The activity concentrations of 40 K, 226 Ra, and 232 Th in the soil samples collected from Owo Local Government of Ondo state, Nigeria, were assessed by gamma spectrometric techniques using a Na(TI) scintillation detector, encapsulated in a 5 × 5-cm-thick lead shield to reduce environmental background radiation. Results show that the ranges (and the corresponding average) of the measured activity concentrations of 40

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In Nigeria, a large number of radiographic examinations are conducted yearly for various diagnostic purposes. However, most examinations carried out do not have records of doses received by the patients, and the employed exposure parameters used are not documented; therefore, adequate radiation dose management is hindered. The aim of the present study was to estimate the dose‐area product (DAP) of patients examined in Nigeria, and to propose regional reference dose levels for nine common examinations (chest PA, abdomen AP, pelvis AP, lumbar AP, skull AP, leg AP, knee AP, hand AP, and thigh AP) undertaken in Nigeria. Measurement of entrance surface dose (ESD) was carried out using thermoluminescent dosimeter (TLD). Measured ESDS were converted into DAP using the beam area of patients in 12 purposely selected hospitals. Results of the study show that the maximum/minimum ratio ranged from 3 for thigh AP to 57 in abdomen AP. The range of determined mean and 75th percentile DAPs were 0.18–17.16, and 0.25–28.59 Gy cm2, respectively. Data available for comparison show that 75th percentile DAPs in this study (in chest PA, abdomen AP, pelvis AP, lumbar AP) are higher than NRPB‐HPE reference values. The DAP in this study is higher by factor of 31.4 (chest PA), 9.9 (abdomen AP), 2.2 (pelvis AP), and 2.1 (lumbar AP) than NRPB‐HPE values. The relative higher dose found in this study shows nonoptimization of practice in Nigeria. It is expected that regular dose auditing and dose optimization implementation in Nigeria would lead to lower DAP value, especially in abdomen AP. The 75th percentile DAP distribution reported in this study could be taken as regional diagnostic reference level in the Southwestern Nigeria; however, a more extensive nationwide dose survey is required to establish national reference dose.PACS number(s): 87.53.Bn, 87.59.B

Diagnostic reference levels (DRLs) is a veritable tool for dose optimisation and patient protection in diagnostic radiology. However, it is essential to have information on the local situation especially in a large hospital with several units or a cluster of healthcare centres within a geographical region with several X-ray units. In the present study, entrance surface doses (ESDs) were measured in twelve (12) healthcare centres consisting of 15 radiological units using thermoluminescent dosimeters (TLDs). Seven radiological procedures such as; chest PA, abdomen AP, pelvis AP, lumbar spine AP, skull AP, knee AP, and hand AP frequently carried out in Nigeria were included in the study, and their local diagnostic reference levels (LDRLs) were determined. The values of the determined LDRLs were compared with established NDRLs in UK, US, Slovenia, Italy and Brazil. The LDRLs determined in the two groups (healthcare centres) studied ranged from 1.78 to 3.01, 2.71 to 2.84, 2.11 to 3.79, 3.93 to 8.79, 1.06 to 1.73 and 1.10 to 1.44 mGy for chest PA, pelvis AP, lumbar spine AP, skull AP, knee AP and hand AP respectively. Large variations were found among the X-ray units studied even within the same centre. Entrance surface doses obtained in pelvis AP and lumbar spine AP in both GROUP A and were found to be lower than the NRPB-HPA 2010 review for UK, while in all other five examinations, value of the measured entrance surface dose (ESD) are higher than the doses reported in the UK review. The relative higher doses found in the study are attributable to higher tube load (mAs) used and indicative of the need for dose optimisation in Nigerian radiological practice.

In this study, risk of exposure to adult patients in some common radiological procedures was estimated at selected diagnostic centers in Lagos State, Nigeria using estimated average effective doses. The results showed that pelvis lateral (LAT) examination with the lowest estimated mean effective dose level (2.61) recorded the highest probability of cancer incidence and mortality occurrences, while lumbar anteroposterior (AP) had the lowest (3.61). A high sum total of probability of fatal cancers and the total weighted probability of non-fatal cancer in a single exposure to low-dose ionizing radiation were recorded in pelvic procedure among others. Also, a high-percentage mortality increase of solid cancers was recorded in chest PA examination (53.7%), while the lowest was in lumbar spine radiography (with lumbar AP = 0.14%, lumbar LAT = 0.15%). The data obtained suggested the possibility of having higher percentage mortality and cancer-related incidence in the chest.

Human exposure to ionizing radiation in the environment is mainly due to naturally occurring radionuclides in the soils, building materials and rocks, but the level may vary depending on the anthropogenic activities prevalent in each location. Presently, in Nigeria, there are concerns due to environmental health implications of all sorts of mineral mining and processing spreading across the southwestern states of the country. As a result, a total of 200 composite soil samples were taken in ve states in the southwest of Nigeria, close to active mining sites at the rooting (0.2 m) and at deep planting zones (0.5 m) for analysis by gamma-ray spectrometry using NaI(Tl) detector. The activity concentrations of natural radionuclides in the composite soil samples were determined to vary in the order of 40 K > 232 Th > 226 Ra/ 238 U for all locations. In contrast to the other locations, Olode and Igbokoda had average radium equivalent activities (Ra eq ) to be 1.6 and 1.8 times higher than the reference limit of 370 Bqkg − 1 . The estimated excess life cancer risk values were lower than the 0.29 x 10 − 3 global average value for soil by UNSCEAR and ICRP. A negative and low skewness value of 0.16 and 1.20 for 40 K and 232 Th were obtained in Olode and Sagamu. The kurtosis analysis of the activity concentrations was low and negative for soil at Itagunmodi for 40 K and 226 Ra/ 238 U; Olode for 40 K and 232 Th; and Igbokoda for 226 Ra/ 238 U and 232 Th where mining activities are common. The variation in the obtained results has been attributed to different agriculture practices and artisanal mining operations in each location.

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