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Radiation Protection > Chapter 2 > Flashcards

Chapter 2 Flashcards

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1
Q

Roentgen - R (Air Kerma)

A

A unit for measuring exposure or intensity. Defined only for radiation effect on air.

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2
Q

The Roentgen is essentially a measure of…

A

How many ion pairs are formed in a given volume of air when it is exposed to radiation

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3
Q

The Roentgen is NOT a measure of…

A

Energy absorbed, or dose. Only applies to gamma and x-rays

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4
Q

The Roentgen’s SI unit is…

A

Grays in air (Gya)

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5
Q

The Gya represents…

A

The quantity of electrical charge in joules produced by the exposure of 1kg of dry air (1 J/kg = 1 Gya)

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6
Q

The Roentgen or Gya does not

A

Relate the amount of exposure to biological effects of radiation in the human body

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7
Q

“Rad” stands for

A

Radiation absorbed dose

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8
Q

The rad is a unit for measuring…

A

Absorbed dose in any material.

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9
Q

The SI unit for absorption is…

A

The Gray in tissue or Gyt

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10
Q

Absorbed Dose

A

Energy being deposited by the radiation. It is defined for any material, and applies to all types of radiation

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11
Q

Gray is

A

1 J of energy absorbed in 1kg of tissue

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12
Q

Gyt does not

A

Take into account the potential effect that different types of raisin have in the body.

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13
Q

Gyt can be used as a measure of ____ but NOT ____

A

Energy absorbed by the body, but NOT AS a measure of the relative biological effect (harm or risk) to the body

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14
Q

4 Types of Ionizing Radiation

A
  1. Alpha Particles
  2. Beta Particles
  3. Gamma Rays
  4. Neutron Particles
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15
Q

Rem

A

Radiation Equivalent Man. Accurately expresses the biological response of exposed individuals to the same quantity of different radiation.

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16
Q

Rem takes into account…

A

The energy absorbed (dose) and the relative biological effect on the body due to different types of radiation (expressed as the “quality factor” of radiation)

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17
Q

Rem is therefore a measure of

A

Relative harm or risk caused by a given dose of radiation when compared to any other doses of radiation of any type (dose equivalent)

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18
Q

Occupational Radiation Exposure is recorded in…

A

Rems

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19
Q

The rem is thought of as the unit of…

A

Biological Hazard

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20
Q

SI equivalent of the rem is…

A

Sievert (Sv)

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21
Q

Quality Factor

A

Where each type of radiation is assigned a number based upon its absorbed energy in a mass of tissue and it’s relative biological effect as compared to x ray

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22
Q

X-rays, gamma rays, electrons, and beta rays have a radiation weighing factor of…

