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Radiobiology > Stochastic Effects > Flashcards

Stochastic Effects Flashcards

1
Q

Results of low doses delivered over long period

A

Stochastic Effects

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2
Q

Experienced low dose and low linear energy transfer

A

Radiation workers

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3
Q

Delivered intermittently over long periods

A

Patient radiation doses

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4
Q

Principal stochastic effects consists of

A

Radiation induced malignancy

Genetic Effects

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5
Q

Reports of local tissue effects and life-span shortening

A

Not Significant

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6
Q

Stochastic effects are assumed as a

A

linear non-threshold dose-response relationship

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7
Q

Radiation exposure in diagnostic radiology are _____ because they are delivered over ______

A

Chronic

Long periods

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8
Q

Stochastic effects exhibit an increasing incidence of response with

A

increasing dose

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9
Q

Stochastic dose-response relationship is _____

A

linear

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10
Q

Chronic irradiation of the skin can result in

A

severe nonmalignant changes

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11
Q

Observed among radiologist who performed fluoroscopic examination without protective gloves

A

Radiodermatitis

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12
Q

Characterized by callused, discolored, and weathered appearance to the skin

A

Radiodermatitis

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13
Q

Can be produced as both deterministic and a stochastic response

A

Chromosome damage in circulating lymphocytes

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14
Q

Physicist developed radiation induced cataracts due to

A

very high radiation doses to the lens of the eye

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15
Q

Radiation induced cataracts occurs on the

A

posterior pole of the lens

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16
Q

Radiosensitivity of the lens of the eye is

A

age dependent

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17
Q

As the age of the individual increases,

A

Radiation effects become greater

Latent period becomes shorter

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18
Q

Latent Period of cataracts

A

5 to 30 years;

Average of 15 years

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19
Q

Dose-response relationship for radiation induced cataracts

A

Nonlinear, threshold

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20
Q

Relationship between life span shortening and dose appears

A

linear, nonthreshold

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21
Q

Humans expect reduced life span of

A

approx. 10 days for every 10mGyt

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22
Q

Radiation induced life span shortening is

A

nonspecific

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23
Q

Life span shortening occurs simply as

A

accelerated premature aging

death

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24
Q

Precise dose-response relationships are often not possible to formulate and resort to

A

Risk estimates

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25
Q

Computed by comparing the number of persons in the exposed population showing a given stochastic effects with the unexposed population who show same stochastic effects

A

Relative Risk

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26
Q

Formula for relative risk

A

Relative Risk = Observed cases/Expected cases

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27
Q

Relative risk of 1

A

no risk at all

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28
Q

Relative risk of 1.5

A

frequency of the late response is 50% higher in the irradiated population

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29
Q

Relative risk for stochastic effects ranges to

A

1 to 2

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30
Q

Relative risk less than 1

A

“very low radiation doses are beneficial” ; theory of hormesis

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31
Q

Low doses of radiation approx. 100mGyt, may provide

A

Stimulating molecular repair

Immunologic response mechanism

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32
Q

Used when an investigation of human radiation response reveals the induction of some stochastic effects

A

Excess risk

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33
Q

Known to occur spontaneously in nonirradiated population

A

Leukemia

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34
Q

Formula for excess risk

A

excess risk= observed - expected cases

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35
Q

used if atleast two different dose levels are known

A

Absolute risk

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36
Q

Absolute risk consists of units of

A

cases/population/dose

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37
Q

Absolute risk of a fatal radiation induced malignant disease

A

5 x 10^-2 Sv^-1

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38
Q

The incidence of radiation-induced leukemia

A

increases with increasing radiation dose

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39
Q

The form of the dose-response relationship of leukemia is

A

linear and nonthreshold

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40
Q

Atomic Bomb Casualty Commission (ABCC) now known as

A

Radiation Effects Research Foundation (RERF)

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41
Q

Radiation induced leukemia is considered to have a

A

latent period of 4 to 7 years

at-risk period of approx. 20 years

42
Q

the time after irradiation during which one might expect the radiation effect to occur

A

at-risk period

43
Q

At-risk period of radiation induced cancer

A

Lifetime

44
Q

Observed most often among atomic bomb survivors

A

Acute leukemia

Chronic myelocytic leukemia

45
Q

Not considered to be a form of radiation -induced leukemia

A

Chronic lymphocytic leukemia

46
Q

Overall relative risk of leukemia is

A

approx. 3:1

47
Q

a deficiency in the production of red blood cells through lack of vitamin B12

A

Pernicious anemia

48
Q

Some of the early radiologist received doses exceeding

A

1 Gyt/yr (100 rad/yr)

49
Q

Arthritis like condition of the vertebral column

A

Ankylosing Spondylitis

50
Q

Records show that the dose to the bone marrow of the spinal cord ranged from

A

1 to 40 Gy (100 to 400 rad)

