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Background: Presently, the British-American Tobacco Company (BAT) located in Ibadan, Oyo State is the only tobacco producing company in Nigeria accounting for about nine different brands of cigarette tobacco smoked in the country. The tobacco leaves are produced from some farmlands located in Oke-Ogun area of Ibadan where special fertilizers are used for the growing of the tobacco leaves. The use of this fertilizer may enhance natural radionuclide contents in the farm soils and through root uptake be accumulated in the leaves. In this study, soil samples from three farmlands used for the production of the tobacco leaves were collected in order to determine the activity concentrations of ²²⁶Ra, ²³²Th and 40K in the farm soil. Materials and Methods: Measurements for the determination of the activity concentrations were carried out using gamma-ray spectrometry comprising a lead-shielded 76 mm × 76 mm NaI(Tl) detector crystal (Model 802 series, Bicron NaI) coupled to a Canberra series 10 plus multichannel analyzer (MCA) (model 1104) through an preamplifier base. Results: Results of measurements showed that the average activity concentrations of the natural radionuclides in the soil samples across the three farms varied from 2550.4± 154.6 to 3208.9 ± 188.7 Bq kg-1 for 40K, 33.1±11.9 to 39.9±9.3 Bq kg^-1 for ²²⁶Ra, while for ²³²Th it varied between 51.98± 8.4 and 56.08±17.51 Bq kg^-1. The activity concentrations of these radionuclides and gamma absorbed dose rates due to the concentration of these radionuclides were found to be higher than world average values while those of the control farm values were lower to world averages and the tobacco leaf farms. Conclusion: From the results obtained the fertilizer type used on the farmlands for the tobacco leaf production was very rich in ⁴⁰K with typical values greater 2000 Bq kg^-1. Also there may be possible high signatures of ²¹⁰Pb and ²¹⁰Po in the tobacco leaves and the cigarette samples smoked in the country. This is a subject for future research consideration given the fact that alpha radiation plays a major role in the etiology of lung cancer. Iran. J. Radiat. Res., 2011 8 (4): 201-206

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Background: Attenuation coefficient (μ) plays an important role in calculations of treatment planning systems, as well as determination of dose distributions in external beam therapy, dosimetry, protection, phantom materials and industry. So, its exact measurement or calculation is very important. The aim of this study was to evaluate the μ in different points in the water phantom analytically as a formula, in addition to derive and parameterize it with dosimetry measurements data results. Materials and Methods: To find the attenuation coefficients at each point along the central axis of the beam in the phantom for every size of the fields, the first mathematical approach was performed for derivation of μs from percentage depth dose (PDD) formula. Then by dosimetry for different fields in different depths of water phantom, one can parameterize the obtained formula for μ in any field and depth. Results: By comparing the mathematical and dosimetry results, the parameters of the μ-expression were derived in terms of the dimension of square field in different depths. From this formula one can find the μ for any field in different depths for two energies of the Varian 2100CD linear accelerator, 6, 18MV with the statistical coefficient of determination of R²>0.98. Conclusion: The measurement of the μ in each field size and depth has some technical problems, but one can easily measure the μ for every point of central axis of the beams in any field size. Iran. J. Radiat. Res., 2012 9(4): 251-255

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Background: One of the means of assessing dose to patients from Computed tomography (CT) procedure is through the determination of the skin entrance dose (ESD) with the appreciation of the concern that ocular exposure effects from CT scan includes possible induction of cancer and cataract. Due to the relatively more recent introduction of CT scans, little work has been done in this area in the country including exposure dose on the lens of the eyes of patients undergoing Cranial Computed Tomography (C-CT). Materials and Methods: The Entrance Surface Dose (ESD) to the lens of eyes of 26 patients who had cranial CT procedures at a University Teaching Hospital in Ile-Ife, Nigeria has been determined in order to assess the level of radiation protection compliance and optimization of radiation safety at the hospital. Results: Results indicate that the doses to the patients ranged between 17.13 mGy and 51.98 mGy within the period under study. The average doses obtained for the pediatric patients (1.5-18 yrs), young adults (19-49 yrs) and adults (&ge50 yrs) were 31.14 ±11.02 mGy, 41.81±12.60 mGy and 31.97 ± 11.31 mGy respectively. The mean dose obtained in this study was lower than threshold for lens damage, therefore the dose recorded in this study is clinically safe. Conclusion: This study represents a requisite pedestal on the need for a nation-wide evaluation and investigation of optimization of procedures in radiological examinations with a view to establishing a national dosimetry protocol and reference dose level or guidance level in the country.

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Background: Vitamin D, especially its most active metabolite 1,25-dihydroxyvitamin D₃(Vit D) is essential in regulating a wide variety of biologic processes, such as regulating mesangial cell activation. The objective of this study was to assess the histopathological changes of effectiveness of Vit D as a protective agent against radiation induced lung injury. Materials and Methods: Eighteen Wistar rats were divided into three groups: control group (group 1:4 rats), irradiation alone group (group 2:7 rats) and irradiation+vit D (group 3:7 rats). Rats in group 2 and 3 were exposed to 20 Gy radiations to the right lung in a Co⁶⁰ radiotherapy machine under general anesthesia. Additionally, rats in group 3 received Vit D at a single dose of 0.2 mcg injected IM 2 hours before exposure to irradiation. Rats were sacrificed and lungs were dissected fifty days after post-irradiation. Myofibroblasts and vitamin D₃receptors (VDR) in extracted lungs were stained by immunohistochemistry using alpha-smooth muscle actin (SMA) and VDR antibodies. Blinded histological evaluation was performed to assess lung injury. Lung injury was assessed by the acute lung injury score and myofibroblastic differentiation score. Results: Acute lung injury scores and myofibroblastic differentiation scores were significantly lower in the radiation+vit D group compared to irradiation alone group (p=0.001 and p=0.001, respectively). Conclusion: This study indicates that administration of vit D plays a protective role against acute lung injury through blocking myofibroblastic differentiation.

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Background: Intraoral radiographs are believed to deliver low doses to patients, thus little work has been done in this regards. Considering the increment in the number of patients reporting for the examination and the probability of delayed somatic effects for accumulated low doses of X-irradiation, it is expedient to determine the doses to three critical organs eye, thyroid and parotid that are at risk during exposure. Materials and Methods: Thermoluminescent dosimeters was used to measure Entrance Surfaces Doses (ESDs) to the thyroid, eye and parotids salivary gland of 40 adult patients undergoing intra-oral radiographic examination at University College Hospital, (UCH) Ibadan, Oyo state. Results: Results indicated entrance surface doses (ESD) ranged between 0.0447 mGy to 0.3898 mGy to the thyroid, 0.0742 mGy to 0.3989 mGy to eye and 0.0467 mGy to 0.4164 mGy to the parotids for the period of study. The mean ESD ± SD to the thyroid, parotids and eyes for male were 0.1798±0.081, 0.2155±0.109 and 0.2197±0.081 mGy with the female patients 0.1957±0.084, 0.2091±0.081 and 0.2280±0.113 mGy respectively. No statistically significant difference was found between these means.  Conclusion: The doses obtained in this study were lower than the documented threshold that could cause significant damage in the various organs, not undermining stochastic effect of radiation. This study will assist in setting Diagnostic Reference Level (DRL) for intraoral radiographic imaging in Nigeria.

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