What percentage of background radiation exposure is attributed to radon and its progeny?
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52% - Global
74% - United States
3
What is the estimated contribution of cosmic radiation to background exposure?
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11%-16%
4
What is the primary source of internal radiation exposure?
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foods containing uranium and thorium and their decay products
5
Which radioactive nuclide contributes most to terrestrial radiation exposure?
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potassium-40
6
What percentage of background exposure comes from ingestion of radionuclides?
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9%-12%
7
What does MDCT stand for in the context of medical sources of radiation exposure?
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Multidetector Computed Tomography
8
Which medical procedure contributes the most to radiation exposure globally?
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CT
9
What is the primary source of radiation exposure in the United States according to the slide?
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CT
10
What does DMFR stand for in the context of the slide?
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Dentomaxillofacial Radiology
11
What is the primary goal of optimizing doses from DMFR examinations?
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To produce a diagnostically acceptable image
12
What threshold should doses from DMFR examinations be less than to avoid deterministic effects?
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The threshold needed to cause any deterministic effects
13
What hypothesis is the current paradigm of radiation protection based on?
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linear no-threshold (LNT) hypothesis
14
What does the LNT hypothesis predict regarding the relationship between dose and cancer risk?
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There is a linear relationship between dose and the risk of inducing a new cancer, even at very low doses
15
According to the LNT hypothesis, what is the risk of added cancer risk at low doses?
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There is no threshold or 'safe dose' below which there is no added cancer risk
16
What dose level results in a dose-dependent increase in cancer rate according to the slide?
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100 mSv
17
What model is currently accepted for developing radiation protection guidelines?
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LNT model
18
What does the LNT model suggest about the risk at doses less than 100 mSv?
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There is a linear relationship between dose and risk and no threshold dose.
19
What is the term used to describe the measure of stochastic risks in patient doses from Diagnostic DMFR?
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Effective dose
20
What does the Effective Dose (ED) consider in terms of radiation exposure?
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The absorbed doses to various organs and the relative sensitivity of the exposed organ to stochastic effects of radiation
21
What factors are not considered in the Effective Dose (ED)?
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Age, gender, and individual susceptibility factors
22
What type of radiographic examination has a median effective dose of 5 µSv?
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Cephalometric
23
How many days of equivalent background exposure is associated with a full-mouth dental examination using PSP or F-speed film?
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24 days
24
Which examination has a median effective dose of 200 µSv?
Show answer
Full-mouth: PSP or F-speed film
25
What does the central axis on the diagram represent?
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The effective dose and the equivalent period of background radiation exposure
26
What do the radiation symbols adjacent to the dose identify?
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The relative radiation level categories
27
Which of the following is NOT a type of dental or medical radiographic examination listed on the slide?
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MRI Scan
28
What does the symbol in the first column represent?
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Relative Radiation Level
29
What is the effective dose range for adults at the third relative radiation level?
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1–10 mSv
30
What is the pediatric effective dose range for the fourth relative radiation level?
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3–10 mSv
31
What is the first step in communicating radiation risks to patients?
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Allow the patient to fully express their thoughts.
32
Why should you contact the patient's previous dentist?
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To obtain previous radiographs that may assist in diagnosis without unnecessary re-exposure.
33
What should you emphasize regarding the need for radiographs?
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That you will make only the exposures you specifically need for the patient's benefit guided by their symptoms and clinical evaluation.
34
What is the ICRP?
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An independent, international organization that develops and disseminates recommendations and guidance on protection against ionizing radiation.
35
Which organization formulates guidance and recommendations on radiation protection in the United States?
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NCRP
36
What is the primary goal of current occupational exposure limits?
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To ensure that no individuals will have deterministic effects and that the probability for stochastic effects is as low as reasonably and economically feasible.
37
What is the principle of justification in radiation protection?
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situations where the benefit to a patient from the diagnostic exposure likely exceeds the risk of harm
38
What does the acronym ALARA stand for?
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As Low As Reasonably Achievable
39
Which principle aims to provide dose limits for occupational and public exposures?
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Dose limitation
40
What is one of the main strategies for reducing X-ray exposure?
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Use Good Clinical Judgment and Apply Evidence-Based Imaging Guidelines
41
When should radiographs be made to minimize unnecessary exposure?
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When they are likely to contribute to diagnosis and treatment planning
42
What can help determine the type and frequency of radiographic examinations?
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Selection criteria
43
What is one method to reduce X-ray exposure during radiographic imaging?
Show answer
Optimize your exposure settings
44
Which type of radiography uses E/F-speed film or digital sensors?
Show answer
Intraoral radiography
45
What is the benefit of using rectangular collimation in radiographic imaging?
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Radiation dose up to 5-fold
46
What voltage range is recommended for making exposures to reduce X-ray exposure?
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60–70 kVp
47
What should be avoided to reduce X-ray exposure?
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Retakes
48
What type of screens are recommended for panoramic radiography?
Show answer
Rare-earth screens for film imaging
49
What is one method to reduce X-ray exposure in cephalometric radiography?
Show answer
Use digital systems
50
How can the field of view be managed in cone beam computed tomography (CBCT)?
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Restrict the field of view to cover the region of interest
51
What type of processing should be used in film-based imaging to reduce X-ray exposure?
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Use time-temperature processing
52
What is the recommended distance to stand from the patient during X-ray exposure?
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6 feet (2 m)
53
What angle range is recommended to stand at in relation to the central ray of the X-ray beam?
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90 to 135 degrees
54
What should be the thickness or density of walls in a dental office to protect nonoccupationally exposed individuals?
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Sufficient density or thickness so that the exposure is less than 0.02 mGy/week (1 mGy/year)
55
What does the blue shading in the images represent?
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The area where scatter radiation is blocked by the shield.
56
What is the correct handling of the device to minimize radiation exposure?
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The device is held horizontal with the collimator ring placed close to the patient's skin surface.
57
What is considered improper handling of the device?
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The device is held back away from the patient.
58
What technology is used in optically stimulated luminescent dosimeter (OSLD)?
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strip of crystalline aluminum oxide (Al2O3:C)
59
What is the recommended annual dose limit for workers who should wear personal dosimeters according to the ADA?
Show answer
1 mSv
60
Which group of workers should use personal dosimeters regardless of anticipated exposure levels?