Occupational exposure to ionizing radiation remains an important radiation-protection concern among diagnostic radiology personnel because repeated low-level exposure may accumulate over time. Continuous personnel monitoring is therefore essential for evaluating occupational exposure and maintaining radiation doses As Low as Reasonably Achievable (ALARA). This study assessed occupational radiation exposure levels among radio-diagnostic personnel in four specialist hospitals in Northwestern Nigeria and evaluated temporal variations and inter-centre differences in personnel dose. A longitudinal prospective study was conducted from March 2024 to March 2025 among occupationally exposed radiology personnel at Murtala Muhammad Specialist Hospital, Kano; Federal Medical Centre, Katsina; Rasheed Shekoni Federal University Teaching Hospital, Dutse; and Federal Medical Centre, Birnin Kudu. Personnel radiation doses were monitored quarterly using calibrated TLD-100 thermoluminescent dosimeters. Environmental radiation surveys were conducted concurrently to assess ambient radiation levels during background and routine equipment operation. Deep dose equivalent, Hp(10), and shallow dose equivalent, Hp(0.07), were evaluated from the quarterly dosimetric records. Descriptive statistics were used to determine dose distributions, while one-way analysis of variance (ANOVA) was employed to assess differences in occupational dose among the four study centres at a significance level of p < 0.05.
Ambient background radiation levels across the study centres ranged from 0.10 to 0.11 μSv/h. During equipment operation, the highest measured ambient radiation level was 0.148 μSv/h in the X-ray room at Rasheed Shekoni Federal University Teaching Hospital, Dutse. The mean quarterly Hp(10) values were 0.456, 0.914, 0.336, and 0.582 mSv for the first, second, third, and fourth quarters, respectively, giving a mean annual cumulative Hp(10) of 2.288 mSv. Corresponding mean quarterly Hp(0.07) values were 0.284, 0.252, 0.217, and 0.319 mSv, respectively, with a mean annual cumulative Hp(0.07) of 1.072 mSv. The highest individual annual cumulative Hp(10) was 3.92 mSv, while the lowest was 0.14 mSv. All monitored personnel therefore remained substantially below the occupational dose limit of 20 mSv per year recommended by the International Commission on Radiological Protection (ICRP) and adopted within Nigerian radiation-protection requirements. The quarterly Hp(10) values showed temporal variation, with the highest mean dose occurring during the second quarter. One-way ANOVA indicated no statistically significant difference in mean occupational radiation dose among the four study centres (F = 0.4616, p = 0.7126) at α = 0.05.
The findings demonstrate that occupational radiation exposure among the monitored radio-diagnostic personnel remained well below the recommended annual occupational dose limit throughout the study period. The relatively low environmental radiation levels and absence of statistically significant differences among the participating hospitals suggest generally comparable radiation-protection conditions across the study centres. Continued personnel dosimetry, effective shielding, appropriate use of personal protective equipment, staff awareness, and consistent application of the ALARA principle are recommended to sustain occupational radiation safety and prevent unnecessary cumulative exposure among radio-diagnostic personnel in Northwestern Nigeria.
Keywords: Occupational radiation exposure; TLD-100; Hp(10); Hp(0.07); radio-diagnostic personnel; radiation protection; ALARA; Northwestern Nigeria; environmental radiation; occupational dose.
Citation: Anzaku, P. E., Bichi, T. S., Hikima, M. S., & Kabo, N. S. (2026). Assessment of occupational Radiation Exposure Levels and Temporal Patterns Associated with Radio-Diagnostic Activities in Four Specialist Hospitals in Northwestern Nigeria. I J T C Physics, 7(2):1-15. DOI : https://doi.org/10.47485/2767-3901.1077