Natural radioactivity in different types of bricks fabricated and used in the Cairo region

The specific radioactivity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K were measured in samples of different types of bricks (clay, cement, and sand) fabricated and used in urban buildings in the Cairo region in Egypt, using a γ-ray spectrometer with a HpGe-detector. The radiation hazard of the total natural radioactivity in the studied brick was estimated by different approaches. The concentrations of the natural radionuclides and the radium-equivalent activity in the studied Egyptian brick samples are compared with the corresponding results for bricks of the different countries and are found to be significantly lower in all cases.     

Natural radioactivity in Algerian building materials.

Samples of natural and manufactured building materials collected from Algiers have been analysed for 226Ra, 232Th and 40K using a high-resolution HPGe gamma-spectrometry system. The specific concentrations for 226Ra, 232Th and 40K, from the selected building materials, ranged from (12-65 Bq kg(-1)), (7-51 B qkg(-1)) and (36-675 Bq kg(-1)), respectively. The measured activity concentrations for these natural radionuclides were compared with the reported data of other countries and with the world average activity of soil. Radium-equivalent activities were calculated for the measured samples to assess the radiation hazards arising from using those materials in the construction of dwellings. All building materials showed Ra(eq) activities lower than the limit set in the OECD report (370 Bq kg(-1)), equivalent to external gamma-dose of 1.5 mSv yr(-1).     

Natural radioactivity of Indian building materials and by-products.

Conventional building materials and by-products from coal power plants which are being used or have the potential for use in buildings in India were analysed for natural radioactivity due to the presence of 226Ra, 232Th and 40K using gamma-ray spectroscopy. The materials examined in this work showed the radioactivity levels below the limit estimated from radium equivalent activity the criterion formula for gamma-activity suggested for acceptable radiation doses attributable to building materials in OECD countries.     

Natural radioactivity measurement in pumice samples used raw materials in Turkey.

The activity concentrations of 232Th, 226Ra, and 40K in different pumice samples have been determined by high-resolution gamma-ray spectrometry using a 110% HpGe detector. The radium equivalent activities (Raeq), external hazard index (Hex), and internal hazard index (Hin) associated with the natural radionuclides and representative level index (Igamma r) are calculated to assess the radiation hazard of the natural radioactivity in the pumice samples. The mean values of the measured radioactivity concentrations of 232Th, 226Ra, and 40K for pumice samples from the region of lakes (ROL) are 232.4+/-8.0, 196.9+/-7.8, and 1325.8+/-20.4 Bqkg(-1) and for pumice samples from Cukurova region (CR) 16.3+/-4.0, 16.1+/-4.9, and 479.7+/-170.4 Bqkg(-1), respectively. The calculated Raeq values vary from 435.9+/-12.5 to 883.6+/-41.5 Bqkg(-1) with a mean of 630.9+/-20.2 Bqkg(-1) for the ROL samples and from 49.7+/-3.3 to 101.9+/-7.2 Bqkg(-1) with a mean of 76.3+/-23.7 Bqkg(-1) for the CR samples. For the ROL samples, Raeq are above the limit of 370 Bqkg(-1), equivalent to external gamma dose of 1.5 mSv yr(-1), recommended for the safe use of construction materials by NEA-OECD, while for the CR samples, Raeq values are lower than the limit.     

Natural radioactivity in building materials from the Brazilian state of Espírito Santo

In order to assess the radionuclide content of building materials utilized in the towns of Guarapari and Meiaipe, located in the Brazilian state Espírito Santo, 48 samples of raw materials and construction products were collected and shipped to our laboratory in Italy. Here, concentrations of background radionuclides in samples were determined by γ-ray spectroscopy with two HPGe detectors. The radium-equivalent activity concentrations in the samples varied between 14.6 (sand) and 1930 Bq kg⁻¹ (plaster).     

Natural diatomite process for removal of radioactivity from liquid waste.

