Nmt 222 Radiation Biology

Front 1

What are the two main subjects of Chapter 08, Radiation Biology?

Back 1

1. To explain the principles of radiation biology.

2. To describe the effects of ionization on normal cells and cancer cells.

Front 2

What are the two major effects on biological from ionizing radiation?

Section: Biological effects of ionizing radiation.

Back 2

Stochastic

Deterministic

Memory Aid
DusTy STONe
Deterministic - Threshold
STOchastic - No threshold

Front 3

What are the two major ways ionizing radiation interacts with the cells?

Section: Biological effects of ionizing radiation.

Back 3

Direct & Indirect

Front 4

Is it possible for cells to repair themselves? Y/N

Section: Biological effects of ionizing radiation.

Back 4

Yes

Front 5

Which effect usually takes longer, Deterministic or Stochastic?

Section: Biological effects of ionizing radiation.

Back 5

Stochastic

Front 6

Which effect is more likely to cause somatic or genetic outcomes, Deterministic or Stochastic?

Section: Biological effects of ionizing radiation.

Back 6

Stochastic

Front 7

This effect of ionizing radiation has a threshold effect, below which no effect occurs.

Section: Biological effects of ionizing radiation.

Back 7

Deterministic

Front 8

What are the types of ionizing radiation that interact either directly or indirectly with cells?

Section: Direct and Indirect Interactions of Radiation

Back 8

beta
positron
alpha
gamma
x-ray

Front 9

What type of interaction with radiation is more likely to happen with high LET? Why?

Section: Direct and Indirect Interactions of Radiation

Back 9

Direct

Because of the high ionization density.

Front 10

What type of interaction with radiation is more likely to happen with low LET?

Section: Direct and Indirect Interactions of Radiation

Back 10

Indirect

Front 11

When ionizing radiation interacts indirectly with the cells, what molecule is usually involved?

Section: Direct and Indirect Interactions of Radiation

Back 11

water

our bodies are 75% water

Front 12

When ionizing radiation interacts with water what is usually produced?

Section: Direct and Indirect Interactions of Radiation

Back 12

free radicals

Front 13

What is so dangerous about free radicals? (3 things)

Section: Direct and Indirect Interactions of Radiation

Back 13

1. they are highly reactive
2. they block or inactivate restoration
3. they create toxins like hydrogen peroxide

Front 14

What biological molecule is the most vulnerable to ionizing radiation?

Section: Effects of Radiation on Genetic Material

Back 14

DNA

Front 15

What are the three main parts of DNA that are typically involved with ionizing radiation?

Section: Effects of Radiation on Genetic Material

Back 15

1. phosphate group
2. sugar molecule (deoxyribose)
3. base pairs

Front 16

When is chromosome damage most likely to happen in the cell cycle?

Section: The Cell Cycle

Back 16

before the S phase

Front 17

When is chromatid damage most likely to happen in the cell cycle?

Section: The Cell Cycle

Back 17

in the S phase

Front 18

What is a cell survival curve?

Section: Cell Survival Curves

Back 18

Graphic curves that display how cells survive radiation.

Front 19

The magnitude of cell killing is measured by the fraction of cells that _________ after radiation exposure.

Section: Cell Survival Curves

Back 19

survive

Front 20

What is plating efficiency?

Section: Cell Survival Curves

Back 20

The ratio of untreated cells that survive compared to the number of untreated cells.

Usually expressed as a decimal or percent.

Front 21

What is the survival fraction?

Section: Cell Survival Curves

Back 21

The number of treated cells that survived divided by ( the number of treated cells * the plating efficiency. )

Front 22

What is the region where dose is not proportional to cell survival and is the region of the most probable sub-lethal dose?

Section: Cell Survival Curves

Back 22

the shoulder region

Front 23

What are the two types of curves you are likely to see on a cell survival curve?

Section: Cell Survival Curves

Back 23

exponential

sigmoid

Front 24

The ____________________ curve is typical when you have a situation where 1 target must be inactivated to kill a cell.

Section: Cell Survival Curves

Back 24

exponential

Front 25

The ____________________ curve is typical when you have multiple targets must be inactivated to kill a cell.

Section: Cell Survival Curves

Back 25

sigmoid

Front 26

What do cell survival curves tell you?

Section: Cell Survival Curves

Back 26

they give a picture of how doses of radiation affect cells in order to minimize the dose related effects to the patient. Helps to maximize the benefits over the damage.

