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RT 206 > 6.1 Biologic Effects of Radiation > Flashcards

6.1 Biologic Effects of Radiation Flashcards

1
Q

Early radiologists who performed fluoroscopic
examinations without protective gloves developed a
very callused, discolored, and weathered appearance to the skin of their hands and forearms.
In addition, the
skin would be very tight and brittle and sometimes
would severely crack or flake.
This stochastic effect was observed many years ago
in radiologists and is called ______

A

radiodermatitis

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2
Q

The dose necessary to produce stochastic effect is very ____. No
such effects occur in the current practice of radiology

A

high

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3
Q

Irradiation of blood-forming organs can produce ____ as a deterministic response or _____ as a stochastic response

A 
hematologic depression (d),
leukemia (s)
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4
Q

_____ damage in
the circulating lymphocytes can be produced as both a
deterministic and a stochastic response

A

Chromosome

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5
Q

even a ___
dose of radiation can produce chromosome aberrations
that may not be apparent until many years after radiation exposure

A

low

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6
Q

This stochastic effect in chromosomes presumably occurs because of
radiation damage to the _____

A

lymphocytic stem cells

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7
Q

In 1932 _____ of the University of California developed the first cyclotron

A

Ernest O. Lawrence

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8
Q

a 12-cm-diameter
device capable of accelerating charged particles to very high energies. These charged particles are used as “bullets” that are shot at the nuclei of target atoms in the study of nuclear structure

A

cyclotron

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9
Q

By ___, every university

physics department of any worth had built its own cyclotron and was engaged in what has become high-energy physics

A

1940

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10
Q

is used principally to produce
radionuclides for use in nuclear medicine, especially
fluorine-18 for positron emission tomography

A

modern cyclotron

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11
Q

was the first physician to apply radionuclides (from his brother’s cyclotron) on humans

A

John Lawrence

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12
Q

received the 1939 Nobel Prize in Physics

A

Ernest O. Lawrence

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13
Q

is considered the Father of Nuclear Medicine

A

John Lawrence

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14
Q

The largest particle accelerators in the world are located at _____ in the United
States and at CERN in Switzerland. These accelerators
are used to discover the ultimate fine structure of matter
and to describe exactly what happened at the moment
of creation of the universe

A

Argonne National Laboratory

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15
Q

Cyclotron physicists used a tool of the radiologic
technologist, the _____, to aid
them in locating the high-energy beam.
Unfortunately,
in so doing, these physicists received high radiation doses to the lens of the eye because they had to look
directly into the beam

A

radiographic intensifying screen

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16
Q

In ____ the first paper reporting cataracts in cyclotron physicists appeared

A

1949

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17
Q

By ____, several hundred such
cases of radiation-induced cataracts had been reported. This was particularly tragic because there were few
high-energy physicist

A

1960

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18
Q

Radiation-induced cataracts occur on the

_____ pole of the lens

A

posterior

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19
Q

The radiosensitivity of the

lens of the eye is ___ dependent

A

age

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20
Q

As the age of the individual increases, the radiation effect becomes _____ and the latent period becomes _____

A

greater,

shorter

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21
Q

(Cataract) Latent periods ranging from _____ have been observed in humans, and the average latent period is approximately ____

A

5 to 30 years,

15 years

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22
Q

High-LET radiation, such as neutron and proton radiation, has a ____ for the production of cataracts

A

high relative biologic

effectiveness (RBE)

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23
Q

The dose-response relationship for radiation-induced cataracts is ______

A

nonlinear, threshold

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24
Q

If the lens dose is high enough, in excess of approximately _____, cataracts develop in nearly
100% of those who are irradiated

A

10 Gyt (1000 rad)

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25
Q

The precise level of
the threshold dose is difficult to assess.
Most investigators would suggest that the threshold
after an acute x-ray exposure is approximately _____

A

2 Gyt

200 rad

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26
Q

The threshold after fractionated exposure,

such as that received in radiology, is probably in excess of _____

A

10 Gyt (1000 rad)

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27
Q

Occupational exposures to the
lens of the eye are too ____ to require protective lens
shields for radiologic technologists. It is nearly impossible for a medical radiation worker to reach the threshold dose

A

low

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28
Q

Cataracts were first manifested as an effect of radiation by

A

High-energy physicists after receiving high radiation doses to
the lens of the eye

