Significant Reduction in Adult CT Radiation Doses Over the Past Decade

A recent study, published in Radiology, highlights a notable decline in radiation doses for adult computed tomography (CT) scans in the United States over the past decade. This research, led by Dr. Kalpana M. Kanal and colleagues, utilized data from 2025 to update the national Diagnostic Reference Levels (DRLs) and Achievable Doses (ADs) for common adult CT examinations.

The study analyzed approximately 5.2 million CT acquisitions from 592 facilities, nearly quadrupling the sample size of the previous analysis in 2014. Facilities included a diverse mix of imaging centers, hospitals, and academic institutions across various locations. The results revealed that the national volume CT dose index (CTDIvol) DRLs decreased by 21.8%, and ADs by 9.3%, compared to the benchmarks set in 2014. The research highlights the largest reductions in chest examinations with contrast material at 31.2% and those without contrast material at 26.7%.

This study employed a modern methodology that allows for near–real-time updates to national benchmarks. This approach is size-normalized and acquisition-level specific, addressing limitations from earlier methods. The size-specific dose estimates (SSDEs) were calculated using standardized water-equivalent diameter (WED) derived from axial CT images, allowing a more accurate assessment of patient dose variations across different sizes.

These updated benchmarks come at a crucial time, as advances in CT technology—including iterative and machine learning-based reconstruction methods—continue to evolve, warranting the regular reassessment of radiation dose benchmarks. The methodology developed for this study enables a scalable framework for updating these standards more rapidly, thus reflecting current technology and clinical practice.

In summary, this study represents a significant advancement in the field of radiology by setting a precedent for how national benchmarks can be updated promptly and adjusted to align with technological changes. It marks a critical step forward in ensuring patient safety while maintaining diagnostic efficacy in CT imaging.