Diatomite has a number of unique physical properties and has found diversified industrial utilization. The filtration characteristics are particularly significant in the purification of liquids. The purpose of this study was to test natural diatomaceous earth (diatomite) as an alternative material that could be used for removal of radioactivity from liquid waste. A pilot-scale column-type device was designed. Natural diatomite samples were ground, sieved and prepared to use as sorption media. In this study, real waste liquid was used as radioactive liquid having special conditions. The liquid waste contained three radionuclides (Cs-137, Cs-134 and Co-60). Following the treatment by diatomite, the radioactivity of liquid waste was reduced from the initial 2.60 Bq/ml to less than 0.40 Bq/ml. The results of this study show that most of the radioactivity was removed from the solution by processing with diatomite.     

Prediction of the length of the femur from its fragments in a Sri Lankan population

ABSTRACT

In many forensic circumstances, the femur is fragmented due to decomposition and mutilation, thus necessitating development and application of regression equations to estimate the length of the femur from its fragments. In this study, regression equations were derived for the prediction of the femoral length, utilizing 11 standard femoral measurements (maximum length of femur, epicondylar breadth, vertical head diameter, transverse head diameter, vertical neck diameter, transverse neck diameter, neck length, subtrochanteric anterior–posterior diameter, subtrochanteric transverse diameter, mid-shaft anterior–posterior diameter and mid-shaft transverse diameter) obtained from 86 femora belonging to a contemporary Sri Lankan population. Univariate regression equations with moderate to high correlations (0.226 to 0.714) were formulated for the estimation of the maximum femoral length from the measurements of fragments of the femur. Of the single variables, the transverse neck diameter emerged as the best predictor (r = 0.714, SEE = 18.6596) of the maximum length of the femur. The multiple regression equations using a combination of variables yielded higher correlations (0.774–0.857) with lower error estimates (14.18–16.96). The regression equations presented in this study can be used to estimate the length of the femur of unknown, mutilated and dismembered human skeletal remains with considerable accuracy.     

Natural radioactivity in tap water and associated age-dependent dose and lifetime risk assessment in Amman, Jordan

With the aim of assessing potential public impact, preliminary investigations on tap waters collected from highly populated areas in Amman and Aqaba, Jordan were conducted by measuring gross alpha and beta activities as well as uranium and radium radionuclides. Gross activities deduced by liquid scintillation counting (LSC) were ranged in <50-250±23 mBq l⁻¹ for alpha and <188-327±29 mBq l⁻¹ for beta in Amman whereas higher concentrations were found in Aqaba. The results show that gross β activities are generally higher than the corresponding gross α activities and direct correlations between gross activities and total dissolved solids (TDS) exist. Moreover, the effect of TDS on gross analyses was studied and devoted to the optimization of LSC parameters. ²³⁴U, ²³⁵U and ²³⁸U concentrations were determined by alpha spectrometry after separation from the matrix by extraction chromatography and electroplating. ²²⁶Ra and ²²⁸Ra concentrations were measured, respectively, using de-gassing and gas proportional counter techniques. Uranium and radium concentrations do not reach the WHO recommended levels and the radioisotopic activity ratios were discussed. The associated age-dependent dose from water ingestion in Amman was estimated. The total dose for adults had an average value of 0.15 mSv y⁻¹, which exceeds the WHO recommended limit of 0.1 mSv y⁻¹ but still below the Jordanian limit of 0.5 mSv y⁻¹. Although the Jordanian limit was exceeded for babies and infants, the lifetime risk assessment showed values as low as 10⁻⁴. Thereby it is concluded that tap waters of Amman is radiologically safe and pose no significant hazard to the public. Finally, a comparison of the investigated waters with worldwide data was made.     

Natural radioactivity levels and heavy metals in chemical and organic fertilizers used in Kingdom of Saudi Arabia

The present work deals with identifying and determining the activity levels of natural occuring radionuclides, (226)Ra and (232)Th series, their decay products and (40)K, in chemical and organic fertilizers used in Kingdom of Saudi Arabia. A total of 30 samples: 20 phosphatic fertilizers (single super-phosphate SSP and triple super-phosphate,TSP) and 10 organic fertilizers (cow, sheep and chicken) collected from markets and farms. The gamma-ray spectrometer consists of NaI(Tl) detector and its electronic circuit was used for measuring γ-ray spectra. The ranges of radioactivity levels of (226)Ra, (232)Th and (40)K in chemical fertilizers are 51.5±5.2-106.3±7.5, 5.1±1.6-9.9±3.2. and 462.6±21-607.3±14Bqkg(-1), respectively. The activities of (226)Ra, (232)Th and (40)K in natural fertilizers (cow, sheep and chicken) are lower than the activities in chemical fertilizers. The obtained data are compared with available reported data from other countries in literature. The Ra(eq) in chemical fertilizer ranges from 100.37 to 161.43Bqkg(-1) and in organic fertilizer ranges from 34.07 to 102.19Bqkg(-1), which are lower than the limit of 370Bqkg(-1) adopted from NEA-OECD (1979). The average heavy metal (Pb, Cd, Ni, Co and Cr) contents of the fertilizers marketed in the Kingdom of Saudi Arabia are also determined and within the limits of those used worldwide.     

