Radioactivity Concentration Research Articles

ASSESSMENT OF KARAMUSTAFA GOLD-BEARING Zn-Pb MINE (GÜMÜŞHANE, TÜRKİYE) AREA IN TERMS OF NATURAL AND ARTIFICIAL RADIOACTIVITY

This study aimed to assess the environmental effects of natural and artificial radioactivity contents, especially in the context of medical geology of base metal-containing mineral deposits. In the study, artificial/anthropogenic (137Cs) and natural (226Ra, 232Th and 40K) radioactivity levels in the soil of the Karamustafa gold-bearing Zn-Pb-(±Cu) mining area, one of the important mines of Gümüşhane (NE Türkiye), were determined and evaluated. In order to determine the natural and artificial radioactivity of the mining area, 9 soil samples were collected from different parts of the field, taking into account the geological and alteration characteristics of the field. 232Th, 226Ra and 40K activities of the samples prepared according to the relevant laboratory procedures were determined by the gamma-ray spectrometry, and the artificial radioactivity values of 137Cs were also measured. As a result of the study, it was determined that the 40K and 226Ra average activities of the Karamustafa gold-bearing Zn-Pb-(±Cu) mining area exceeded the world averages in most sampling points, while the 232Th activities were above the world averages at some sampling points. It has been determined that the artificial/human-derived 137Cs radioisotope values in the field are remarkably high. Considering the major radio indices calculated for the field, it was determined that the absorbed dose rate and annual effective dose rate indices of the mine site exceeded the relevant threshold values. When all the data obtained from the field were evaluated together, it was concluded that the mine field needed detailed study in the context of radiation risk.

A Preliminary Study on Evaluation of Time-Dependent Radionuclide Removal Performance Using Artificial Intelligence for Biological Adsorbents

Background: Recently, biological adsorbents have been developed for removing radionuclides from radioactive liquid waste due to their high selectivity, eco-friendliness, and renewability. However, since they can be damaged by radiation in radioactive waste, a method for estimating the bio-adsorbent performance as a time should consider the radiation damages in terms of their renewability. This paper aims to develop a simulation method that applies a deep learning technique to rapidly and accurately estimate the adsorption performance of bio-adsorbents when inserted into liquid radioactive waste.Materials and Methods: A model that describes various interactions between a bio-adsorbent and liquid has been constructed using numerical methods to estimate the adsorption capacity of the bio-adsorbent. To generate datasets for machine learning, Monte Carlo N-Particle (MCNP) simulations were conducted while considering radioactive concentrations in the adsorbent column.Results and Discussion: Compared with the result of the conventional method, the proposed method indicates that the accuracy is in good agreement, within 0.99% and 0.06% for the R<sup>2</sup> score and mean absolute percentage error, respectively. Furthermore, the estimation speed is improved by over 30 times.Conclusion: Note that an artificial neural network can rapidly and accurately estimate the survival rate of a bio-adsorbent from radiation ionization compared with the MCNP simulation and can determine if the bio-adsorbents are reusable.

Development of a Methodology for Estimating Radioactivity Concentration of NORM Scale in Scrap Pipes Based on MCNP Simulation

Development of a Methodology for Estimating Radioactivity Concentration of NORM Scale in Scrap Pipes Based on MCNP Simulation

Detectability of cold tumors by xSPECT bone technology compared with hot tumors: a supine phantom study.

Detecting cold as well as hot tumors is vital for interpreting bone tumors on single-photon emission computed tomography (SPECT) images. This study aimed to visually and quantitatively demonstrate the detectability of cold tumors using xSPECT technology compared with that of hot tumors in the phantom study. Five tumors of different sizes and normal bone contained a mixture of 99mTc and K2HPO4 in a spine phantom. We acquired SPECT data using an xSPECT protocol and transverse images were reconstructed using xSPECT Bone (xB) and xSPECT Quant (xQ). Mean standardized uptake values (SUVmean) in volumes of interest (VOI) were calculated. Recovery coefficients (RCs) for each tumor site were calculated with reference to radioactive concentrations. The SUVmeans of the whole vertebral body for hot tumor bone image in cortical bone phantom reconstructed by with xB and xQ were 5.77 and 4.86 respectively. The SUVmean of xB was similar to the true value. The SUVmeans for xB and xQ reconstructed images of cold tumors were both approximately 0.16. The RC of the cold tumor on xQ images increased as the tumor diameter decreased, whereas that of xB remained almost constant regardless of the tumor diameter. In conclusion, the quantitative accuracy of detecting hot and cold tumors was higher in the xB image than in the xQ image. Moreover, the visual detectability of cold tumors was also excellent in xB images.

