سال:1390 | دوره: | شماره: |تعداد مقالات:9

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.

Background: Everyone is exposed to radon because it is present everywhere with varying concentrations. Radon and its progeny are well established as lung carcinogenic.Materials and Methods: Track etch technique using LR-115 plastic track detectors has been used to measure the effective radium content and radon exhalation rates in soil samples collected from urban area of Etah district of Uttar Pradesh province in Northern India.Results: The values of effective radium content are found to vary from 27.87 to 45.14 Bq.kg-1 with a mean value of 34.98 Bq.kg-1. The mass exhalation rates of radon vary from 2.38 × 10-6 to 3.86 × 10-6 Bq.kg-1.d-1 with a mean value of 2.99 × 10-6 Bq.kg-1.d-1. The surface exhalation rates of radon have been found to vary from 6.19 × 10-5 to 10.03 × 10-5 Bq.m-2.d-1 with a mean value of 7.77 × 10-5 Bq.m-2.d-1.Conclusion: Radon exhalation study is important for understanding the relative contribution of the material to the total radon concentration found inside the dwellings. The values of radium and radon exhalation rates are found to be below the safe limit recommended by OECD, 1979.

Background: Natural radiation is constantly present in the environment and is emitted from a variety of natural and artificial sources. It affects human body and environment.Materials and Methods: The activity concentrations of 238U, 232Th and 40K have been determined by Gamma ray spectrometer with an HPGe detector in sediments of Cauvery River, Tamilnadu, India.Results: The absorbed dose rate, radium equivalent concentration, external (Hex) and internal (Hin) hazardous indices are calculated from criteria formula and compared with the international recommended limits. The radioactive heat production rate and activity concentration index are also calculated. The observed dose rate measurements from ERDM (Environmental Radiation Dosi Meter) at 1m above the ground level at each site of the both rivers are measured and correlated with calculated absorbed dose rate.Conclusion: From the various parameters and correlation between them, the Cauvery River does not pose a radiological hazard except the site no.21, 22, 23, 30, 31 and 35.

Background: Radioprotective effect of famotidine was previously shown on radiation induced micronuclei and chromosomal aberrations in human peripheral lymphocytes and mouse bone marrow cells; however, its radioprotective property has never been studied in mouse spermatogenesis. It was also shown that vitamin C as an antioxidant also exert its radioprotective effect on many biological systems, but in some studies no protective effect is reported.Materials and Methods: Mice were injected by small and nontoxic amount of vitamin C and famotidine (3 and 2mg) inter-testicular 2 hours before irradiating by gamma ray.29 days after irradiation, mice were sacrificed and testes were removed, weighed and either fixed for histological study or homogenized in 1.5 mL de-ionized water and 0.5 mL SDS solution. Sperm head count was done under a light microscope. Survival fractions were calculated and plotted as a function of dose of gamma rays.Results: The sperm head count in groups treated with vitamin C and famotidine before gamma irradiation show significant increase compared to groups only irradiated by gamma rays (p<0.01). Values of calculated dose reduction factor (DRF) are 2 and 2.68 for vitamin C and famotidine respectively. Both vitamin C and famotidine could reduce radiation induced pathological alterations in seminiferous tubules.Conclusion: These results suggest that vitamin C and famotidine have radioprotective property and could reduce cytotoxic effect of radiation in mouse spermatogenesis, one of the most radiosensitive biological systems. The possible mechanism of protection by famotidine and vitamin C might be radical scavenging. The radioprotection index for famotidine was found to be more than vitamin C.

Background: The purpose of this paper is to establish an easy and reliable biodosimeter protocol to evaluate the biological effects of proton beams.Materials and Methods: Human peripheral blood lymphocytes were irradiated using proton beams (LET: 34.6 keV mm-1), and the chromosome aberrations induced were analyzed using cytokinesis-blocked (CB) micronucleus (MN) assay. To determine the efficiency of MN assay in estimating the doses received by 50MeV proton beams and to monitor predicted dose of victims in accidental exposure, here we have evaluated the performance of MN analysis in a simulated situation after exposure with proton beams. Peripheral lymphocytes were irradiated by 50MeV proton beams up to 6Gy and analyzed by Giemsa staining of CB MN assay.Results: The detected MN was found to be a significant dose-effect curve in the manner of dose-dependent increase after exposure with proton beams in vitro. When plotting on a linear scale against radiation dose, the line of best fit was Y=0.004+(1.882x10-2±9.701x10-5) D+(1.43x10-3±1.571x10-5) D2. Our results show a trend towards increase of the number of MN with increasing dose. It was linear-quadratic and has a significant relationship between the frequencies of MN and dose (R2=0.9996). The number of MN in lymphocyte that was observed in control group is 5.202±0.04/cell.Conclusion: Hence, this simple protocol will be particularly useful for helping physicians to decide medical therapy for the initial treatment of victims with rapid and precise dose estimation after accidental radiation exposure. Also it has potential for use as a valuable biomarker to evaluate the biological effectiveness for cancer therapy with proton beams.

