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Dose-aware 5-star image quality rating in CT: Findings from the IAEA-MGH study
Madan M Rehani1, Vesna Gershan2, Mohak Narang3
1Massachusetts General Hospital (MGH), Harvard Medical School, Boston, USA.
European Journal of Radiology
|August 10, 2026
Summary
A new 5-star system for rating computed tomography (CT) image quality (IQ) is reproducible across institutions. This dose-aware approach identifies optimization opportunities for radiation reduction in diagnostic imaging.
Area of Science:
- Medical Imaging
- Radiology
- Health Informatics
Background:
- Standardized assessment of computed tomography (CT) image quality (IQ) is crucial for optimizing diagnostic accuracy and patient safety.
- Existing IQ assessment methods may not adequately incorporate radiation dose considerations, leading to potential overuse of radiation.
- Multicenter validation is essential to ensure the generalizability of new IQ assessment tools.
Purpose of the Study:
- To assess the feasibility, reproducibility, and operational impact of a structured, dose-aware 5-star CT IQ rating system.
- To evaluate the system's performance across diverse institutions and clinical indications.
- To identify opportunities for radiation dose optimization in CT imaging.
Main Methods:
- A retrospective, multinational study involving 2737 adult CT examinations across six hospitals in five European countries.
- Three radiologists per hospital scored CT images using a standardized 5-star system, considering diagnostic IQ and radiation dose.
- Data on CT scanner type, clinical indication, patient characteristics, CTDIvol, and DLP were collected and analyzed for inter-reader agreement and dose metrics.
Main Results:
- The 5-star rating system demonstrated robust reproducibility, with three-reader concordance up to 93% in standardized centers.
- A significant inverse correlation was found between CTDIvol and star ratings, particularly in larger patients.
- Noise-tolerant examinations (e.g., for pulmonary nodules, kidney stones) showed high radiation exposure, indicating optimization potential.
- Some centers utilized higher-dose protocols, resulting in a prevalence of lower star ratings.
Conclusions:
- The 5-star CT IQ rating system is reproducible and facilitates dose-aware CT optimization.
- Noise-tolerant CT examinations can maintain diagnostic quality at reduced radiation doses, supporting the wider adoption of low-dose protocols.
- The system highlights potential for multinational and manufacturer-level protocol harmonization and guides optimization strategies.