Novel environmental monitoring detector for discriminating fallout and airborne radioactivity

Early warning networks are used for detecting abnormal radioactivity levels in the environment. State-of-the-art networks are equipped with both dose rate detectors and spectrometric stations. Current networks don’t automatically discriminate between radioactivity on the ground and in the air. A novel directional sensing gamma radiation detector utilizing a collimated phoswich scintillator was developed. The signals from the two scintillator materials are separated using a pulse shape discrimination. The separated signals are employed to determine the radioactivity concentrations on the ground and in the air assuming specific concentration distributions. Limitations related to imperfect directional sensing and dead time are discussed.

IMPACT OF LEGISLATIVE CHANGE ON THE CLASSIFICATION OF RAW MATERIALS AND BUILDING MATERIALS IN TERMS OF NATURAL RADIOACTIVITY

Natural radioactivity is present in the human environment to a greater or lesser extent, also in varioustypes of raw or building materials. Monitoring of the concentration of natural radioactive isotopesof potassium 40K, radium 226Ra and thorium 228Th or 232Th in samples of raw and/or constructionmaterials allows assessing the exposure of people to ionizing radiation emitted by these materials.Exceeding the limit value of the radioactive concentration index for raw and/or building materials,defined in the Ordinance of the Council of Ministers (Polish Journal of Laws/Dz.U. No. 33/2021),may result in an effective radiation dose greater than 1 mSv/year – the dose limit for the population.In Poland, pertinent legislation requiring the establishing of the natural radioactivity of raw and/orbuilding materials dates back to the 1970s and has been changed several times by now. However, themost significant changes in the legislation have occurred recently. Due to the obligation of imposingthe application of the provisions of the of European Council 2013/59/EURATOM of 5 December2013 laying down basic safety standards for protection against risks arising from exposure to theeffects of ionizing and repealing Directives 89/618/Euratom, 90/641/ Euratom, 96/29/Euratom,97/43/Euratom and 2003/122/Euratom (the so-called BSS version), it was necessary to adopt theamendment to the Atomic Law. The implementation of the BSS Directive in Poland was issued on thebasis of the resolution of the Parliament of June 13, 2019 amending the Atomic Law Act and the FireProtection Act (Polish Journal of Laws/Dz.U. 2019, item 1593). The amendment of the Atomic LawActs led to the harmonisation of regulations on radioactivity in raw and building materials betweenPoland and the Member States. This article presents the impact of an amendment of the AtomicLaw and of the accompanying normative acts on the studies of the natural radioactivity of raw andconstruction materials, using the example of an analysis of the concentration of natural radioactiveisotopes present in the coal combustion products (CCP), i.e. fly ash, slags and ash-slag mixtures.

Production and synthesis of a novel 191Pt-labeled platinum complex and evaluation of its biodistribution in healthy mice