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29
Q

Radiation administered to patients who are undergoing head and neck examination by fluoroscopy or
computed tomography can be significant. In computed
tomography the lens dose can be ____

A

50 mGyt (5 rad)

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30
Q

In either case, protective lens shields are not normally
required. However, in computed tomography, it is common to modify the examination to ____ the dose
to the eyes

A

reduce

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31
Q

the relationship between

life span shortening and dose is apparently ______

A

linear, non-threshold

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32
Q

At worst, humans can expect a reduced life span

of approximately ___ days for every ____

A 
10,
10 mGyt (0.01 Gyt)
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33
Q

Expected Days
of Life Lost
-Being male rather than female

A

2800

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34
Q

Expected Days
of Life Lost
-Heart disease

A

2100

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35
Q

Expected Days
of Life Lost
-Being unmarried

A

2000

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36
Q

Expected Days
of Life Lost
-One pack of cigarettes a day

A

1600

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37
Q

Expected Days
of Life Lost
-Working as a coal miner

A

1100

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38
Q

Expected Days
of Life Lost
-Cancer

A

980

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39
Q

Expected Days
of Life Lost
-30 pounds overweight

A

900

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40
Q

Expected Days
of Life Lost
-Stroke

A

20

41
Q

Expected Days
of Life Lost
-All accidents

A

435

42
Q

Expected Days
of Life Lost
-Service in Vietnam

A

400

43
Q

Expected Days
of Life Lost
-Motor vehicle accidents

A

200

44
Q

Expected Days
of Life Lost
-Average occupational accidents

A

74

45
Q

Expected Days
of Life Lost
-Speed limit increase from 55 to 65 mph

A

40

46
Q

Expected Days
of Life Lost
-Radiation worker

A

12

47
Q

Expected Days
of Life Lost
-Airplane crashes

A

1

48
Q

Radiation-induced life span shortening is ______,
that is, no characteristic diseases are associated with it, and it does not include late malignant effects. It occurs
simply as accelerated premature aging and death

A

nonspecific

49
Q

RSNA

A

Radiological Society of North America

50
Q

ACP

A

American College of Physicians

51
Q

AAOO

A

American Academy of Ophthalmology and Otolaryngology

52
Q

The _____ effects of high-dose radiation exposure are usually easy to observe and measure

A

deterministic

53
Q

_____ are also easy to observe, but it is nearly
impossible to associate a particular late response with a
previous radiation exposure

A

stochastic effects

54
Q

Consequently, precise dose-response relationships

are often not possible to formulate, and we therefore resort to ____

A

risk estimates

55
Q

There are three types of risk estimates

A

relative risk, excess risk, and absolute risk

56
Q

If one observes a large population for stochastic radiation effects without having any precise knowledge of the
radiation dose to which they were exposed

A

Relative risk

57
Q

is computed by comparing the number of persons in the
exposed population showing a given stochastic effect
with the number in an unexposed population who show
the same stochastic effect

A

Relative risk

58
Q

Relative risk =

A

Observed cases/Expected cases

59
Q

A relative risk of ___ indicates no risk at all

A

1.0

60
Q

A relative
risk of ___ indicates that the frequency of a late response
is 50% higher in the irradiated population than in the nonirradiated population

A

1.5

61
Q

The relative risk for

radiation-induced stochastic effects of particular importance observed in human populations is in the range of _____

A

1 to 2

62
Q

Occasionally, an investigation results in the identification of a relative risk of less than 1. This indicates
that the radiation exposed population receives some
protective benefit, which is consistent with the theory of radiation _____

A

hormesis

63
Q

The theory of radiation _______ suggests that

very low radiation doses are beneficial

A

hormesis

64
Q

Radiation hormesis suggests that low levels

of radiation—less than approximately _____—are good for you

A

100 mGyt (10 rad)

65
Q

when an investigation of human radiation
response reveals the induction of some stochastic effect,
the magnitude of the effect is reflected by the excess
number of cases induced

A

Excess Risk

66
Q

the difference between the observed number of cases and the expected number

A

Excess Risk

67
Q

Excess risk =

A

Excess risk = Observed cases - Expected cases

68
Q

If at least two different dose levels are known, then it may be possible to determine

A

Absolute Risk

69
Q

In
contrast to the relative risk, which is a dimensionless
ratio, the ______ consists of units of cases/
population/dose

