MIDTERM 2

Question 1

cell that is radiosensitive

Answer 1

stem cell

Question 2

cell that is radioresistant

Answer 2

mature cells

Question 3

law of bergonis & tribondeau states that these are radiosensitive

Answer 3

younger organs & tissues
tissues with high metabolic activity

Question 4

____ & _____ results in increased radiosensitivity

Answer 4

high proliferation rate (cells)
high growth rate (tissue)

Question 5

factors affecting radiosensitivity

Answer 5

physical: LET, RBE, dose rate (protraction & fractionation)
biologic: Oxygen effect, age, recovery, chemical agents & hormesis

Question 6

what is LET

Answer 6

linear energy transfer

Question 7

what is rbe

Answer 7

Relative biologic effectiveness

Question 8

measure rate which energy is transferred from ionizing radiation to soft tissue

Answer 8

LET

Question 9

what is LET measured in

Answer 9

keV/um
kiloelectron volt per micrometer

Question 10

diagnostic xray = ___ RBE & ___ LET

Answer 10

1 RBE
3 LET

Question 11

ratio of dose of standard radiation necessary to produce given effect to dose of test radiation needed for same effect

Answer 11

RBE

Question 12

function of metabolic state of tissue being irradiated

Answer 12

radiosensistivity

Question 13

increase LET what happens

Answer 13

increase probability to produce radiation and probability of interaction with target molecule

Question 14

the dose delivered continuously but at a lower dose rate

Answer 14

protraction

Question 15

the dose is delivered at same dose in equal portion at regular intervals

Answer 15

fractionation

Question 16

what does fractionation reduce

Answer 16

effect of radiation

Question 17

ratio of dose necessary to produce a given effect under anoxic conditions to the dose necessary to produce same effect under aerobic conditions

Answer 17

oxygen enhancement ratio

Question 18

used in radiation oncology

Answer 18

high pressure oxygen

Question 19

low LET = ____ OER

Answer 19

high

Question 20

radiosensitivity and radioresistent of age

Answer 20

before birth & old age: radiosensitive
Maturity: radioresistent
After birth: decrease radiosensitivity

Question 21

intracellular repair + repopulation

Answer 21

recovery

Question 22

occurs when cell dies before replicating

Answer 22

interphase death

Question 23

repair mechanism inherent in biochemistry of cell

Answer 23

intracellular repair

Question 24

high LET = what model

Answer 24

single target, single hit model

Question 25

more damage low repairability

Answer 25

single target single hit model

Question 26

low LET = what model

Answer 26

multi target, single hit model

Question 27

less damage higher repairability

Answer 27

multi target, single hit model

Question 28

what increases radiosensitivity

Answer 28

oxygen

Question 29

2 types of radiation response

Answer 29

deterministic stochastic

Question 30

a late response to radiation and follows a low dose exposure

Answer 30

stochastic

Question 31

examples of stochastic

Answer 31

cancer, leukemia, genetic effects

Question 32

a early response to radiation and follows a high dose exposure

Answer 32

deterministic

Question 33

what are the 2 characteristic of dose response relationship

Answer 33

linear or non linear threshold or non threshold

Question 34

level below a certain dose at which there is no response/ no effects seen

Answer 34

threshold dose

Question 35

linear dose response relation ship intercept dose axis at some value greater than 0

Answer 35

linear threshold type

Question 36

what linear dose response relationship does cancer, leukemia, & genetic effect follow

Answer 36

linear non threshold

Question 37

any dose carries a risk and produces a response

Answer 37

non threshold

Question 38

what happens to tissue / organ when it receives sufficient radiation dose

Answer 38

atrophy

Question 39

linear seen in____ non linear seen in___

Answer 39

stochastic effects deterministic effects

Question 40

examples of radiosensitizers

Answer 40

vitamin k hydroxyurea methotrexate halogenated pyramidines actinomycin d

Question 41

examples of radioprotectors

Answer 41

sulfhydryl group: cystein cysteamine

Question 42

little bit of radiation is good for you as it stimulates hormonal & immune responses to toxic environmental agents

Answer 42

hormesis

Question 43

what is applied despite hormesis

Answer 43

ALARA

Question 44

effect of high dose fluoroscopy

Answer 44

sigmoid dose response

Question 45

a response directly proportional to radiation dose

Answer 45

linear

Question 46

incremental dose at high levels results in less relative damage than some dose at low level dose or vise versa

Answer 46

non linear threshold

Question 47

response increases at doses above threshold dose until inflection point of curve is reached

Answer 47

non linear threshold