Determination of natural radioactivity in building materials used in the Rawalpindi/Islamabad area by gamma-ray spectrometry and instrumental neutron activation analysis.

Samples of sand and manufactured building materials collected from the Rawalpindi/Islamabad area have been analyzed for the primordial natural radionuclides 238U, 232Th and 40K using gamma-ray spectrometry. The uranium and thorium contents have also been determined by instrumental neutron activation analysis (INAA). The specific activities of these radionuclides in the samples are compared with those of the world averages for soil. The comparison shows that, of the nine samples analyzed, only the three brick samples have higher activities than the world averages for soil. The specific activities in these materials, having a radium equivalent activity of less than 370 Bq kg-1, when evaluated for radiological effects show that all materials meet the external gamma-ray dose limitation of 1.5 mSv y-1. The gamma-spectrometric and INAA techniques complemented each other well in this study.     

Gamma activity and geochemical features of building materials: estimation of gamma dose rate and indoor radon levels in Sicily.

A high-purity germanium detector has been used to measure the abundance of radium (Ra), thorium (Th) and potassium (K) in building materials used in Sicilian dwellings. The measurements were performed to evaluate which material was suitable for the construction of an enclosure, which would have a low background emission. The materials examined in this work showed concentrations of 226Ra, 232Th and 40K dramatically variable depending on the lithologies, particularly in the case of blocks, sands and aggregates commonly used in building materials in Sicily. The results are discussed and a criterion is indicated to reduce the radiation dose to humans. Since radon inlet is a major health problem, all the radiometric data and the geochemical features have been used to determine the radon exhalation, which arises from the disintegration of 226Ra in soils and walls of houses. From our experimental data it can be seen out that one of the geochemical parameters, Total Alkali (TA), may be an appropriate index to select materials of low radiological risk.     

A comparison of alpha and gamma spectrometry for environmental natural radioactivity surveys.

An alpha-spectrometry, using automated borate fusion and sequential extraction and exchange chromatography, was used to determine the uranium and thorium based on environmental radioactivity of 20 soil samples. The same set of the samples was analysed using gamma-spectrometry with an HPGe detector. The two data sets were checked for coherence using Z-score and chi2 statistical tests. We show that gamma-spectrometry is a valid alternative to time-consuming alpha-spectrometry for the determination of natural uranium and thorium activity in soil (activity range: 12.5-58.2 Bq/kg). The measured activities were compared with the theoretical activities to ensure secular equilibrium in the 238U and 232Th series. For 226Ra, a special study was made on deconvolution of the 186 keV multiplet with the Levenberg-Marquardt algorithm. Finally, the combined use of Z-score and chi2-tests was found to be a powerful tool for comparing the results obtained with two different methods.     

Practical determination of patient-specific marrow dose using radioactivity concentration in blood and body.

Accurate determination of red marrow radiation is important because myelotoxicity is often dose limiting in radioimmunotherapy. The S-value methodology assumes a fixed red marrow mass as defined by the standard Medical Internal Radiation Dose (MIRD) mathematic phantom. Substantial error can be introduced in marrow radiation estimates because red marrow mass varies from patient to patient. In this work we describe a patient-specific marrow dosimetry methodology that does not require an explicit estimate of marrow mass. METHODS: Photon radiation to marrow from all sources can be considered as the total body to marrow. Based on photon radiation from body and electron radiation from blood, a patient-specific marrow dose can be determined by counting blood and total body radioactivity and measuring body weight. RESULTS: The deviation in marrow dose calculation using total body to represent all photon radiation was 3.9% in 66 patients administered 131I-labeled antibodies and was 9.1% in 18 patients administered 67Cu-labeled antibodies. The differences between this patient-specific approach and estimates based on standard anatomy were considerable, ranging from -35% to 88%. The differences were greater when patients' weights differed substantially from the MIRD reference man phantom. CONCLUSION: For radiopharmaceuticals that do not bind marrow, patient-specific marrow dosimetry can be independent of the actual marrow mass of a patient. Patient-specific marrow dosimetry can be determined using radioactivity concentration in blood and body.     

