chapter 9 EXAM 4

Question 1

late effects

Answer 1

radiation induced damage at the cellular level that may lead to somatic and genetic damage in the living organism later in life

Question 2

epidemiology definition

Answer 2

science that deals with the incidence, distribution, and control of disease in a population

Question 3

dose response curves establish relationships between

Answer 3

radiation and dose response

Question 4

radiation dose response relationship

Answer 4

graph that maps out the effects of radiation observed in relation to the dose of radiation received

Question 5

horizontal axis of dose response curve =

Answer 5

dose received

Question 6

vertical axis of dose response curve =

Answer 6

biologic effects observed

Question 7

the curve on the dose response curve can be either

Answer 7

linear or non linear

Question 8

the curve on a dose response curve can depict

Answer 8

threshold dose or non threshold dose

Question 9

threshold relationship

Answer 9

a point at which a response or reaction to an increasing stimulation occurs
below a certain radiation level or dose, no biologic effects are observed

Question 10

nonthreshold relationship

Answer 10

means that any radiation dose will produce a biologic effect
no dose is believed to be “safe”

Question 11

what is the BEIR committee

Answer 11

committee on the Biologic Effects of Ionizing Radiation (BEIR)

Question 12

the BEIR committee report of 1980 stated

Answer 12

the majority of stochastic somatic effects at low dose levels appear to follow a linear quadratic nonthreshold curve (LQNT)

Question 13

the BEIR committee report of 1990 stated

Answer 13

the risk of radiation exposure was about 3-4 times greater than previously projected

Question 14

currently BEIR committee recommends the use of what for most types of cancer

Answer 14

the linear nonthreshold curve

Question 15

linear nonthreshold curve (LNT) implies

Answer 15

that the chance of a biologic response to ionizing radiation is directly proportional to the dose received

Question 16

The LNT curve accurately reflects the effects of

Answer 16

high LET radiation at higher doses

Question 17

deterministic (nonstochastic) effects of significant radiation may be demonstrated graphically through the use of a

Answer 17

linear threshold curve

Question 18

the sigmoid or s-shaped (nonlinear) threshold curve is generally used in

Answer 18

radiation therapy to demonstrate high dose cellular response to radiation within specific tissues

Question 19

somatic effects

Answer 19

biologic effects that occur in the living organism that have been exposed to radiation

Question 20

non somatic effects

Answer 20

irradiation of an individuals genetic material leading to genetic malformation
called genetic/heritable effects

Question 21

somatic effects may be subdivided into

Answer 21

1. stochastic effects

2. deterministic effects (nonstochastic effects)

Question 22

stochastic effects

Answer 22

non threshold
mutational or randomly occurring biologic changes independent of dose
ex: cancer

Question 23

deterministic (nonstochastic) effects

Answer 23

effects directly related to the dose received
cell killing effects that exhibit a threshold dose
ex: cataracts

Question 24

late somatic effects

Answer 24

consequences of radiation exposure that appear months or years after exposure

Question 25

late deterministic somatic effects are directly related to

Answer 25

the dose received

Question 26

late stochastic effects

Answer 26

do not have a threshold and occur in random and have a severity that is not dose dependent

Question 27

low level radiation is defined as

Answer 27

an absorbed dose of 0.1 Sv (10rem) or less delivered over a short period of time

Question 28

a typical routine chest xray is about what dose

Answer 28

0.06 Sv (6mrem)

Question 29

3 major types of late effects

Answer 29

1. carcinogenesis 2. cataractogenesis 3. embryonologic effects

Question 30

absolute risk model predicts

Answer 30

that a specific number of excess cancers will occur as a result of exposure

Question 31

relative risk model predicts

Answer 31

that the number of excess cancers will increase as the natural incidence of cancer increases with advancing age predicts a percentage increase rather than a specific number of cases

Question 32

what is the most important late stochastic somatic effect caused by exposure to ionizing radiation

Answer 32

cancer

Question 33

radium watch-dial painters

Answer 33

``` 1920-1930 pointed their radium containing brush tips with their lips and spit this caused osteoporosis osteogenic carcinoma other malignancies ```

Question 34

uranium miners

Answer 34

they mined uranium and sustained lethal doses of radiation caused by breathing dust and drinking radioactive water died from cancer and respiratory diseases

Question 35

early medical radiation workers

Answer 35

exposed to large amounts of radiation developed cancerous skin lesions higher incidence of aplastic anemia and lukemia

Question 36

pts. injected with contrast agent thorotrast

Answer 36

