Study Links Pediatric Medical Imaging to Small but Measurable Increase in Blood Cancer Risk

New research published in the New England Journal of Medicine adds weight to long-standing concerns about radiation exposure in children, finding that medical imaging during childhood may contribute to the later development of hematologic cancers.

The population-based study analyzed the health records of more than 3.7 million children born between 1996 and 2016. Over a median follow-up period of roughly a decade, nearly 3,000 cases of blood cancers were identified. Researchers estimate that more than 10% of those cases could be attributed to radiation from medical imaging—particularly CT scans.

Although the absolute risk is small, the team observed a clear dose–response relationship between cumulative radiation exposure and cancer incidence. Children exposed to less than 15 mGy were about 1.4 times more likely to develop blood cancer than peers who had not undergone imaging. At higher exposures—50 to 100 mGy—the risk increased more than threefold. For context, a single CT scan of the head or neck delivers an average dose of 13.7 mGy.

Most cancers observed were lymphoid malignancies (79.3%), followed by myeloid cancers, primarily acute leukemia (15.5%), and histiocytic or dendritic-cell cancers (4.4%). Children who eventually developed blood cancer had received an average radiation dose of 24.5 mGy, compared with 14 mGy among exposed children who did not develop malignancy.

“While imaging can be lifesaving and often essential for diagnosis, our findings underscore the importance of using it judiciously and with the lowest possible radiation dose, especially in children,” said lead author Rebecca Smith-Bindman, MD, professor of epidemiology and biostatistics at the University of California, San Francisco.

The study builds on earlier work by Smith-Bindman and colleagues, including a 2023 JAMA analysis that modeled the population-level effects of CT use in adults. That research projected that roughly 100 million CT scans performed annually in the U.S. could contribute to more than 100,000 new cancer cases each year—about 5% of the nation’s total cancer burden. Unlike that study, which relied on statistical modeling, the current work directly ties pediatric exposure to subsequent outcomes, reinforcing concerns about cumulative dose in younger patients.

The authors emphasized that while the relative risks are significant, the overall contribution of imaging to pediatric cancer incidence remains small. Even so, the findings highlight the need for strict adherence to best practices in radiation safety. This includes reserving imaging for situations in which results are expected to influence management, tailoring protocols to minimize exposure, and exploring non-ionizing alternatives such as ultrasound or MRI whenever feasible.

“These data make it clear that careful justification and dose optimization in pediatric imaging are not just best practice—they are critical for long-term health,” Smith-Bindman and colleagues concluded.