Distribution Of Radioactivity Research Articles

Biological effects of uranium in water, soil and rice in uranium deposits in southern China

The content of radionuclide uranium in the water, soil and rice around the decommissioned uranium mine was analyzed, and the radioactive pollution, distribution characteristics, migration pattern and health risks were evaluated. Its radioactive contamination may have potentially harmful biological effects on the ecosystem and food chain. This paper pays more attention to the pollution of radionuclide 238U, 235U around the tailings dam, and makes a comprehensive comparative analysis of the pollution of water, soil and rice at 500 m, 1000 m and even 60 km around the dam. The single factor index method was mainly used to evaluate the pollution degree, and it was found that the water, soil and rice in the area around the uranium field were all polluted to different degrees. Radionuclide uranium pollution is mainly caused by uranium mining, quarry discharge and ecological cycle in the early stage. According to the characteristics of the uranium content in the study area, it is recommended to use the farmland around the tailing dam as a test site to study the radioactivity of different crops, improve wastewater treatment technology, and prevent crops with excessive levels of radioactive elements from entering the market.

An electrochemical technique for fabrication of Mn-54 sources towards characterization of gamma counting nuclear instruments

Long lived sealed radioactive sources are used for the energy calibration and efficiency determination of counting systems used in the nuclear sector. Using a sulphate bath, a facile electrochemical method was developed by electrodeposition of 54Mn on 5 mm (φ) stainless steel substrates for the preparation of 54Mn sources for such uses. Inactive sources prepared under suitable experimental parameters characterized by XRD revealed that manganese is deposited in oxide form. SEM and EDS analyses of electrodeposited surfaces confirmed uniform distribution of elements and the absence of fractures, flaws, and spatial variations. Cyclic voltammetry (CV) scans provided information about the electrochemical processes involved in the deposition process. Uniform distribution of radioactivity on surface of source was ascertained by autoradiography. Swipe tests of the encapsulated sources confirmed negligible removable surface contamination. The 54Mn sources containing up to 185KBq of 54Mn on stainless steel discs were prepared. These sources along with other longer lived sources were supplied to various users as a package of radiation sources for characterization of gamma counting systems over a wide energy range.

Improved Radium-223 Therapy with Combination Epithelial Sodium Channel Blockade.

Background: Radium-223 dichloride ([223Ra]RaCl2) is the first approved alpha particle-emitting therapy and is indicated for treatment of bone metastatic castrate resistant prostate cancer. Approximately half of the dose is absorbed into the gastrointestinal (GI) tract within minutes of administration, limiting disease-site uptake and contributing to toxicity. Here, we investigate the role of enteric ion channels and their modulation for improved therapeutic efficacy and reduced side effects. Methods: Utilizing primary human duodenal organoids (enteroids) as in vitro models of the functional GI epithelium, we found that Amiloride (ENaC blocker) and NS-1619 (K+ channel activator) presented significant effects in 223Ra membranal transport. The radioactive drug distribution was evaluated for lead combinations in vivo, and in osteosarcoma and prostate cancer models. Results: Amiloride shifted 223Ra uptake in vivo from the gut, to nearly double the uptake at sites of bone remodeling. Bone tumor growth inhibition with the combination as measured by bioluminescent and X-ray imaging was significantly greater than single agents alone, and the combination resulted in no weight loss. Conclusion: This combination of approved agents may be readily implemented as a clinical approach to improve outcomes of bone metastatic cancer patients with the benefit of ameliorated tolerability.

Improved Accuracy of Amyloid PET Quantification with Adaptive Template-Based Anatomic Standardization.

Amyloid PET noninvasively visualizes amyloid-β accumulation in the brain. Visual binary reading is the standard method for interpreting amyloid PET, whereas objective quantitative evaluation is required in research and clinical trials. Anatomic standardization is important for quantitative analysis, and various standard templates are used for this purpose. To address the large differences in radioactivity distribution between amyloid-positive and amyloid-negative participants, an adaptive-template method has been proposed for the anatomic standardization of amyloid PET. In this study, we investigated the difference between the adaptive-template method and the single-template methods (use of a positive or a negative template) in amyloid PET quantitative evaluation, focusing on the accuracy in diagnosing Alzheimer's disease (AD). Methods: In total, 166 participants (58 healthy controls [HCs], 62 patients with mild cognitive impairment [MCI], and 46 patients with AD) who underwent 11C-Pittsburgh compound B (11C-PiB) PET through the Japanese Alzheimer's Disease Neuroimaging Initiative study were examined. For the anatomic standardization of11C-PiB PET images, we applied 3 methods: a positive-template-based method, a negative-template-based method, and an adaptive-template-based method. The positive template was created by averaging the PET images for 4 patients with AD and 7 patients with MCI. Conversely, the negative template was created by averaging the PET images for 8 HCs. In the adaptive-template-based method, either of the templates was used on the basis of the similarity (normalized cross-correlation [NCC]) between the individual standardized image and the corresponding template. An empiric PiB-prone region of interest was used to evaluate specific regions where amyloid-β accumulates. The reference region was the cerebellar cortex, and the evaluated regions were the posterior cingulate gyrus and precuneus and the frontal, lateral temporal, lateral parietal, and occipital lobes. The mean cortical SUV ratio (mcSUVR) was calculated for quantitative evaluation. Results: The NCCs of single-template-based methods (the positive template or negative template) showed a significant difference among the HC, MCI, and AD groups (P < 0.05), whereas the NCC of the adaptive-template-based method did not (P > 0.05). The mcSUVR exhibited significant differences among the HC, MCI, and AD groups with all methods (P < 0.05). The mcSUVR area under the curve by receiver operating characteristic analysis between the positive group (MCI and AD) and the HC group did not significantly differ among templates. With regard to diagnostic accuracy based on mcSUVR, the sensitivity of the negative-template-based and adaptive-template-based methods was superior to that of the positive-template-based method (P < 0.05); however, there was no significant difference in specificity between them. Conclusion: In quantitative evaluation of AD by amyloid PET, the adaptive-template-based anatomic standardization method had greater diagnostic accuracy than the single-template-based methods.

