Pediatric emergency medicine trisk 1975 1975
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TABLE 90.10
INTERNATIONAL RADIATION UNITS
Metric
Definition
Exposure
Roentgen, R
R = 2.58 × 10− 4 C/kg air
Absorbed dose
Gray, Gy
1 Gy = 1 J/kg
Effective dose
1 Gy = 100 rads
Sievert, Sv
1 Sv = 1 J/kg, weighted for tissue
sensitivity
Quantity of radioactivity
1 Sv = 100 rems
Becquerel, Bq
Curie, Ci
1 Bq = 1 disintegration/s
1 Ci = 3.7 × 1010 Bq
1 mCi = 37 MBq
Note: C = coulomb.
TABLE 90.11
COMMON RADIATION DOSES
Sources
Effective dose
Roundtrip intercontinental air flight
20–30 μSv
Chest radiograph
Living in brick house
50–100 μSv
0.20 μSv/yr
Natural radiation
Angiography
3 mSv/yr
10 mSv
Abdominal computed tomographic scan
10–30 mSv
We are exposed to about 3 mSv of radiation each year from natural sources.
During a 70-year lifetime, a person’s total radiation exposure from natural sources
