Rad Bio Risk Flashcards

1
Q

what is the definition of maximum permissible dose

A

that amount of radiation which in the light of present knowledge will not produce any serious, harmful, or deleterious effects on the individual receiving it

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2
Q

what are the occupational MPD limits

A

5.0 rem/year (5,000mrem)
50 mSv

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3
Q

what are the non occupational MPD limits

A

0.5 rem/year (500mrem)
5 mSv

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4
Q

what is the MPD of dental personnel average

A

0.2mSv

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5
Q

what is the x ray dx dose

A

0.39

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6
Q

what is the nuclear medicine dose

A

0.14

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7
Q

what is the natural plus artifical dose

A

3.60 mSv

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8
Q

medical xrays and nuclear medicine accounts for ____ of radiation exposure

A

1/6

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9
Q

medical imaging accounts for ______ of radiation exposure

A

more than 50%

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10
Q

_____ of radiation induced cancers at greater than 40 years old

A

2%

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11
Q

_____ of radiation induced cancers at 65-74 years

A

56%

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12
Q

what is the order of organs that gets the most to least dose in a head CT scan

A
  • brain, bone, bone marrow, thyroid
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13
Q

what is the order of organs that gets the most to least dose in a abdominal CT scan

A

stomach, liver, ovaries, colon, bone marrow

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14
Q

what is the order of organs that gets the most to least lifetime radiation induced cancer risk from a single head CT scan

A
  • brain, leukemia
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15
Q

what is the order of organs that gets the most to least lifetime radiation induced cancer risk from a single abdominal CT scan

A
  • digestive, other, leukemia
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16
Q

cancer risks decrease with _______

A

increasing age

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17
Q

how long are latency periods for solid tumors

A

typically decades

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18
Q

why are children more radiosensitive

A
  • larger proportion of dividing cells
  • less shielding of radiation sensitive organs
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19
Q

females less than 10 years old are ______ more likely to develop fatal cancer than a 50 year old

A

5.5-6 times

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20
Q

20 year old females are ______ more likely to develop fatal cancer than a 50 year old

A

3-3.5 times

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21
Q

30 year old females are ______ more likely to develop fatal cancer than a 50 year old

A

3 times

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22
Q

40 year old females are ______ more likely to develop fatal cancer than a 50 year old

A

1.5 times

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23
Q

males less than 10 years old are ______ more likely to develop fatal cancer than a 50 year old

A

4-5 times

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24
Q

20 year old males are ______ more likely to develop fatal cancer than a 50 year old

A

3 times

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25
Q

30 year old males are ______ more likely to develop fatal cancer than a 50 year old

A

2.8 times

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26
Q

40 year old males are ______ more likely to develop fatal cancer than a 50 year old

A

1.2 times

27
Q

what is the percentage risk of fatal radiation induced cancer in females at 10,20, 30, 40 and 50

A

-10: 16.8%
- 20: 9.5%
- 30: 8.5%
- 40: 4.0%
- 50: 2.8%

28
Q

what is the percentage risk of fatal radiation induced cancer in men at 10,20, 30, 40 and 50 years

A
  • 10: 12.5%
    -20: 7.5%
  • 30: 7.0%
  • 40: 3.0%
  • 50: 2.5%
29
Q

pediatric tissues at greatest level of radiosensitivty due to:

A

rate of cellular and organ growth

30
Q

____ shielding of radiation sensitive organs

A

less

31
Q

greater life expectancy puts children at _____ greater risk of being afflicted with a radiation induced cancer

A

2-10

32
Q

what is the median dose in female ortho pts

A

300 uSv

33
Q

what is the max dose in female ortho pts

A

1514 uSv

34
Q

Us dentists may cause _____ cases of cancer per year from dental radiography

A

967

35
Q

use of _________ could reduce cancer cases from dental radiology per year to 237

A

rectangular collimation and selection criteria

36
Q

the trend in orthodontic treatment is to:

