It has been proven that more than half of the exposure to natural background radiation originates from radon isotopes and their decay products. The inhalation of radon and its decay products causes the irradiation of respiratory tracts, thus increasing the risk of lung cancer. In this study, the concentrations of radon and thoron in thermal baths at a spa in Dehloran (Iran) were investigated. The concentrations of dissolved 226 Ra in samples of water from thermal baths were also measured. Additionally, the activity concentrations of abundant naturally occurring radionuclides in farmland soils irrigated with water from hot springs was measured and compared with other soil samples irrigated with water from other sources to estimate possible radioecological effects of natural radiation staff, patients and tourists at the spa are exposed to. In addition, the search for a link between the concentration of naturally occurring radionuclides in soil and the use of water from hot springs for irrigation was one of the main goals of the study. The activity concentrations of three major naturally occurring radionuclides in soil samples were measured; the ranges for 40 K, 226 Ra and 228 Ra were 101 AE 8 to 240 AE 12, 276 AE 7 to 322 AE 12 and 20 AE 7 to 80 AE 10 Bq.kg À1 , respectively. Higher activity concentrations of 226 Ra and 228 Ra were recorded in soil samples irrigated with hot spring water. The water from the same spring was used in all thermal baths so concentrations of dissolved 226 Ra in water samples from different thermal baths were approximated to also be 0.42 AE 0.20 Bq.l À1 . The indoor radon concentrations in the private thermal baths over a period of 45 days (including both occupied and vacant time) were measured to be between 1880 AE 410 and 2450 AE 530 Bq.m À3 and the radon concentrations in the spa galleries were measured to be between 790 AE 135 and 1050 AE 120 Bq.m À3 , however, thoron concentrations were below the detection limit. The ventilation and centralized heating systems at the spa under investigation are inefficient so the radon concentrations in the therapy rooms and baths are high.The maximum radiation doses originating from the inhalation of radon for tourists and the staff were estimated to be 0.13 and 5.5 mSv.yr À1 , respectively, which is slightly over the national limit in Iran (5 mSv.yr À1 ). The exposure duration was estimated 15 and 1468 h per year for visitors and workers, respectively.
In this study, mass activity of naturally occurring radioactive materials were measured in twenty-three building material samples, use extensively in the area exposed to a high level of natural background radiation (Mahallat, Iran), to determine the radioactivity index and changes to the level of indoor gamma radiation. The mass activity of 232Th, 226Ra and 40K were within the ranges from 18 ± 3 to 44 ± 10 Bq/kg (average of 27 ± 6 Bq/kg), 22 ± 5 to 53 ± 14 Bq/kg (average of 34 ± 6 Bq/kg) and 82 ± 18 to 428 ± 79 Bq/kg (average of 276 ± 58 Bq/kg), respectively. The gamma dose rates for population were estimated between 48 ± 9 and 111 ± 26 nGy/h with exception of radon exhalation from building materials. Since the air kerma rate in the town varies from 0.8 to 4 μGy/h, the attenuation coefficient was calculated for buildings made of the aforementioned materials. Additionally, the annual gamma radiation doses for inhabitants were calculated based on time spent outdoors and indoors.
Impact assessment of building materials is a focused topic in the field of radioecology. A radiological survey has conducted to monitor radioactivity of most common building materials in Semnan Province, Iran, and assess the radiation risk. Activity concentrations of 226Ra, 232Th, and 40K were measured in 29 samples including nine commonly used building materials that were collected from local suppliers and manufacturers, using a high purity germanium gamma-ray detector. The activity concentrations of 226Ra, 232Th, and 40K varied from 6.7±1 to 43.6±9, 5.9±1 to 60±11, and 28.5±3 to 1085±113 Bq kg−1 with averages of 26.8±5, 22.7±4, and 322.4±4 Bq kg−1, respectively. By applying multivariate statistical approach (Pearson correlation, cluster, and principal component analyses (PCA)), the radiological health hazard parameters were analyzed to obtain similarities and correlations between the various samples. The Pearson correlation showed that the 226Ra distribution in the samples is controlled by changing the 232Th concentration. The variance of 95.58% obtained from PCA resulted that the main radiological health hazard parameters exist due to the concentration of 226Ra and 232Th. The resulting dendrogram of cluster analysis also shows a well coincidence with the correlation analysis.