We previously reported that our sugar-conjugated platinum complex (cis-dichloro [(2-fluoro-α-d-glucopylanosidyl) propane-1,3-diamine] platinum: FGC-Pt) has low toxicity and tumor growth inhibitory effect comparable to that of cisplatin. We focused on radioactive Pt isotopes in order to analyze the kinetics of FGC-Pt using gamma-ray imaging techniques, assuming that FGC-Pt could be used for chemotherapy in the future. Therefore, in this study, we aimed to develop a non-invasive method to analyze the biodistribution of FGC-Pt using 191Pt-labeled FGC-Pt ([191Pt]FGC-Pt).191Pt was produced via the (n,2n) reaction induced by accelerator neutrons. [191Pt]FGC-Pt was prepared using two different methods. In the first method, [191Pt]FGC-Pt (method A) was obtained through the accelerator neutron irradiation of FGC-Pt. In the second method, [191Pt]FGC-Pt (method B) was synthesized using [191Pt]K2PtCl4, which was obtained by the accelerator neutron irradiation of K2PtCl4. Highly purified [191Pt]FGC-Pt was obtained using the latter method, which suggests that the synthetic method using a 191Pt-labeled platinum reagent is suitable for the radioactivation of platinum complexes.We also aimed to investigate whether a significant correlation existed between the biodistribution of FGC-Pt and [191Pt]FGC-Pt in healthy mice 24 h after tail vein administration. FGC-Pt and [191Pt]FGC-Pt were similarly distributed in healthy mice, with a higher accumulation in the liver and kidney 24 h post injection. In addition, a significant correlation (p < 0.05, r = 0.92) between the 191Pt radioactivity concentration (%ID/g (gamma counter)) and platinum concentration (%ID/g (ICP-MS)) was observed in 13 organs. These results suggest that 191Pt-labeled compounds, synthesized using radioactive platinum reagents, can be used to confirm the biodistribution of platinum compounds. Our study on the biodistribution of [191Pt]FGC-Pt is expected to contribute to the development of novel platinum-based drugs in the future.

Evaluation of Chemical and Impacts of Radionuclides in Borehole Waters in Igbajo Town, Osun State, Nigeria

Water is a universal solvent on earth and sources such as wells, rivers, springs, boreholes, and other freshwater bodies typically serve as a pathway for contaminants to enter the ecosystem while also supplying water for domestic and drinking purposes. The activity concentrations of radionuclides in borehole water in Igbajo town were assessed using gamma-ray spectroscopy, so as to effectively determine the degree of radiological risk to the environment and its inhabitants, the outcomes were used to calculate all the radiological impact parameters. The activity concentrations obtained for 40K, 238U and 232Thranged from 7.25±0.60 to 62.15±4.48Bq.L–1; 3.08±0.45 to 15.24±3.07 Bq.L–1and 1.08±1.10 to 17.75±1.59 Bq.L–1 and with average values of 23.12±1.59 Bq.L–1, 6.27±2.01 Bq.L–1 and 7.01±0.89 Bq.L–1 respectively. The Annual Effective Dose (AED) for ingested radionuclide in drinking water for an adult was1.4872 μSv.yr–1. The Radium Equivalent Activity Index, Raeq obtained was 34.9186 Bq.L–1. The estimated hazard indices Hint and Hext were 0.04876 and 0.06574 respectively. The Excess Lifetime Cancer Risk, ELCR (x10–6) was 5205.15. With a lifetime expectancy of 70 years, this high value suggests that there is a high chance of developing cancer.The value of the Annual Gonadal Equivalent Dose, AGED in the water was 55.9175μSv.yr–1. The estimated Gamma Index, Iγ was0.1273 mSv.yr–1. There is a significant health hazard to the environment and people living in the area owing to the radioactivity contents and radiological impact parameters. Hence, the need for urgent attention and means to prevent hazards which the overdose could cause.

Phase I/IIa trial of 18F-prostate specific membrane antigen (PSMA) 1007 PET/CT in healthy volunteers and prostate cancer patients.