Background: The existence of some radionuclides in soil and some building materials produce a b-Y radiation field, which in some regions the exposure of these radionuclides to human is high.Materials and Methods: The air-absorbed dose, indoor and outdoor annual effective dose of soil and some building material samples (ceramic, granite, gypsum, etc.). The samples were collected from 35 different regions in the northwest of Iran were calculated. Specific activity of natural radionuclides 226Ra, 232Th and 40K were measured by using a b-Y spectrometer consisted of NaI (Tl) and organic scintillators. The analysis of measured spectra was based on maximum likelihood estimation. The calculated data were compared with world's mean values.Results: It is found that the specific activity of 40K ranges from 573.8 to 1392 Bqkg-1, for 232Th ranges from 6 to 54.6 Bqkg-1 and for 226Ra ranges from and 5.1 to 36.2 Bqkg-1. In some regions, the concentrations of natural radionuclides (40K, 232Th, 226Ra) were higher than standard level.Conclusion: Experimental results related to specific activity, indoor and outdoor annual effective doses of 226Ra, 232Th and 40K revealed that radionuclide concentration in soil and some building material samples of some regions of northwest of Iran are of some radiological importance.

Background: Chlorotoxin is a 36-amino acid peptide found in the venom of the Leiurus quinquestriatus which blocks small-conductance chloride channels. Chlorotoxin binds preferentially to glioma cells that allow development of new methods for the treatment and diagnosis of several types of cancer. Thus chlorotoxin derivative was labeled with 131I for further investigation.Materials and Methods: A chlorotoxin derivative was synthesized on a solid phase using a standard Fmoc strategy. Labeling with iodine-131 was performed through chloramine-T method and radiochemical analysis involved sephadex G-25 and HPLC methods. The stability of radiopeptide was checked in the presence of PBS and human serum at 37oC up to 24 h. The biodistribution was studied in mice.Results: The chemical purity of synthesized peptide as assessed by analytical RP-HPLC was 95%. Labeling of peptide resulted in a radiochemical yield of 80% with radiochemical purity of>95% with specific activity of 0.740 GBq/μmol. Result of in vitro studies demonstrated acceptable stability of compound in human serum and PBS solution. Biodistribution data showed moderate blood clearance, with concentration of radioactivity in the kidneys, liver, intestine and stomach.Conclusion: Results indicates that the labeled Chlorotoxin derivative might be useful in determining tumor extent and also, tumor therapy of gliomas or possibily other cancers.

Background: Radioiodine therapy has proven to be an effective method in the treatment of patients with differentiated thyroid carcinoma after thyroidectomy. The scope of this study is to describe a method to obtain the dose of organs using medical internal radiation dosimetry (MIRD) method. At the end, the results of MIRD calculations were compared with thermoluminescent dosimeter (TLD-100).Materials and Methods: The study was performed on 27 patients using TLD for thyroid, sternum and cervical vertebra. There were 5 TLDs for each organ which they were taken after 4, 8, 12, 20 and 24 hr. To calculate the amount of activity in the thyroid a head and neck phantom with a source of 10 mCi of 131I was used. A head and neck phantom was used to determine the absorbed dose. A source of 10 mCi of 131I was putted on phantom. Several TLDs were placed on the surface of thyroid on phantom for 24 hr and then compared with the dose of phantom and patients followed by calculation of the activity in patient's thyroid. Finally, MIRD formula was used to calculate absorbed dose in cervical vertebra and sternum.Results: The average of measurements of TLDs on phantom for 10 mCi of iodine was 33.3 cGy. The absorbed activity in thyroid in three groups for 100, 150 and 175 mCi administered 131I were 94.9, 104.6 and 108.8 mCi cumulated activity in 24 hrs. The absorbed dose obtained by MIRD calculations was found to be 419.9, 463.2, and 481.5 for thyroid, 288.9, 252.4 and 252.4 for sternum and 288.9, 252.4 and 252.4 for cervical vertebra.Conclusions: The results of MIRD method was similar to the results obtained experimentally. It was shown that 75% of absorbed dose calculated by the MIRD method is detectable by the TLD method.

The perioperative imaging of a pregnant woman presents a unique challenge to orthopaedics surgeon as concern about the radiation risk to the embryo or fetus. This article highlights effect of radiation exposure on foetus.I would like to discuss about the amount of radiation exposure in a pregnant woman during fluoroscopic guided closed femoral Interlock nailing as radiation has significant cancerous and non cancerous effect on fetus.