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C1 > LATE EFFECTS OF RADIATION AND HEALTH PHYSICS > Flashcards

LATE EFFECTS OF RADIATION AND HEALTH PHYSICS Flashcards

1
Q

What is health physics concerned with?

A

Providing occupational radiation protection and minimizing radiation dose to the public.

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2
Q

A radiation scientist focused on research, teaching, or operational aspects of radiation safety.

A

health physicist

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3
Q

What is the rationale behind practicing ALARA?

A

The linear nonthreshold radiation dose-relationship (LNT) for stochastic effects

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4
Q

What are examples of stochastic effects?

A

Cancer, leukemia, and genetic effects.

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5
Q

How should time be managed to minimize radiation exposure?

A

Keep the exposure time as short as possible.

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6
Q

What is the effect of minimizing time in radiography?

A

Reduces motion blur.

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7
Q

How is radiation dose related to exposure duration?

A

It is directly related.

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8
Q

Sequences on-off to reduce exposure rather than continuous use.

A

fluoroscopic footswitch

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9
Q

Reminds the radiologist of the elapsed fluoroscopic time.

A

5-minute reset timer

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10
Q

How long do most fluoroscopic procedures take?

A

Less than 5 minutes.

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11
Q

How does distance affect radiation dose?

A

Radiation dose is inversely related to the distance from the source.

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12
Q

What law applies to distance and radiation intensity?

A

The inverse square law.

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13
Q

What is an x-ray tube target considered as?

A

A point source of radiation.

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14
Q

Lines representing positions of equal radiation exposure

A

isoexposure lines

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15
Q

How much is the exposure rate at a normal position in a fluoroscopy room?

A

300 mR/hr or 3 mGya/hr.

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16
Q

How does moving two steps back affect the exposure rate in fluoroscopy?

A

Reduces it to 5 mR/hr.

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17
Q

What is assumed about occupational effective dose?

A

It is assumed to be 10% of the monitor dose.

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18
Q

How does a protective apron reduce occupational exposure?

A

0.5 mm Pb apron reduces exposure to 25%.

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19
Q

The thickness of absorber needed to reduce radiation intensity by half.

A

half-value layer (HVL).

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20
Q

The thickness of absorber needed to reduce radiation intensity to one-tenth.

A

tenth-value layer (TVL).

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21
Q

What is the effective dose in radiation terms?

A

The equivalent whole-body dose.

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22
Q

What is the tissue dose for a CT of the abdomen and pelvis?

A

2000 mrad.

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23
Q

What is the effective dose for a PA chest radiograph?

A

1.35 mrad.

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24
Q

What is the weighting factor for gonads?

A

0.20.

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25
Q

What is the weighting factor for active bone marrow?

A

0.12.

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26
Q

What is the weighting factor for the colon?

A

0.12.

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27
Q

What is the weighting factor for the liver?

A

0.05.

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28
Q

A sealed radioactive source that directly exposes people.

A

Radiation Exposure Device (RED)

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29
Q

What is not required for a RED?

A

Decontamination, as it does not disperse radioactive material.

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30
Q

A bomb that disperses radioactive contamination over a wide area.

A

Radiologic Dispersal Device (RDD)

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31
Q

A device containing nuclear material capable of a nuclear explosion.

A

Improvised Nuclear Device (IND)

32
Q

At what exposure rate is the inner boundary established in a radiologic event?

A

10 R/hr.

33
Q

How should radiation detection equipment alarms function?

A

Emit alarms at 10 mR/hr, 10 R/hr, and 50 R/hr.

34
Q

What is the main basis for radiation protection guides?

A

Late effects of radiation and linear, nonthreshold dose-response relationships.

35
Q

What are late effects of radiation also known as?

A

Stochastic effects.

36
Q

What are principal late effects of radiation exposure?

A

Radiation-induced malignancy and genetic effects.

37
Q

What does the stochastic radiation response indicate?

A

The probability of a biologic response as a function of dose, with no threshold.

