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Science and Technology 1 > Biological Effects Of Radiation > Flashcards

Biological Effects Of Radiation Flashcards

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Biology 101 flashcards
1
Q

Where is most DNA located?

A

In the cell nucleus

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2
Q

Where are small amounts of DNA found?

A

In the mitochondria

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3
Q

How many pairs of chromosomes does each cell usually contain?

A

23 pairs

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4
Q

What are chromosomes made of?
(2)

A

Proteins
A single DNA molecule

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5
Q

What is the DNA structure?
(4)

A

2 linked strands to create a double helix.
Each strand has a backbone made of sugar and phosphate groups.
Attached to each sugar is one of 4 bases- adenine, thymine, cytosine and guanine
A+T, C+G

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6
Q

What happens in mitosis?
(7)

A

The cell begins to divide

The DNA replicates to form 2 copies of each chromosome

The nuclear membrane breaks down.

The chromosomes line up across the centre of the cell

One set of chromosomes is pulled to each end of the cell

The nucleus divides

The cytoplasm and cell membranes divide to form 2 identical cells

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7
Q

What are the 2 stages of the cell cycle?

A

Interphase

Mitotic phase

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8
Q

What are the 3 stages of interphase?

A

Gap phase 1 (G1)

Synthesis (S)

Gap phase 2 (G2)

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9
Q

Which stage of the cell cycle is most sensitive to radiation?
Why?

A

Mitotic phase

Because that’s where the sister cells are being produced

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10
Q

What are the 2 types of radiation damage?

A

Direct damage

Indirect damage

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11
Q

When does direct radiation damage occur?

A

When radiation directly damages the DNA, causing either single or double strand breaks

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12
Q

What does direct radiation damage cause?

A

The breaks in the DNA that it causes, cause disruption to cell replication/duplication

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13
Q

When does indirect radiation damage occur?

A

It occurs when radiation interacts with non-critical targets within the cell,usually water

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14
Q

What does indirect radiation damage cause?

A

It causes the production of free radicals which attack other parts of the cell

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15
Q

What are examples of fast growing cells?
(3)

A

Epithelial cells

Fingernail cells

Hair cells

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16
Q

Are fast or slow growing cells spend more time in mitosis?

A

Fast growing cells

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17
Q

What is an example of slow growing cells?

A

Brain cells

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18
Q

What are the consequences of direct radiation damage?
(4)

A

The cell may be undamaged

The cell may become repaired and work normally

The cell may repair abnormally, where the wrong amino acid bases replace the break, e.g. A+G instead of A+T

The cell may die

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19
Q

What can happen in the cell repairs itself abnormally by the wrong amino acid replacing the break?

A

This causes cell mutation, so during the next cell division, the abnormality is replicated. This leads to malignancy

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20
Q

During direct radiation damage, where does the radiation hit on the DNA?
(2)

A

The DNA base

The DNA backbone

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21
Q

During direct radiation damage, what are the 2 types of breaks that can occur?

A

Single strand break

Double strand break

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22
Q

Which type of radiation damage is more likely to happen?
Why?

A

Direct radiation damage

Because there’s lots of water in a cell

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23
Q

What % of a cell is water?

A

90%

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24
Q

What are free radicals?

A

Atoms or molecules that have an unpaired electron and are highly reactive

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25
Q

What do the free radicals in indirect radiation damage do?

A

They can attack critical targets, such as the DNA

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26
Q

How does indirect radiation damage work?
(3)

A

Radiation interacts with DNA

It breaks the water, leaving 2 hydrogens and 1 oxygen- this leaves OH and H+

The H+ is the free radical and it’s looking for an OH to pair with and produce water again

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27
Q

What is the free radical?

A

H+ (hydrogen atom)

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28
Q

What are photons also known as?

A

X-rays

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29
Q

Why does radiation lose energy when it interacts with matter?

A

Because it’s interacting with atoms

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30
Q

What does LET stand for?

A

Linear
Energy
Transfer

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31
Q

What does the LET (linear energy transfer) do?