Front 27

The reason for dose fractionation is to ....

Section: Cell Survival Curves

Back 27

allow time for cell repair before the next fractional does is given. this minimizes the effect of a full dose.

Front 28

Why aren't all cells killed by radiation?

Section: Cell Survival Curves

Back 28

some cells repair
some cells sustain sub-lethal doses
some cells simply do not get hit

Front 29

What is radiosensitivity?

Section: Radiosensitivity

Back 29

the measure of how sensitive different tissue types are to radiation

Front 30

Name three generalizations you can say about the radiosensitivity of cells.

Section: Cell Survival Curves

Back 30

tumors are more affected

dividing cells are more affected

stem cells are more affected

high metabolic cells are more affected

high proliferating cells are more affected

mitosis is important when considering biological effects

Front 31

What factors affect radiosensitivity?

Section: Factors affecting radiosensitivity

Back 31

high LET (no dose rate with high LET, ionization dominates)

higher dose rate with low LET

oxygen (mechanism thought to be from radical formation)

cell cycle

Front 32

What is the OER index?

Section: Cell Survival Curves

Back 32

ratio between dose required to produce an effect without oxygen to the dose required to produce an effect with oxygen.

Front 33

Mammalian cells have an OER approximately ______.

Section: Cell Survival Curves

Back 33

2.5

Front 34

What are the three main types of deterministic effects of whole-body radiation?

Section: Acute effects of Whole Body Irradiation

Back 34

hematopoietic

gastrointestinal

cerebrovasular

Front 35

What are three characteristics of whole body radiation?

Section: Acute effects of Whole Body Irradiation

Back 35

preceded by a prodromal phase and latency period

time of onset and severity are dose dependent

length of latency period is inversely proportional to magnitude of exposure

Front 36

The carcinogenic effects of radiation are _____________ effects because they arise from random mutations in ________ or _______ cells

Section: Carcinogenic effects of Radiation

Back 36

stochastic, somatic, germ

Front 37

Name three types of tumors induced by radiation.

Section: Carcinogenic effects of Radiation

Back 37

leukemia
thyroid
breast
lung
bone
skin

Front 38

Name two ways in which carcinogenesis occurs.

Section: Carcinogenic effects of Radiation

Back 38

activation of oncogenes
inactivation of suppressor genes

Front 39

Carcinogenic effects of radiation are from DNA damage to ___________ cells.

Section: Hereditary effects of Radiation

Back 39

somatic

Front 40

Hereditary effects of radiation is from DNA damage to ___________ cells.

Section: Hereditary effects of Radiation

Back 40

germ

Front 41

The radiation effects on the testes is most sensitive to the ______________.

Section: Radiation effects on the Embryo and Fetus

Back 41

spermatogonia

Front 42

How are the oocytes of the ovary different than the spermatogonia of the sperm.

Section: Radiation effects on the Embryo and Fetus

Back 42

all oocytes are present by the age of 3 and remain in a resting state

there is no possibility of temporary sterilization

Front 43

What doses (rad) can cause permanent male sterility?

Section: Radiation effects on the Embryo and Fetus

Back 43

350-600 rad single dose
200 rad per year (prolonged dose)

Front 44

What doses (rad) can cause permanent female sterility?

Section: Radiation effects on the Embryo and Fetus

Back 44

250-600 rad single dose
20 rad per year (prolonged dose)

Front 45

Hair loss, skin erythema and cataracts are examples of ____________ effects.

Back 45

deterministic

Front 46

What causes bonds to break in DNA when it encounters a direct interaction of radiation?

Back 46

primary ionizations

Front 47

The most damaging free radical in the body is what?

Back 47

OH*, the hydroxyl free radical

Front 48

T/F. Free radicals are a type of ion?

Back 48

False

They are electrically neutral, unlike an ion, but they have shell with a unfilled electron.

Front 49

T/F. The effectiveness of repair to DNA can be thwarted by free radicals binding to the broken strand of DNA.

Back 49

True

Front 50

T/F. Single strand and double strand DNA breaks can occur from radiation.

Back 50

True

Front 51

What are the two types of curves typically seen on cell survival graphs?

Back 51

sigmoid (multi-target)
exponential (actually linear-exponential) (single target)

Front 52

Acute radiation syndrome is defined as whole body radiation exposure in excess of ____ to ____ rad.

Back 52

100, 200