Radioisotope Activity Research Articles

CHARACTERISTICS OF RADIONUCLIDE ACCUMULATION IN DANDELION ROOTS IN THE CENTRAL BLACK EARTH REGION

The aim of the study is to examine accumulation patterns of natural and man-made radioactive isotopes in dandelion roots (Taraxacum officinale F.H. Wigg.), harvested in different areas of the Voronezh region. Materials and Methods. Under experiment, the specific activity of the main long-lived artificial radioisotopes (cesium-137, strontium-90) and naturally occurring radionuclides (thorium-232, potassium-40, radium-226) was determined in the samples of top soil and dandelion roots using a MKGB-01 RADEK spectrometer-radiometer. Results. All the studied samples of dandelion roots conform to the existing radiation safety requirements (first group). With the increase in the specific activity of strontium-90, cesium-137, thorium-232, potassium-40, and radium-226 in the soil, their specific activity in plant roots also increased. Correlation analysis of the specific activity of man-made and natural radionuclides in the soil and roots demonstrated a very noticeable correlation, which confirmed the predominant trans-soil root contamination. The calculated accumulation factors of radionuclides in dandelion roots showed fast accumulation of strontium-90 and radium-226 from soils. The specific activity of these radioisotopes in medicinal plant raw materials was significantly higher than that in soil. A detailed analysis of the dependence of the calculated accumulation coefficients of natural and man-made radioisotopes in dandelion roots allowed us to note the tendencies towards their decrease with an increase in the specific activity of the radionuclide in soil. This fact indicates the existence of physiological mechanisms regulating their accumulation in plant roots. The transition patterns of the studied natural and man-made radionuclides are described by mathematical dependencies with the maximum coefficient of approximation reliability.

Radiation-thermal modification of fluoroplastic composite and evaluation of its radiation-protective characteristics

In the work the composite on the basis of fluoroplastic with filler WO3 is studied and its efficiency for protection against X-ray and gamma radiation is proved. The technological scheme of composite production has been developed and its physical and mechanical characteristics have been studied. The composite with 60 wt% of WO3 content has the following properties: density 3.35 ± 0.02 g/cm3, Vickers microhardness (at 300 g load) 5.38 ± 0.32 HV, flexural strength 18.86 MPa. The γ-radiation sources used were E(207Bi) = 0.570 MeV with an activity of 50 kBq, E(137Cs) = 0.662 MeV with an activity of 9 kBq, and E(60Co) = 1.252 MeV with an activity of 100 kBq. The X-ray radiation sources were isotopes 241Am (half-life T1/2 = 432.1 years; photon energy E = 59.5 keV; radioisotope activity 46 μCi) and 109Cd (half-life T1/2 = 461.4 years; photon energy E = 88 keV; radioisotope activity 15 μCi). It is shown that for reduction of gamma radiation with energy 1.252 MeV by 50 % a screen from pure fluoroplastic with thickness of 6.301 ± 0.654 cm is required, and for composite with 60 wt% WO3 the thickness of screen is 1.5 times less (4.077 ± 0.509 cm). Comparison of the linear attenuation coefficient at energy 0.662 MeV with modern analogs confirmed the high efficiency of radiation protection of the developed material. Radiation-thermal modification of the samples was carried out, which allowed to increase their radiation resistance to gamma radiation many times. After radiation-thermal modification the radiation resistance increased up to 1 ± 0.1 MGy and 4.5 ± 0.2 MGy for fluoroplastic and composite with 60 wt% WO3 content, respectively. And the initial bending strength increased in both materials by 15 % and more.

Geochemical features and radiological risk assessment of Wadi El-Regeita granites, South Central Sinai, Egypt