51
Q

Relative risk (patient w/ ankylosing spondylitis) is

A

10:1

52
Q

Ionizing radiation can cause

A

cancer

53
Q

First two groups irradiated in thyroid gland during childhood

A

Ann Arbor series

Rochester series

54
Q

Dose used in order to shrink an enlarged thyroid

A

5 Gyt (500rad)

55
Q

Subjected to high levels of radioactive fallout during hydrogen bomb test

A

21 children in Rongelap Atoll (1954)

56
Q

Radiation dose received by the children from both external exposure and internal ingestion

A

approx 12Gyt (1200rad)

57
Q

Two population groups have contributed an quantity of data that radiation can cause bone cancer

A

Radium watch-dial painters

Patients treated with radium salts for arthritis to tuberculosis

58
Q

This would continuously excite the luminous compounds so the watch dial would glow in the dark

A

Radium salts (alpha and beta particles)

59
Q

Radium’s half life

A

1620 years

60
Q

Doses received by the dial painters

A

500 Gyt (50,000 rad)

61
Q

Overall relative risk for the radium watch-dial painters

A

122:1

62
Q

Radiation-induced skin cancer follows a

A

threshold dose-response relationship

63
Q

Latent period (skin cancer)

A

approx 5 to 10 years

64
Q

At dose delivered to the skin i n the range of 5 to 20 Gyt, relative risk is

A

4:1

65
Q

if the dose was 40 to 60 Gy

or 60 Gy to 100 Gy, relative risk was

A

14: 1
27: 1

66
Q

Relative risk for radiation-induced breast cancer is

A

10:1

67
Q

Radiation-induced breast cancer developed in patients treated for

A

acute postpartum mastitis

68
Q

Dose to the patients ranged from

A

0.75 to 10 Gyt

69
Q

Relative risk factor in this population

A

approx 3:1

70
Q

Radiation induced breast cancer has been observed among

A

atomic bomb survivors

71
Q

Approx 50% of workers died of lung cancer in

A

Bohemian pitchblende mines of Germany

72
Q

Cause of death for the bohemian pitchblende workers

A

radiation exposure from radon in the mines

73
Q

Decay product of uranium

A

radon (222Rn)

74
Q

Dose to lung tissue as high as 30Gy (3000 rad), relative risk is

A

8:1

75
Q

Smoking uranium miners have a relative risk of

A

approx. 20:1

76
Q

Thorium dioxide (ThO2) in a colloidal suspension known as

A

Thorotrast

77
Q

Thorotrast is responsible for several types of carcinoma after a latent period of

A

approx. 15 to 20 years

78
Q

Overall absolute risk for induction of malignancy is

A

approx 8 cases/100 Sv

at-risk period for 20 to 25 years

79
Q

Risk of death from radiation-induced malignant disease

A

5/100

80
Q

Three Mile Island incidemt result to

A

no more than two additional malignant deaths

81
Q

Areas of concern

Before pregnancy:

A

Interrupted fertility

82
Q

Areas of concern

During pregnancy:

A

Possible congenital effects in newborns

83
Q

Areas of concern

Postpregnancy:

A

Suspected genetic effects

84
Q

Low dose chronic irradiation

A

Does not impair fertility

85
Q

Two types of radiation exposures

A

Radiation worker

Patient

86
Q

Rapidly developing cell system, particularly sensitive to radiation

A

Embryo

87
Q

Most radiosensitive period during pregnancy

A

First trimester

88
Q

If radiation-induced congenital abnormalities are severe enough results will be

A

Neonatal death

89
Q

a dose of 2 Gyt (200rad) to the mouse

A

100% of fetuses suffered significant abnormalities

90
Q

Relative risk of childhood leukemia after irradiation in utero is

A

1.5

91
Q

Unexpected finding in the offspring of atomic bomb survivors

A

Mental retardation

92
Q

Irradiation in utero has been associated with

A

Microcephaly (small head)

Mental retardation

93
Q

Weakest area of knowledge in radiation biology is the area of

A

Radiation genetics

94
Q

Nobel prize-winning geneticist H.J Muller from University of Texas reported the results of

A

Irradiation of Drosophilia

95
Q

Dose-response relationship for radiation-induced genetic damage

A

Linear non threshold

96
Q

Muller’s concluded that mutations were

A

Single-hit phenomena (no fractionation effects)

97
Q

All radiation protection guides have assumed a

A

Linear, nonthreshold dose response relationship

98
Q

A large mouse colony which was exposed to radiation dose rates from 0.001 to 0.90 rad per minute and total doses of 1000rad (10 Gy)

A

Megamouse Project

99
Q

Dose of radiation that produces twice the frequency of genetic mutations as would have been observed without the radiation

A

Doubling Dose

100
Q

Mutation rate depends upon the rate at which the dose is given

A

Dose-rate effect

Radiobiology (10 decks)

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