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Children who receive computed tomo-graphy (CT) scans may be exposed to excess radiation that can increase their cancer risk later in life, according to a study published in the American Journal of Roentgenology (AJR) (2001;176:289-296). Thus, according to the investigators, while the benefits of CT scans still outweigh the risks, radiation doses should be lowered to protect children from unnecessary radiation. 

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Figure  . Cancer risk and CT scans in children

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Lead researcher David J. Brenner, PhD, professor of radiation oncology at Columbia University in New York City, says about 1.6 million children under the age of 15 undergo CT scanning of the head or abdomen every year in the US, and an estimated 1,500 of them may eventually die from a cancer that was caused by excess radiation.

Children's Cells Divide More Rapidly

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  2. Children's Cells Divide More Rapidly
  3. Same Benefit, Less Risk

“Children are more sensitive to radiation than adults because their cells are dividing more rapidly, and radiation has the potential to damage the DNA that controls that division,” Brenner says.

Brenner is quick to explain, however, “We're not talking about a situation where a child should not have a CT scan. We're trying to estimate what the long-term risks are, and the answer is they're pretty small, but potentially they might be reduced even more by lowering the radiation exposure in childhood CT scans.”

Other researchers writing in the same issue of AJR say too many institutions do not adjust radiation dosage when scanning children.

A team led by Lane F. Donnelly, MD, a radiologist at Children's Hospital in Cincinnati, reviewed CT scans performed on all the pediatric patients referred to the facility in a recent eight-month period. The scans were performed at the referring institutions. “Our survey asked whether there were any adjustments being made when children were scanned, and the conclusion was that there really weren't—that most kids were being scanned with parameters suitable for adults,” Donnelly reported.

Radiologists can reduce CT radiation to an appropriate level for children by adjusting the tube current and the pitch (which influences the exposure time). “In many instances, we are able to use five or six times less radiation compared to the adult dosage, and we get just as good a picture,” Donnelly notes.

Same Benefit, Less Risk

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  2. Children's Cells Divide More Rapidly
  3. Same Benefit, Less Risk

Charles Land, PhD, senior investigator in the radiation epidemiology branch of the National Cancer Institute, supports the idea of adjusting CT scans to reduce the amount of radiation to which children are exposed. “I would agree with Brenner that the procedures are beneficial and the benefits outweigh the risks, but if you can have the same benefit for less risk, then by all means, do it.”

Brenner estimates childhood radiation exposure adds about one-third of 1% to the lifetime risk of dying from cancer.