18F-PSMA 1007 is a promising PET tracer for prostate cancer. We aimed to examine the safety, biodistribution, radiation dosimetry, and clinical effectiveness in Japanese healthy volunteers and patients with prostate cancer. Part A evaluated the pharmacokinetics and exposure doses in three healthy volunteers. Part B evaluated the diagnostic accuracy in patients with untreated preoperative prostate cancer (Cohort 1, n=7) and patients with biochemical recurrence (Cohort 2, n=3). All subjects received a single dose of 3.7MBq/kg 18F-PSMA 1007. Results: 18F-PSMA 1007 was found to be safe and well tolerated in all subjects. No serous AEs or drug-related AEs were identified during the present study. The average blood radioactivity concentration reached a maximum of 47.87±1.05 (percentage of injected dose [%ID]/ml) at 5min and then decreased to 1.60±0.78 in 6h. The systemic radioactivity reached a maximum of 211.05±6.77 (%ID$\times$103) at 5min and decreased to 7.18±3.91 in 6h. The sensitivity and positive predictive value were 100% and 100% based on both pathologic and imaging confirmation as gold standard. In Cohort 1, 15 primary foci (11.9%) were >5mm in the largest diameter and identified in 39 of 126 segments (30.1%). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for 60min uptake time acquisition were 80.0, 96.5, 91.4, 91.2 and 91.3%, respectively. Our study revealed that 18F-PSMA 1007 was safe, well tolerated and showed high accuracy in the diagnosis of prostate cancer.

Assessment of the use of tailings based on the legal requirements for radiation protection, from niobium mining in Minas Gerais – Brazil

Brazil is the world's largest supplier of niobium to industry, accounting for 98% of world production, with Minas Gerais supplying 80% of total production. The mineral exploration industry generates millions of tons of waste annually. In several mining industries, waste is considered a burden for companies. Based on the radiation protection exemptions for the disposal of mining waste, the study analyses the use of waste as a raw material for the construction industry. The minimum dose rate found for gamma radiation in the waste was 0.24 µSv/h and a maximum dose of 0.33 µSv/h, which corresponds to an annual dose above the population exposure limit. The radio concentrations from gamma spectrometric analyses with the Ge(HP) detector for the two samples are a maximum of 240 Bq/kg for Ra-226 and a maximum of 840 Bq/kg for Ra-228. Despite the dose values determined for gamma radiation, CNEN Resolution 179 of 2014 considers materials with natural radioactive concentrations of radium 226 and 228 of up to 1000 Bq/kg suitable for use in the cement industry. Nevertheless, further analysis must be carried out. Since the tailings contain a concentration of Ra-226 and the radio is a source of radon gas, new analyses need to be carried out targeting the exhalation of radon.

Determination of natural and artificial radioactivity levels and radiation hazard indices for soil samples in Kırşehir

Abstract The aim of this study is to create a radiological map of Kırşehir province in Turkey by analyzing the radioactivity levels of soil samples and environmental radiation measurements. 226Ra, 232Th, 40K and 137Cs radionuclides were analysed in soil samples collected from 47 locations using gamma spectrometry with an HPGe detector. According to the results obtained, gamma radioactivity concentration ranges and mean values for 226Ra, 232Th, 40K and 137Cs were determined as 133 ± 15–1515 ± 128 Bq/kg (599.40 Bq/kg), 0.3 ± 0.09–21.1 ± 1.7 Bq/kg (4.61 Bq/kg), 8.7 ± 0.9–128.5 ± 8.5 Bq/kg (29.66 Bq/kg) and 11.6 ± 8.6–273.8 ± 19.9 Bq/kg (48.80 Bq/kg) respectively. Average radioactivity levels for 40K and 232Th are above the world average. The mean radium equivalent activity (Raeq), gamma dose rate (D), annual effective dose equivalent (AEDE), external hazard index (H ex ), and the excess lifetime cancer risk (ELCR) were calculated as 145.45 Bq/kg, 122.13 nGy/h, 0.15 mSv/h, 0.39 and 0.29 × 10−3 respectively.

Assessment of radioactivity concentration for building materials used in Babadogo Estate, Nairobi City County, Kenya.

Natural radioactive materials in certain conditions can get to hazardous radiological level. The aim of the present work was to evaluate the natural activity concentration from sampled building materials collected from different locations in Babadogo Estate within Nairobi City County. The analysis done using gamma ray spectrometer, which was put into action for spectral data acquisition and then analysis. The activity concentration levels of 238U, 232Th and 40K for the selected samples of building materials was measured by the use of gamma ray spectrometry method. The analyzed data compared with the standard acceptable values. The activity concentration in 40K varied from 55±3 to 2647±132Bq kg-1, giving an average (sum of all values divided by 33) value of 831±42Bq kg-1; 238U varied from 39±2 to 3602±180Bq kg-1, giving average figures of 378±19Bq kg-1 and 232Th ranged from 5.000±0.300 to 4213±211Bq kg-1, giving average figure of 290±15Bq kg-1. The calculated average figures for activity concentration surpassed the world average values of 420, 33 and 45Bq kg-1 in 40K, 238U and 232Th, respectively.

