Assessment of the Effects of X-Ray Leakage Exposure in Some Selected Teaching Hospitals in South Western Nigeria

Abstract

Leakage and scattering of X-rays through structural openings such as windows and doors during imaging procedures may lead to unintended exposure, increasing the risk of cancer, tissue and organ damage, and genetic mutations. Radiology personnel are particularly susceptible to these hazards, underscoring the need for continuous monitoring and evaluation of occupational radiation levels. This study aimed to quantify radiation exposure within X-ray rooms and adjoining areas in four selected teaching hospitals: LAUTECH Teaching Hospital (LTH), BOWEN Teaching Hospital (BTH), UNIOSUN Teaching Hospital (UTH), and UNIMED Teaching Hospital (UNIMEDTH). In-situ measurements were conducted using a handheld Radiation Alert Monitor at three standardized locations; the X-ray room, cubicle corridor, and waiting area at a height of 1.2 m, representing the approximate level of vital organs in adults. The estimated annual effective dose equivalent (AEDE) across the hospitals ranged from 0.73 ± 0.13 mSv/yr to 1.45 ± 0.32 mSv/yr, all within the International Commission on Radiological Protection (ICRP) occupational exposure limit of 20 mSv/yr. Radiation distribution patterns in UNIMEDTH, UTH, and BTH indicated effective structural shielding, whereas LTH exhibited significantly elevated exposure levels beside and behind the X-ray room (1.261 and 1.260 mSv/yr, respectively), suggesting potential shielding deficiencies. Overall, the findings show that although measured dose rates comply with international safety standards, localized areas of increased exposure highlight the need for improved shielding and stricter adherence to radiation protection practices. These results provide a vital baseline for enhancing occupational radiation safety and guiding structural optimization within medical imaging environments.

Keywords

Introduction

Plate 1: Radiation Alert Monitor 200

3.1.1 LAUTECH Teaching Hospital

The annual effective dose equivalent estimated at LAUTECH Teaching Hospital for the X-ray room, Beside, front and back of X-ray room and waiting room range from 0.622 mSv/yr to 1.319 mSv/yr with mean value 1.061 mSv/yr which are below ICRP occupational dose limit of 20 mSv/yr and this suggests that radiology staff at this location are not at immediate risk of radiation. LTH presents a more varied pattern. Statistical analysis shows significant differences (P < 0.05) in radiation exposure at the back and beside the X-ray room during multiple comparison tests, while no significant differences were found in the front X-ray room, main X-ray room, and waiting room. The significant P-values suggest localized hotspots of scatter or leakage radiation at the back and side of the X-ray room, possibly due to design weaknesses, equipment positioning, or inadequate shielding in those specific directions. This finding is also consistent with (UNSCEAR, 2020) data which shows that engineering controls (structural design) are the most reliable method of minimizing occupational exposure. Locally, Nigerian studies (Adedeji et al., 2019) have consistently reported challenges such as aging equipment, insufficient shielding, and poor maintenance as major contributors to scattered radiation exposure. The front X-ray room and waiting room, on the other hand, likely benefit from structural shielding and lower occupancy times, keeping exposure levels negligible.

3.1.2 BOWEN Teaching Hospital

The annual effective dose equivalent for all the five locations; X-ray room (1.308 mSv/yr), beside of X-ray room (1.062 mSv/yr), front of X-ray room (0.946 mSv/yr) and back of X-ray room (0.665 mSv/yr) and waiting room (0.876 mSv/yr) at BOWEN teaching hospital. The study shows that the radiation levels around the X-ray department are generally within acceptable limits for public exposure, with a mean value of 0.971 mSv/yr. However, the doses recorded inside and beside the X-ray room exceed the 1 mSv/year public limit, implying the need for restricted access, possible shielding improvements and periodic monitoring. Implementing these measures will ensure that the department fully complies with international radiation safety standards while maintaining a safe environment for both workers and the public.  At BTH, no significant differences in radiation exposure (P > 0.05) were found across all measured areas: X-ray room, front X-ray room, waiting room, and beside X-ray room. This uniformity across high and low-risk zones suggests a high level of structural integrity and shielding efficiency. Even peripheral areas such as the waiting room and beside the X-ray room do not show elevated or variable radiation levels, indicating that scatter radiation is effectively contained. Thus, BTH demonstrates a model radiation safety profile, with both absorbed dose rate and the estimated annual effective dose equivalent being well-managed and statistically uniform across areas of different risk levels.