A

1

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23
Q

Protons have a Radiation weighing factor of

A

5

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24
Q

Neutrons (depending on energy) have a radiation weighing factor of

A

5-20

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25
Alpha Particles have a radiation weighing factor of
20
26
The Curie (Ci) is
The traditional unit of radioactivity, named after Marie and Pierre Curie
27
The Curie (Ci) is defined as
1 Ci = 3.7 x 10^10 decays per second
28
One Curie is roughly the activity of
1 Gram of the radium isotope Ra^226
29
The SI unit of radioactivity (opposite Ci) is
The Becquerel (Bq) which equates to 1 nucleus decay per second
30
The Bq represents
One emission of an alpha or beta particle or a gamma ray from a radioactive object
31
X-Rays ionize substances by removing electrons, potentially creating
Free radicals (an energized electron and an unstable atom) within the body
32
Most effects of exposure are short lived because
The great majority of cellular injures are repaired by enzymatic action and free radicals are neutralized (electrons find a new home and return to normal)
33
In some cases, cell damage can have a negative impact on...
Cell function and reproduction
34
Free radicals can permanently damage...
Cells and its DNA programming. Can be passed to cells offspring
35
French Physicists Bergonie and Tribondeau came up with
Laws regarding the characteristics of different cells and their corresponding radioactivity
36
4 Factors of Cell Sensitivity
1. Age (younger cells are more sensitive) 2. Differentiation (more primitive/simple cells are more sensitive) 3. Metabolic Rate (cells with a higher metabolism are more sensitive) 4. Mitotic Rate (cells that divide and multiply more rapidly/prolific cells are more sensitive)
37
Stem cells are ____ while mature cells are ____
Radiosensitive; radioresistant
38
A highly differentiated cell is _____
Highly specialized (like a neuron)
39
Cells with High Radiosensitivity
1. Lymphocytes 2. Erythroblasts (in bone marrow) 3. Lens of the eyes 4. Oocytes (egg cells) 5. Spermatogonia
40
Cells with Intermediate Radiosensitivity
1. Myelocytes (bone marrow) 2. Intestinal crypt cells (GI lining cells) 3. Skin basal cells (internal linings) 4. Endothelial cells (internal linings) 5. Glands in general 6. Osteoblasts (precursor for bones) 7. Spermatoblasts 8. Spermatozoa 9. Osteocytes 10. Erythrocytes
41
Cells with Low Radiosensitivity
Muscle Connective Tissue (cartilage, ligaments, tendons) Nerve/brain cells
42
Radiation Dose-Response Relationship
Allows us to predict the effects of radiation dose on the human body
43
Radiation Dose-Response relationships are demonstrated
Graphically through a curve that maps the observed effects of radiation exposure (y/vertical axis) in relation to dose of radiation received (x/horizontal axis)
44
As dose escalates...
So do most effects
45
Every radiation dose-response relation has 2 characteristics:
Linear and Nonlinear & Threshold and Non Threshold
46
Linear
Response is directly proportionate to the dose and represented by a straight line on graphs
47
Nonlinear
Response is not directly proportionate to the dose and represented by a curved line
48
Threshold
Indicates that there is a certain dose that must be obtained before a response will be seen (intercept the dose axis at some value greater than 0)
49
Nonthreshold
Indicates that any dose, regardless of its size, will produce a response (intercept the dose axis at zero)
50
Somatic Effects
The biological damage of an organism due to the exposure of that organism to ionizing radiation. Can be classified as early or late depending on the length of time from exposure to appearance of symptoms
51
Genetic Effects
The biological damage or abnormalities expressed in the offspring of a parent that has been exposed to ionizing radiation
52
Factors of Somatic and Genetic Effects
1. The quantity of ionizing radiation to which the subject is exposed 2. The ability of the IR to cause ionization of human tissue 3. The amount of body area exposed 4. The specific body parts exposed
53
Nonstochastic (deterministic) Effects (early or short term)
When biological effects of radiation occur relatively soon after receiving high doses of IR (usually occur within 3 months of exposure). Result of a very high dose of IR exposure.
54
Early (Nonstochastic) | effects are defined as when
the magnitude/severity of the somatic effect is directly proportional/dependent to the size of the dose (has a Threshold)
55
As dose increases, so does...
The severity of biologic damage
56
Acute Radiation Syndrome (ARS)
Also known as radiation sickness; occurs in humans after whole body reception of large doses of IR in a short period of time
57
The initial stage of ARS occurs
Within hours of a whole body absorbed dose of 1 Gyt or more. Symptoms include nausea, vomiting, diarrhea, fatigue, erythema, and leukopenia (decrease in WBC count)
58
3 Dose related syndromes as part of total-body syndrome
1. Hematopoietic Syndrome (1-10 Gyt) 2. Gastrointestinal Syndrome (whole body Threshold dose around 6 Gyt) 3. Cerebrovascular Syndrome (Whole body doses of 50 Gyt or more)
59
LD 50/30
The radiation dose that would result in death of 50% of the population within 30 days of exposure. The dose is about 3 Gy.
60
Late/Long Term Radiation Effects
When there is a long time between the exposure to IR and the observation of biologic effect (5-30 years, although greatest percentage occurs between 10-15)
61
Late Stochastic (probabilistic) somatic effects
Late effects that can be directly related to the dose received and occur months or years after a high level radiation exposure
62
Examples of Late Stochastic (probabilistic) effects
Fibrosis/Organ atrophy/loss of paraenchymal cells Reduces fertility and sterility
63
Long term effects can be more ____ than short term effects because short term effects are more ____
Random; predictable
64
Characteristics of Late Stochastic (probabilistic) somatic effects
Do not have a Threshold, occur in an arbitrary or probabilistic manner, have a severity that does not depend on Dose, and occur months or years after exposure
65
Likelihood of stochastic effects is _____ when Dose is _____
Increases when dose is increased (effects may be the result of repeated small doses)
66
In general, Stochastic Effects are
Associated with all levels of radiation exposure, including very small doses
67
Some documented latent effects of low dose IR over a long period of time include
Cataracts Carcinogenesis (increased risk of malignant disease) Birth defects Life span shortening
68
What is the most radiosensitive molecule in the human body
DNA (can be easily damaged by the energy in radiation or by the action of free radicals the radiation creates)
69
With sperm cells...
The radiation to the stem cells that produce sperm can become damaged and produce sperm with genetic mutations
70
Mutated genes may be _____ but are still _____
Recessive; possessed
71
Annual whole body effective dose limit for the occupational work is
5 rem/50 mSv
72
ALARA
Occupational exposure should be kept As Low As Reasonably Possible
73
Lifetime accumulated whole body dose equivalent follows the formula:
10mSv x age in years
74
3 principles in radiation protection
Time, distance, and shielding
75
Dosimetry is required for
Any radiation workers that are likely to risk receiving 10% or more of the annual occupational effective dose limit of 50mSv
76
Unlike Stochastic (Late) Effects, Nonstochastic Effects have...
A clear relationship between exposure and effect

Radiation Protection (2 decks)

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