The exposed rocks in the Wadi El-Regeita area are quartz monzonite, granodiorite and monzogranite intruded by andesite and diorite dikes. The monzogranites studied show a marked enrichment in Rb, Ba and Sr (large ion lithophile elements, LILE) and Zr, Nb and Y (high field strength elements, HFSE), but depletion in P and Ti. The genetic characteristics of the granites revealed calc-alkaline affinity, metaluminous and/or peraluminous characteristics. The studied quartz monzonite, granodiorite, and diorite rocks represent I-type granites that were emplaced in a volcanic arc tectonic environment. The monzogranite falls into post-collisional A-type granite that was emplaced within a plate environment under extensional regime. The calculated isovalents LREE/HREE, La/Yb, La/Sm and Tb/Yb show a relative enrichment of the lighter ones in the monzogranite. The quantities of 238U, 232Th and 40K in diorite samples have been investigated by gamma-ray spectroscopy. The measured radioisotope activity concentrations in Wadi El-Regeita varied from 100 to 1604 Bq.kg−1, with a mean of 370 ± 341 Bq.kg−1 for 238U. For 232Th, the range was from 35 to 140 Bq.kg−1, with a mean of 68 ± 27 Bq.kg−1. Finally, for 40K, the range was 501–3067 Bq.kg−1, with a mean of 1355 ± 570 Bq.kg−1. The levels of 238U, 232Th, and 40K detected in the diorite samples examined were found to exceed the worldwide limits of 35, 45, and 412 Bq.kg−1, respectively. The primary radiological hazards associated with these diorite dikes were attributed to the gamma rays emitted by the radioactive elements. Estimates of the radiological hazards in the granites were made and statistical methods were used to demonstrate the relationships between radionuclides and radiological factors. The statistical evaluation confirmed that uranium and its associated minerals in the diorite dikes were the main factors contributing to the radiological risks. Consequently, the study concluded that the diorite dikes found in the study area were unsuitable for construction purposes due to their elevated levels of radioactivity.

Geochemical evaluation and hazard indices due to radioactive minerals associated with granitic areas

The present study employed statistical methods to evaluate the possible radiological hazards linked to granitic rocks-bearing mineralization in the ELgarra region of Egypt. The geological structures influence the occurrence of uranium mineralization in this area and are primarily associated with altered granites. Gamma-ray spectrometry was utilized to examine the quantities of 238U, 232Th, and 40K in granitic rock samples. The recorded levels of radioisotope activity concentrations in the analyzed regions ranged from 374 to 1740 Bq.kg−1238U, with an average of 1018 Bq.kg−1. For 232Th, the range was between 71 and 163 Bq.kg−1, with an average of 119 Bq.kg−1. Lastly, for 40K, the range was 756–1789 Bq.kg−1, with an average of 1212 Bq.kg−1. The detected levels of 238U, 232Th, and 40K in the examined rock samples were observed to exceed the permissible limits of 35, 45, and 412 Bq.kg−1, respectively. The primary radiological risks linked to these granitic rocks were attributed to the gamma rays released by the radioactive elements. Estimations of the radiological hazards in the granitic rocks were made, and statistical approaches were utilized to demonstrate the associations among radionuclides and radiological factors. The assessment confirmed that uranium, potassium, and their respective minerals in the granitic rocks were the key factors contributing to the radiological risks. As a result, the study determined that the granite rocks found in the study area needed precautions to be taken due to their high levels of radioactivity.

Assessment of the Radioactivity, Metals Content and Mineralogy of Granodiorite from Calabria, Southern Italy: A Case Study.

In this paper, an assessment of the natural radioactivity level, radon exhalation, metal contamination, and mineralogy of a granodiorite rock sample from Stilo, in the Calabria region, Southern Italy is presented as a case study. This rock was employed as a building material in the area under study. The specific activity of 226Ra, 232Th and 40K natural radioisotopes was assessed through high-purity germanium (HPGe) gamma-ray spectrometry. Then, several indices such as the absorbed gamma dose rate (D), the annual effective dose equivalent (AEDE), the activity concentration index (ACI) and the alpha index (Iα), were quantified to determine any potential radiological health risk related to radiation exposure from the analyzed rock. Furthermore, E-PERM electret ion chambers and inductively coupled plasma mass spectrometry (ICP-MS) measurements were carried out to properly quantify the radon exhalation rate and any possible metal pollution, respectively. In particular, to further address metal pollution factors, the geo-accumulation index (Igeo) was calculated to properly address the toxicity levels of the ecosystem originating from the detected metals. Finally, with the aim of successfully discriminating the provenance of such naturally occurring radionuclides, a combined approach involving X-ray diffraction (XRD) and µ-Raman spectroscopy was employed for the identification of the main radioisotope-bearing minerals characterizing the investigated granodiorite. The results achieved in this case study can be taken as the basis for further inquiries into background levels of radioactivity and chemical contamination in natural stone employed as building materials.

