Establishment of the first National diagnostic reference levels by clinical indication for adult head computed...

The widespread and growing use of computed tomography (CT) in emergency care across Morocco has raised critical concerns about radiation safety, particularly in the absence of national Diagnostic Reference Levels (DRLs). Without DRLs tailored to specific clinical indications, it becomes difficult to identify unjustified dose variations and ensure safe practices. This study aims to establish Morocco's first national, clinical indication-based DRLs for adult head CT examinations, promoting radiation dose optimization and alignment with international safety standards.

A retrospective multicenter analysis was performed on 1,299 adult head CT examinations across 20 Moroccan hospitals. Clinical indications were categorized into seven groups: stroke, acute neurological symptoms, post-contrast imaging (tumor/abscess), CT angiography, oncology planning, sinus and temporal bone imaging. Key parameters and dose metrics were extracted and the 75th percentile (third quartile) of volumetric CT dose index (CTDIvol) and dose-length product (DLP) distribution per indication was used to propose DRLs.

DLP varied significantly across protocols (highest: oncology [1794.8 ± 128.8 mGy·cm]; lowest: temporal bone [398.4 ± 20.3 mGy·cm]). Geographic disparities emerged, with Agadir (2211 mGy·cm) and Al Hoceima (2204 mGy·cm) showing the highest doses versus Dakhla (790 mGy·cm). Stroke DLPs (880.7 ± 70.5 mGy·cm) were lower than some international benchmarks, reflecting protocol and regional differences in Moroccan practice.

The study establishes the first set of national, indication-specific DRLs for adult head CT. These benchmarks provide a foundational tool for dose optimization, helping radiology departments evaluate current practices, reduce unnecessary exposure and promote compliance with international guidelines.