An assessment of Sri Lankan radiographer's knowledge and awareness of radiation protection and imaging parameters related to patient dose and image quality in computed tomography (CT)

IntroductionAs computed tomography (CT) examinations have considerably risen, safe operation is essential to reduce the patients’ dose. The main objective of this study was to evaluate the level of knowledge and awareness regarding the CT exposure parameters and radiation protection in CT imaging among Sri Lankan radiographers.MethodsAn online survey-based study was devised and distributed among the Sri Lankan CT radiographers working in 63 CT units. Questions were divided into three subsections that collected data on the participants’ demographic features, knowledge of the radiation protection, and imaging parameters.ResultsEighty-eight radiographers from 32 CT units (out of 63 CT units) distributed across 11 districts (out of 27 districts) participated in this survey.The percentages of correct responses for the questions related to radiation protection, imaging parameters, noise, Diagnostic Reference Level (DRL), and CT dosimetric parameters were 71%, 79%, 87%, 50%, and 66%, respectively. Although the years of experience did not influence any of above aspects, the level of education significantly impacted the knowledge about radiation protection, exposure parameters, and noise.ConclusionThe radiographer's knowledge of radiation protection and most imaging parameters associated with patient safety and image quality is satisfactory. However, findings also show that participants should fill the knowledge gap in radiation-related risks, CT exposure parameters, dosimetric parameters, and DRL.Implications for practiceThe study suggests the necessity of initiating continuous education programs for radiographers in line with national radiation protection legislation requirements that can be linked with code of practice.     

Cellular retention of radioactivity and increased radiation dose. Model experiments with EGF-dextran

Targeting of tumor cells with radiolabeled biomolecules is a possible approach to inactivate disseminated tumor cells. However, rapid degradation of the biomolecules after cellular internalization and subsequent excretion of the radioactivity is a problem. We studied the possibility of using dextran as a carrier of radionuclides to improve the intracellular retention. An EGF-dextran conjugate, aimed for targeting of tumor cells overexpressing the EGF-receptor, was used as model. Retention tests were performed with (125)I on different parts: [(125)I]-EGF-dextran-[(125)I], [(125)I]-EGF-dextran and EGF-dextran-[(125)I]. Comparisons were made with [(125)I]-EGF. The radiolabeled compounds were incubated with cultured glioma cells for different times. The cellular retention of radioactivity was then measured for up to 24 h. Expected radiation doses at the cellular level were calculated assuming that (131)I, instead of (125)I, was coupled to EGF and EGF-dextran. The results indicated that the EGF-part of the conjugate was degraded and the EGF-attached radioactivity was rapidly excreted, whereas radioactivity on dextran was retained intracellularly to a high degree, i.e. 70-80% of the radioactivity bound to dextran was still cell-associated after 24 h. The retention after 24 h was significantly higher (p < 0.001) when the radioactivity was on the dextran instead of the EGF-part. The radiolabeled EGF-dextran had a notably high specific radioactivity; up to 11 MBq/microg. There was potential for at least hundred times increased radiation dose per receptor interaction when the radioactivity was on the dextran part. The advantage with radioactivity on the dextran part was the high cellular retention and the high specific radioactivity (higher than previously reported for other residualizing labels) without severe loss of receptor specific binding. Thus, dextran seems suitable as a carrier of radionuclides aimed for therapy and gives potential for a highly increased radiation dose.     

Linkage,recombination and mutation rate analyses of 16 X-chromosomal STR loci in Sri Lankan Sinhalese pedigrees

International Journal of Legal Medicine - This study investigated genetic linkage, recombination fractions and mutation rates of 16 X chromosomal short tandem repeat (X-STR) markers using a...     

Natural radioactivity in groundwaters around a fertilizer factory complex in South of Spain.