Radioactivity of Technosols on thermal power station ash disposal sites: Assessment of potential radiological human‐health risk

AbstractSoil radioactivity is a poorly recognized form of land degradation; however, there are regions all around the world where it can be dangerous to the environment and human health. The aim of the study was to analyze the radioactivity of Technosols developed on thermal power station (TPS) ash disposal sites. Total concentration of uranium (U), thorium (Th), and cesium (Cs), as well as the radioactivity of select radionuclides in Technosols were determined to recognize the level of radioactivity and to assess the potential radiological health risk. Total U, Th and Cs concentrations in Technosols were in ranges 1.5 to 11.3, 4 to 22.9, and 0.2 to 21.3 mg·kg−1, respectively. The radioisotope activities in Technosols (in Bq·kg−1) were in the 1.6–25.5 (137Cs); 29.2–1265 (40K); 26.2–99.9 (228Th); 27.9–100 (228Ra); 20.5–134. (226Ra); 32.8–177 (210Pb); 23.9–144 (238U); 1.2–7.0 (235U) ranges. The activity concentrations were slightly higher than the activities of non‐contaminated soils. Technosols developed from bituminous coal ash had higher 40K, 228Th, and 228Ra activity concentrations than soils developed from lignite ash. Artificial 137Cs occurred in surface horizons of Technosols due to fall of atmospheric dust enriched in 137Cs. Annual effective dose (AED) in Technosols amounted 0.07–0.16 mSv·a−1 and was somewhat higher than the global and Polish average (0.06 and 0.07 mSv·a−1, respectively) for outdoor external terrestrial radiation. The radioactivity of the investigated Technosols is slightly above the average radioactivity of native soils. The radiological human‐health risk related to the analyzed soils is low.

Natural Radioactivity in Raw Building Materials for Underground Parking Lots and Assessment of Radiological Health Risk for the Population.

This article reports the results of an investigation into the activity concentration of natural radionuclides in raw building materials for underground parking lots, together with the assessment of the radiation hazard for the public related to exposure to ionizing radiations. To this purpose, high-purity germanium (HPGe) γ-ray spectrometry was employed in order to quantify the average specific activity of 226Ra, 232Th, and 40K natural radioisotopes. With the aim to assess any possible radiological health risk for the population, the absorbed γ-dose rate (D), the annual effective dose equivalent outdoor (AEDEout) and indoor (AEDEin), the activity concentration index (I), and the alpha index (Iα) were also estimated, resulting in values that were lower than the maximum recommended ones for humans. Finally, the extent of the correlations existing between the observed radioactivity and radiological parameters and of these parameters with the analyzed samples was quantified through statistical analyses, including Pearson's correlation, a principal component analysis (PCA), and a hierarchical cluster analysis (HCA). As a result, three clusters of the investigated samples were recognized based on their chemical composition and mineralogical nature. Noteworthily, this paper covers a certain gap in science since its topic does not appear in literature in this form. Thus, the authors underline the importance of this work to global knowledge in the environmental research and public health fields.

Time-dependent leakage model for the identification of defective fuel assemblies of VVER-type nuclear reactors, part 1: Theory

Level of radioactive contamination in primary coolant of nuclear reactors must be kept as low as possible, therefore essential conditions is the leakage-free state of the fuel rods. To monitor the leakage defects in VVER reactors, the radioactivity of fission products must be measured in the primary loops. From radioactivity data it is possible to infer the fuel assemblies' hermetic or time-dependent leakage state. A new, time-dependent leakage model was developed for operating conditions of VVER nuclear reactors. This leakage model is able to calculate isotopes’ radioactivity inside the fuel and in the primary coolant originating from nuclear fission and neutron-activated reactions. The core of the leakage model consists of several systems of differential equations describing dominant nuclear processes on time-dependent number of radioactive isotope nuclei within fuel assemblies and primary coolant. The model considers the effect of technological parameters on the activity of radioisotopes in the primary coolant.

Изучение особенностей накопления искусственных и естественных радионуклидов в корнях лопуха большого Arctium lappa L.

