11/17/2025
Researchers have warned that the modern reliance on CT scans in the United States could carry a measurable long term cancer burden at the population level.
A modeling study published in JAMA Internal Medicine in 2025 examined detailed radiation dose data from the UCSF International CT Dose Registry, which collects anonymized information from 143 hospitals and imaging centers across the country.
Using real world dose distributions and scan types, the team estimated that roughly 93 million CT examinations were performed in 2023 on about 61.5 million patients.
By combining these figures with standard lifetime cancer risk models, they projected that these scans could lead to about 103,000 radiation induced cancers over the coming decades.
The study found that adults received the majority of CT scans, but children faced a higher cancer risk per scan because their tissues are more sensitive to ionizing radiation and they have more years ahead for radiation related cancers to develop.
Only about 4 percent of scans were in children, yet the model suggests those pediatric scans could still result in around 9,700 future cancers.
The largest number of projected cases came from scans of the abdomen and pelvis in adults, which accounted for about 37 percent of the estimated cancers and roughly one third of all CT exams.
Chest CT was the next largest contributor. Overall, the model indicates that if current scanning patterns persist, CT related cancers could eventually represent about 5 percent of all new cancer diagnoses in the United States each year.
It is important to stress that for any individual patient the additional risk from one medically justified CT scan appears to be small, and CT imaging can be life saving.
Randomized evidence from the National Lung Screening Trial, which enrolled 53,454 high risk participants, showed that periodic low dose CT scans reduced lung cancer mortality by about 20 percent compared with standard chest X rays.
This trial is one of the strongest demonstrations that CT based screening can save lives when targeted appropriately.
Medical physicists and radiology societies have also pointed out that the JAMA analysis uses theoretical risk models and that direct clinical studies have not yet demonstrated a clear increase in cancer at the relatively low doses typical of modern CT, especially below cumulative exposures of around 100 millisieverts.