Environmental radioactivity, radiological hazards, and trace elements assessment of nearshore sediment in the Bay of Bengal

The current study focuses on the environmental radioactivity and multi-risk assessment of nearshore sediment as a source of marine pollution along the Bay of Bengal. The study examines the distribution of primordial radionuclide concentrations using a thallium-activated sodium iodide (NaI(Tl)) detector-based gamma-ray spectrometer and Potentially Toxic Elements (PTE) through atomic adsorption analysis. The data also were used to characterize ecological threats, radiological risks, and the geospatial distribution of toxic compounds in nearshore sediment as a proxy for marine pollution. The active concentration of primordial radionuclides such as uranium-238 (238U), thorium-232 (232Th), and potassium-40 (40K) was found in the range from ≤ 3 to 68 (11.4), ≤ 9.5 to 142.7 (41.2), and 85.2 to 603.4 (362) Bq/kg, and the results show that the average radioactive concentration of the average radionuclides was less than suggested by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) ranges. Potentially toxic elements iron (Fe), chromium (Cr), nickel (Ni), lead (Pb), and zinc (Zn) were higher in deeper water depths. The current study reveals that mud distribution primarily controls such elements. A decreasing order has been seen as follows by the ecological risk index of individual elements: copper (Cu) > lead (Pb) > nickel (Ni) > chromium (Cr) > zinc (Zn). The significant Pb, Cu, and Zn concentrations indicated high pollution at most stations, possibly resulting from regional and terrestrial sources such as industrial activity, urban drainage, manufacturing, and farming. The migration of contaminated soil from the industrial and transportation sectors may be the source of the increased levels of hazardous elements and naturally occurring radionuclides in the sediment transported into the coastal ecosystems of Bay of Bengal.

Geology, Petrography, and Geochemistry of Younger Granites and Related Radioactive Pegmatite from Gabal El Urf Area, North Eastern Desert, Egypt: Implications for the Evolution of the NYF-Type Rare-Elements Granitic Pegmatite

Gabal El Urf region is located in the northern Egyptian Eastern Desert and overlain essentially by older and younger granitoids of Late Proterozoic age. These granitoids contain numerous outcrops of pegmatites, mostly occurring as dikes and veins or huge separated masses. In the contrary, pegmatites form lens-like bodies enclosed within the younger granites along their margins. Previous radiometric surveys showed anomalous concentrations of radioactivity on pegmatite body, located to the south of the study region. The younger granites and the associated radioactive pegmatite are studied in details with the aim to describe this pegmatite, petrogenesis and its relation with the encolsing granite. The younger granites are monzogranite and syenogranite according to mineralogical and chemical classification. Petrographically, the two younger granitic phases are strikingly similar. Both consist of potash feldspar, plagioclase and biotite with some hornblende in the earlier phase. Gabal El Urf younger granites are categorized as highly fractionated I-type granites with metaluminous to mildly peraluminous characters, which emplaced at 600 ± 11 Ma in post-collisional environment. The radioactive pegmatite is located within the syenogranite and enriched with Zr, Nb, Ta, Y, Th, U and REEs; accordingly it was classified as NYF-type rare-elements pegmatite. Metal-bearing generations of minerals within the rare-elements pegmatite include zircon, uranothorite, betafite, aeschynite, fluorite, pyrite and ilmenite.