A

replace lower dose panoramic and cephalometric radiography with higher dose CBCT

37
Q

there is an _____ cancer risk after low dose radiation exposure from CT scans in young pts

A

increased

38
Q

what are the effects of low dose ionizing radiation

A

induces genetic and epigenetc changes and is associated altered immune system, abnormal brain development with resultant cognitive impairment, cataractogenesis, abnormal embryonic development, circulatory diseases, weight gain, premature menopause in female animals, tumorigenesis and shortened lifespan

39
Q

what are the beneficial effects from LDRIR

A

reduction in tumorigensis, prologed lifespan and enhanced fertility

40
Q

what is the difference between LDIR and LDRIR

A

depends on animal genetic background, age, sex, nature of radiation exposure, type of radiation, combination of radiation with other toxic agents or animal experimental designs

41
Q

overall cancer incidence was greater among individuals exposed to ________ than among nonexposed individuals after adjusting for age and sex

A

diagnostic low dose ionizing radiation

42
Q

cancer incidence increased signficantly after radiation exposure such as:

A

mouth, pharynx, breast, thyroid, lymphoid, hematopoietic and myelodysplasia cancers

43
Q

increased cancer risk with exposure to diagnostic low dose ionizing radiation should:

A
  • incentivize ALARA
  • have justifiable exposure indication to low dose ionizing radiation (benefits of any imaging examination should be weighed against this associated increased cancer risk to justify each imaging exposure)
44
Q

what is the dose response curve for radiation

A

non linear

45
Q

describe the threshold non linear dose response curve

A
  • small exposures to a substance do not produce measurable changes
  • a threshold must be reached before changes are observed
    -most biologic effects are non linear
46
Q

what is the threshold radiation erythema dose

A

250 rads

47
Q

what is the average radiation erythema dose

A

500 rads

48
Q

what is the maximum radiation erythema dose

A

750 rads

49
Q

in 1959 dental radiation dose was:

A

1 rad/second with an 8” focal distance 10mA, 65kV

50
Q

what was the maximum allowable xray exposure limits in 1959

A

50% of TED, 125 Rads

51
Q

what amount of exposures deliver the TED in 1959

A

62 exposures
1,250/20

52
Q

in 1959 1/3 of the TED is delivered with ____ intraoral dental exposures (one FMS)

A

20

53
Q

in 2020 8” focal distances at 7mAs and 0.2s was:

A

1.4mAs/exposure

54
Q

it takes ______ for 298 exposures

A

417 mAs/1.4 mAs

55
Q

in 2020 1/3 of the TED is delivered with _____ intraoral dental exposures

A

298

56
Q

describe the linear non threshold curve

A
  • dose is proportional to the response
  • non matter how small the dose, there is some damage
  • linear
  • no threshold
  • minimal damage at first with increased rate of damage with increased dose
57
Q

in the dose response curve there is no data available at _____

A

low doses

58
Q

what is the selection criteria of the FDA/ADA

A
  • imaging required justification
  • an initial clinical exam is required to make this assessment
  • need a specific question or a diagnostic task where radiographs will provide unique information not readily available from other diagnostic means
59
Q

what has been done to reduce x radiation dose

A
  • AAOMR position and guideline papers
  • high speed sensors
  • micro processor timers
  • rectangular collimation
  • improved shielding of x ray tube head
  • selection critera
  • thyroid collars with Pb equivalent
  • thoracic/abdominal/pelvic aprons with pb equivalent
  • increased focal length of xray tube head
60
Q

what are the 2 recommendations for patient shielding during dentomaxillofacial radiology

A
  • discontinue shielding of the gonads, pelvic structures and fetuses during all dentomaxillofacial radiographic imaging procedures
  • thyroid sheilding not be used during intraoral, panoramic, cephalometric, and CBCT imaging as the risks of thyroid cancer are negligible from contemporary maxillofacial imaging radiation doses
61
Q

do clinicians that use PSPP or sensors report making more radiographs than film

A

sensors

62
Q

do clinicians report more retakes with PSPP or sensors than with film

A

sensors

63
Q
A