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. ..
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. ..
Julian Gibbs, DDS, PhD


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