A groundbreaking new study published in the prestigious New England Journal of Medicine has cast light on the subtle but meaningful risks associated with radiation exposure from medical imaging in children and adolescents. Spearheaded by researchers at the University of California and supported by the National Cancer Institute, this extensive investigation quantitatively links ionizing radiation from diagnostic procedures, notably CT scans, with an increased—but still small—risk of blood cancers among pediatric populations. Despite these findings, experts emphasize that the lifesaving benefits of medical imaging vastly outweigh the minimal risks when scans are justified and performed with advanced dose-reduction techniques.
At the heart of this landmark study is the pioneering work of Dr. Wesley Bolch, a distinguished professor in biomedical and radiological engineering at the University of Florida. Dr. Bolch and his team utilized a sophisticated library of three-dimensional computerized whole-body anatomical models to recreate bone marrow radiation doses in over 3.7 million pediatric patients who underwent CT imaging from 1996 to 2016. These virtual patient representations, meticulously tailored across various ages, heights, weights, and sexes, allowed for an unprecedentedly precise organ-dose reconstruction—a crucial innovation that significantly surpasses previous risk assessments relying on outdated or indirect data sources.
Historically, models estimating cancer risk from radiation exposure heavily leaned on epidemiological data from atomic bomb survivors in 1945 Japan. However, Dr. Bolch insightfully points out that medical X-ray examinations differ dramatically from atomic radiation in intensity, duration, and distribution. This critical distinction underscores the originality of this study, which for the first time in U.S. and Canadian history, incorporates individual patient variables such as body size and imaging parameters to generate personalized dose-risk profiles. Such granular analysis heralds a new era of radiation safety and risk management tailored explicitly to vulnerable pediatric populations.
The comprehensive nature of the study extends beyond CT scans to encompass other commonly used imaging modalities involving ionizing radiation, including nuclear medicine, conventional radiography, and fluoroscopy. By integrating these varied sources into their dosimetric calculations, researchers could provide a holistic mapping of cumulative bone marrow doses. Notably, CT scans of the head and neck region were associated with the highest average bone marrow doses, reaching approximately 30.8 milligray, while standard head CT scans delivered an average dose near 13.7 milligray. Importantly, fewer than 1% of these millions of children received cumulative doses exceeding this threshold, underscoring the rarity—yet potential significance—of higher exposures.
Dr. Bolch contextualizes these findings against a backdrop of evolving radiologic practice. The study calls back to a watershed moment 25 years ago when Columbia University researchers revealed a connection between pediatric leukemia and radiologic imaging doses. That report sparked widespread concern, primarily because imaging protocols at the time neglected vital adjustments for patient size, resulting in infants or small children inadvertently receiving radiation doses calibrated for adults, sometimes far exceeding necessity. In previous decades, for example, a petite seven-year-old girl might receive the residual high-intensity X-ray settings configured for a preceding obese adult male patient, dramatically increasing her radiation dose beyond what was needed for diagnostic clarity.
Recognizing these early inadequacies, the medical community initiated vital reforms in the early 2000s. Radiologists and imaging technologists began to carefully tailor X-ray beam energy and intensity settings based on individual patient characteristics, significantly mitigating unnecessary exposure. Concurrently, CT manufacturers introduced cutting-edge hardware and software solutions that drastically lowered doses without sacrificing image quality or diagnostic accuracy. Today, pediatric CT imaging is faster, more precise, and far safer than in previous decades, benefits that this study helps quantify and validate.
The meticulous data collection underpinning this research was orchestrated by lead authors Dr. Rebecca Smith-Bindman, a radiologist and epidemiologist from the University of California, San Francisco, alongside Dr. Diana Miglioretti, a biostatistician at UC Davis. This collaborative team aggregated and harmonized millions of medical records detailing each patient’s imaging history—when scans were performed, specific imaging modalities used (CT, radiography, nuclear medicine, or fluoroscopy), and acquisition parameters. Crucially, their epidemiological work established vital linkages between these records and cancer registries, identifying patients who later developed bone marrow or hematologic malignancies.
Dr. Bolch’s laboratory then deployed advanced computer simulations replicating every imaging procedure to estimate organ-specific radiation doses for each child. These dose reconstructions considered the diversity of imaging techniques, patient anatomy, and technology evolution over two decades, providing a dynamic, patient-centric risk profile. The complex computational models reflect a new frontier in medical physics, enabling clinicians to balance minimal radiation exposure against the imperative to detect and diagnose disease early and accurately.
The study’s findings are both scientifically compelling and clinically reassuring. While a detectable correlation between radiation dose and hematologic cancer risk exists, the absolute risk increase remains very low from a population perspective. For instance, among children with bone marrow doses exceeding 30 milligray, the incidence of blood cancers by age 21 was only 0.3%. Given the small fraction of pediatric patients reaching this level of exposure (less than 1%), the overall risk remains minimal. Moreover, ongoing technological innovations and stricter imaging protocols will likely further reduce these numbers in the future.
Beyond the science, this research embodies a crucial message for parents, physicians, and radiologists alike: fear should not deter medically indicated imaging that can guide life-saving diagnoses and treatments. Instead, it highlights the responsibility of healthcare providers to meticulously justify imaging exams, adopt dose-optimization techniques, and remain vigilant about radiation safety, particularly in the sensitive pediatric population. The synergy of technological progress, rigorous scientific evaluation, and clinical prudence promises a future where diagnostic imaging is both safer and more effective.
This study also underscores the role of academic institutions like the University of Florida in advancing patient safety through cutting-edge biomedical engineering research. Dr. Bolch’s leadership and the innovative methodologies developed at his Advanced Laboratory for Radiation Dosimetry Studies showcase how interdisciplinary collaboration and computational modeling can transform healthcare practice. The study’s impact extends beyond North America, offering a data-driven framework that can inform global guidelines and standards for pediatric imaging safety.
In sum, while the specter of radiation-induced cancer risk understandably evokes concern, this comprehensive new evidence offers a nuanced narrative balancing risk and benefit with unprecedented clarity. Continued research, technology enhancements, and clinical vigilance will ensure that imaging remains a vital diagnostic tool that maximizes patient benefit while minimizing harm, particularly for children and adolescents whose health trajectories depend on the precision and safety of these modern medical modalities.
Subject of Research: Radiation exposure from medical imaging and pediatric hematologic cancer risk
Article Title: Medical Imaging and Pediatric and Adolescent Hematologic Cancer Risk
News Publication Date: 17-Sep-2025
Web References:
New England Journal of Medicine DOI 10.1056/NEJMoa2502098
Keywords: Cancer risk; Pediatrics; Computerized axial tomography; Medical imaging; Hematologic cancers; Radiation dosimetry
