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Biology And safety Flashcards

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0
Q

SI unit of radioactivity

A

Becquerel (Bq)

1 Bq = 2.7 x 10^-11

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1
Q

Radioactivity

A

The measurement of decay rate or a radioactive material

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2
Q

Exposure

A

Measure of radioactive KINETIC ENERGY emitted from a source and is quantified a generally by its capacity to ionize air

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3
Q

SI units of exposure

A

Coulombs/kg

1 C/kg = 3876 R (roentgen)

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4
Q

Absorbed dose

A

The energy absorbed by any type of matter and is derived by calculating the imparted energy divided by the mass absorbing it

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5
Q

SI unit or absorbed dose

A

Gray

1 gray = 100 rad

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6
Q

Equivalent dose

A

Used to compare the biological effect on a tissue for different types of radiation

DEPENDENT ON LINEAR ENERGY TRANSFER

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7
Q

SI unit of equivalent dose

A

Sievert

1 sievert = 100 rem

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8
Q

Linear energy transfer

A

The rate at which energy is transferred from the ionizing radiation to soft tissue.

Used to determine equivalent dose

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9
Q

Effective dose

A

Used to measure the estimated risk to humans

  • deleterious effect
  • radio sensitivity of different tissues

Tissues with a higher effective dose show more affects to the same level of dose. More radio sensitive.

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10
Q

SI unit for effective dose

A

Sievert

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11
Q

Greater the number of effective dose

A

The greater the risk to that position of the human body

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12
Q

What tissues have the highest effective dose factor?

A 
Bone marrow 
Breast tissue
Stomach 
Colon 
Lung
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13
Q

Radiobiology

A

The study of ionizing radiation effects on living systems

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14
Q

Direct effect

A

When a photon or secondary electron ionizes biological macromolecules.

Photon + RH –> R* + H*

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15
Q

What are free radicals fates? (2)

A

Dissociation: R* –> X + Y *
Cross linking: R* + S* –> RS

Altered molecules differ structurally and functionally from originals

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16
Q

Radiolysis of water

A

Photon absorbed by water.

H2O + photon –> H* + OH*

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17
Q

In the presence of O2…

A

Produce hydrogen peroxide

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18
Q

Is hydrogen peroxide damaging?

A

YES! It is cytotoxic to the cell

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19
Q

Ionization of water leads to …

A

Free radical production

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20
Q

Indirect effect

A

The radicals produced by water radiolysis interacting with biological macromolecules

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21
Q

What are a radicals?

A

Unstable molecule with an unpaired electron. Will react with anything to become stable. Damaging to the cell and DNA

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22
Q

How much does the direct effect account for in biological adage from X-rays ?

A

1/3

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23
Q

How much does indirect effects account for in biological damage?

A

2/3

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24
What is the primary cause of radiation induced cell death?
Damage to DNA
25
Damaged DNA results from: (4)
Breakage of one or both DNA strands Cross linking DNA change or loss of base Disruption of hydrogen bonds between DNA strands
26
Deterministic Effect
Radiation injury is DEPENDENT on the dose Requires higher level of exposure There IS an exposure threshold Generally tissue related
27
What is a exposure threshold
The amount of exposure required to have an effect occur which is clinically observable Below the threshold - there is no effect, no clinical observations
28
Short term deterministic effects are seen primarily where?
Seen in it issues that have rapidly dividing and many undifferentiated stem cells Bone marrow, GI tract, oral mucous
29
Long term deterministic effects
Loss of parenchymal cells - replaced by fibrous connective tissues Loss of capillaries
30
Loss of capillaries results in (3) impaired...
Oxygen transport Nutrient transfer Waste removal
31
What factors can you modify to reduce deterministic effects? (4)
Dose Dose rate Oxygen LET
32
What type of cells have high sensitivity to radiology?
Cells that... Divide regularly Long mitotic futures Undergo little or no differentiation BONE MARROW MUCOUS MEMBRANES SEX ORGANS
33
Cells that have low sensitivity to radiology ?
Cells that ... Are highly differentiated Incapable of division MUSCLE EYE
34
List oral manifestations of irradiation? (6)
``` Lose of taste Mucositis Xerostomia Radiation caries Trismus Osteoradionecrosis ```
35
What is the stochastic effect?
Radiation injury based on PROBABILITY of occurrence "All or nothing" Probability increases with dose NO threshold -- there is no level of exposure at which there is 0 risk ---
36
How do stochastic effects damage?
Sublethal damage to DNA | Induced cancers and genetic alterations
37
Greater dose = greater or lesser stochastic damage?
Greater
38
What is the average natural effective dose of radiation does someone get per year?
2.4 micro sievert
39
What is the average effective does an individual gets from man made radiation?
2.5 micro sievert
40
How much does do you get from one dental X-ray?
.005 millisievert | Comparable to one day of natural exposure
41
1400 dental X-rays = 240 five hour flights = 19 years of smoking a pack of cigarettes a day
.
42
What dental X-ray has the highest dose?
Panoramic -except a full mouth set with digital X-ray
43
What is the probability of getting a long term risk from a pano?
One in a million
44
What are the three guiding principles in radiation safety?
Justification ALARA Dose limitation
45
Justification
Selecting radiographs that benefit the patient | The dentist has an obligation to do more good than harm
46
ALARA
As low as reasonably achievable | Keep radiation exposures to a minimum for adequate diagnosis and evaluation
47
Dose limits
There are no dose limits in diagnostic and therapeutic radiology
48
Should dentists prescribe routine X-rays at preset intervals?
No Prescribe radiographs pertaining to a patients needs. If a high caries risk pt you might want to take radiographs every six months
49
What type of film speed should be used that requires less radiation?
High speed E or F
50
What type of film speed is slow
D
51
Does digital imaging require more or less radiation?
Less
52
What are intensifying screens?
Contain rare earth elements that give off light photons when struck by X-rays. These light photons strike the underlying film. Requires less radiation
53
Longer source to skin reduces exposure. T or F
True
54
Rectangular collimators do not focus the beam to an area. Therefore do not reduce the exposure. T or F
False - they reduce exposure and focus the beam
55
How does filtration of the X-ray beam work?
Aluminum filter removes low energy photons
56
How far for the radiation source should you stand?
2 meters or 6 feet
57
Radiation exposure decreases inversely or directly to the square of the distance
Inversely
58
Where should the operator be positioned in relation to the he primary X-ray beam?
90-135 degrees
59
How often do you need to inspect the X-ray unit?
Every 5 years
60
Ionizing radiation is...
Radiation is sufficient energy to displace atomic electrons thus breaking bonds that hold a molecule together. Produces molecular changes
61
What are three types of ionizing radiation?
X-rays Gamma rays UV light
62
What is the number one natural source of radiation?
Radon
63
What is the number one source of man made radiation?
CT scans
64
Name the two types of ionizing radiation:
Particular radiation | Electromagnetic radiation
65
What does particulate radiation consist of?
Alpha Beta Neutrons
66
What does elctromagnetic radiation consist of?
Gamma and x rays
67
Radiation
Transmission of energy through space and matter
68
What can ionizing radiation lead to in living cells?
Cell death | Molecular alteration leading to harmful affects

Radiology (5 decks)

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