A

It determines the biological consequence that a specific type of radiation causes

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32
Q

What is the linear energy transfer (LET) measured in?

A

Kiloelectronvolts (KeV) per micrometer

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33
Q

What does the linear energy transfer (LET) depend on?
(2)

A

The type of radiation

The type of material traveled through

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34
Q
A

They deposit

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35
Q

What does high LET include?

A

Particles with a lot of mass and charge

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36
Q

What is an emerging form of cancer treatment for children?

A

Protons

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37
Q

Why are protons used as an emerging form of cancer treatment for children?

A

Because they deposit all their energy at the end of their trajectory- making them better than x-rays

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38
Q

Where does low LET come from?

A

External electromagnetic radiation, such as x-rays

39
Q

What does high LET include?

A

Protons

40
Q

What is the linear energy transfer (LET)?

A

It measures of the amount of energy that an ionising particle transfers to a material per unit distance

41
Q

What happens in high LET?

A

The protons deposit a large amount of energy in a small distance, which can cause a lot of biological damage in a small area

42
Q

What happens in low LET?

A

The x-rays penetrate tissues very easily but they deposit energy infrequently. This means that the energy deposits are spread out, so less damaging events can occur in one cell from one x-ray

43
Q

What are the 3 dose quantities?

A

Absorbed dose

Equivalent dose

Effective dose

44
Q

What is the absorbed dose?

A

Per kg of a person, how much do the tissues absorb the energy produced by radiation? (It varies depending on the radiation type)

Basically, how much of the energy we put in stays inside the person

45
Q

What is the equivalent dose?

A

The effect of radiation on human tissue

46
Q

What does the equivalent dose allow us to do?

A

It allows us to compare different types of radiation

47
Q

What is an ODP?

A

Someone who isn’t wearing lead

48
Q

What is an effective dose?

A

The probability of a harmful effect (cancer) depending on the organs/tissues exposed. The radiation and the tissue both have their own weighting factors

49
Q

What is exposure measured by?

A

What the radiation does to substances, so the effect that the radiation has on the substance it’s in.

50
Q

What’s important about the effect that radiation has on the substance it’s in?

A

The radiation could cause a different effect depending on the substance, e.g. there’s a higher effect in the eyes than in the bones

51
Q

What is the absorbed dose expressed in?

A

Gray (Gy)

52
Q

How many times smaller is a milligray compared to a Gray

A

1000x smaller

53
Q

Why is the absorbed dose not a good indicator of likely biological effect?

A

Because weighting factors need to be applied to find the equivalent dose and the tissue

54
Q

Why is the absorbed dose not a good indicator of likely biological effect?

A

Because weighting factors need to be applied to find the equivalent dose and the tissue

55
Q

Does each type of radiation have the same weighting factor?

A

No- they all have their own weighting factor

56
Q

What is the equivalent dose measured in?

A

Sieverts

57
Q

How do we work out the equivalent dose?

A

Radiation weighting factor
X
absorbed dose to organ/tissue

58
Q

What is the relative biological effectiveness (RBE)?

A

The ratio of the doses required by the 2 types of radiation to cause the same level of effect.

59
Q

Does high or low LET cause more damage?

A

High LET always causes more damage

60
Q

What do tissue tolerances do?

A

They tell us how much dose of radiation a tissue can tolerate before the point of no return

61
Q

Why are protons used in the cancer treatment of children?

A

Because we can use a lower dose of them to cause more of an effect, so the side effects are easier to overcome

62
Q

What does anything above the tolerance dose mean?

A

Any damage can’t be repaired

63
Q

What does anything below the tolerance dose mean?

A

Any damage is repairable

64
Q

What did knowledge about tissue tolerances allow the creation of?

A

Dose reference levels (DRLs) e.g. doses that certain x-rays shouldn’t exceed, like chest x-rays

65
Q

Which type of cell are frequently reproducing?

A

Most sensitive cells, e.g. epithelial cells

66
Q

Where do we get exposed to radiation?

