Medical imaging is one of the most important tools doctors use to diagnose and treat health problems, often saving lives through early detection.
But new research from UC San Francisco and UC Davis has found that radiation from these procedures may come with a cost, particularly for children.
The study, published in The New England Journal of Medicine, looked at the medical records of nearly 4 million children and adolescents across the U.S. and Canada.
The researchers found that about one in ten cases of pediatric blood cancers—around 3,000 in total—may be linked to radiation exposure from medical imaging. The risk grew higher with the amount of radiation children received over time.
Blood cancers, including leukemia and lymphoma, are the most common cancers in children.
The new study is the first in North America to comprehensively measure how radiation from medical imaging is connected to these diseases in young patients.
While imaging such as computed tomography (CT) scans and X-rays can be critical for diagnosis, they also expose patients to ionizing radiation.
This type of radiation can damage DNA and increase the risk of cancer. Children are especially vulnerable because their developing bodies are more sensitive to radiation and they have many decades ahead in which cancers could emerge.
“Children are particularly vulnerable to radiation-induced cancer due to their heightened radiosensitivity and longer life expectancy,” explained Dr. Rebecca Smith-Bindman, a UCSF radiologist and first author of the study.
“Our findings underscore the need to carefully evaluate when imaging is truly necessary and to minimize radiation doses whenever possible.”
The research team used a retrospective design, reviewing imaging histories for children born between 1996 and 2016. These children were treated at six health care systems in the U.S. and Ontario, Canada.
During the study period, 2,961 blood and bone marrow cancers were diagnosed. About 79% of these were lymphoid cancers, while acute leukemia and myeloid cancers accounted for another 15%. Nearly half were found in children under the age of five, and boys made up about 58% of the cases.
The risk varied depending on the type of imaging. CT scans, which are often used to examine the head, brain, or chest, expose children to much higher doses of radiation than standard radiographs (X-rays).
The study found that just one or two head CTs were associated with a nearly doubled risk of developing a blood cancer, while children who had more scans faced a risk more than three times higher.
In contrast, radiographs, such as chest X-rays often used for diagnosing pneumonia or broken bones, contributed to far fewer cases.
Overall, the researchers estimated that reducing unnecessary scans and adjusting radiation doses could prevent up to 10% of pediatric blood cancers. They emphasized that in many cases, safer alternatives such as ultrasound or MRI could be used instead, since these methods do not rely on ionizing radiation.
The researchers stressed that medical imaging remains a valuable tool. But their findings highlight the importance of balancing the short-term benefits of rapid and accurate diagnosis with the long-term risks of cancer.
“This study provides strong evidence of a clear dose-response relationship between medical imaging radiation and blood cancer risk in children,” said Dr. Diana Miglioretti of UC Davis Health, a co-author of the study.
“Clinicians must carefully weigh these risks and ensure imaging is only used when truly necessary, while using the lowest possible doses.”
In short, while medical imaging will continue to play a central role in pediatric care, this research shows the need for greater caution.
Avoiding excessive scans, limiting radiation exposure, and considering safer alternatives could save thousands of children from developing cancer later in life.
