are the types of ionizing radiation?
A
- alpha
- beta
- gama
- x rays
- neutrons
7
Q
What are the types of nonionizing radiation?
A
- UV
- Visible
- IR
- Microwave/ RF
8
Q
What is ionizing radiation?
A
particles with enough energy to push electrons out of a material and generate ions
9
Q
What is nonionizing radiation?
A
- particles that have enough energy to excite atoms into higher energy state, but cannot ionize
10
Q
What effects can nonionizing radiation have?
A
radiation and field effects
11
Q
what is the name of the measurement for exposure (x)
A
roentgen
12
Q
What is the name of the measurement for absorbed dose (D)?
A
Rad or gray
13
Q
What is the measurement for activity (A)?
A
CUrie or becquerel
14
Q
What is the measurement for dose equivalent (H)
A
roentgen equivalent in man or sievert
15
Q
What are the types of ionizing particles?
A
- Alpha
- Beta
- Neutrons
- Protons
16
Q
Are ionizing particles charged?
A
They can be charged or uncharged
17
Q
What are the types of ionizing electromagnetic waves
A
gamma rays
x rays
18
Q
What are radioactive materials?
A
unstable forms of elements (radioisotopes or radionuclides) that decay to stable elements
19
Q
What happens to radioactive materials as they decay?
A
emit ionizing radiation
20
Q
Where are radioactive materials found? where are they more concentrated?
A
soil, water, air
more concentrated in houses, mines
21
Q
What size elements are unstable?
A
Anything heavier than 209Bismuth
22
Q
What is radioactive decay?
A
atom moves from an unstable to a stable state resulting in a series of emissions of energy and or matter from the atom
23
Q
Do all radioactive elements decay into a stable element?
A
No- some decay into different radioisotopes until they are finally stable
24
Q
Is there always radiation with radioactive material?
A
Yes
25
Does radiation always come from radioactive material?
no- can be artificially generated
26
Are electron microscopes radioactive?
No
27
What is the defining characteristic of radioactive materials?
radioactivity
28
Does the presence of radiation always imply a radioactive source
No
29
How do radiation-producing machines work?
Accelerate a beam of electrons in a vacuum tube and emit x-rays
30
Can radiation-producing machines be turned on and off?
yes
31
Give examples of radiation producing machines
medical devises, security, electron microscopes
32
How do nuclear reactors work?
Split large atoms (fission) by bombarding them with neutrons and generate energy (heat)
33
What type of testing has left some residues of radioactive material in the atmosphere?
nuclear weapons testing
34
What are the different forms for sources of ionizing radiation?
- sealed sources
- radiation machines
- radioisotopes + machine
- unique radioisotopes
35
What are the examples of radiation machines sources?
- x rays
| - computed (axial) tomography (CAT Scan)
36
What are the examples of radioisotopes + machine sources?
- Positron emission tomography (PET, gamma)
| - research
37
What are examples of unique radioisotopes?
- U & Pu
| - Hydrogen 3- tritium
38
Name workplaces where one would find ionizing radiation?
- healthcare
- radiography
- refineries & chemical plants
- fracking
- airport screeners (TSA)
- research
- nuclear plants
- weapons
39
What workplaces would one find nonionizing radiation?
- outdoor occupations
- ovens, molten metal
- power transmission
- welding
- radar
- lasers
- electrical equipment
40
What is the relationship between the number of protons and nuetrons in the typical atom?
usually the same
41
When doesn't the atom have an electrical charge?
when protons and electrons are the same
42
What are ions?
atoms of molecules in which the total number of electrons is not equal to the total number of protons (net positive or negative charge)
43
Give an example of a radioactive element
Uranium
44
What is given off as a heavy, unstable element like uranium decays?
- alpha particles
- gamma rays
- protons
- beta particles (electrons)
- neutrons
45
What type of ionizing radiation is the alpha particle?
corpuscular ionizing radiation
46
How many protons/ neutrons do alpha particles have?