A

absolute risk

70
Q

is a considerable simplification of the

results of many studies

A

8×10^−2 Sv^−1 / (8×10^−4 rem^−1)

71
Q

The absolute risk of a fatal radiation-induced malignant disease is

A

5×10^−2 Sv^−1 / (5×10^−4 rem^−1)

72
Q

This is the risk coefficient used by
radiation scientists to predict stochastic radiation
response in exposed populations

A

5×10^−2 Sv^−1 / (5×10^−4 rem^−1)

73
Q

To determine the absolute radiation risk, one must

assume a _____ dose-response relationship

A

linear

74
Q

If the dose-response relationship is assumed to be ______,

then only one dose level is required

A

nonthreshold

75
Q

The value of the

absolute radiation risk is equal to the ____ of the dose-response relationship

A

slope

76
Q

The absolute risk of total radiation-induced malignant disease as determined by the National Academy of Science Committee on the Biologic Effects on Ionizing Radiation (BEIR)

A

8×10^−2 Sv^−1 (8/10,000/10 mSv)

77
Q

The absolute risk of fatal radiation-induced malignant disease as determined by the National Academy of Science Committee on the Biologic Effects on Ionizing Radiation (BEIR)

A

5×10^−2 Sv^−1 (5/10,000/10 mSv)

78
Q

Leukemia dose-response relationship is _____

A

linear and nonthreshold

79
Q

A number of human
population groups have exhibited an elevated incidence
of leukemia after radiation exposure:

A
  • atomic bomb survivors (Hiroshima and Nagasaki),
  • (American) radiologists,
  • radiotherapy patients,
  • children irradiated in utero
80
Q

Probably the greatest wealth of information that we have accumulated regarding radiation-induced leukemia in humans has been drawn from observations of
survivors of the atomic bombings of _____

A

Hiroshima and Nagasaki

81
Q

At the time of the bombings, approximately
_____ people lived in those two cities.
Nearly _____ were killed from the blast and from deterministic effects of radiation. Another _____ people received significant doses of radiation and survived

A

300,000,
100,000,
100,000

82
Q

The remainder were unaffected of the bombing because their

radiation dose was less than _____

A

100 mGyt (10 rad)

83
Q

After World War II, scientists of the ______, attempted
to determine the radiation dose received by each of the
atomic bomb survivors in both cities

A

Atomic Bomb Casualty Commission (ABCC), now known as the Radiation Effects Research Foundation (RERF)

84
Q

They estimated
the dose to each survivor by considering not only distance from the explosion but also terrain, type of bomb,
type of building construction if the survivor was inside,
and other factors that might influence radiation dose

A

Atomic Bomb Casualty Commission (ABCC), now known as the Radiation Effects Research Foundation (RERF)

85
Q

ABCC

A

Atomic Bomb Casualty Commission

86
Q

RERF

A

Radiation Effects Research Foundation (RERF)

87
Q

A rather rapid rise in leukemia incidence reached a

plateau after approximately _____

A

5 years

88
Q

The incidence declined
slowly for approximately ____ years, when it reached
the natural level experienced by the nonexposed

A

20

89
Q

Radiation-induced leukemia is considered to have a latent period of ____ years and an at-risk
period of approximately ___ years

A

4 to 7,

20

90
Q

is that time after irradiation during

which one might expect the radiation effect to occur

A

at-risk period

91
Q

The at-risk period for radiation-induced cancer is

A

lifetime

92
Q

Of the 300,000 total residents, ___ persons are estimated to have survived doses in excess of ____

A 
335,
6 Gy (600 rad)
93
Q

were observed most often

among atomic bomb survivors

A

Acute leukemia,

chronic myelocytic leukemia

94
Q

is rare and therefore
is not considered to be a form of radiation-induced
leukemia

A

Chronic lymphocytic leukemia

95
Q

By the second decade of radiology, reports of pernicious anemia and leukemia in _____ began to
appear

A

radiologists

96
Q

It has been estimated that some of these early radiologists received doses exceeding ______

A

1 Gyt/yr (100 rad/yr)

97
Q

is an arthritis-like condition of the vertebral column

A

Ankylosing spondylitis

98
Q

Other population groups that have provided evidence, both positive and negative, regarding the leukemia-inducing action of radiation include

A

-radium watch-dial painters,
-children receiving superficial x-ray
treatment,
-some additional adult radiation therapy groups

RT 206 (9 decks)

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