Dose-aware 5-star image quality rating in CT: Findings from the IAEA-MGH study

To evaluate the feasibility, reproducibility, and operational impact of a structured, dose-aware 5-star CT image quality (IQ) rating system across multiple institutions and clinical indications.

This retrospective, multinational, IAEA study included 2737 adult (1247 chest, 1490 abdomen) CT examinations across six hospitals in five countries of Europe. Three radiologists per hospital scored CT images using a standardized 5-star system designed to evaluate diagnostic IQ with consideration of radiation dose. Data collected included CT scanner type, clinical indication, patient characteristics, CTDIvol, and DLP. Inter-reader agreement, concordance of star ratings, and dose metrics were evaluated per hospital and clinical indication.

The rating framework demonstrated robust reproducibility, with three-reader concordance reaching up to 93% in highly standardized centers and complete discordance remaining exceptionally rare (1.6% cases overall). A compelling inverse correlation between CTDIvol and star ratings was observed, especially for larger patients. Analysis by clinical indication revealed that some intrinsically noise-tolerant exams (for pulmonary nodules and kidney stones) showed high radiation exposure, highlighting an opportunity for optimization. Certain centers used higher-dose protocols, heavily skewing toward 2-star ratings.

The 5-star CT IQ rating system is reproducible and supports dose-aware CT optimization. Noise-tolerant examinations should maintain diagnostic quality at lower radiation dose, supporting wider use of low-dose protocols. The method highlights opportunities for multinational and manufacturer-level protocol harmonization and may guide optimization strategies, including the number of series and reconstruction approaches.