Impact of tailored feedback on optimization and radiation dose reduction in coronary CT angiography: a comparative survey between 2021 and 2023 in Mie prefecture.

Purpose: Despite advances in dose-reduction strategies for coronary CT angiography (CCTA), a 2021 regional survey in Mie Prefecture revealed that the 75th percentile CT dose index volume (CTDIvol) remained 48 mGy-lower than Japan's 2020 diagnostic reference level (66 mGy), yet substantially exceeding international benchmarks (~ 25 mGy). Tailored feedback based on Society of Cardiovascular Computed Tomography (SCCT) guidelines was disseminated to each institution in 2022. This study aimed to evaluate the impact of these intervention on cardiac CT practice in Mie Prefecture in 2023.

Materials and methods: Institutions with 64-row or greater multidetector CT scanners across Mie Prefecture were invited; 17 hospitals ultimately enrolled. Each site provided CCTA scan protocols and radiation dose data from 20 to 30 consecutive patients aged 20-80 years and weighing 50-70 kg. Examinations performed for coronary artery bypass graft evaluation or aortic valve assessment were excluded. Imaging parameters and radiation dose metrics were compared with a 2021 pre-feedback survey.

Results: Data from 487 patients (median age: 71 years, 62% male) were analyzed. Of the 16 institutions participating in both surveys, 88% (14/16) modified protocols. Prospective ECG-triggered scanning increased (47-68%), retrospective scanning decreased (46-18%), and adoption of low tube potential rose (33-67%). The 75th percentile CTDIvol decreased from 48 to 31 mGy. No increase in adverse events or image quality deterioration was observed; rather, image quality exhibited an upward trend.

Conclusion: Tailored regional feedback substantially improved CCTA radiation practices in Mie Prefecture, achieving significant dose reductions without compromising image quality or requiring equipment upgrades. These findings may inform protocol optimization efforts nationwide.