Medical Imaging Radiation Exposure for Children with Down Syndrome

Children with Down syndrome are frequently subjected to intensive medical procedures, including imaging, which may involve the use of ionizing radiation. At the same time, genetic abnormalities such as Down syndrome have been linked to an increased risk of certain cancers, making early radiation exposure less than optimal. Until recently, there had been minimal research into the typical imaging radiation exposure rates for children with Down syndrome.

Those rates of exposure are quantified in a recent study conducted by UC Davis Health experts. Emily C. Marlow, a former epidemiology doctorate student at UC Davis and current postdoctoral researcher at the American Cancer Society, is the author of the paper.

“Medical Imaging Utilization and Associated Radiation Exposure in Children with Down Syndrome,” a PLOS ONE journal article, reveals her research team’s analysis of a decade’s worth of data from over 4 million children’s medical records at six U.S. health care systems. They discovered that children with Down syndrome had nearly ten times the number of medical imaging examinations as normal children, which has implications for their lifelong cancer risks.

The study’s principal author is Diana Miglioretti, a cancer center researcher and professor and division chief of biostatistics at the UC Davis School of Medicine. She claims that this is the first study of its sort to use a big, comprehensive data set to quantify radiation exposure from medical imaging in Down syndrome infants.

Down syndrome and ionizing radiation

Ionizing radiation can be found in a variety of medical imaging, including chest X-rays and nuclear medicine. People are also exposed to modest levels of background radiation from the sun, the atmosphere, and other sources. Other routinely used scans, such as MRIs and ultrasounds, do not require radiation.

While ionizing radiation can assist doctors in detecting sickness within the body, repeated exposure to radiation from any source can increase one’s cancer risk. Because the danger of cancer from radiation exposure in medical imaging is extremely low, required medical scans should not be ignored.

The researchers were concerned about children with Down syndrome, who may be more susceptible to radiation because they are already at a higher risk of acquiring cancer. For example, Marlow’s research confirmed the substantial link between leukemia risk and Down syndrome.

People with Down syndrome may have extensive medical imaging at an early age since they frequently have additional diseases such as congenital heart disease and musculoskeletal abnormalities. Furthermore, medical imaging rates for all children in the United States have risen over time. Although imaging is useful for diagnosing medical problems, the researchers wanted to learn more about the differences in radiation exposure between children with and without Down syndrome.

“For children with Down syndrome, specifically, we’re seeing an increase in CT imaging and angiography, both of which have a relatively high dose of radiation—many times more than standard radiographs,” Marlow explained.

Miglioretti’s interest is to minimize any harms of medical imaging and her biggest concern for children with Down syndrome is CT (computerized tomography) scans. Leukemia is one of the most sensitive cancers to radiation, with one of the shortest times to develop it. “We are concerned that children with Down syndrome might be more sensitive to developing leukemia from radiation exposure,” she said.

Options for patients with Down syndrome

Between 1996 and 2016, medical data from six US health care systems were used in the retrospective cohort study. It includes 4,348,226 patients, including 3,095 children with Down syndrome.

The researchers looked at the radiation dose received into a child’s red bone marrow, which they approximated using patient data from medical scans, as the key risk of radiation exposure because of its link to leukemia.

They discovered that children with Down syndrome were considerably more likely than other children to be exposed to ionizing radiation. They got imaging at 9.5 times the rate of other children before the age of one year, and at 2.3 times the rate of other children between the ages of one and eighteen.

Though risks of developing cancer from medical imaging are small, the researchers suggest some caution. “There are always pros and cons to medical imaging,” Marlow said.

For example, using a CT scan for a noncommunicative child can be far easier than expecting them to lay still for an MRI. “Doctors and parents just need to take into account how frequently the child is being exposed,” she added.

“The message we want to convey is that medical imaging should be used judiciously,” said study co-senior author Rebecca Smith-Bindman, a professor of epidemiology and biostatistics and director of the Radiology Outcomes Research Laboratory at UC San Francisco. “Physicians and parents should work together to ensure that imaging is used only when there is clear need for additional information that imaging can provide, and that the potential benefit justifies the additional risk.”

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