The topic of radiation risk from medical imaging has been in the news lately with growing concern over potential dangers, along with programs to minimize exposure. A new web site www.xrayrisk.com allows you to calculate your patients' (or your own) lifetime increased risk of cancer based on the CT scans or X-rays performed.

DOTmed News spoke with the host of the web site, Michael Hanley, M.D., a second-year radiology resident at the Medical University of South Carolina.

DOTmed (DM): We have had a lot of stories on our web site about the dangers of radiation from medical exams and efforts by the American College of Radiology (ACR) designed to limit the problem, including the Image Gently program.
Michael Hanley (MH): Every time I open the paper I see an article on radiation risk. Many news reports make inflammatory claims that are scary for patients. What we tried to do was get real numbers out there with facts about radiation and cancer and how much radiation is involved with different types of medical imaging studies.

DM: So I could go to the site and put in all the mammograms I have had over the years?

MH: The site features a calculator where you can pick a study, enter your age and gender then calculate the additional risk of cancer based on the radiation exposure from those medical tests.

Screening mammograms are unique in that they are performed on health patients, making the weighing of risks and benefits much more important. The reason mammograms are recommended is because they have been proven to save lives. One of the worst things that could come of all the news media attention is that people wouldn't go to get a test like that, which would be bad for women and bad for everybody.

Alternatively, if a patient presents to the emergency room with a cough and fever, it is absolutely indicated to have a chest X-ray. You should never even think of the risk [of radiation exposure] because the risk of something bad happening because of an untreated pneumonia is so much greater than the tiny assumed risk of cancer ten years down the line.

DM: How dangerous are medical tests exactly?

MH: If you had 100 chest X-rays, you couldn't even get whole numbers [such as a one percent increase] in your lifetime risk of cancer. If you enter 100 chest X-rays into the website's calculator, you'll find that increases your risk of cancer 0.09 percent. This is added to a background risk of 45% for men. So, in general, people should not be scared of chest X-rays and mammograms.

The concern arises with CT scans because CT scans are hundreds of times more radiation than a chest X-ray. A chest CT is about 500 times the radiation of a chest X-ray. So that's a big difference. If a doctor orders a chest CT, patient should feel comfortable asking why. If there is good reason, again there is little reason to worry about the cancer risk.

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