2 neutrons/ 2 protons (Helium nucleus)
47
Do all alpha particles have the same energy?
yes
48
How do alpha particles interact with other substances?
- quick interaction with substances and creation of ions
| - high ionization along path of emission, releases energy all in one place
49
What type of LET do alpha particles have?
High linear energy
50
Are alpha particles externally dangerous?
No- short range and easily stopped
51
Are alpha particles dangerous internally?
through inhalation or ingestion - very damaging to cells
52
Give examples of alpha emitters
U-238, Pu-238, Pu-239, Ra-226, Rn-222, Po-210, Am-241
53
What is LET?
linear energy transfer
54
What type of radiation are beta particles?
corpuscular ionizing radiation
55
What are beta particles and how are they formed?
Electrons & Positrons emitted by radioactive material
| - breakup of a neutron into electrons and positrons
56
How do beta particles interact with other atoms?
interact with electrons of materials they go through and ionize
57
Compare LET between alpha and beta particles
Beta- less interaction than alpha particles and low LET
58
What are secondary x-rays produced when a beta moves through a material?
Bremsstrahlung radiation
59
Do beta particles have natural or artificial sources?
both
60
What industries use beta particles?
medical research and industrial applications
61
What do health effects of beta particles depend on?
Skin, Eye, and Internal Health risk
62
Give examples of low energy b emitters
H-3, C-14, S-35, Pu-241
63
Give Examples of high-energy b emitters
P-31, Sr-90, I-131
64
What type of ionizing radiation are neutrons?
corpuscular ionizing radiation
65
What is a neutron?
neutral charge from the nucleus of the atom
66
What are the different energy levels of the neutron?
- High- travel farther, penetrate more
| - Low- less travel distance, less penetration
67
What are the health risk and exposure risks of neutrons?
Significant health risk, rare exposure except near reactors or accelerators
68
How can workers be shielded from neutrons?
high-hydrogen content- water, paraffin, concrete
69
What type of ionizing radiation are protons?
corpuscular ionizing radiation
70
What are protons?
positive charge inside the atom's nucleus
71
How often are protons encountered?
rarely
72
What careers may be concerned about protons?
astronauts, doctors, researchers
73
Describe the LET of protons
lose energy relatively slowly (low LET) until energy spike at the end of their path (high LET)
74
What wavelengths are capable of producing ionization?
<300 nm
75
Energy is directly related to ____
frequency
76
What is directly proportional to E & F
wavelength
77
What are gamma rays?
energy emission (photons) from the nucleus as a result of radioactive decay
78
What is the health risk for gamma rays?
significant health risk
79
What are examples of low energy gamma rays
I-125, I-129, Am- 241
80
What are examples of medium - high energy gamma rays?
I-131, Cs-137, Co-60, Ir-192
81
What are x-rays?
energy emission (photons) from the outside of the nucleus when electrons drop to lower energy orbitals
82
How can x-rays be artificially produced
bombardment of a target chemical with high speed electrons
83
What is the health risk with x-rays?
significant health risk
84
What are the different energy and wavelengths for x-rays?
- Hard- shorter wavelength, higher energy, more penetrating
| - Soft- longer wavelength, lower energy, less penetrating
85
Describe penetration of alpha, beta, and gamma rays
alpha- easily stopped, does not penetrate
beta- penetrates skin, stopped by aluminum
gamma- penetrates and stopped by thick lead
86
Increased energy to tissue ___ risk
increases
87
What are the key components for any radiation?
1) source
2) transmission
3) receiver
88
Describe the historical health effects of radiation?
X-rays used since 1898- medical personnel had damage to hands (deterministic exposure) and developed cancer (stochastic exposure)
89
When are deterministic effects experienced?
When dose is high enough
90
What is a deterministic effect?
Severity of the outcome depends on the dose
91
How can you avoid deterministic effects?
stay below threshold
92
What are examples of deterministic effects?
