Proposing computed tomography diagnostic reference levels in Jordan: a national multicentre analysis

The increased use of CT has raised concerns about patient radiation exposure. DRLs play a crucial role in optimising radiation dose while maintaining diagnostic quality. In Jordan, the absence of officially established national DRLs across a wide range of CT procedures may contributes to dose variability between healthcare facilities.

A multicentre, retrospective study was conducted across 10 hospitals in Jordan, involving 4310 adult patients (aged 18-96 years). Radiation dose metrics, including volume CTDI_vol and DLP, were collected from PACS and RIS. The proposed national DRLs were derived from the 75th percentile of the distribution of median CTDI_vol and DLP values from each hospital. Stepwise multiple regression analysis was performed to identify factors contributing to dose variability.

Marked dose variations were observed across hospitals. Head routine non-contrast CT demonstrated the highest median CTDI_vol (65 mGy) and DLP (1572 mGy·cm), while high-resolution chest CT exhibited the lowest (CTDI_vol: 12 mGy; DLP: 230 mGy·cm). The product of mAs was identified as the most significant predictor of dose across all CT examinations. When compared to international DRLs, Jordan's CT dose levels were generally within acceptable ranges, though L-spine CT showed higher than average values.

This study proposes the first national DRLs for 14 common CT examinations in Jordan, based on data collected from hospitals across the country. These benchmarks support dose optimisation, promote standardised protocols, and highlight the need for continuous radiographer training. Future initiatives should expand DRL development to paediatric populations and integrate dose tracking into national quality frameworks.