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000 Radiobiology > Ch 34 Stochastic Effects > Flashcards

Ch 34 Stochastic Effects Flashcards

1
Q

What are Stochastic effects?

A

Late Effects

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2
Q

Stochastic effects follow a…

A

Linear, non-threshold dose response relationship

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3
Q

What are principle stochastic effects?

A
  • Radiation induced malignancy

- Genetic effects

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4
Q

What type of effects are the result of low doses of radiation over a long period of time

A

Stochastic Effects

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5
Q

What are Local tissue Stochastic effects?

A
  • Erythema (sunburning)
  • Desquamation
  • Late developing carcinoma
  • Radiodermatitis
    • Calluses
    • Discoloration
    • Tight, Brittle skin
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6
Q

What are local tissue effects of Chromosomes?

A
  • Leukemia
  • Chromosome damage to circulating lymphocytes
  • Chromosome aberration that may not be apparent for years
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7
Q

What are cataracts?

A

Caused by high radiation to the lens of the eye

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8
Q

Test

Where do radiation induced cataracts occur?

A

Posterior pole of the lens

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9
Q

Who were the first people to have their lens affected by radiation?

A

Cyclotron physicists (1949)

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10
Q

By 1960 hundreds of cases of radiation induced ______ were reported.

A

Cataracts

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11
Q

Radiosensitivity of the eye is _____ ______

A

Age dependent

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12
Q

Radiation effect increases as…

A

Age increases

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13
Q

What is the latent period for radiation causing cataracts?

A
  • 5-30 years

- Average is 15 years

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14
Q

Radiation induced cataracts follow a…

A

Non linear, threshold dose response relationship

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15
Q

During occupational exposure, are protective shields required for protection of the lens?

A

No, it is too low

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16
Q

What is the threshold dose before causing cataracts?

A

200 rad (2 Gy t)

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17
Q

At what dose do nearly 100% of irradiated subjects get cataracts?

A

Greater than 1,000 rad (Gy t)

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18
Q

At worst, humans can expect a reduced life span of ____ days for every rad (mGy t)

A

10

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19
Q

What causes radiation induced life span shortening?

A

Accelerated premature aging and death

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20
Q

What are some risky conditions that shorten life span?

A
  • Being male (2,800)
  • Heart disease (2,100)
  • Smoker (1,600)
  • Cancer (980)
  • MVA (200)
  • Occupational accidents (74)
  • Rad worker (12)
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21
Q

What are the (3) ways to calculate risk?

A
  1. Relative
  2. Excess
  3. Absolute
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22
Q

What is Relative Risk?

A

Estimation of late radiation effects in large populations without knowing radiation dose

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23
Q

What is Radiation Hormesis?

A

Low radiation doses can be beneficial (less than 10 rad)

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24
Q

Relative risk =

A

Observed Cases
______________
Expected Cases

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25
Q

What is Excess Risk?

A

Difference between observed and expected number of cases

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26
Q

Excess risk =

A

Observed cases - Expected cases

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27
Q

What is Absolute Risk?

A
  • At least two different dose levels are known
  • Other data, such as # of cases, dose etc are known
  • Predicts stochastic radiation response in exposed population
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28
Q

What is the ideal risk?

A

Absolute Risk

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29
Q

Radiation induced Leukemia follows a…

A

Linear, non threshold dose response relationship

30
Q

What is the latent period of Radiation induced Leukemia?

A

4-7 years

31
Q

After being exposed to radiation how long are you at risk for acquiring Leukemia?

A

20 years

32
Q

Who provided the greatest amount of information about radiation induced leukemia in humans?

A

Atomic bomb survivors

33
Q

Do radiologists have an elevated risk of Leukemia?

A

No

34
Q

Patients started to develop Leukemia after being treated with radiation for what?

A

Ankylosing Spondylitis

35
Q

Can radiation cause cancer?

A

Without question

36
Q

What are types of cancer associated with radiation:

A
  • Thyroid cancer
  • Bone cancer
  • Skin cancer
  • Breast cancer
  • Lung Cancer
  • Liver cancer
37
Q

What is the risk of death from radiation induced malignancy

A

5/100 or 0.05%

38
Q

What is the at risk period after exposure to radiation?

A

20-25 years

39
Q

Overall absolute risk for induction of malignancy is approximately…

A

8 caser per 100 Sv

40
Q

What are the concerns of radiation effects before pregnancy?

A

Interrupted Fertility

41
Q

What are the concerns of radiation effects during pregnancy?

A

Congenital effects on newborns

42
Q

What are the concerns of radiation effects after pregnancy?

A

Suspected genetic effects

43
Q

During pregnancy, what is the most radiosensitive period?

A

1st trimester

44
Q

Low dose chronic irradiation does not impair fertility? T/F

A

True

45
Q

The effects of irradiation in utero are time and dose related? T/F

A

True

46
Q

What are the possible effects of irradiation in utero?

A
  • Prenatal death
  • Neonatal death
  • Congenital abnormalities
  • Malignancy induction
  • Growth impairment
  • Genetic effects
  • Mental retardation
47
Q

Out of all the possible effects of irradiation in utero, which one stays constant?

A

Leukemia

48
Q

Within (2) weeks of fertilization, what can high radiation doses cause?

A

Spontaneous abortion (miscarriage

49
Q

What dose level can cause a 0.1% spontaneous abortion rate?

A

10 rad dose

50
Q

What is the normal chance of spontaneous abortion without radiation?

A

25-50%

51
Q

What period of time is of least concern because the response is all or none?

A

The first 2 weeks

52
Q

What weeks of pregnancy is the period of major organogenesis?

A

Weeks 2-12

53
Q

What two effects during pregnancy can occur as a result of radiation exposure?

A
  1. Skeletal and organ abnormalities

2. Congenital abnormalities of the CNS

54
Q

An Oxford survey (1946) found that childhood malignancy is associated with…

A

Irradiation in utero

55
Q

The relative risk of childhood leukemia after irradiation in utero is…

A

1.5, which is a 50% increase

56
Q

What does radiation exposure in utero do?

A

Retards the growth and development of the newborn

57
Q

How often does a 10 rad dose occur in radiology?

A

Very rarely

58
Q

Radiation exposure in utero can result in what?

A

Microcephaly (small head) and mental retardation

59
Q

What was Muller’s study on genetic effects about?

A

Fruit flies were irradiated to determine if radiation altered mutations

60
Q

What did Muller’s study conclude?

A

That radiation does not alter the quality of the emulations, but did increase the frequency of the mutations

61
Q

Muller’s study concluded that…

A

Irradiation did not alter quantity, but frequency

62
Q

What was Russell’s study?

A

He irradiated a large mouse colony with different doses of radiation

63
Q

What did Russell’s study show?

A
  • A dose rate effect does exist

- Confirmed the linear, non threshold dose response relationship

64
Q

What is doubling dose?

A

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

65
Q

What is the doubling dose in humans?

A

50-250 rad (0.5-2.5 Gy t)

66
Q

If 7% of the offspring in each generation are born with mutation, the doubling dose eventually increases the number of mutations to how many?

A

14%

67
Q

Are radiation doses used occupationally or medically, responsible for any effects on fetal growth or development?

A

No

68
Q

Congenital abnormalities mentioned in this chapter are based on…

A

Doses greater than 100 rad

69
Q

What does a high dose of radiation over a short period of time result in?

A

Early effects

70
Q

What are radiation protection guidelines based on?

A

Stochastic effects

000 Radiobiology (52 decks)

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