The Voronezh region has traditionally been the most significant area for crop production and agriculture. However, the development of mineral resources, the implementation of chemical fertilisers in agriculture, and the consequences of the Chernobyl accident have highlighted the necessity to ensure the food industry has access to safe and effective plant raw materials. The use of low-quality plant raw materials and products derived from them represents a significant source of exposure to various ecotoxicants, including radionuclides, which can enter the human body. Objective: to examine the accumulation of the most significant artificial and natural radionuclides in the roots of a large burdock plant, harvested in different territories of the Voronezh region, with a view to determining the extent of the anthropogenic impact. Materials and methods. Under experimental conditions, the specific activity of the main long-lived artificial radioisotopes (cesium-137, strontium-90) and naturally occurring radionuclides (thorium-232, potassium-40, radium-226) on a spectrometer (RADEK MKGB-01 radiometer) was determined in samples of the upper layers of soils and roots of large burdock. Results. All of the studied samples of large burdock roots, which had been prepared in natural and artificial phytocenoses in the Voronezh region, met the existing radiation safety requirements (first group). With an increase in the specific activity of strontium-90, cesium-137, thorium-232, potassium-40, radium-226 in the soil, there was an accompanying increase in the specific activity of these radionuclides in the roots of a large burdock. Correlation analysis of the specific activity of artificial and natural radionuclides in the soil and roots of large burdock revealed a highly significant relationship between these numerical indicators, thereby confirming the predominant transposed pollution. Conclusion. The accumulation patterns in roots of large burdock, naturally occurring and anthropogenic radionuclides are described by mathematical dependencies, with an accuracy of approximation that is as high as possible.

Natural Radioactivity of Granitic Rocks and Their Health Risk around Ingesana Mountains, Sudan.

This work was carried out mainly to analyze radioactive elements 40 K, 232 Th, and 226 Ra and non-radioactive elements in some granitic rocks and study their health risk for humans and non-humans. Radioisotope activity was evaluated using a high-purity germanium (HPGe) detector, and various radiological hazard indices were calculated. We also measured some non-radioactive elements using x-ray fluorescence analysis and performed Pearson correlation analysis to examine the relationships between the radionuclides and the non-radioactive elements. Furthermore, we used the ERICA software to estimate the total dose rate per organism for some non-human biota. The means of 226 Ra, 232 Th, and 40 K are 25.13 ± 5.22 Bq kg -1 , 29.01 ± 6.95 Bq kg -1 , and 323.07 ± 97.83 Bq kg -1 , respectively. Hence, 226 Ra, 232 Th, and 40 K radioactivities were lower than the worldwide average limits. The 226 Ra, 232 Th, and 40 K levels were under the global average values. The hazardous radiometric variables were computed, and the findings observed that the mean absorbed dosage was 23.48 ± 7.36 nGy h -1 , the yearly effective dose rate was 29.82 ± 10.46 μSv y -1 , and the radium equivalent activity was 88.88 ± 18.64 Bq kg -1 . The average dose and yearly effective dose rates were lower than the global average absorbed dose rate of 60 nGy h -1 and the ICRP standard of 1.0 mSv y -1 . The results of Ra-equivalent activity were lower than the recommended maximum criterion for building materials limit of Ra-equivalent activity (370 Bq kg -1 ) proposed by UNSCEAR. Tests of Pearson correlation coefficients indicate a substantial positive relationship between 226 Ra and 232 Th and a modest correlation between 226 Ra and 40 K. Meanwhile, no association between 226 Ra and 40 K and non-radioactive components has been identified. Thorium-232 exhibits a moderately favorable connection with Ti, Fe, and Ni. The estimated total dose rate per organism for the studied non-human is less than the ambient dose rate. However, the total dose rate for small burrowing mammals and reptiles exceeds the background exposure rate. In accordance with the findings, granite rocks may be safe to use as construction materials and pose no threat to human health.

Liquid scintillation counting at the limit of detection in biogeosciences.

Liquid scintillation is widely used to quantify the activity of radioisotopes. We present an overview of the technique and its application to biogeosciences, particularly for turnover rate measurements. Microbial communities and their metabolism are notoriously difficult to analyze in low energy environments as biomass is exceedingly sparse and turnover rates low. Highly sensitive methods, such as liquid scintillation counting, are required to investigate low metabolic rates and conclusively differentiate them from the background noise of the respective analyzer. We conducted a series of experiments to explore the effects of luminescence, measurement time and temperature on scintillation measurements. Luminescence, the spontaneous emission of photons, disproportionally affects samples within the first few hours after sample preparation and can be minimized by following simple guidelines. Short measurement times will negatively affect liquid scintillation analysis or if background noise makes up a significant proportion of the detected events. Measurement temperature affected liquid scintillation analysis only when the temperature during the measurement reached approximately 30°C or higher, i.e. the liquid scintillation analyzer was placed in an environment without temperature control, but not in cases where chemicals were stored at elevated temperatures prior to measurement. Basic understanding on the functionality of a liquid scintillation analyzer and simple precautions prior to the measurement can significantly lower the minimum detection limit and therefore allow for determination of low turnover rates previously lost in the background noise.