In this study, samples of building material additives were analyzed for naturally occurring radioisotope activity such as uranium, radium, and radon. The radon exhalation and the annual effective doses, were also calculated. The activities of the samples, were determined using HPGe gamma spectrometry and ionization detector. The results were used to calculate dose values by using RESRAD BUILD code. The activity concentration of the samples ranges between 9–494 Bq/kg Ra-226, 1–119 Bq/kg Th-232 and 24–730 Bq/kg K-40. In conclusion the investigated samples can be used safely as building material additives as they do not pose a major risk to humans.
Background Our aim was to present a new data analysis technique for the early detection of tumorous lesions using single-photon emission computed tomography (SPECT) imaging. Beyond standardized uptake value (SUV) and standardized uptake concentration (SUC), the skewness and kurtosis parameters of whole liver activity distribution histograms were examined in SPECT images to reveal the presence of tumorous cells. Methods Four groups of mice were used in our experiment: a healthy control group, a group of obese mice with high body mass index, and two tumorous groups ( primary liver cancer group with chemically induced hepatocellular carcinoma (HCC); metastatic liver tumor group —xenograft of human melanoma (HM)). For the SPECT measurements, 99m Tc-labeled aggregated albumin nanoparticles were administered intravenously 2 h before the liver SPECT scans (NanoSPECT/CT, Silver Upgrade, Mediso Ltd., Hungary) to image liver macrophages. Finally, SUV, SUC, skewness, and kurtosis of activity distributions were calculated from segmented whole liver volumes. Results HCC animals showed moderate 99m Tc-albumin particle uptake with some visually identified cold spots indicating the presence of tumors. The visual detection of cold spots however was not a reliable marker of tumorous tissue in the metastatic group. The calculated SUV, SUC, and kurtosis parameters were not able to differentiate between the healthy and the tumorous groups. However, healthy and tumorous groups could be distinguished by comparing the skewness of the activity distribution. Conclusion Based on our results, 99m Tc-albumin nanoparticle injection followed by liver SPECT activity distribution skewness calculation is a suitable image analysis tool. This makes possible to effectively and quantitatively investigate liver macrophage inhomogeneity and identify invisible but present liver cold spot lesions. Skewness as a direct image-derived parameter is able to show altered tissue function even before the visual manifestation of liver tumor foci. The skewness of activity distribution might be related to an inhomogeneous distribution of macrophage cells as a consequence of microscopic tumor burden in the liver. Electronic supplementary material The online version of this article (10.1186/s13550-019-0532-7) contains supplementary material, which is available to authorized users.
Exposure to toxic heavy metal content in soil and inherent naturally occurring radioactive materials (NORM) needs to be monitored, especially after industrial accidents and remediation efforts. Just such an accident happened near Ajka city in Hungary; a large quantity of red mud flooded out from a reservoir. The afflicted area was remediated, and the red mud deposition technology was changed from a wet to a dry procedure. Concerns have been raised about potential hazards from airborne NORM dust in this area. The objectives of this study were to assess the use of explanted tobacco plants as an active biomonitoring system for airborne NORM dust and to reveal weather-related correlations of Po-210 in airborne dust. In 2011, 2012 and 2014, measurements were taken of the following at six monitoring sites in the polluted area and at eight sites in unpolluted areas: soil and tobacco plant Po-210 isotope levels, airborne Rn-222, Ra-226 in soil, Th-232 and K-40 radioactivity concentrations. The transfer factors (TFs) of tobacco were calculated yearly for these isotopes. Association of data with local weather features was determined. In 2012 (the windiest and driest year), the mean Po-210 activity concentrations of tobacco samples in polluted areas were significantly higher than in 2011 and in 2014 (p ¼ 0.044 and p ¼ 0.024, respectively). The mean TF of samples in 2012 was also significantly higher in tobacco plants grown in the polluted area compared to ones grown in unpolluted areas (p ¼ 0.020). These results presumably originate from red mud dust-particle adsorption on tobacco plant leaves. Tobacco plants are promising active bioindicators of airborne particulate pollution by Po-210 or other atmospheric NORM content.
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