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Radiation Protection > Chapter 7 > Flashcards

Chapter 7 Flashcards

Molecular & Cellular Radiation Biology

1
Q

What are four things that may occur if a cell is damaged by radiation?

A

-Cell may repair itself completely
-Cell may partially repair itself but not able to function correctly
-Cell may continue to function but will pass on incorrect genetic information
-Cell may die

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2
Q

What is chromosome aberration(or mutation)?

A

Any permanent damage to chromosomes

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3
Q

If somatic cells are involved in chromosome aberration, what will it result in?

A

-Loss of function, malignancy (cancer), or even death
-Affects only the person irradiated

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4
Q

If gonadal cells are involved in chromosome aberration, what will it result in?

A

-Mutations in future generations
-Affects future generations

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5
Q

What is radiation biology?

A

Branch of biology concerned with the effects of ionizing radiation on living systems

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6
Q

What is ionizing radiation?

A

Damages living systems by ionizing the atoms comprising the molecular structure of these systems

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7
Q

What does biologic damage begin with?

A

The ionization produced by various types of radiation

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8
Q

What are examples of radiation that produces ionization?

A

-X-rays
-Gamma Rays
-Alpha Particles
-Beta Particles
-Protons

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9
Q

Ionized atom will or will not bond properly in molecules?

A

Will not

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10
Q

What are determinants of radiation energy transfer?

A

-Charge, mass, and energy vary among the different types of radiation
These attributes determine the extent to
which different radiation modalities transfer
energy into biologic tissue

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11
Q

What are three important concepts to help us understand the way ionizing radiation causes injury and how the effects may vary in biologic tissue?

A

-Linear energy transfer
-Relative biologic effectiveness
-Oxygen enhancement ratio

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12
Q

What is LET (Linear energy transfer)?

A

A measure of the rate at which energy is transferred from a beam of ionizing radiation to the tissue through which it is traveling

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13
Q

How is LET measured?

A

Measured in kiloelectron volts (keV) of energy transferred per micrometer of tissue

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14
Q

What is LET very important factor for?

A

Assessing potential tissue and organ damage from exposure to ionizing radiation

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15
Q

What is the LET for diagnostic x-rays?

A

About 3keV/micrometer

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16
Q

As LET increases, what happens to biological damage and radiation damage?

A

They both increase

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17
Q

What happens to LET if there is an increase in the ability to penetrate?

A

Decreases

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18
Q

What are the two radiation categories according to LET?

A

-Low-linear energy transfer radiation
-High-linear energy transfer radiation

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19
Q

What are Low-LET radiation?

A

-Gamma rays
-X-rays

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20
Q

What are High-LET radiation?

A

-Alpha particles
-Ions of heavy nuclei
-Charged particles released from interactions between neutrons and atoms
-Low-energy neutrons

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21
Q

What is relative biologic effectiveness (RBE)?

A

Takes into consideration the amount of damage caused by different types of radiation

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22
Q

Radiation with higher LET will cause _____ biological damage.

A

more

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23
Q

An increase in LET will cause RBE to?

A

Increase

LET & RBE are proportional

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24
Q

What RBE does x-rays have?

A

1

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25
Q

What is oxygen enhancement ratio (OER)?

A

The ratio of the radiation dose required to cause a particular biologic response of cells or organisms in any oxygen-deprived environment to the radiation dose required to cause an identical response under normal oxygenated conditions

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26
Q

X-rays and gamma rays have an OER of?

A

About 3.0 when radiation does is high

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27
Q

Biologic tissue is _______ radiosensitive when it is well oxygenated, than when it is poorly oxygenated (hypoxic).

A

MORE

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28
Q

What are the three levels biologic damage stemming from exposure to ionizing radiation may be observed?

A

-Molecular
-Cellular
-Organic systems

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29
Q

If there is any visible radiation-induced injuries of living systems at the cellular or organic level, it began with?

A

With damage at the molecular level

30
Q

What does molecular damage result in?

A

The formation of structurally changed molecules that may impair cellular functioning

31
Q

What are the effects of irradiation on cells?

A

it may disturb the cell’s chemical balance and ultimately the way it operates. The affected cell can then no longer perform its normal task.

32
Q

What happens if a sufficient quantity of somatic cells are affected by irradiation?

A

The entire body processes may be disrupted

33
Q

What happens if radiation damages the genetic cells?

A

The damage may be passed on to future generations in the form of genetic mutations

34
Q

What are the two classifications of ionizing radiation interaction on a cell?

A

-Direct Effect (e.g., in DNA)
-Indirect Effect (e.g., in H2O)

35
Q

What classification of ionizing radiation interaction do essentially all effects of low-LET irradiation in a living cell result from?

