Evaluating CT Dose Variation Across Scanner Technologies: Implications for Compliance with New CMS CT Radiation Dose Measure.

Abstract

Rationale and objectives: In 2025, the Centers for Medicare and Medicaid Services introduced a computed tomography (CT) dose measure for pay-for-performance programs. Hospitals employ diverse scanner fleets, but the impact of scanner technologies on dose benchmarking remains unclear. This study evaluates dose variation across scanner models and its benchmarking implications.

Materials and methods: A retrospective analysis examined CT exams from January to December 2023 at a quaternary-care hospital, focusing on median-sized adults (water-equivalent diameter: 16-19cm head, 18-22cm neck, 29-33cm torso). Dose indices from seven scanner models across eight adult exams were evaluated. The 50^th and 75^th percentile doses were calculated per exam and scanner model combination, compared to American College of Radiology achievable doses and diagnostic reference levels.

Results: Analyzing 34,166 studies, significant dose variations with scanner models emerged. Head without contrast (N=21,654) had median volume CT-dose-index (CTDI_vol) of 36.1-68.3mGy and dose-length-product (DLP) 704-1307.8mGy·cm; 75^th percentiles were 43.1-69.1mGy and 838.2-1378.1mGy·cm. Chest with contrast (N=3065) showed median CTDI_vol of 6.7-16.1mGy and DLP 263.8-579.7mGy·cm; 75^th percentiles were 8.2-19.5mGy and 329-713.7mGy·cm. Abdomen/pelvis with contrast (N=2740) had median CTDI_vol of 8.8-15.2mGy and DLP 429.3-782.1mGy·cm; 75^th percentiles were 10-18.5mGy and 533.4-941.5mGy·cm. While the number of studies was smaller, five other exams also showed large dose variations across scanner models.

Conclusion: Single-value dose benchmarks ignoring scanner technology may be inadequate, even for similar-sized patients, potentially requiring scanner removal. Incorporating benchmarks with diverse technologies could prevent increased healthcare costs and patient care disruptions.