- radiation detmatitis
- cataracts
- sterility
- microcephaly of babies
- mental retardation of babies
93
What are stochastic effects?
Occur by chance and without a threshold dose, all or nothing
94
Describe risk of stochastic effects
- risk of developing condition of disease increase with increase in exposure but only a fraction of those exposed develop the health effects
95
describe severity of stochastic effects
severity the same regardless of exposure
96
What are examples of stochastic effects
- smoking and lung cancer (all get the same cancer regardless of the amount smoked)
- birth defects & genetic diseases
97
What are chronic health effects of ionizing radiation?
1) lung cancer
2) leukemia
3) decreased lifespan
98
What are acute health effects of ionizing radiation?
1) damage to central nervous system
2) damage to inner lining of GI tract, esp. intestinal villi
3) immune system: destruction of leukocytes (WBC) and stem cells
4) skin burns
99
What is the average annual dose to natural background radiation?
2.4 mSv
100
How can uranium cause cancer?
breaks into smaller atoms and particles that enter human cell, strike nucleus and damage DNA. Causing it to divide uncontrollably- cancer
101
What is the difference between exposure and contamination?
Exposure- energy transmitted to the target in the body
Contamination- radioactive substance on an external surface or in a medium (air, water...) that can usually be removed
102
Can you have exposure and contamination independent of one another? and together?
can have exposure only, exposure and contamination, and contamination only
103
Are contaminated substances intrinsically radioactive?
no
104
If contamination removed is the substance still radioactive?
no
105
What is the general term for measuring devices for ionizing radiation?
ionization devices
106
How do ionization devices work?
air molecules in sealed chamber are ionized- current proportional to the exposure
107
What are examples of area samplers used for ionization?
- ionization chambers
- Geiger Mueller counters
- Proportional counters
108
What are the limitations of ionization devices?
have limitations with low-energy photon materials
109
instrument where molecules are ionized producing an emission of light related to the energy output and unique energy level of the specific type of radioisotope
scintillation counters
110
What are personal sampling devices for ionizing radiation?
1) dosimeter
2) Film badges
3) Thermoluminescence Detector
4) Pocket dosimeter
111
Describe dosimeters
- passive or instant read
- multiple detectors sensitive to multiple types of radiation or may need to wear multiple
- extremity monitoring common (ie ring)
- do have electronic, limited in functionality
112
What is the difference between passive dosimeter and instant read dosimeters?
passive- worn for a while then evaluated
Instant read- give immediate result but not available for as wide a range of radiation types as passive
113
Describe film badges
film exposed to radiation and developed (obsolete)
114
Describe TLDs
- lithium fluoride reacts with radiation and electrons are excited
- readout device heats the TLD, excites electrons, and they emit light proportional to exposure
115
Describe the pocket dosimeter
Electrostatic charging of a fiber wand that moves along a scale
116
What is calibration necessary for?
Electronic dosimeters
117
What other sampling methods are used for ionizing radiation?
- stationary monitors
- wipe sampling
- alpha track detectors (radon)
118
How are wipe samples read?
with scintillators
119
What are the main controls for ionizing radiation?
1) Keep dose ALARA (As Low As Reasonably Achievable)
2) Time (1/2 the time, 1/2 the exposure)
3) Distance (Dose rate decreases with increased distance)
4) Shielding
120
What is the equation for distance?
DR2=DR1 x r1^2/r2^2
121
DR2=DR1 x r1^2/r2^2
What is DR1 and r?
DR- dose rate
r1- distance from the point source
122
SLIDE 4/486- Equation
Slide 46- Equation
123
What is the half value layer?
thickness of a material required to stop half of the radiation
124
What are additional controls for ionizing radiation?
- PPE
- Education
- Need to consider other characteristics such as the chemical nature of a radioisotope
- overall radiation safety program
125
What are the concerns with ionizing radiation?
- money and technology to handle radioactive waste- store locally vs. 1 central storage site?
