Original Source
Health Physics Society
November 18, 2004
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Answer to Question #4125 Submitted to "Ask the Experts"
Health Effects of Medical Radiation
Question:
I have had several tests done in the past couple of months and I am a
little bit worried about the health effects due to the radiation exposure. I
had a barium meal in the month of August and two months later I had two liver
scans-one with red blood cells radiolabeled with technetium-99m and the other
was direct injection of technetium-99m IV to look at liver function. Because
of conflicting results, I then underwent a CT (computed tomography) scan of
the abdomen approximately two weeks later. From the information I gathered on
the Internet, the maximum allowable dose for radiation technicians is in the
range of 5,000 mrem/yr. I know that the abdominal CT is approximately 1,000
mrem and the barium meal is approximately 500 mrem. What about the liver
scans? Although I think I am still within the allowable limits, I am concerned
that the tests were done too close to one another. Please help, I am really
worried.
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Answer:
Your history of exposure to diagnostic medical radiation is not at all
uncommon. There is at present no firm evidence of adverse effects from any
such exposure using modern technology. Early studies-from exposures
generally in the 1920s to 1940s-did find some harm, but equipment then was
much cruder and doses were much greater than today. Dose limits established
for radiation workers and the public are somewhat arbitrary. The limit of 50
millisievert in any year for occupational exposure does not mean that 49 is
safe and 51 harmful. This limit is set based on current knowledge to keep
risks of harmful effects no greater than occupational risks for many other
worker groups. There is no recommended dose limit for patients. It would not
be appropriate to refuse a medically necessary x-ray exam just because some
arbitrary dose limit had been reached. Patients receive clear benefit from
medical exposure, which outweighs any potential for harm. You should not
worry about your medical radiation exposure. Instead, you should be grateful
that this exposure could improve your health.
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Julian Gibbs, DDS, PhD
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