38
Q

What type of exposure do radiology personnel typically experience?

A

Low dose, low LET, and chronic exposure.

39
Q

What can high-LET radiation, like neutron and proton radiation, cause?

A

High RBE for the production of cataracts.

40
Q

What device did E.O. Lawrence develop in 1932?

A

The first cyclotron.

41
Q

What is the threshold dose for cataract formation from acute x-ray exposure?

A

200 rad.

42
Q

What is the life span shortening expectation for radiation workers?

A

About 12 days of life lost.

43
Q

What type of leukemia is rare and not linked to radiation exposure?

A

Chronic lymphocytic leukemia

44
Q

What is the at-risk period for radiation-induced leukemia?

A

20 years after exposure.

45
Q

What type of cancer did watch dial painters develop?

A

Bone cancer due to radium ingestion.

46
Q

How does radium behave in the body?

A

It acts like calcium and deposits in bones.

47
Q

What is the half-life of uranium in the context of lung cancer risk?

A

10⁹ years.

48
Q

What type of cancer is caused by Thorotrast exposure?

A

Liver cancer.

49
Q

What is the main pregnancy concern before conception?

A

Interrupted fertility.

50
Q

What is the main pregnancy concern during gestation?

A

Potential congenital effects in the newborn.

51
Q

What are the effects of in utero irradiation?

A

Prenatal death, congenital malformation, malignancy, growth impairment, and genetic effects.

52
Q

Why are the first two weeks of pregnancy considered least concerning for radiation?

A

Due to the all-or-nothing response.

53
Q

What happens during major organogenesis (2nd-10th week)?

A

Risk of skeletal and organ abnormalities.

54
Q

What is the relative risk of childhood leukemia after in utero exposure?

A

1.5 overall, but 8.3 during the first trimester.

55
Q

what is the time frame for congenital abnormalities risk in pregnancy?

A

2-10 weeks.

56
Q

What is the natural occurrence rate of spontaneous abortion?

A

25%.

57
Q

What is the radiation-induced risk for congenital abnormalities?

A

1% with 10 rad exposure.

58
Q

Who reported the genetic effects of radiation on fruit flies?

A

H.J. Muller.

59
Q

What did H.J. Muller conclude about radiation-induced mutations?

A

They are linear and nonthreshold.

60
Q

What is the doubling dose in radiation genetics?

A

The dose needed to double the frequency of genetic mutations.

61
Q

What is a key characteristic of most radiation-induced mutations?

A

They are recessive and may not show for generations.

62
Q

What does the radiation response of mental retardation depend on?

A

Time of exposure, with the highest risk at 2-15 weeks.

63
Q

What is the primary concern for post-pregnancy radiation exposure?

A

Potential genetic effects.

64
Q

What cancer risk is associated with dusty mine environments?

A

Lung cancer, especially among uranium miners.

65
Q

What did the first cyclotron developed in 1932 accelerate?

A

Charged particles to high energies.

66
Q

What are examples of high-LET radiation with high cataract RBE?

A

Neutrons and protons

67
Q

What radiation-induced cancers have no threshold?

A

Stochastic effects, like thyroid and skin cancer.

68
Q

What was Thorotrast used for historically?

A

As a contrast agent in angiography.

69
Q

What is the half-life of radium

A

1620 years.

70
Q

How long is the latent period for radiation-induced cataracts?

A

Can range from 5 to 30 years.

71
Q

What are isotopic sources of radiation in medical use?

A

Tritium and promethium.

72
Q

What was a common treatment in early radiology that caused skin cancer?

A

Orthovoltage x-ray therapy.

73
Q

What are the most sensitive periods for radiation exposure in pregnancy?

A

The first trimester and organogenesis weeks.

74
Q

What dose of radiation to the eye lens is unlikely to be reached occupationally?

A

More than 1000 rad.

75
Q

What is the average effective dose for a CT scan of the abdomen?

A

740 mrem.

C1 (9 decks)

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