Radiation Exposure from Medical Imaging May Drive One in Ten Childhood Blood Cancers, Major Study Finds

A landmark study led by researchers at UC San Francisco and UC Davis has found that radiation exposure from medical imaging—including CT scans—may be responsible for up to 10% of blood cancers in children and adolescents in North America. Published in September 2025 in The New England Journal of Medicine, the research analyzed nearly 4 million pediatric medical records from the United States and Canada between 1996 and 2016 to investigate the link between imaging-associated radiation and the development of cancers such as leukemia and lymphoma.

Key Findings: Study Design and Outcomes

Researchers conducted a retrospective cohort analysis, tracking 3.7 million children and adolescents across several health care systems. Over an average follow-up of 10 years per child, nearly 3,000 cases of hematologic cancers—including leukemia and lymphoma—were observed. The study found:

• Approximately 10.1% (95% CI, 5.8–14.2) of blood cancers could be attributed to radiation exposure from diagnostic medical imaging, with the highest risks linked to high-dose modalities like CT scans.

• Structural imaging using CT scans, particularly of the head, conferred a quarter of these attributable cases, far more than standard X-rays, which delivered much lower radiation doses.

• Just one or two head CT scans corresponded to a 1.8-fold increased cancer risk, rising to 3.5-fold for children who underwent more scans.

• Cancer risk increased with cumulative radiation dose: relative risk of 1.41 for 1-5 mGy, 1.82 for 15-20 mGy, and 3.59 for 50-100 mGy exposures to bone marrow.

• Lymphoid malignancies accounted for 79.3% of cases, with myeloid cancers making up 15.5%; 58% of all cancers occurred in males, and half were diagnosed under age five.

Expert Perspective: Commentary on Findings

“Children are particularly vulnerable to radiation-induced cancer due to their heightened radiosensitivity and longer life expectancy,” explained Dr. Rebecca Smith-Bindman, lead author and radiologist 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.” The study’s senior authors stressed the importance of imaging only when clinically essential and advocated for using the lowest effective radiation dose.

Independent experts also responded to the research. Dr. Alan Cohen, pediatric hematologist not involved in the study, commented, “The results offer compelling evidence of a dose-dependent relationship between ionizing radiation from imaging and blood cancers, reinforcing prior data while filling gaps specific to North American populations. Pediatricians and radiologists must balance the urgent need for diagnosis with every effort to limit unnecessary exposure.”

Context: Why Medical Imaging Is Both Vital and Risky

Medical imaging, including CT scans and X-rays, is indispensable for diagnosing life-threatening conditions, such as head trauma, suspected tumors, heart defects, or lung problems. Yet ionizing radiation, especially from CT, carries a known cancer risk—more so in children, whose bodies are still developing and more susceptible to DNA damage.

Alternatives such as ultrasound and MRI do not use ionizing radiation and may be safer choices in many clinical contexts. The study urges clinicians to opt for these methods where possible and to follow best-practice guidelines that reduce or even eliminate avoidable scans.

Implications: Impact on Clinical Practice and Public Health

Findings from the study suggest:

• Calculated reductions in unnecessary imaging and optimization of dose protocols could potentially prevent up to 10% of pediatric blood cancers.

• In many cases, switching to non-ionizing imaging modalities (MRI, ultrasound) is feasible without sacrificing diagnostic accuracy.

• The American Association of Physicists in Medicine and pediatric specialists have long advocated for “as low as reasonably achievable” (ALARA) radiation doses, particularly in young patients.

• Parents and clinicians should discuss the necessity of each imaging test, weighing benefits against risks, and seek facilities that adhere to pediatric safety standards.

Limitations: Cautions and Counterarguments

While the study is robust, some limitations remain:

• As a retrospective cohort, direct causation cannot be confirmed; confounding factors may have influenced risk.

• The study did not measure the effects of very low-dose imaging or account for genetic predispositions to blood cancers.

• Some recent studies suggest that a single CT scan might not significantly increase the risk, highlighting the importance of cumulative exposure in driving risk rather than isolated instances.

• Despite potential risks, imaging often remains medically necessary, and withholding scans in urgent cases could be dangerous.

Practical Implications for Families and Clinicians

For families:

• Always ask health care providers if a scan is essential and whether non-radiation alternatives are available.

• If imaging is necessary, ensure the center uses pediatric safety protocols and the lowest effective dose.

For health care professionals:

• Evaluate necessity of each imaging order and consider alternatives.

• Employ standardized dose reduction strategies for pediatric imaging.

• Educate parents about benefits and risks of diagnostic imaging.

Conclusion: Balanced, Responsible Health Reporting

This research provides strong evidence that judicious use of medical imaging—paired with vigilant dose management—can reduce the burden of childhood blood cancers, protecting the youngest patients’ health without compromising the diagnostic power of modern medicine.

Medical Disclaimer: This article is for informational purposes only and should not be considered medical advice. Always consult with qualified healthcare professionals before making any health-related decisions or changes to your treatment plan. The information presented here is based on current research and expert opinions, which may evolve as new evidence emerges.

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