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CT-related radiation blamed for up to 2% of US cancers

CT-related radiation blamed for up to 2% of US cancers

A New England Journal of Medicine review article is highlighting the cancer risks of computed tomography at the same time that hundreds of scientific presentations and new product announcements at the 2007 RSNA meeting are fueling the continued growth of multislice CT.

David J. Brenner, PhD, DSc, and Eric J. Hall, DPhil, DSc, both associated with the Center for Radiological Research at Columbia University, conclude from an examination of CT physics and often-quoted historical data from survivors of the Hiroshima and Nagasaki atomic bomb blasts that the growth of medical CT utilization may be responsible for 1.5% to 2% of US cancer cases.

They estimate that perhaps 20 million adults and more than 1 million children per year in the United States are irradiated unnecessarily from medical CT (N Engl J Med 357:2277-2284, 2007).

The rapid growth of CT utilization—from 3 million procedures in 1980 to 62 million scans per year in the mid-2000s—form that basis for Brenner and Hall's concerns. They say the risks for any one person are not large, but the increasing exposure to radiation may be a future public health issue.

Their analysis pegs that growth to the proliferation of multislice CT technology and screening applications for adults and children. They expressed concern about the growing popularity of CT for presurgical diagnosis of appendicitis for children, for example, because diagnostic ultrasound, a modality that involves no ionizing radiation, is probably equally effective for the same procedure.

They cite estimates indicating that 6% to 11% of CT studies are performed on children. A chart in the review indicates that a neonatal abdominal CT exposes a newborn infant to 20 mSv of radiation.

Screening is also an important motivation for increased CT use for asymptomatic adults, according to the authors. They predict that future utilization growth will arise from virtual CT colonoscopy, CT lung cancer screening, cardiac screening, and whole-body screening.

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