Nearly one in three CT scans exceed radiation dose thresholds

Clinical takeaway: Work with radiology teams to review CT radiation performance by exam category and target protocols with high rates of above-threshold doses. Individual patients may appropriately require doses above these thresholds, so protocol changes should preserve diagnostic quality and clinician discretion.

CT radiation exposure varies widely, and prior research suggests audit and feedback can reduce doses without compromising diagnostic quality. CMS’s new ExRad measure provides automated feedback on both radiation dose and image noise, helping facilities identify specific opportunities to improve.

Among nearly 784,000 adult CT examinations, 30.7% exceeded category-specific radiation dose thresholds; just 0.06% exceeded image-noise thresholds. Facility-wide percentages of out-of-range examinations ranged from 1.8% to 82.4%, indicating substantial variation among participating sites.

Routine abdomen and pelvis, chest, and head CT accounted for approximately 72% of out-of-range scans despite representing 56% of examinations. Within facilities, the median gap between the best- and worst-performing CT categories was 74 percentage points, suggesting that an overall facility score can obscure protocols needing attention.

Researchers analyzed examinations submitted by 254 facilities across 21 states between May 2025 and August 2026 during voluntary implementation of ExRad. The primary outcome was each facility’s percentage of eligible examinations exceeding size-adjusted radiation dose or image-noise thresholds specific to the body region and clinical indication; these early adopters may not represent US facilities overall.

Future analyses will use broader CMS-reported data to assess representativeness and examine how extra scan phases versus higher doses within individual phases contribute to excessive exposure. As facilities reduce doses, continued monitoring of image noise will be essential; whether implementation reduces cancer incidence requires long-term follow-up.

“Lowering the dose is no longer a technology problem — it's a measurement and feedback problem,” lead author Rebecca Smith-Bindman, MD, said in a press release

Source: Smith-Bindman R, et al. (2026 Nov 2) J Am Coll Radiol. Early Implementation Performance of the CMS Electronic Clinical Quality Measure for Excessive Radiation Dose or Inadequate Image Quality in Diagnostic CT: An Evaluation of 254 Facilities