June 11, 2013
Reducing Kids’ CT Scans Cuts Cancer Rates By 62 Percent
Brett Smith for redOrbit.com - Your Universe Online
Computed tomography (CT) has become an invaluable tool for diagnostic and research purposes, and a new study in the journal JAMA Pediatrics has found that eliminating unnecessary scans and lowering the radiation doses of some scans could lower the risk of developing imaging-related cancers in children by 62 percent.
The study concluded that the 4 million CT scans performed on children in the US each year could lead to approximately 4,900 cancer cases in the future. The researchers also determined that reducing the highest 25 percent of radiation doses could prevent almost 43 percent of these future cancers, while eliminating unnecessary CT scans could prevent another 3,000 future instances of cancer, bringing the total risk reduction to 62 percent.
One of the study´s focuses was the Image Gently initiative, a multi-organizational campaign dedicated to promoting radiation protection during the medical imaging of children.
"We estimated that the number of cancers caused by CT scans performed on children could fall dramatically — by 62 percent — if dose-reduction strategies like that instituted by the Image Gently initiative were targeted to exams with the highest quarter of doses and if CT scans were used only when medically necessary," said lead author Diana Miglioretti, a professor in the Department of Public Health Sciences at the University of California, Davis.
To reach their findings, the team used a new approach for analyzing effective radiation doses developed by the Cancer Institute. They also used models based on studies of the survivors of Hiroshima and Nagasaki to estimate how radiation doses affect the body.
The team determined how radiation was absorbed by each organ and the effective, or overall, dose from 744 CT scans in children conducted between 2001 and 2011 across five different healthcare systems.
"Children tend to absorb more radiation from imaging than adults do, because their bodies are smaller," Miglioretti explained. "And the radiation children absorb will lead to greater harm, because they are more likely than adults to develop cancer from radiation exposure."
However, children's smaller sizes also mean less CT radiation is necessary to produce useful images.
"That's why radiology technologists should use lower settings for children than for adults," Miglioretti said. "But that doesn't necessarily always happen."
"CT scans are extremely useful for diagnosing many conditions in children," added study co-author Dr. Rebecca Smith-Bindman from the radiology department at UC San Francisco. "We need to be judicious in using CT in children because of their greater sensitivity of developing cancer from radiation exposure, and the long life spans ahead of them."
"CT exams should be used only when this information will improve diagnosis and clinical care,” she added.
Smith-Bindman suggests using alternatives to CT scans for some diagnoses, including magnetic resonance imaging (MRI) and ultrasound technologies, which do not use ionizing radiation.
"The most important result of our study is that we can substantially reduce the risk of cancer from CT simply by reducing the doses used at the highest dose range," Smith-Bindman said. "There is rarely any advantage in using such high doses."