A

Indirect
- Because the human body is 80% water and less than 1% DNA

36
Q

What is direct effect?

A

a photon form the primary beam of radiation ionizes a molecule critical to the cell (ex. DNA)

37
Q

What is indirect effect?

A

After an initial ionizing event, there will be an ejected electron and either a secondary or scattered photon that may ionize another atom or molecule (H2O)

38
Q

Does Direct or Indirect cause the most radiation damage?

A

Indirect

39
Q

What happens to water when it is irradiated?

A

It easily breaks down into molecular products

40
Q

When water breaks into molecular products, these molecules can break down into?

A

Ions of hydrogen(H), hydroxyl molecules(OH), & a free electron

41
Q

What can the ions of hydrogen, hydroxyl molecules and a free electron recombine as?

A

Harmless-
H20 (water) or H30 (heavy water)

Harmful (Toxic in large enough quantities can kill the cell-
H202 (hydrogen peroxide)

42
Q

A cell can absorb radiation damage and continue to function unless what is damaged?

A

a key or target molecule(DNA)

43
Q

What happens if the target molecule is damaged?

A

the cell will die

44
Q

What is necessary for the survival of the cell?

A

Master, or key molecule

45
Q

What can target theory be used to explain?

A

Cell death and nonfatal call abnormalities caused by exposure to radiation

46
Q

What percentage of mutations are harmful?

A

99.9%

47
Q

What are the 6 ways damage to the cell’s nucleus reveals itself?

A

-Instant death
-Reproductive death
-Apoptosis, or programmed cell death (interphase death)
-Mitotic, or genetic, death
-Mitotic delay
-Interference with function

48
Q

When does instant death in large numbers of cells occur?

A

When a volume is irradiated with an x-ray or gamma ray dose approx. 1000gy

49
Q

What is gross distribution caused by?

A

The cell form and structure

50
Q

Is the radiation dose high enough to cause instant death used in diagnostic exams or therapeutic treatments?

A

No

51
Q

Do reproductive cells die?

A

No, they permanently lose its ability to procreate

52
Q

When does reproductive death result?

A

From exposure of cells to doses of ionizing radiation in the range of 1-10Gy

53
Q

What is apoptosis?

A

Non-mitotic, or non-division form of cell death that occurs when cells die without attempting division during the interphase portion of the cell cycle

54
Q

What is another name for apoptosis?

A

Programmed cell death

55
Q

What is an example of apoptosis?

A

Human skin cells die, are replenished, and maintain a protective outer coating known as skin

56
Q

What is mitotic death?

A

-Occurs when a cell dies after one or more divisions
-Small doses of radiation have the ability to cause this type of cell death

57
Q

What is mitotic delay?

A

-Exposing a cell just before it begins to divide
-Failure of the cell to start dividing on time
-After this delay normal mitotic functions can resume

58
Q

What are radioinsensitive cells?

A

-Brain cells
-Muscle cells
-Nerve cells

59
Q

What are radiosensitive cells?

A

-Basal cells of the skin
-Blood cells such as lymphocytes and erythrocytes
-Intestinal crypt cells
-Reproductive (germ) cells

60
Q

What enhances the effects of ionizing radiation on biologic tissue by increasing tissue radiosensitivity?

A

Oxygen

61
Q

During diagnostic imaging procedures, what human tissues are exposed to x-radiation or gamma radiation?

A

fully oxygenated

62
Q

What is the LET for diagnostic exams?

A

low, very few cells are killed because low doses of radiation are given

63
Q

What is used sometimes in conjunction with radiation to treat certain types of cancerous tumors?

A

High-pressure (hyperbaric) oxygen

64
Q

What does using high-pressure (hyperbaric) oxygen with radiation do?

A

It increases tumor radiosensitivity

65
Q

What does the Law of Bergoine and Tribondeau state?

A

-Immature cells are more radiosensitive than mature ones
-Young tissue and organs are more radiosensitive than older ones
-The higher the metabolism of given cell, the more radiosensitive it will be
-rapidly dividing cells are more sensitive

66
Q

Why are rapidly dividing cells more radiosensitive?

A

They are more sensitive because they are more sensitive during mitosis/meiosis

67
Q

Why is an embryo/fetus more susceptible to radiation damage than a child or adult?

A

They contain a large number of immature cells

68
Q

Why do nerve, brain, and muscle cells have a reduced radiosensitivity?

A

Because people are born with nearly all of these cells; they are nearly immature nor rapidly dividing

69
Q

What cells are the MOST radiosensitive?

A

cells undergoing mitosis, blood cells, and gonadal cells

70
Q

The most mature and specialized in performing functions a cell is, the ______ sensitive it is to radiation.

A

less

71
Q

What is hematologic depression?

A

decreasing number of active cells

Radiation Protection (8 decks)

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