TABLE 90.10 INTERNATIONAL RADIATION UNITS Metric Definition Exposure Roentgen, R R = 2.58 × 10− C/kg air Absorbed dose Gray, Gy Gy = J/kg Effective dose Gy = 100 rads Sievert, Sv Sv = J/kg, weighted for tissue sensitivity Quantity of radioactivity Sv = 100 rems Becquerel, Bq Curie, Ci Bq = disintegration/s Ci = 3.7 × 1010 Bq 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 mSv/yr 10 mSv Abdominal computed tomographic scan 10–30 mSv We are exposed to about mSv of radiation each year from natural sources During a 70-year lifetime, a person’s total radiation exposure from natural sources