3.1.3 UNIMED Teaching Hospital

The annual effective dose equivalent estimated across three key areas of the X-ray department at UNIMEDTH; (X-ray Room, Cubicle Corridor, and Waiting Room) demonstrate the variations in exposure levels experienced by workers within (1.261 – 2.243 mSv/yr) with mean value 1.445 mSv/yr, (0.771 – 1.051 mSv/yr) with mean value 0.864 mSv/yr, and (0.420 – 0.701 mSv/yr) with mean value 0.579 mSv/yr respectively. All these radiation levels measured at UNIMEDTH demonstrate overall compliance with international radiation protection standards. The X-ray room shows elevated but occupationally acceptable levels, while the corridor and waiting room remain within safe limits for public exposure. At UNIMEDTH, no statistically significant differences (P > 0.05) in radiation exposure were found among the X-ray room, cubicle corridor, and waiting room. This suggests a homogeneous radiation distribution within these areas, albeit at different dose magnitudes. The X-ray room, being the primary source zone, predictably has the highest radiation levels. However, this is well controlled, often through lead shielding and operational protocols. The cubicle corridor and waiting room are not directly exposed to the primary beam, radiation in these areas arises from scatter or leakage. Despite these differences in function and expected exposure, the lack of significance implies that shielding and structural design are effective in minimizing exposure gradients. This finding is consistent with (UNSCEAR, 2020) data which shows that engineering controls in the sense of structural designs are the most reliable method of minimizing occupational exposure. Locally, Nigerian studies (Adedeji et al., 2019) have consistently reported challenges such as aging equipment, insufficient shielding, and poor maintenance as major contributors to scattered radiation exposure. Therefore, while the X-ray room remains the controlled high-dose area, the equivalent and effective doses in surrounding zones are statistically similar, emphasizing adequate safety measures across UNIMEDTH.

3.1.4 UNIOSUN Teaching Hospital

UTH estimated annual effective dose equivalent for the three locations at radiology department; Waiting Room, Common Room, and Conventional Room demonstrate generally effective radiation protection practices. AEDE range within 0.539–0.939 mSv/yr with mean value 0.731 mSv/yr for the waiting room, 0.771–1.402 mSv/yr for common room with mean value 0.018 mSv/yr, and the conventional room 0.539–1.318 mSv/yr with mean value 0.913 mSv/yr. However, the Common Room exceeds the public dose limit (1 mSv/yr according ICPR) and requires further attention to shielding, occupancy control, or area classification. Overall, the department remains largely compliant with international standards, provided that corrective measures are taken in borderline areas to maintain long-term radiological safety. Similarly, UTH exhibits no significant P-values (< 0.05) in the X-ray room, common room, and conventional room. The X-ray room maintains its role as the primary radiation source but does not statistically differ in exposure levels from adjacent rooms. This uniformity indicates that radiation control protocols are consistently applied, preventing unsafe accumulation in non-primary areas. The Annual Effective Dose across these locations remains within internationally recommended limits of 0.73 ± 0.13 mSv/yr and 1.45 ± 0.32 mSv/yr, depending on the site, showing that personnel and patients are not subject to differential risk based on room usage in UTH. The annual effective dose measured across the radiology units in the hospitals studied ranged between 0.73 ± 0.13 mSv/yr and 1.45 ± 0.32 mSv/yr, depending on the site. These values are well below the ICRP occupational dose limit of 20 mSv/yr averaged over five years and the 50 mSv single-year maximum. While this suggests that radiology staff are not at immediate risk of exceeding internationally accepted dose thresholds, it is important to emphasize that no dose of ionizing radiation is entirely safe because of the stochastic nature of long-term effects such as malignancies (ICRP, 2007).

3.2 General Observations on the Radiology Departments

The variation in measured absorbed dose rates between X-ray rooms and adjoining areas underscores the importance of shielding and room design. Facilities with well-structured walls, proper door closures, and minimal leakages recorded lower dose values in adjoining spaces. This finding is consistent with (UNSCEAR, 2020) data which shows that engineering controls are the most reliable method of minimizing occupational exposure. Locally, Nigerian studies (Adedeji et al., 2019) have consistently reported challenges such as aging equipment, insufficient shielding, and poor maintenance as major contributors to scattered radiation exposure. Radiation exposure varies across hospital areas, the X-ray room is the primary radiation zone where direct exposure from the X-ray machine occur with highest radiation but well controlled. While other locations like the cubicle corridor, conventional rooms has the scattered radiation from the X-ray room. Exposure here is from leaked radiation likewise the waiting room and the exposure here is negligible due to structural shielding and intermittent occupancy. In summary, radiation exposure levels across hospital environments are largely determined by their proximity to the X-ray source and the effectiveness of structural shielding. UNIMEDTH and UTH show no significant dose variation among their locations, indicating consistent application of radiation protection standards. LTH reveals localized exposure concerns, necessitating further shielding at the back and side of the X-ray room. BTH displays ideal radiation uniformity, suggesting optimal design and maintenance of radiation control systems.

CONCLUSION

The absorbed dose rate was measured and the annual effective dose equivalent were estimated for four teaching hospitals; LTH, BTH, UTH, and UNIMEDTH using a handheld Radiation Alert 200 (RAM 200), Radiation levels were generally uniform across rooms in UNIMEDTH and UTH, indicating effective shielding practices, whereas LTH showed localized hotspots near the X-ray unit, suggesting insufficient structural protection; BTH demonstrated consistently well-controlled exposure conditions. The annual effective dose equivalents remained below international occupational limits in all hospitals studied. These findings provide baseline evidence on X-ray leakage and occupational risk awareness.

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