A study of the concentration of the U isotopes, 226Ra and 230Th in a groundwater system has been carried out. This aquifer, located in the provinces of Sevilla and Huelva, is the most important in the south of Spain having a surface area of 2500 km2. The proximity of a fertilizer factory complex to this aquifer system is of particular concern given that it releases a significant part of its waste directly into the estuary of the Odiel and Tinto rivers, also storing a further part on the right bank of the Tinto river. Investigation has been made of the environmental impact of the fertilizer factory, either as a result of leaching of radionuclides from the phosphogypsum piles or otherwise as a result of intrusion of the Odiel and Tinto waters, both of which are in close contact with the aquifer. Results show U concentration in waters of this system around the phosphogypsum piles to be significantly higher than those in other areas of the same aquifer. The low 226Ra concentrations found in the same locations add support to the origin of part of the U in these samples.     

Natural radioactivity and radon exhalation rate of soil in southern Egypt

The level of natural radioactivity in soil of 30 mining samples collected from six locations in southern Egypt was measured. Concentrations of radionuclides in samples were determined by γ-ray spectrometer using HPGe detector with a specially designed shield. The obtained results of uranium and thorium series as well as potassium (K-40) are discussed. The present data were compared with data obtained from different areas in Egypt.

Also, a solid state nuclear track detector SSNTD (Cr-39) was used to measure the radon concentration as well as exhalation rate for these samples. The radon concentrations were found to vary from 1.54 to 5.37 Bq/kg. The exhalation rates were found to vary from 338.81 to 1426.47 Bq/m²d. The values of the radon exhalation rate are found to correspond with the uranium concentration values measured by the germanium detector in the corresponding soil samples.     

Natural radioactivity levels in granitic plutons and groundwaters in Southeast part of Eskisehir, Turkey.

The present work investigated the radioactivity level of the granitoid plutons and its effect on the groundwaters in the southeast part of Eskisehir. Fourteen granitic samples from the Kaymaz and Sivrihisar plutons and 11 groundwater samples from the near vicinity of the pluton were analyzed. The activity concentrations measured for (238)U and (232)Th ranged from 43.59+/-2 to 651.80+/-24 Bq/kg, and 51.16+/-3 to 351.94+/-13 Bq/kg, respectively. The activity concentrations obtained for (40)K varied from 418.50+/-17 to 1618.03+/-66 Bq/kg. The absorbed dose rates in air outdoors ranged from 87.14 to 531.81 nGy/h. All the results obtained from the Kaymaz pluton are higher than those from the Sivrihisar. The U (ave. 16.6 ppm) and Th (ave. 49.9 ppm) values of the Kaymaz pluton are higher than the average concentrations of the magmatic rocks of granitic composition. These results are consistent with high dose rates of the pluton. The gross-alpha activities in the groundwater samples ranged from 0.009 to 1.64 Bq/l and the gross-beta activities from 0.006 to 0.89 Bq/l. The highest gross-alpha value was found in the sample taken from near the Kaymaz pluton. The concentrations of (222)Rn varied from 0.060 to 0.557 Bq/l.     

云南省部分地区环境放射性水平调查及居民所受外照射剂量估算

目的 探讨云南省部分地区的环境放射性水平及所致居民外照射剂量。方法 通过对表层土壤、近地面空气气溶胶和水中放射性核素的γ能谱测量分析,利用卫生系统全国土壤调查中选用的模式,估算环境中²³⁸U、²²⁶Ra、²³²Th、⁴⁰K和¹³⁷Cs所致居民的受照剂量。利用美国航空管理局的CARI-6软件,估算了调查地区居民的宇宙辐射剂量。 结果 调查地区近地面空气气溶胶和水样中各核素比活度都低于探测下限。土壤中放射性核素所致居民人均外照射年有效剂量为0.5206 mSv/年,其中,0.52 mSv/年来自土壤中天然放射性核素,0.6 μSv/年来自土壤中¹³⁷Cs。宇宙辐射所致居民剂量为0.61 mSv/年。结论 宇宙辐射和土壤中天然辐射对居民所受外照射剂量贡献为99.95%,人工放射性核素¹³⁷Cs所致居民的外照射剂量贡献仅为0.05%。