Investigation and assessment of natural radioactivity in commercial animal feeds in Texas

Commercial animal feed in Texas was characterized by determining natural gamma emitters including 40K,137Cs, and Uranium (235U and 238U) and Thorium (232Th) series to obtain basic radioactivity values. The measured activity concentration of natural radionuclides in animal feed was low enough for safe consumption by animal and largely depended on the type of animal feed.40K was the predominant radionuclide showing the highest activity concentration in animal feed. The radioactivity concentration of 214 Bi and 214Pb in 238U decay series was 1.39 and 1.33 Bq/kg in corn, respectively, lower than in other animal feed types. On the other hand, the vitamin/mineral mix samples showed higher concentrations of 214 Bi (9.04 Bq/kg) and 214Pb (10.19 Bq/kg). Beef cattle feed, poultry feed, and vitamin/mineral mix exhibited higher activity concentration of 228Ac and 212Pb in 232Th decay series. Gamma radionuclides appeared to be highly and significantly correlated within each decay series. 235U was present at low levels in all feed samples while the anthropogenic radionuclide of 137Cs was not detected irrespective of the type of animal feed. This study highlights an importance of establishing a current baseline of radioactivity concentration in animal feed in Texas in which the largest animal feed consumption in the US exists.

DETERMINATION OF GROSS ALPHA/BETA RADIOACTIVITY OF WATER SAMPLES AROUND MINING SITES, DANGE-SHUNI LGA, SOKOTO STATE

Mining activities in the Iullumeden (Sokoto) basin is often heard of due to its prominence in artisanal mode of ransacking the Earth in search of minerals and metal of high economic values. The unabated demand in the growing post-industrial era have decimated any health impact that could be borne by the inhabitants of the mining communities. Dange-Shuni is an enclave of this basin that was covered in a bid to determine the gross alpha and beta radioactivity in domestic water in and around mining points. Water samples were collected and analyzed via Hidex 300 SL system of Liquid Scintillation Counting from a systematic sampling of fifteen mining points. The results indicate that both the gross alpha and beta radioactivity concentrations were in elevation with about 80% and 85% above the global limits of 0.5 and 1.0 . The results are good reasons to work hard in order to bring dose of radioactivity exposure to the inhabitants to as low as reasonably achievable (ALARA) being a mandate of WHO.

Natural radioactivity content and elemental composition in different grain sizes of Mamallapuram beach sand

Measurement of natural radioactivity content as well as elemental composition in three different grain sizes (600–425 μm, 425–250 μm and 250–125 μm) of Mamallapuram beach sand, obtained from three sites, have been undertaken using gamma ray spectroscopy and SEM-EDX respectively. 238 U and 232Th activities are higher at the lowest grain size sands (250–125 μm); 40 K activity is seen, only in those samples, where 238 U and 232Th activities are comparatively lesser. In SEM-EDX analysis of the beach sand samples, fourteen elements have been identified. Besides Oxygen (39.06 %) and Silicon (24.59 %), other elements identified, which are more than 1 % are, Iron (13.46 %), Titanium (10.75 %), aluminum (5.22 %), calcium (1.46 %), magnesium (1.28 %) and Potassium (1.28 %). Six elements in trace levels have also been observed viz., Mn (0.68 %), Ni (0.38 %), V (0.36 %), Cr (0.35 %), Zn (0.35 %) and Co (0.32%).

The diagnostic value of quantitative bone SPECT/CT in solitary undetermined bone lesions.

