Radiation: Catching Rays
How much radiation is a person exposed to during medical procedures—and every day?
3
Average dose of “background radiation,” in millisieverts, a person receives each year from cosmic rays, radon gas and decaying rocks
1
Percentage by which lifetime exposure to background radiation increases cancer risk
64
Years since the atomic bomb was dropped on Hiroshima, the event that provided most of the quantitative information science has on the medical risks of radiation exposure
1895
Year the German scientist Wilhelm Röntgen took the first X-ray, an image of his wife’s hand
0.02
Average dose of radiation, in millisieverts, delivered by one chest X-ray
0.15
Estimated exposure from a full series of dental X-rays (about 19)
0.7
Approximate exposure from one mammogram
12
Average dose from a cardiac computed tomography angiography, which is equal to 1.2 times the dose of an abdominal CT study or 600 X-rays
2008
Year that Image Gently—a multinational alliance of health care organizations—was formed to lower imaging radiation doses for child patients
88
Percentage of compliance in a recent study of Massachusetts General Hospital staff for administering pediatric chest CTs using new dosage-lowering techniques, with reductions ranging from 74% to 83% and no loss of clinically relevant image quality