Study of cosmogenic activation above ground for the DarkSide-20k experiment

The activation of materials due to exposure to cosmic rays may become an important background source for experiments investigating rare event phenomena. DarkSide-20k, currently under construction at the Laboratori Nazionali del Gran Sasso, is a direct detection experiment for galactic dark matter particles, using a two-phase liquid-argon Time Projection Chamber (TPC) filled with 49.7 tonnes (active mass) of Underground Argon (UAr) depleted in 39Ar. Despite the outstanding capability of discriminating γ/β background in argon TPCs, this background must be considered because of induced dead time or accidental coincidences mimicking dark-matter signals and it is relevant for low-threshold electron-counting measurements. Here, the cosmogenic activity of relevant long-lived radioisotopes induced in the experiment has been estimated to set requirements and procedures during preparation of the experiment and to check that it is not dominant over primordial radioactivity; particular attention has been paid to the activation of the 120 t of UAr used in DarkSide-20k. Expected exposures above ground and production rates, either measured or calculated, have been considered in detail. From the simulated counting rates in the detector due to cosmogenic isotopes, it is concluded that activation in copper and stainless steel is not problematic. The activity of 39Ar induced during extraction, purification and transport on surface is evaluated to be 2.8% of the activity measured in UAr by DarkSide-50 experiment, which used the same underground source, and thus considered acceptable. Other isotopes in the UAr such as 37Ar and 3H are shown not to be relevant due to short half-life and assumed purification methods.

Sorption behavior studies of Cs and its migration in soil samples around Visakhapatnam, India.

Meeting the requirement of high specific activity of radioisotopes and carrying out comprehensive research and development activities in the nuclear field, different nuclear facilities, including their waste disposal facilities, are going to be operational at Visakhapatnam, India. Due to environmental processes, the engineered disposal modules may lose their structural integrity and may release some radioactivity to the geo-environment. The subsequent migration of radionuclides reaching the geological environment will be governed by the distribution coefficient (Kd). Cs was chosen for the sorption study in two soil samples (soil-29 and 31) and to estimate the Kd in all the 40 soil samples through the laboratory batch method at the new campus of DAE, Visakhapatnam, India. Different soil chemical parameters like pH, organic matter, CaCO3, and cation exchange capacity were determined in 40 soil samples and their effect on Cs sorption was investigated. The effect of solution pH and initial concentration of Cs on sorption was also studied. The results show that the sorption of Cs increases with increasing pH. The Cs sorption was well explained by Freundlich and Dubinin-Radushkevich (D-R) isotherm models. Site-specific distribution coefficients (Kd) were also estimated and the values were found to vary from 75 ± 1 to 540 ± 12 L kg-1. The observed wide variation in Kd could be due to large variations in the physico-chemical properties of collected soil. The competitive ions effect study suggests that K+ has higher interference for Cs+ sorption as compared to Na+. The present study results will help assess the environmental impact due to Cs release in any unforeseen scenario and in planning effective remediation strategies.

Eco-friendly zeolites for innovative purification of water from cationic dye and heavy metal ions.

Along with industrial development, coal consumption and the amount of waste fly ash increase, negatively impacting the environment. Fly ash contains silicon and aluminum oxides, and could serve as a substrate for the synthesis of zeolite. The novelty of this study was to assign a potential of fly ashes from lignite combustion in three energy blocks operating on circulating fluidized bed boilers to convert them into zeolites. The X-ray diffraction, X-ray fluorescence, Fourier-transform infrared spectroscopy; pore volume, size and specific surface area tests; thermal analysis; leaching test; and radioisotope activity analysis were applied to characterize the materials. Zeolites were synthesized using hydrothermal and fusion methods modified in the molar concentration of NaOH, the ratio of NaOH to raw material, drying and heating temperatures, and treatment time. Both, hydrothermal and fusion synthesis were found to result in the efficient formation of the zeolite Linde Type A, gismondine, and sodalite; with the largest specific surface area of zeolite developed after fusion synthesis (132 m2 g−1). The zeolite had surpassingly high efficiency of adsorption of cationic impurities from post-production wastewater, ranging from 85% to 97% and from 89% to 100%, when tested with methylene blue and lead ions, respectively. The costs of zeolite production were estimated to range from 3.82 to 6.36 $ per 1 kg, thus reducing the price of commercial zeolite by up to 99.5%. The new engineering method of zeolite is an attractive alternative to the storage of hazardous byproducts from coal-fired power plants. Eco-zeolite is also a technological innovation in the cleaning of post-production wastewater from harmful impurities, while water reuse in a closed circuit. Our studies provide tools for novel and integrated environmental management in line with the 'Cleaner Production' goal to reduce the production of waste, while improving use efficiency of energy, resources, and water.

