Medical test doubled in use despite link to cancer
In this DML Report…
Head CT scans in U.S. emergency departments increased from 7.8 million in 2007 to nearly 16 million in 2022, rising as a percentage of all ER visits from 6.7 percent to 10.3 percent, according to a Yale School of Medicine analysis of national hospital data. Patients aged 65 and older were most likely to receive these scans, at a rate of 20.6 percent in 2022, accounting for about 36 percent of all head CTs and being six times more likely than those under 18. Scans were more common for those presenting with headaches, stroke symptoms, or seizures, and three times more likely to result in a neurological diagnosis. Disparities exist, with Black patients 10 percent less likely to receive a scan than white patients, Medicaid patients 18 percent less likely due to low reimbursements, and rural hospital patients 24 percent less likely than those in urban areas. Up to one-third of CT scans nationwide are considered medically unnecessary, often used to confirm known information, and the growth shows no signs of slowing.
Radiation from a single head CT scan does not cause cancer, but repeated exposures accumulate and elevate risks, with studies linking at least five to 10 scans before age 15 to tripling the odds of leukemia and brain tumors in children—from a baseline of 1 in 2,000 for leukemia to about 1 in 600. CT scans may contribute to five percent of all U.S. cancers, with risks three to four times higher than earlier estimates, particularly for children, and associated with brain, thyroid, skin, eye, leukemia, and salivary gland tumors. From 1995 to 2008, 74 children and teens developed leukemia and 135 brain tumors linked to repeat scans; in 2023, scans on 2.5 million children could result in 9,700 cancers. Adults aged 50-79 face the highest projected burden, with 93,000 radiation-induced cases in those 50-59, though infants have the greatest per-scan risk while adults receive the most scans overall.
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Head CT scans are essential for diagnosing emergencies like strokes but should only be used when benefits outweigh radiation risks and costs, and if they won't alter treatment, they are likely unnecessary. Neurologists emphasize balancing underuse, which risks missed diagnoses, with overuse, which increases radiation exposure, financial strain, and ER delays. Dr. Layne Dylla, lead author of the Yale study, noted the need for equitable neuroimaging access and evaluation of each scan's appropriateness per clinical guidelines. Alternatives like MRI or ultrasound, which avoid radiation, may be suitable in non-emergency cases.