VOA常速英语2007年-Study Says CT Scans Raise Cancer Risks

CT scans, also known as CAT scans, have long served as lifesaving tools to expose deadly diseases. But a new study finds that CT scans might also cause diseases. VOA's Carolyn Presutti has the story.

C.J. Sutphin, 5, has received numerous CT scans. He has seven brain tumors. Now his mother has to choose between continuing the scans or heeding¹ a new report that says the scans are harmful for children like C.J.

CT scans, also known as CAT scans, give doctors a peek² at what is going on inside the human body. They take three-dimensional images that can help detect cancer. But a report in The New England Journal of Medicine warns that scans could eventually cause cancer and that one in three scans is unnecessary.

Dr. David Brenner is co-author of the study says, "When someone comes into the emergency room for example with a pain in the belly³ or chronic⁴ headaches, they will automatically get a CT scan even before the physician has examined the patient. We would question whether that is appropriate."

Brenner's study claims that the radiation from CT scans will cause nearly two percent of all cancers in the next few decades.

The authors base their figures on Japanese atomic bomb survivors⁵. The survivors demonstrated increased cancer risks after receiving the same amount of radiation as several CT scans.

CT scans use considerably⁶ higher doses of radiation than regular X-rays. But the study found that three out of four doctors surveyed underestimated the dosage and did not make the connection between the cumulative⁷ radiation and cancer risks.

At risk most are children like CJ, whose tinier bodies are more sensitive to radiation.

Dr. Raymond Sze ("Z") is chief of radiology at Children's National Medical Center in Washington, D.C. explains, "Kids are different. They are smaller. There are certain organs such as the thymus, the gonads, that are more sensitive in kids. Having said that though, the take home for me is to have your care done in a hospital that specializes in children. We decrease dosage. We target our therapies. We do not use excessive technique."

Dr. Sze let's the patient know what's happening, "Ok bud. We are going to take the some pictures."

These pictures take less than a second, eliminating the need for anesthesia to prevent the child from moving. That is why the numbers of pediatric CT scans have risen considerably. The study says one million pediatric scans a year are unneeded, putting those kids at higher risk for cancer.

But after reviewing the study, C.J.'s mom, Kathy Sutphin, says the benefits outweigh⁸ the danger. "Without CT, we wouldn't be able to know if the shunts are malfunctioning⁹ or what the tumors are doing. So I think they are very helpful.

The authors agree CT scans are a valuable medical tool, but patients should make certain the scan is justified¹⁰ and the radiation levels are weight and height appropriate.