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Radiation protection > chapter 9 EXAM 4 > Flashcards

chapter 9 EXAM 4 Flashcards

1
Q

late effects

A

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

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2
Q

epidemiology definition

A

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

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3
Q

dose response curves establish relationships between

A

radiation and dose response

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4
Q

radiation dose response relationship

A

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

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5
Q

horizontal axis of dose response curve =

A

dose received

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6
Q

vertical axis of dose response curve =

A

biologic effects observed

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7
Q

the curve on the dose response curve can be either

A

linear or non linear

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8
Q

the curve on a dose response curve can depict

A

threshold dose or non threshold dose

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9
Q

threshold relationship

A

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

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10
Q

nonthreshold relationship

A

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

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11
Q

what is the BEIR committee

A

committee on the Biologic Effects of Ionizing Radiation (BEIR)

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12
Q

the BEIR committee report of 1980 stated

A

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

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13
Q

the BEIR committee report of 1990 stated

A

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

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14
Q

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

A

the linear nonthreshold curve

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15
Q

linear nonthreshold curve (LNT) implies

A

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

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16
Q

The LNT curve accurately reflects the effects of

A

high LET radiation at higher doses

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17
Q

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

A

linear threshold curve

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18
Q

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

A

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

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19
Q

somatic effects

A

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

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20
Q

non somatic effects

A

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

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21
Q

somatic effects may be subdivided into

A
  1. stochastic effects

2. deterministic effects (nonstochastic effects)

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22
Q

stochastic effects

A

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

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23
Q

deterministic (nonstochastic) effects

A

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

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24
Q

late somatic effects

A

consequences of radiation exposure that appear months or years after exposure

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25
Q

late deterministic somatic effects are directly related to

A

the dose received

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26
Q

late stochastic effects

A

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

27
Q

low level radiation is defined as

A

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

28
Q

a typical routine chest xray is about what dose

A

0.06 Sv (6mrem)

29
Q

3 major types of late effects

A
  1. carcinogenesis
  2. cataractogenesis
  3. embryonologic effects
30
Q

absolute risk model predicts

A

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

31
Q

relative risk model predicts

A

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

32
Q

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

A

cancer

33
Q

radium watch-dial painters

A 
1920-1930 pointed their radium containing brush tips with their lips and spit 
this caused 
osteoporosis 
osteogenic carcinoma
other malignancies
34
Q

uranium miners

A

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

35
Q

early medical radiation workers

A

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

36
Q

pts. injected with contrast agent thorotrast

A 
1925-1945
radioactive material emitted alpha particles and were deposited in pts. 
causing liver and spleen cancer 
angiosarcoma
biliary duct carcinomas
37
Q

infants treated for enlarged thymus gland

A

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

38
Q

children of the marshall islanders

A

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

39
Q

ethos projects

A

research project in aftermath of chernobyl

40
Q

nonspecific life span shortening

A

the reduction in life cycle due to radiation

41
Q

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

A

high

42
Q

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

A

a neutron dose of 0.01 (1 rad)

43
Q

radiation induced cataracts in humans follow a

A

threshold nonlinear dose response relationship

44
Q

3 stages of gestation in humans

A
  1. preimplantation
  2. organogenesis
  3. fetal stage
45
Q

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

A

death or causes congenital abnormalities

46
Q

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

A

prenatal death and usually results in spontaneous abortion

if this does not happen pregnancy will continue with no adverse effect

47
Q

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

A

in a dose of 0.05-0.15 Gyt

embryonic death will occur

48
Q

during oganogenesis if you are irradiated,

A

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

49
Q

if radiation occurs during late stages of organogensis,

A

the presence of abnormalities in the fetus will cause neonatal death

50
Q

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

A

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

51
Q

international chernobyl project

A

study compared seven contaminated russian villages with 6 uncontaminated villages

52
Q

spontaneous mutations

A

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

53
Q

mutagens

A

agents that increase the frequency of occurrence of mutations

54
Q

agents of mutagens include

A

elevated temps.
ionizing radiation
viruses
absorption of certain chemicals

55
Q

what is one of the more effective mutagen

A

ionizing radiation

56
Q

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

A

various genetic diseases

57
Q

point mutations

A

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

58
Q

dominant point mutations

A

expressed in offspring

59
Q

recessive point mutations

A

not expressed for several generations

60
Q

radiation is thought to cause what mutations

A

primarily recessive mutations

61
Q

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

A

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

62
Q

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

A

allergies
slight alteration in metabolism
decreased intelligence
predisposition to certain diseases

63
Q

doubling dose is

A

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

64
Q

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

A

1.56 Sv (156 rem)

Radiation protection (12 decks)

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