June 04, 2010 02:18am EST 

The Archives of Internal Medicine published a new study that shows that radiation from hospital CT scans done in 2007 will cause approximately 29,000 cancers and kill nearly 15,000 Americans. The findings only add to the evidence that Americans are exposed to too much radiation stemming from diagnostic tests in hospitals.
In this case, a specialized kind of X-ray named a computed tomography, or CT scan, causes overradiation in hospital patients. Computed tomography scans use X-rays and computers to produce images of the body. Hospital patients often drink a contrast liquid before the scan or have the liquid injected into the vein. Patients lie on a table as the X-ray tube rotates around them, sending massive doses of radiation through them.
“What we learned is there is a significant amount of radiation with these CT scans, more than what we thought, and there is a significant number of cancers,” said Dr. Rita Redberg, editor of the Archives of Internal Medicine, “It’s estimated that just from the CT scans done in one year, just in 2007, there will be 15,000 excess deaths,” Redberg said in an interview.
As hospitals in the United States conduct millions of CT scans every year, the impact of these findings is severe. The number of scans is only increasing in hospitals around the United Statse.
The scans give doctors a chance to view inside the body, eliminating the need for risky exploratory surgery. CT scans are estimated to expose the patient to more than 100 times the radiation dose of a chest X-ray. With around 70 million CT scans done in hospitals on Americans in 2007, up from 3 million scans in 1980.
The National Cancer Institute’s Amy Berrington de Gonzalez and her colleagues developed acomputer model to estimate the impact of so many hospital CT scans. They found that the scans done in 2007 were likely to cause 29,000 cancers and that a third of the projected cancers will occur in people aged 34 to 54 when they got their CT, two-thirds will occur in women and 15 percent will be in children or teens.
Dr. Rebecca Smith-Bindman of the University of California, San Francisco, and colleagues found and analyzed data from 1,119 hospital patients undergoing CT scans at four different institutions in 2008. They found that radiation dosage varied widely between different types of CT scans, ranging from 2 millisieverts for a routine head scan to 31 millisieverts for a scan of the abdomen and pelvis.
Researchers suggested that hospitals and physicians need to make an effort to cut down on CT radiation exposure, by reducing the number of unnecessary tests, cutting the dose, or standardizing the doses across different hospitals. Hospitals in particular will have to reconsider their CT equipment, as imaging equipment makers such as GE are working to develop new, lower-dose CT scanners.