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23 Radiology > 4.2 - Radiation Safety and Protection > Flashcards

4.2 - Radiation Safety and Protection Flashcards

1
Q

natural background exposures from most to least percent

A

radon > space radiation > internal radionuclides > terrestrial radiation

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2
Q

what is this:

73% of the total background radiation
Uranium-238 decays to form this

A

radon

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3
Q

what is this:

11% of total background radiation
a function of altitude

A

space radiation

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4
Q

what is this:

7% of total background radiation
Uranium-238 and Thorium-232 decay to form other elements like Potassium-40
Releases gamma radiation

A

terrestrial radiation

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5
Q

what is this:

9% of total background radiation
Ingested (mainly food) substances that contain Uranium, Thorium, and their decay products (Potassium-40, Carbon-14, etc.)

A

internal radionuclides

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6
Q

how many xrays and nuclear examinations per year (worldwide)

A

3.6 billion

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7
Q

what is the biggest source of medication radiation exposure

A

CT

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8
Q

what percent of total exposures from medical sources are dental related

A

0.26%

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9
Q

is radiation cumulative?

A

YES! all radiation individual is exposed to accumulated over time

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10
Q

what is a “linear” relationship between radiation dose and the risk of biological effects (cancer in this case)

A

linear no-threshold hypothesis

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11
Q

even at low doses, is patient at risk

A

yes

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12
Q

is LNT model a fact or hypothesis

A

HYPOTHESIS!

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13
Q

what is LNT used for

A

to help experts set dose limits

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14
Q

can even ONE photon induce biological risks

A

YES

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15
Q

what can we do if one photon can induce biological risks

A

Limit the dose: only necessary radiographs, use safety and protective precautions
Dose limits: set by policymakers to stay within a certain “low-dose” range

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16
Q

guiding principles to implement radiation protection

A
  1. justification
  2. optimization
  3. dose limitation
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17
Q

Benefit to a patient from the diagnostic exposure likely exceeds the
risk of harm
Influences which patients are selected for radiographic examinations and
what examinations are chosen

A

justification

18
Q

what principle:
ALARA
Dentists should use every reasonable means to reduce unnecessary
exposure
to their patients, their staff, and themselves

A

optimization

19
Q

what principle:
Applies to dentists and their staff who are exposed occupationally but not
to patients because there are no dose limits for individuals exposed for
diagnostic purposes

A

dose limitation

20
Q

what is used for patient protection

A
  1. patient selection criteria
  2. film and digital sensors
  3. intensifying screen and film
  4. source-to-skin distance
  5. collimation
  6. filtration
  7. aprons and thyroid collars
  8. film and sensor holders
21
Q

is film or digital faster

A

digital

22
Q

what are types of films and rank from slowest to fastest

A

D < E < F

23
Q

what screens to used with high-speed films

A

rare-earth intensifying screens

24
Q

what technique:
with an increase in distance, the beam becomes less divergent, which in return reduces the total volume of tissue that is being exposed

A

Long cone technique

25
Q

in collimation, field of radiation at patient’s skin surface should be no more than what diameter

A

7 cm

26
Q

where is collimator located

A

fixed within PID or attached to end of PID

27
Q

shapes of collimator? what is recommended

A

round or rectangular.
rectangular recommended (5 fold reduction in radation exposure when compared to round and improved image quality)

28
Q

do low energy photons add diagnosis value in imaging? explain

A

NO! it exposes patients and personnel to unnecessary radiation

29
Q

filtration minimzes what

A

low energy photons

30
Q

Federal regulations:
___ mm of aluminum in machines that operate below 70 kV
___ mm of aluminum at higher kV ranges

A

1.5; 2.5

31
Q

what are aprons lined with? why?

A

lead lined to attenuate xrays and reduce gonad and thyroid gland exposure

32
Q

what is gland is most susceptible to radiation exposure during dental radiographic exams

A

thyroid gland

33
Q

what do film and sensor holders limite

A

limit cone cutnig and reduce instances of remade exposures

34
Q

why do exposure times vary from region to region

A

Bone density differs in different areas of the mouth. Exposure time must be altered to achieve optimal images in each area.

35
Q

improperly processes film can lead to what

A

patient being exposed to ionizing radiation unnecessarily to compensate

36
Q

what are materials that attenuate radiation?

A

barriers

37
Q

barriers should have what to do what

A

have leaded glass window to observe patient during exposure

38
Q

position and distance rule

A

if no barriers are available, you should stand at least six feet away from the patient at an angle of 90-135 degrees to the direction of the X-ray beam, on either side of the patient

39
Q

what provdes a zone where backscatter radiation is negligible

A

backscatter shield

40
Q

where should handheld radiographic device be positioned

A

perpendicular to operator

41
Q

what is a personal monitoring device

A

dosimeter

42
Q

what is devices worn by occupational professionals that measure the amount of radiation the professionals are exposed to
This information is monitored to ensure that the professionals are not
exposed to inordinate amounts of radiation

A

dosimeters

23 Radiology (15 decks)

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