Assessment of Occupational Radiation Exposure of Medical Radiation Workers at Usmanu Danfodiyo University Teaching Hospital, Sokoto, Nigeria

Abstract

The routine use of ionising radiation in diagnostic and therapeutic medicine creates the potential for cumulative occupational exposure among health-care workers. Comprehensive dosimetric surveillance is essential for regulatory compliance and for guiding radiation protection practice, yet data from tertiary hospitals in north-western Nigeria remain limited. To assess occupational radiation exposure levels in the Radiotherapy, Radiology, and Dental departments of Usmanu Danfodiyo University Teaching Hospital (UDUTH), Sokoto, and to estimate associated lifetime cancer risks. Sixty-three Thermoluminescent Dosimeters (TLDs), read on a Harshaw 4500 system, were distributed across three departments: 19 in Radiotherapy, 30 in Radiology, and 14 in Dental. Quarterly whole-body doses were recorded over five years (2014-2018). Key parameters computed included Average Annual Effective Dose (AAED), Annual Collective Dose (ACD), Individual Dose Distribution Ratio (NRE/SRE), and Cancer Lifetime Risk (LFTR) per the BEIR VII (2006) model. Statistical analysis was performed using SPSS v21.0 (one-way ANOVA, Tukey HSD post-hoc test). AAED 1.35 ± 0.73 mSv, ACD 25.66 man•mSv. Radiology workers: AAED 1.13 ± 0.51 mSv, ACD 33.90 man•mSv. Dental workers: AAED 0.76 ± 0.61 mSv, ACD 10.64 man•mSv. Dose distribution analysis revealed that 91.89% of Radiotherapy workers, 46.88% of Radiology workers, and 40.27% of Dental workers received doses exceeding 1 mSv annually. No worker exceeded 10 mSv. Cancer lifetime risk estimates (LFTR) remained below 70% (ERR model) and 50% (EAR model) per BEIR VII, indicating low risk. All recorded doses were well within the ICRP-recommended annual occupational limit of 20 mSv, and dose trends indicated a progressive decline. These findings affirm the adequacy of existing radiation protection protocols at UDUTH, while emphasizing the ongoing importance of dosimetric surveillance and the ALARA principle.