Rita F. Redberg and Rebecca Smith-Bindman, writing for the New York Times:
While it is difficult to know how many cancers will result from medical imaging, a 2009 study from the National Cancer Institute estimates that CT scans conducted in 2007 will cause a projected 29,000 excess cancer cases and 14,500 excess deaths over the lifetime of those exposed. Given the many scans performed over the last several years, a reasonable estimate of excess lifetime cancers would be in the hundreds of thousands. According to our calculations, unless we change our current practices, 3 percent to 5 percent of all future cancers may result from exposure to medical imaging.
We know that these tests are overused. But even when they are appropriately used, they are not always done in the safest ways possible. The rule is that doses for medical imaging should be as low as reasonably achievable. But there are no specific guidelines for what these doses are, and thus there is considerable variation within and between institutions. The dose at one hospital can be as much as 50 times stronger than at another.
Sigh.