Establishing local diagnostic reference levels for high-resolution chest CT in the Gaza Strip during the COVID-19 pandemic

Chest computed tomography (CT) was widely used during the COVID-19 pandemic, particularly where access to laboratory testing was limited. Its associated radiation exposure necessitates dose optimization through Diagnostic Reference Levels (DRLs). This study establishes the first local DRLs for high-resolution, non-contrast chest CT in the Gaza Strip and compares them with international benchmarks. A retrospective multicenter study was conducted on 600 adult patients scanned between September 2020 and December 2022 at three major hospitals using identical 64-slice multidetector CT systems (Philips Brilliance) and standardized protocols. The third-quartile values of the volume CT dose index (CTDIvol) and dose-length product (DLP) were used to define local DRLs, following International Commission on Radiological Protection recommendations (ICRP). The DRLs were 9.4 mGy for CTDIvol and 277 mGy cm for DLP. The CTDIvol was comparable to values in Norway (9 mGy), Saudi Arabia (8 mGy), and Taiwan (7.7 mGy), but lower than those reported in India (12 mGy), Canada (14.1 mGy), Nigeria (17 mGy), and South Africa (32 mGy). Similarly, the DLP was lower than Nigeria (735 mGy cm), Malaysia (600 mGy cm), South Africa (593 mGy cm), and Canada (521 mGy cm), while close to Norway (300 mGy cm) and Saudi Arabia (355 mGy cm). These findings show that Gaza's DRLs are well aligned with international standards despite resource limitations. Establishing these benchmarks marks a critical step toward radiation safety, protocol harmonization, and the creation of national CT guidelines in Palestine, supporting optimized imaging practice while safeguarding patients.