Production and characterization of 111Ag radioisotope for medical use in a TRIGA Mark II nuclear research reactor

Radio Pharmaceutical Therapy (RPT) comes forth as a promising technique to treat a wide range of tumors while ensuring low collateral damage to nearby healthy tissues. This kind of cancer therapy exploits the radiation following the decay of a specific radionuclide to deliver a lethal dose to tumor tissues. In the framework of the ISOLPHARM project of INFN, 111Ag was recently proposed as a promising core of a therapeutic radiopharmaceutical. In this paper, the production of 111Ag via neutron activation of 110Pd-enriched samples inside a TRIGA Mark II nuclear research reactor is studied. The radioisotope production is modeled using two different Monte Carlo codes (MCNPX and PHITS) and a stand-alone inventory calculation code FISPACT-II, with different cross section data libraries. The whole process is simulated starting from an MCNP6-based reactor model producing the neutron spectrum and flux in the selected irradiation facility. Moreover, a cost-effective, robust and easy-to-use spectroscopic system, based on a Lanthanum Bromo-Chloride (LBC) inorganic scintillator, is designed and characterized, with the aim of using it, in the future, for the quality control of the ISOLPHARM irradiated targets at the SPES facility of the Legnaro National Laboratories of INFN. natPd and 110Pd-enriched samples are irradiated in the reactor main irradiation facility and spectroscopically characterized using the LBC-based setup and a multiple-fit analysis procedure. Experimental results are compared with theoretical predictions of the developed models, showing that inaccuracies in the available cross section libraries prevent an accurate reproduction of the generated radioisotope activities. Nevertheless, models are normalized to our experimental data allowing for a reliable planning of the 111Ag production in a TRIGA Mark II reactor.

Distribution of 90Sr and 137Cs in biotic and abiotic elements of the coastal zone of the King George Island (South Shetland Archipelago, Antarctic Peninsula)

For many years Antarctic ecosystems have been considered pristine, however recent studies, including our results, contradict this assumption. Our comprehensive study on the activity of anthropogenic radioisotopes (137Cs and 90Sr) in the most common species of green algae, bryophytes, lichens, and vascular plants, as well as soil and guano samples collected over a large area on King George Island (South Shetland Archipelago) in the austral summer 2018/2019 clearly indicate the importance of large-scale transport in shaping the level of pollution in areas very distant from potential sources of contamination. Additionally, radioisotope pollution can be measured even after a very long period (>60 years) since their occurrence. The mean activity of 137Cs measured in lichens, bryophytes, vascular plants, green algae, soil, and guano was, respectively: 3.72 Bq kg−1dw, 3.70 Bq kg−1dw, 2.62 Bq kg−1dw, 2.26 Bq kg−1dw, 4.07 Bq kg−1dw and 2.08 Bq kg−1dw. For 90Sr mean activity in lichens, bryophytes, vascular plants, green algae, and soil was, respectively: 1.99 Bq kg−1dw, 3.05 Bq kg−1dw, 2.42 Bq kg−1dw, 1.08 Bq kg−1dw, and 6.43 Bq kg−1dw. Increased activities of 90Sr and 137Cs were observed in species collected in the area influenced by glacier melt and penguin guano.

Investigation of the Suitability of a Commercial Radiation Sensor for Pretherapy Dosimetry of Radioiodine Treatment Patients.

