Man in Scanner

A study published today, Nov. 29, in the New England Journal of Medicine says that the American population may be getting too much exposure to radiation from CT (computed tomography) scans, and this could lead to cancer.

Experts say, however, that people who need to be scanned should get them. The authors of the report also state that the risks for any one person are not great — but the rising levels of radiation exposure to the American population could become a future public health issue.

The researchers estimate that CT scans may eventually account for up to 2 percent of all cancers in the US in the next two or three decades.

CT imaging has become widely used for diagnosing many diseases, from brain hemorrhage to appendicitis. It involves X-ray machines rotating around specific body sections and taking cross-sectional images, which are assembled by computers into a 3-D image. The image is vastly improved, but radiation received is also greatly increased.

Children are particularly at risk with increased exposure because they are 10 times more sensitive to radiation as adults. But the risk for any one individual is very small.

Radiologists agree that there is a small risk of cancer, but dispute the study’s estimate of how high the risk is. The study used radiation data from atomic bomb blasts, but there is a difference in the kind of radiation generated. Atomic bombs produce mainly gamma radiation, which is received in a single exposure, while medical radiation is mainly beta radiation, which has lower energy.

Although there is disagreement with the degree of risk, radiologists and researchers agree that there are too many CT scans.

From about three million CT scans in 1980, approximately 62 million CT scans were performed in 2006, and over 4 million of these were on children. These volumes have increased the average American’s total radiation exposure by almost two times the 1980 level.

Previous studies have estimated that about one-third of scans are not necessary. If the one-third figure is accurate, the study says that 20 million adults and 1 million children each year are receiving unnecessary radiation.

There could be two reasons for the increase.

* CT scans are used simply because it is available; its use has been made part of protocol and careful assessment of the patient is set aside.
* Doctors use all available technologies for diagnosis, to defend against potential lawsuits.

Safety Tips:
* Ask your doctor if a CT scan is really needed. CT scans should be for emergency situations only.
* Ask your doctor if an alternative test will work just as fine. For non-emergencies, MRI or ultrasound may be equally effective as diagnostic tools.