and glass and ceramics contribute approximately 2% of the total annual effective dose per person. (United States Nuclear Regulatory Commission, 2020). Industrial radiation includes sources such as nuclear power generation; disposal of nuclear waste; airport inspection systems; and industrial, medical, educational, and research activities. Occupational exposure is employee-related radiation exposure that occurs in a variety of work situations, such as medical (includes dental and veterinary medicine), aviation, nuclear power, military, academic, and industrial environments. Among occupationally exposed individuals, the medical and aviation categories comprise the greatest number of workers and the highest collective effective dose. Individuals in the aviation industry experience a higher concentration of natural radiation at higher altitudes due to a higher amount of radiation from cosmic rays present at higher altitudes than the level of cosmic radiation at ground level (Alden, 2020). However, industrial and occupational sources combined account for less than 0.01% of the total annual effective dose per person. Table 4 summarizes radiation sources and exposure doses, revealing that the radiation from natural and artificial sources results in an average effective dose of 6.2 mSv per year for persons living in the United States (United States Environmental Protection Agency, 2021b). Table 4: Source Contribution to Annual Effective Dose
Table 3: Diagnostic Examinations with Typical Effective Dose Type Examination Effective Dose (mSv) Effective Dose (mrem)
Chest radiography
0.1
10
Medicine (exposure from single diagnostic x-ray)
Mammography
0.4
40
Upper GI series
6.0
600
Coronary CT angiography
12
1,200
Kidney (filtration rate) 99mTc DTPA Thyroid scan (sodium iodide-123) Bone scan 99mTc MDP
6.0
600
1.9
190
Nuclear medicine (exposure from entire procedure)
6.3
630
Brain (PET) 18F FDG 14.1
1,410
Heart stress-rest test 201Tl chloride
41
4,100
Four bitewings PSP or F-speed film rectangular collimation
0.005
0.5
Effective Dose (mrem)
Radiation Source Radon (internal inhalation)
Percent Contribution
Effective Dose
Type
Panoramic
0.01
1
37
2.28
228
FM survey PSP or F-speed film
0.035
3.5
rectangular collimation
Cosmic (space)
5
0.33
33
Natural 3.1 mSv
Dental
FM survey PSP or F-speed film round collimation Dentoalveolar CBCT small and medium field view Maxillofacial CBCT large field view
0.171
17.1
Internal terrestrial External terrestrial
5
0.29
29
3
0.21
21
0.011 to 0.674
1.1 to 67.4
Computed tomography
24
1.47
147
0.030 to 1.073
3 to 107.3
Nuclear medicine
12
0.77
77
FM = full mouth; PSP = photostimulable phosphor; CBCT = cone beam computed tomography. Note . Adapted from American Dental Association. (2016). Oral health topics: X-rays. Retrieved from http://www.ada.org/en/member- center/oral-health-topics/x-rays; (American Dental Association, 2019; Health Physics Society, 2021; Effective doses in radiology and diagnostic nuclear medicine: A catalog. Radiology, 248 (1), 254-263; and Radiological Society of North American. (2016). Radiation dose in X-ray and CT exams: Effective radiation doses in adults . Retrieved from http://www.radiologyinfo.org/en/info.cfm?pg=safety-xray#safety- benefits-risks. Consumer products and activities , industrial sources , and occupational exposure also contribute to the amount of artificial radiation received by the U.S. population, although the amount of radiation received in this way is small. Sources derived from consumer products and activities include building materials, commercial air travel, cigarette smoking, mining and agriculture, combustion of fossil fuels, road construction materials, television,
Medical 3.0 mSv
Interventional fluoroscopy Conventional radiography/ fluoroscopy (dental 2.5%)
7
0.43
43
5
0.33
33
Consumer
2
0.13
13
Other 0.1 mSv
Occupational
<0.1
0.005
0.5
Industrial
<0.1
0.003
0.3
Total 620 Note : Adapted from Health Physics Society, 2020; United States Nuclear Regulatory Commission, 2020. All sources 100 6.2
RADIATION SAFETY AND PROTECTION
Radiation safety and protection are based on the ALARA principle. ALARA is an acronym for “as low as reasonably achievable.” This principle maintains that exposures to ionizing radiation should be kept as low as possible (American Dental
Association, 2019). It means that every effort should be made to reduce unnecessary radiation exposure for patients and dental professionals alike.
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