``` 1925-1945 radioactive material emitted alpha particles and were deposited in pts. causing liver and spleen cancer angiosarcoma biliary duct carcinomas ```

Question 37

infants treated for enlarged thymus gland

Answer 37

1940-50s infants were treated with therapeutic doses to reduce size of thymus gland resulted in development 20 yrs later of thyroid nodules and carcinoma

Question 38

children of the marshall islanders

Answer 38

children on neighboring islands received substantial absorbed doses to thyroid from external and internal exposures

Question 39

ethos projects

Answer 39

research project in aftermath of chernobyl

Question 40

nonspecific life span shortening

Answer 40

the reduction in life cycle due to radiation

Question 41

the probability that a single dose of radiation about 2 Gy (200rad) will induce formation of cataracts is

Answer 41

high

Question 42

neutron dose of what has been known to cause cataracts in mice

Answer 42

a neutron dose of 0.01 (1 rad)

Question 43

radiation induced cataracts in humans follow a

Answer 43

threshold nonlinear dose response relationship

Question 44

3 stages of gestation in humans

Answer 44

1. preimplantation 2. organogenesis 3. fetal stage

Question 45

irradiation of embryo dureing the first 12 weeks of development to EqD in excess of 200 mSV (200rem) frequently results in

Answer 45

death or causes congenital abnormalities

Question 46

when a high dose of radiation is received witihin aprox. 2 weeks of fertilization, what happens

Answer 46

prenatal death and usually results in spontaneous abortion | if this does not happen pregnancy will continue with no adverse effect

Question 47

if during the preimplantation stage you are irradiated with a dose in the range of what, what will occur

Answer 47

in a dose of 0.05-0.15 Gyt | embryonic death will occur

Question 48

during oganogenesis if you are irradiated,

Answer 48

fetus is more susceptible to abnormalities such as growth inhibition, mental retardation, microcephaly, genital deformities etc.

Question 49

if radiation occurs during late stages of organogensis,

Answer 49

the presence of abnormalities in the fetus will cause neonatal death

Question 50

the United Nations Scientific Committee on Effects of Atomic Radiation proposed an upper limit combined radiation risk for these fetal effects to be

Answer 50

3 chances per 1000 children for reach rem of fetal dose (0.3%)

Question 51

international chernobyl project

Answer 51

study compared seven contaminated russian villages with 6 uncontaminated villages

Question 52

spontaneous mutations

Answer 52

a natural phenomenon involving alterations in genes and DNA occur at random and without a known cause are permanent and heritable and can be transmitted from 1 generation to the next cause a wide variety of disorders/diseases

Question 53

mutagens

Answer 53

agents that increase the frequency of occurrence of mutations

Question 54

agents of mutagens include

Answer 54

elevated temps. ionizing radiation viruses absorption of certain chemicals

Question 55

what is one of the more effective mutagen

Answer 55

ionizing radiation

Question 56

because mutant genes cannot properly run cell's normal chemical reactions, it results in

Answer 56

various genetic diseases

Question 57

point mutations

Answer 57

genetic mutations in which the chomosome is not broken but the DNA within it is damaged may be either dominant or recessive

Question 58

dominant point mutations

Answer 58

expressed in offspring

Question 59

recessive point mutations

Answer 59

not expressed for several generations

Question 60

radiation is thought to cause what mutations

Answer 60

primarily recessive mutations

Question 61

in order for recessive mutation to appear in offspring, both parents must have

Answer 61

have the same genetic defect, therefore it is not likely to appear in a population

Question 62

damage from recessive mutations may sometimes manifest itself more subtly and may appear as

Answer 62

allergies slight alteration in metabolism decreased intelligence predisposition to certain diseases

Question 63

doubling dose is

Answer 63

the radiation dose that causes the number of spontaneous mutations occurring in a given generation to increase to two times their original number

Question 64

for humans the doubling dose is estimated to have a mean value of

Answer 64

1.56 Sv (156 rem)