Radioiodine (I-131) therapy is routinely used to treat conditions of the thyroid. Dosimetry planning in advance of I-131 therapy has been shown to improve patient treatment outcomes. However, this pretherapy dosimetry step requires multiple outpatient appointments and is not feasible for patients living at greater distances. Here, the feasibility of a commercially available smartphone-operated radiation sensor (Smart Geiger Pro, Technonia) for at-home patient pretherapy dosimetry has been investigated. The influence of both treatment-specific parameters (radioisotope activity, gamma photon energy, patient size) and external factors (sensor placement and motion) on the ability of the radiation sensor to accurately quantify radiation dose rates has been studied. The performance limits of the radiation sensor have been identified. A preliminary trial of the sensor on four I-131 patients prior to their therapy, conducted at the Nuclear Medicine/Endocrinology departments of St James's Hospital Dublin, is also presented. A comparable performance between the low-cost radiation sensor and that of a hospital-grade thyroid uptake probe is reported. This work demonstrates the potential of low-cost commercially available radiation sensors as a solution for at-home pretherapy dosimetry for long distance patients, or indeed for hospitals who wish to implement dosimetry at reduced cost. Recommended conditions for optimum sensor performance use are presented.

Radionuclide activity in cryoconite from glaciers of the Central Caucasus, Russia

This work presents the results of a study of radionuclide activity in cryoconite from glacier and glacial soil of the Central Caucasus. Cryoconite were sampled from the surface of the Garabashi glacier, and soil samples were taken from the humus horizon of periglacial mountain forest-meadow soil. Measurements were performed with low-background germanium gamma spectrometers located inside a passive shield consisting of ∼20 cm of copper, ∼15 cm of lead, and ∼8 cm of borated polyethylene. The specific activity of radionuclides (Be-7, K-40, Th-232, U-235, U-238, Cs-137) was established. It was revealed that all measured spectra contain γ-lines from decays of K-40, decay chains of U-238, U-235 and Th-232. In addition, the spectra of cryoconite samples from the Garabashi glacier show a 477.6 keV line from the decay of the cosmogenic isotope Be-7, and in the soil sample a 661.7 keV line from the radionuclide Cs-137. No radionuclide Be-7 was detected in the mountain forest-meadow soil. Radionuclide Cs-137 is present in the soil sample, while in cryoconite, is not detected. Radioisotope activities in the Garabashi glacier cryoconite, except for the cosmogenic isotope Be-7, do not differ significantly in terms of mass, i.e., the content of K-40, U-238, U-235 and Th-232 in them is approximately the same. The activity of all the studied radionuclides in the soil sample compared to cryoconite samples is lower, although the differences are not significant, except for Th-232, whose activity in soil is almost two times lower.

Multivariate Statistics, Mineralogy, and Radiological Hazards Assessment Due to the Natural Radioactivity Content in Pyroclastic Products from Mt. Etna, Sicily, Southern Italy.

In this article, an investigation of the natural radioactivity content of pyroclastic products from Mt. Etna, eastern Sicily, Southern Italy, was carried out. In particular, the assessment of the average activity concentration of the investigated radionuclides, related to the mineralogical phase composition of the analyzed samples, and the radiological health risk for the population, was performed. High Purity Germanium (HPGe) gamma-ray spectrometry was employed in order to quantify the average specific activity of 226Ra, 232Th, and 40K natural radioisotopes. The absorbed gamma dose rate (D), the radium equivalent activity (Raeq), the hazard indices (Hin and Hex), the annual effective dose equivalent outdoor (AEDEout), and the excess lifetime cancer risk (ELCR) were also estimated in order to assess any possible radiological hazard for the population. In our case, they were found to be lower than the maximum recommended values for the population members, thus reasonably excluding radiological hazard effects. Moreover, the identification of the source of the aforementioned naturally occurring radionuclides was attempted by X-ray Diffraction (XRD) and Micro-Raman Scattering (MRS), thereby recognizing the main radioisotope-bearing minerals present in the investigated pyroclastic products. Finally, Pearson correlation, Principal Component Analysis (PCA), and Hierarchical Cluster Analysis (HCA) were performed by processing observed radioactivity and radiological parameters in order to determine their correlation with the sampling locations.

Effect of I-131 Radioisotope Activities on Organ Dose Used in Nuclear Medicine

There are many ways to be exposed to radiation in life. Medical applications, in particular, are the most important form of severe exposure. In medical applications, Computed Tomography (CT) scans are in the first place, while nuclear medicine is in the second place. Of course, the dose absorbed by the exposed tissue and therefore the organs is directly proportional to the risks to health. In nuclear medicine, due to the radioisotopes placed in the body for therapeutic purposes, some doses are not given only to the organ and/or tissues where the tumor is placed, but also to other surrounding organ and tissues. In this study, the change in the doses received by the thyroid gland, thymus, and lymph nodes according to the activities of the iodine radioisotope I-131 placed in the thyroid gland of adult phantoms (both male and female) were investigated with the Monte Carlo-based code.