By Martha A. Simpson, D.O., M.B.A.
Assistant Professor of Family Medicine
Ohio University College of Osteopathic Medicine

READER SHOULDN’T WORRY ABOUT MINIMAL RADIATION FROM CHEST X-RAYS

Question: I have had a number of X-rays over my lifetime. Now, whenever I have to undergo an X-ray I get very stressed. In fact, nowadays there is a requirement to have a complete medical checkup before taking up a new job, and so I have to appear for another routine chest X-ray! I have had six or seven chest X-rays before. Please give me some advice. Will it really have a bad effect on my health?

Answer: You ask a very interesting question that raises issues of concern to many people. First of all, the type of X-ray you are talking about, a chest X-ray, is referred to as a diagnostic X-ray. A diagnostic X-ray is used to discover what might be wrong with you. For example, an X-ray of the arm would answer the question: Is the arm broken or not? As the name implies this is part of the process that doctors use in arriving at a diagnosis.

Therapeutic X-rays -- used to treat conditions like cancer -- have much higher levels of radiation. For instance, a cancer patient might be given the equivalent of 800 chest X-rays each treatment session over a number of days. So, as you can see, exposure is a matter of degree. The radiation you’ll receive from one additional chest X-ray presents very little risk.

Another way to put this in perspective is to take a look at the natural sources of background radiation that we are all exposed to on a daily basis. These include cosmic radiation, terrestrial radiation, and internal sources.

Cosmic radiation is composed of particles from the sun, other stars, and events deep in space. The atmosphere acts as a shield, and most cosmic rays don’t reach the earth. Cosmic radiation levels are higher at higher altitudes, so a person living in Denver gets about twice as much cosmic radiation as a person living at sea level. Air travel increases your dose of cosmic radiation as well.

Terrestrial radiation comes from the naturally occurring radioactive particles in soil and in building materials used in construction. A brick home is a source of terrestrial radiation.

Our bodies also produce natural isotopes -- radioactive particles -- as a consequence of general metabolism. This is internal radiation.

The most prominent source of environmental radiation is radon gas. This gas comes from radioactive decay in the soil, and it is inhaled. The average radon gas exposure is about as much as the cosmic, terrestrial and internal sources combined.

The average total yearly exposure to radiation from all of these background sources for the average, low-land, non-smoking American is about 325 millirem per year. A single chest X-ray, by comparison, is 8 millirem. If you smoke, that activity alone increases your dose of radiation exposure by 280 millirem per year -- the equivalent of an additional 35 chest X-rays. A cross country round trip by air is 5 millirem per trip.

So you see, a chest X-ray -- even once or twice a year -- is not a significant increase in exposure. Other types of diagnostic X-rays, such as an upper GI, use higher levels of radiation. The benefits, though, of having a correct diagnosis still far outweigh any radiation risk.

Some cautions about getting X-rays are advisable, though. If you are pregnant or think you might be pregnant, X-ray studies that are not ABSOLUTELY necessary should be postponed.

Family Medicine® is a weekly column. To submit questions, write to Martha A. Simpson, D.O., M.B.A., Ohio University College of Osteopathic Medicine, P.O. Box 110, Athens, Ohio 45701. Or, e-mail Dr. Simpson at simpsonm@ohio.edu. Past columns are available online at http://www.FamilyMedicineNews.org.