Radbiology

Question 1

The law of _____ states that the radiosensitivity of living tissue is a function of the metabolism and maturation of that tissue.

Answer 1

Bergonie and Tribondeau

Question 2

Tissues that are _____ with a _____ metabolic rate are more radiosensitive.

Answer 2

immature, high

Question 3

_____ is a measure of the rate that energy is transferred from ionizing radiation to soft tissue.

Answer 3

LET

Question 4

As LET _____, the RBE _____.

Answer 4

increases, increases

Question 5

A protracted dose of radiation is given _____.

Answer 5

over a long period of time

Question 6

A dose of 10 Gy given to a patient in 5 doses of 2 Gy per day is a _____ dose.

Answer 6

fractionated

Question 7

The LET of diagnostic x-rays is _____ keV/m.

Answer 7

3.0

Question 8

The RBE of diagnostic x-rays is equal to _____.

Answer 8

1

Question 9

Tissue is _____ radiosensitive under high oxygen conditions and _____ radiosensitive under hypoxic conditions.

Answer 9

more, less

Question 10

Fractionation and protraction are used for radiation therapy because they allow the patient to _____.

Answer 10

a. recover between doses
b. have higher total doses
c. repair damaged tissues

Question 11

Humans are most radiosensitive during _____.

Answer 11

a. fetal stages

Question 12

The human application of radioprotective agents would _____.

Answer 12

be fatally toxic

Question 13

Human cells cannot recover from radiation damage after there is _____.

Answer 13

interphase death

Question 14

Studies of the effects of radiation show that low doses may _____.

Answer 14

stimulate the immune system

Question 15

The possible beneficial effect of a small amount of radiation is called _____.

Answer 15

hormesis

Question 16

A _____ response to radiation is directly proportional to the dose received.

Answer 16

linear

Question 17

If a response to radiation is expected, no matter how small the dose, then that dose-response is _____.

Answer 17

linear

Question 18

Radiation induced genetic damage follows a _____ dose-response relationship.

Answer 18

linear-nonthreshold

Question 19

Which dose-response relationship can follow a sigmoid curve?

Answer 19

nonlinear-threshold

Question 20

The human dose-response relationship at low ranges of radiation is calculated using _____.

Answer 20

extrapolation from high ranges

Question 21

If a macromolecule has (a) _____, it will break down into smaller molecules.

Answer 21

point lesion

Question 22

In vitro irradiation of macromolecules causes _____ damage to macromolecules.

Answer 22

a. repairable
b. reversible

Question 23

The most radiosensitive macromolecule is _____.

Answer 23

DNA

Question 24

DNA is contained in the _____ of the cell nucleus.

Answer 24

chromosomes

Question 25

A type of DNA damage that may not be reversible is a _____.

Answer 25

base change or loss

Question 26

Radiation damage to DNA can result in _____.

Answer 26

a. cell death b. malignant disease c. genetic changes

Question 27

Molecular lesions of DNA are called _____.

Answer 27

point mutations

Question 28

The principal radiation interaction within the human body is with _____.

Answer 28

water

Question 29

The disassociation of water molecules following irradiation is termed _____.

Answer 29

radiolysis

Question 30

Two OH* free radicals can join to form _____ molecules.

Answer 30

hydrogen peroxide

Question 31

When an atom of water is irradiated it first dissociates into _____.

Answer 31

an ion pair

Question 32

Free radicals can be damaging because they are _____.

Answer 32

a. unstable b. highly reactive

Question 33

An indirect effect from ionizing radiation occurs on a _____ molecule.

Answer 33

water

Question 34

Ionizing events from irradiation are considered to be direct effects if they occur with _____ molecules.

Answer 34

DNA

Question 35

The principal radiation interactions within the human body are assumed to be _____.

Answer 35

indirect effects

Question 36

Irradiation hits occur through _____.

Answer 36

a. indirect effects b. direct effects

Question 37

According to target theory, the target molecule of a cell is _____.

Answer 37

the DNA in the nucleus

Question 38

A target molecule that is _____ will always cause cell death.

Answer 38

inactivated

Question 39

A hit to a cell target can occur from a(n) _____ effect.

Answer 39

a. indirect b. direct

Question 40

The probability of a hit is increased with _____ oxygen and _____ LET radiation.

Answer 40

high, high

Question 41

The lethal effects of cell irradiation are measured by cell _____.

Answer 41

survival

Question 42

The _____-target, _____-hit model of radiation induced cell death applies to simple cells only.

Answer 42

single, single

Question 43

The DO represents the _____ dose for human cells.

Answer 43

mean lethal

Question 44

Human cells are most radiosensitive during the _____ phase of the cell cycle.

Answer 44

mitosis

Question 45

Which of the following types of radioactive particle has the highest LET?

Answer 45

Alpha particle

Question 46

The mean lethal dose for high LET radiation is ______ than after low LET radiation.

Answer 46

lower

Question 47

If oxygen is present during low-LET radiation the effect of radiation is?

Answer 47

maximal

Question 48

If oxygen is present during high-LET radiation the effect of radiation is?

Answer 48

the same

Question 49

The minimum dose lethal to humans is _____ Gy to the whole body.

Answer 49

2

Question 50

What would be the most likely immediate response to a whole body dose of 2 Gy?

Answer 50

diarrhea, nausea, and vomiting

Question 51

A single chromosome aberration represents _____ to the DNA within the chromosome.

Answer 51

severe damage

Question 52

The most radiosensitive cells in the hematopoietic system of the human body are the _____.

Answer 52

lymphocytes

Question 53

Radiation protection guidelines are based on _____.

Answer 53

stochastic effects of radiation

Question 54

_____ is a stochastic effect of radiation exposure.

Answer 54

Cancer

Question 55

A _____ effect increases in incidence but not severity as the dose increases.

Answer 55

stochastic

Question 56

Low doses of radiation have been shown to cause _____.

Answer 56

chromosome damage

Question 57

Chronic low doses of radiation have _____ effect on fertility.

Answer 57

no

Question 58

Studies of A-bomb survivors indicate that leukemia has a _____ dose-response relationship to radiation.

Answer 58

linear, nonthreshold

Question 59

Radiation-induced leukemia has a latent period of _____ years.

Answer 59

4-7

Question 60

Ankylosing spondylitis patients treated with radiation showed an increased incidence of _____.

Answer 60

leukemia

Question 61

It is difficult to link cancer to radiation exposure because it occurs _____ in the population.

Answer 61

in high proportion

Question 62

People who had radiation treatments to their thymus gland as children later showed excess risk for _____.

Answer 62

thyroid cancers

Question 63

People who were employed painting radium watch dials later showed excess risk for _____ cancer.

Answer 63

bone

Question 64

The theory of radiation hormesis suggests that radiation doses below 0.1 mGy are _____.

Answer 64

beneficial

Question 65

Our information on the genetic effects of radiation has come from studies of _____.

Answer 65

a. mice b. fruit flies

Question 66

A protracted dose of radiation is given _____.

Answer 66

over a long period of time

Question 67

A dose of 10 Gy given to a patient in 5 doses of 2 Gy per day is a _____ dose.

Answer 67

fractionated

Question 68

The RBE of diagnostic x-rays is equal to _____.

Answer 68

1

Question 69

Tissue is _____ radiosensitive under high oxygen conditions and _____ radiosensitive under hypoxic conditions.

Answer 69

more, less

Question 70

The lethal effects of cell irradiation are measured by cell _____.

Answer 70

survival