Life-Saving But Not Risk-Free: Medical Imaging Linked To Increased Risk Of Blood Cancers In Children, Says Study

A major study led by researchers at UC San Francisco and UC Davis has found that radiation from medical imaging is associated with a significantly higher risk of blood cancers in children and adolescents.

Published in The New England Journal of Medicine, the study examined data from nearly 4 million children and estimated that one in ten blood cancers—approximately 3,000 cases—could be attributed to radiation exposure from medical imaging. The risk increased proportionally with the cumulative radiation dose received by the children.

This is the first large-scale study in North America to quantify the link between medical imaging radiation and hematologic cancers, including leukemia and lymphoma—the most common cancers affecting children and adolescents.

While medical imaging is a critical tool for diagnosis and treatment, many techniques—especially computed tomography (CT) scans—expose children to ionizing radiation, a known carcinogen.

“Children are particularly vulnerable to radiation-induced cancer due to their heightened radio-sensitivity and longer life expectancy,” said Dr. Rebecca Smith-Bindman, lead author and professor of Epidemiology, Biostatistics, and Radiology at UCSF.

“While medical imaging can be lifesaving, our findings underscore the critical need to carefully evaluate and minimize radiation exposure during pediatric imaging to safeguard children's long-term health,” she added.

The research team conducted a retrospective cohort study, analyzing the complete imaging histories of 3.7 million children born between 1996 and 2016, treated at six healthcare systems across the U.S. and Ontario, Canada.

Key findings from the study revealed that CT scans carry the highest risk of radiation exposure due to their higher doses, while chest radiographs (X-rays)—the most common form of imaging—contribute much less to cancer risk because of their lower radiation levels. Among CT scans, head CTs were the most frequently performed. Children who underwent one or two head CT scans had a 1.8 times higher risk of developing blood cancers, and this risk increased to 3.5 times for those who had multiple scans. During the study period, a total of 2,961 hematologic malignancies were diagnosed, with 79.3% being lymphoid malignancies, 15.5% myeloid malignancies or acute leukemia, 58% of cases occurring in boys, and about half diagnosed in children under the age of five.

The researchers estimate that up to 10% of childhood blood cancers could be prevented by reducing unnecessary imaging, using non-ionizing alternatives such as MRI or ultrasound, and optimizing radiation doses when imaging is essential.

“This study provides robust, directly observed evidence of a clear dose-response relationship between radiation from medical imaging and hematologic malignancy risk in children and adolescents,” said Dr. Diana Miglioretti, co-author and chief of Biostatistics at UC Davis Health.

“Our findings align with international research highlighting that children are especially radiosensitive. It's crucial for clinicians to weigh the immediate benefits of imaging against potential long-term health risks and to optimize imaging protocols to minimize radiation exposure.”

The researchers emphasized that the goal is not to avoid imaging altogether, but to use it judiciously—reserving high-radiation imaging for situations where it’s clinically essential and using the lowest effective dose whenever possible.

“Imaging must provide essential information for the child's care, and when it does, every effort should be made to reduce radiation exposure,” said Smith-Bindman.