Ultra-Low Dose CT Outperforms X-rays in Detecting Fractures, French Study Finds

A large-scale study across five French hospitals has found that ultra-low dose (ULD) CT scans identify fractures more accurately than traditional X-rays, without significantly increasing radiation exposure. The findings could reshape how emergency departments assess trauma patients.

“The diagnostic performance of ultra-low dose CT is very close to standard CT, which was surprising to us,” said Oumaya Ben Said, MD, who presented the research Wednesday. “This approach improves patient care while keeping radiation exposure near that of a conventional X-ray.”

Led by Joël Greffier, PhD, and Maxime Pastor, MD, of the Department of Medical Imaging at Nimes University Hospital, the study evaluated ULD-CT as a first-line imaging tool in the emergency department (ED). The hospital first began using ULD-CT in 2015 for chest imaging and has since expanded it to musculoskeletal imaging for trauma.

Between October 2019 and September 2023, the researchers enrolled 533 adult ED patients with suspected fractures of the spine, pelvis, hip or limbs. Each participant underwent three imaging tests: a standard-dose CT (STD-CT), an ultra-low dose CT, and conventional X-rays. Two radiologists independently reviewed the images, blinded to each other’s results.

Out of the total cohort, 282 patients had at least one fracture. ULD-CT identified fractures with a sensitivity of 95% and specificity of 98%, closely matching the performance of standard-dose CT and vastly outperforming radiography.

“Ultra-low dose CT missed only 13 fractures and produced six false positives,” Dr. Ben Said reported. “By comparison, X-ray missed 81 fractures and had nine false positives, with an overall sensitivity of just 71%.”

Radiologists rated 97% of ULD-CT exams as fully or mostly interpretable, and 91% as high or excellent in diagnostic confidence. Conventional radiographs, on the other hand, were rated only 83% interpretable, with just half considered high in diagnostic confidence.

The performance gains of ULD-CT were seen across all major fracture locations, including the spine, pelvis and limbs. Some limitations were noted in fine-detail areas such as the hands, wrists and feet, but overall results exceeded expectations.

“We expected ULD-CT to outperform X-ray, but its sensitivity and image quality approaching that of standard-dose CT exceeded our expectations,” Dr. Ben Said noted.

While ULD-CT interpretation took slightly longer than X-rays—about 1.3 minutes per exam compared to 0.7 minutes—the researchers emphasized that the improved accuracy may ultimately save time and resources by reducing the need for repeat imaging.

“This method can prevent follow-up scans when X-rays are inconclusive, which is common in trauma care,” Dr. Ben Said added.

The study highlights the value of multidisciplinary collaboration in implementing advanced imaging protocols. The research team plans to conduct a cost-effectiveness analysis to explore replacing standard radiography with ULD-CT in ED settings. They also aim to assess how ULD protocols might integrate with emerging spectral and photon-counting CT technologies.

“This research confirms that ultra-low dose CT is a compelling alternative to standard radiography for trauma patients,” Dr. Ben Said said. “It offers high diagnostic confidence and near-gold-standard performance, while maintaining low radiation exposure. That’s a win for both patients and emergency departments.”