A

Everywhere- we’re always exposed to radiation

67
Q

What do the physical effects of radiation depend on?

A

The amount of exposure - high dose or low dose

68
Q

What can significant side effects depend on?
(4)

A

Internal exposure

External exposure

Local exposure (to a specific body part)

Whole body exposure

69
Q

What are examples of internal exposure?
(3)

A

Food

Inhalation

Radiopharmaceuticals

70
Q

What are examples of external exposure?
(3)

A

Sun

Ground

Radiation generator

71
Q

What are examples of external exposure?
(3)

A

Sun

Ground

Radiation generator

72
Q

How do we have data on the physical effects of radiation?

A

Because of radiation disasters, e.g. Chernobyl (1986). The rates of cancer increased and long term effects exist years later

73
Q

When do deterministic effects only occur?

A

When the threshold of exposure has been exceeded

74
Q

When does the severity of deterministic effects increase?

A

As the absorbed dose increases

75
Q

What is important about the radiation doses involved in deterministic effects of radiation?
(2)

A

They’re usually substantial ( a lot)

They’re usually delivered over a short space of time

76
Q

What are the effects of the deterministic effects of radiation?
(3)

A

Cataracts

Erythema (skin reddening)

Sterility

77
Q

What determines the side effects seen in the deterministic effects of radiation?

A

The dose received

78
Q

What does the stochastic effects of radiation mean?

A

There’s only a probability of an effect occurring, so it’s due to chance

79
Q

What is the threshold dose for the deterministic effects of radiation?

A

It has to be below where no clinical effect is obseved

80
Q

What is the threshold dose for the stochastic effects of radiation?

A

There’s no threshold level for these effects- the risk of an effect occurring increases as the absorbed dose increases

81
Q

Are the stochastic effects of radiation easy or hard to detect on wide scale?
Why?

A

Very hard to detect

Because of low dose exposure

82
Q

What are the effects of the stochastic effects of radiation?
(2)

A

Cancer

Hereditary effects

83
Q

Since the stochastic effects of radiation have no threshold dose, what does it mean?

A

All doses of radiaton have a chance of causing side effects

84
Q

What 4 things can be caused by deterministic and stochastic effects?

A

Acute disorders

Fatal disorders

Late-onset disorders

Hereditary effects

85
Q

What are the 4 points of pregnancy?

A

Pre-implantation period

Organogenesis period

Early fetal period

Late fetal period

86
Q

What is the time period of the pre-implantation period?

A

0-2 weeks after conception

87
Q

What is the time period of the organogenesis period?

A

2-8 weeks after conception

88
Q

What is the time period of the early fetal period?

A

8-15 weeks after conception

89
Q

What is the time period of the late fetal period?

A

15 weeks after conception to delivery

90
Q

What is the consequence of irradiating a woman at the pre-implantation period of pregnancy?

A

Miscarriage

91
Q

What is the consequence of irradiating a women at the organogenesis period of pregnancy?

A

Dysplasia (malformation)

92
Q

What is the consequence of irradiating a woman at the early fetal period of pregnancy?

A

Mental retardation

93
Q

What are some things we should take into account to prevent deterministic or stochastic effects of radiation when imaging patients?
(3)

A

Be mindful of the total exposure time, e.g. if the same patch of tissue is constantly being irradiated, the patient is receiving a high dose of radiation overall

Is the patient seeking a 2nd opinion (lying about already going to another hospital?) We can use PACS as they show proof of image, as all x-ray images get uploaded here

Is there an alternative imaging method which uses less radiation?

94
Q

What are some things we should take into account to prevent deterministic or stochastic effects of radiation when imaging patients?
(3)

A

Be mindful of the total exposure time, e.g. if the same patch of tissue is constantly being irradiated, the patient is receiving a high dose of radiation overall

Is the patient seeking a 2nd opinion (lying about already going to another hospital?) We can use PACS as they show proof of image, as all x-ray images get uploaded here

Is there an alternative imaging method which uses less radiation?

Science and Technology 1 (17 decks)

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