NEW YORK (Reuters Health) - Radiation from medical imaging is the largest manmade source of radiation in Western countries, but physicians and patients are often unaware of the long-term health risks such imaging entails, according to an article in the British Medical Journal for March 6.

The author, Dr. Eugenio Picano, a senior researcher at the Institute of Clinical Physiology in Pisa, Italy, notes that by 1997 the amount of radiation coming from medical sources had nearly caught up with the amount produced by natural sources in industrialized countries. If current trends continue, medical radiation may soon surpass that coming from natural sources, he predicts.

The exact risks of medical radiation are unclear, Dr. Picano notes. The risk of cancer with a single chest X-ray is negligible, whereas up to 1 in 1000 patients could be expected to develop cancer from exposure to certain CT or nuclear medicine scans. These risks tend to be higher in females than males and in children rather than adults due to a greater life expectancy.

Physicians often do not weigh the long-term risks of imaging against the immediate diagnostic benefits, Dr. Picano points out. Part of the problem is that doctors are simply unaware how much radiation a particular patient is being exposed to during imaging.

Another problem is unnecessary radiologic examinations, Dr. Picano states. Recent reports suggest that up to a third of such exams are totally or partially inappropriate.

To solve this problem, Dr. Picano proposes that doctors should have a radiologic "drivers license" in which points are taken off for ordering inappropriate imaging studies. Once a certain limit is reached, the doctor must attend a radiobiology course. With repeated violations, the physician could temporarily lose their license.

Another way to improve radiologic testing would be to use informed consent forms that clearly spell out the radiation dose and cancer risks of the test being considered, Dr. Picano notes.

"A real change in radiological practice is not likely to come from new technologies or new laws. We already have excellent technologies and good laws to defend high levels of safety for individuals and the population," Dr. Picano states. "We have to implement the law into clinical practice."

BMJ 2004;328:578-580.

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