To investigate the diagnostic value of the maximum standard uptake value (SUVmax) of quantitative single-photon emission computed tomography/computed tomography (SPECT/CT) in solitary undetermined bone lesions. In Part I, retrospective study, 167 untreated patients with extra-skeletal malignant tumors by pathology were consecutively enrolled for staging with Tc-99m methyl-diphosphonate (99mTc-MDP) whole-body bone scan (WBS) and quantitative SPECT/CT, and a total of 396 bone lesions with abnormal radioactivity concentration in 167 patients were included from April 2019 to September 2020. The differences in SUVmax among the benign bone lesions, malignant bone lesions, and normal vertebrae were analyzed. The receiver operating characteristic (ROC) curve and cutoff value of SUVmax were obtained. Part II, prospective study, 49 solitary undetermined bone lesions in SPECT/CT in 49 untreated patients with extra-skeletal malignant tumors were enrolled from October 2020 to August 2022. The diagnostic efficacy of SUVmax in solitary undetermined bone lesions was assessed. The final diagnosis was based on follow-up imaging (CT, MRI, or 2-deoxy-2-[18F]fluoro-D-glucose-positron emission tomography/computed tomography) for at least 12 months. In Part I, a total of 156 malignant and 240 benign bone lesions was determined; the SUVmax of malignant lesions (26.49 ± 12.63) was significantly higher than those of benign lesions (13.92 ± 7.16) and normal vertebrae (6.97 ± 1.52) (P = 0.00). The diagnostic efficiency of the SUVmax of quantitative SPECT/CT revealed a sensitivity of 75.00% and a specificity of 81.70% at a cutoff value of 18.07. In Part II, 17 malignant and 32 benign lesions were determined. Using SUVmax ≥18.07 as a diagnostic criterion of malignancy, it has a sensitivity of 82.35%, a specificity of 93.75%, and an accuracy of 89.80%. The SUVmax of quantitative SPECT/CT is valuable in evaluating solitary undetermined bone lesions. Using a cutoff SUVmax value of 18.07, quantitative SPECT/CT demonstrated high sensitivity, specificity, and accuracy in differentiating malignant from benign bone lesions.

Contributions of 238U, 232Th, and 40K to the radiogenic heat production in selected river sediment samples of South Africa

In this study, 16 sediment samples were collected from Bree, Klein-Brak, Bakens and uMngeni rivers of South Africa and were prepared, analysed and evaluated for the activity concentration of 238U, 232Th and 40K concerning its radiogenic heat production using a high-purity germanium detector. The results show that 238U is the prevalent radionuclide in radiogenic heat production, with 232Th and 40K emerging as trace elements. The mean activity concentrations are 28.97%, 63.69% and 7.34% for uranium, thorium and potassium, respectively, from all sampling locations. This shows that a high radioactive concentration of a specific radionuclide does not necessarily imply its increased contribution to radiogenic heat production. The radionuclide contributions to radiogenic heat production at all sampled locations are 59.39%, 35.11% and 5.50% for uranium, thorium and potassium, respectively. The mean radiogenic heat production rate in the study area ranged from 0.0180 μW m − 3 in sediment samples from the Bree River in Western Cape to 0.0072 μW m − 3 in sediment samples of uMgeni River in KwaZulu-Natal. All values obtained for this study are five times lower than the average continental radiogenic heat production of 1 μW m − 3 . This study provides insight into the radiogenic heat production rate due to the presence of radionuclides in all river samples.

89Zr-leukocyte labelling for cell trafficking: in vitro and preclinical investigations

BackgroundThe non-invasive imaging of leukocyte trafficking to assess inflammatory areas and monitor immunotherapy is currently generating great interest. There is a need to develop more robust cell labelling and imaging approaches to track living cells. Positron emission tomography (PET), a highly sensitive molecular imaging technique, allows precise signals to be produced from radiolabelled moieties. Here, we developed a novel leukocyte labelling approach with the PET radioisotope zirconium-89 (89Zr, half-life of 78.4 h). Experiments were carried out using human leukocytes, freshly isolated from whole human blood.ResultsThe 89Zr-leukocyte labelling efficiency ranged from 46 to 87% after 30–60 min. Radioactivity concentrations of labelled cells were up to 0.28 MBq/1 million cells. Systemically administered 89Zr-labelled leukocytes produced high-contrast murine PET images at 1 h–5 days post injection. Murine biodistribution data showed that cells primarily distributed to the lung, liver, and spleen at 1 h post injection, and are then gradually trafficked to liver and spleen over 5 days. Histological analysis demonstrated that exogenously 89Zr-labelled human leukocytes were present in the lung, liver, and spleen at 1 h post injection. However, intravenously injected free [89Zr]Zr4+ ion showed retention only in the bone with no radioactivity in the lung at 5 days post injection, which implied good stability of radiolabelled leukocytes in vivo.ConclusionsOur study presents a stable and generic radiolabelling technique to track leukocytes with PET imaging and shows great potential for further applications in inflammatory cell and other types of cell trafficking studies.