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Radiology > Biology And safety > Flashcards

Biology And safety Flashcards

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
Q

What is the primary cause of radiation induced cell death?

A

Damage to DNA

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25
Q

Damaged DNA results from: (4)

A

Breakage of one or both DNA strands
Cross linking DNA
change or loss of base
Disruption of hydrogen bonds between DNA strands

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26
Q

Deterministic Effect

A

Radiation injury is DEPENDENT on the dose
Requires higher level of exposure
There IS an exposure threshold
Generally tissue related

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27
Q

What is a exposure threshold

A

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
Q

Short term deterministic effects are seen primarily where?

A

Seen in it issues that have rapidly dividing and many undifferentiated stem cells

Bone marrow, GI tract, oral mucous

29
Q

Long term deterministic effects

A

Loss of parenchymal cells - replaced by fibrous connective tissues
Loss of capillaries

30
Q

Loss of capillaries results in (3) impaired…

A

Oxygen transport
Nutrient transfer
Waste removal

31
Q

What factors can you modify to reduce deterministic effects? (4)

A

Dose
Dose rate
Oxygen
LET

32
Q

What type of cells have high sensitivity to radiology?

A

Cells that…
Divide regularly
Long mitotic futures
Undergo little or no differentiation

BONE MARROW
MUCOUS MEMBRANES
SEX ORGANS

33
Q

Cells that have low sensitivity to radiology ?

A

Cells that …
Are highly differentiated
Incapable of division

MUSCLE
EYE

34
Q

List oral manifestations of irradiation? (6)

A 
Lose of taste
Mucositis
Xerostomia 
Radiation caries
Trismus
Osteoradionecrosis
35
Q

What is the stochastic effect?

A

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
Q

How do stochastic effects damage?

A

Sublethal damage to DNA

Induced cancers and genetic alterations

37
Q

Greater dose = greater or lesser stochastic damage?

A

Greater

38
Q

What is the average natural effective dose of radiation does someone get per year?

A

2.4 micro sievert

39
Q

What is the average effective does an individual gets from man made radiation?

A

2.5 micro sievert

40
Q

How much does do you get from one dental X-ray?

A

.005 millisievert

Comparable to one day of natural exposure

41
Q

1400 dental X-rays = 240 five hour flights = 19 years of smoking a pack of cigarettes a day

A

.

42
Q

What dental X-ray has the highest dose?

A

Panoramic

-except a full mouth set with digital X-ray

43
Q

What is the probability of getting a long term risk from a pano?

A

One in a million

44
Q

What are the three guiding principles in radiation safety?

A

Justification
ALARA
Dose limitation

45
Q

Justification

A

Selecting radiographs that benefit the patient

The dentist has an obligation to do more good than harm

46
Q

ALARA

A

As low as reasonably achievable

Keep radiation exposures to a minimum for adequate diagnosis and evaluation

47
Q

Dose limits

A

There are no dose limits in diagnostic and therapeutic radiology

48
Q

Should dentists prescribe routine X-rays at preset intervals?

A

No
Prescribe radiographs pertaining to a patients needs. If a high caries risk pt you might want to take radiographs every six months

49
Q

What type of film speed should be used that requires less radiation?

A

High speed

E or F

50
Q

What type of film speed is slow

A

D

51
Q

Does digital imaging require more or less radiation?

A

Less

52
Q

What are intensifying screens?

A

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
Q

Longer source to skin reduces exposure. T or F

A

True

54
Q

Rectangular collimators do not focus the beam to an area. Therefore do not reduce the exposure. T or F

A

False - they reduce exposure and focus the beam

55
Q

How does filtration of the X-ray beam work?

A

Aluminum filter removes low energy photons

56
Q

How far for the radiation source should you stand?

A

2 meters or 6 feet

57
Q

Radiation exposure decreases inversely or directly to the square of the distance

A

Inversely

58
Q

Where should the operator be positioned in relation to the he primary X-ray beam?

A

90-135 degrees

59
Q

How often do you need to inspect the X-ray unit?

A

Every 5 years

60
Q

Ionizing radiation is…

A

Radiation is sufficient energy to displace atomic electrons thus breaking bonds that hold a molecule together.

Produces molecular changes

61
Q

What are three types of ionizing radiation?

A

X-rays
Gamma rays
UV light

62
Q

What is the number one natural source of radiation?

A

Radon

63
Q

What is the number one source of man made radiation?

A

CT scans

64
Q

Name the two types of ionizing radiation:

A

Particular radiation

Electromagnetic radiation

65
Q

What does particulate radiation consist of?

A

Alpha
Beta
Neutrons

66
Q

What does elctromagnetic radiation consist of?

A

Gamma and x rays

67
Q

Radiation

A

Transmission of energy through space and matter

68
Q

What can ionizing radiation lead to in living cells?

A

Cell death

Molecular alteration leading to harmful affects

Radiology (5 decks)

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