Ecdysteroid metabolism in mammals: The fate of ingested 20-hydroxyecdysone in mice and rats

Phytoecdysteroids are molecules derived from sterol metabolism and found in many plants. They display a wide array of pharmacological effects on mammals (e.g. anabolic, anti-diabetic). Although these effects have been long established, the molecular targets involved remain to be identified. Like endogenous steroid hormones and bile acids, which are biochemically related, ingested or injected phytoecdysteroids undergo a set of reactions in mammals leading to the formation of numerous metabolites, only some of which have been so far identified, and it is presently unknown whether they represent active metabolites or inactivation products. In the large intestine, ecdysteroids undergo efficient 14-dehydroxylation. Other changes (reductions, epimerization, side-chain cleavage) are also observed, but whether these occur in the liver and/or large intestine is not known. The purpose of this study was to investigate the pharmacokinetics of 20-hydroxyecdysone (20E), the most common phytoecdysteroid, when administered to mice and rats, using, when required, tritium-labelled molecules to permit metabolic tracking. Bioavailability, the distribution of radioactivity and the kinetics of formation of metabolites were followed for 24−48 hours after ingestion and qualitative and quantitative analyses of circulating and excreted compounds were performed. In mice, the digestive tract always contains the majority of the ingested 20E. Within 30 min after ingestion, 20E reaches the large intestine, where microorganisms firstly remove the 14-hydroxyl group and reduce the 6-one. Then a very complex set of metabolites (not all of which have yet been identified) appears, which correspond to poststerone derivatives formed in the liver. We have observed that these compounds (like bile acids) undergo an entero-hepatic cycle, involving glucuronide conjugation in the liver and subsequent deconjugation in the intestine. Despite the very short half-life of ecdysteroids in mammals, this entero-hepatic cycle helps to maintain their plasma levels at values which, albeit low (≤0.2 μM), would be sufficient to evoke several pharmacological effects. Similar 20E metabolites were observed in mice and rats; they include in particular 14-deoxy-20E, poststerone and 14-deoxypoststerone and their diverse reduction products; the major products of this metabolism have been unambiguously identified. The major sites of metabolism of exogenous ecdysteroids in mammals are the large intestine and the liver. The entero-hepatic cycle contributes to the metabolism and to maintaining a low, but pharmacologically significant, concentration of ecdysteroids in the blood for ca. 24 h after ingestion. These data, together with parallel in vitro experiments provide a basis for the identification of 20E metabolite(s) possibly involved in the physiological effects associated with ecdysteroids in mammals.

Pioneering Iodine-125-Labeled Nanoscale Covalent Organic Frameworks for Brachytherapy.

Brachytherapy has been clinically used for the treatment of malignant solid tumors. However, the classic therapeutic radioactive 125I seed must be surgically implanted directly into tumors. To avoid the surgery and prevent irrational radioactive distribution, radioiodine-loaded nanomaterials are ever-developing for brachytherapy. Hence, it is still a notable challenge to obtain an advanced material that simultaneously incorporates features of high radiolabeling rate, short labeling time, good radiolabeling stability, and long tumor retention time. Covalent organic frameworks (COFs), which are crystalline polymers with ordered pores, are widely applied in guest delivery of drugs based on their high porosity and modifiable skeleton. Herein, we developed a functionalized nanoscale PEG-COF-Ag material, which could rapidly capture radioiodine reaching a 94% radiolabeling yield in 30 s. In addition, more than 95% 125I was maintained after 24 h in PBS (phosphate-buffered saline) as well as in serum and over 90% for nearly 1 week. PEG-COF-Ag-125I (125I-COF) demonstrated excellent cancer cell killing performance in vitro, and further experiments in vivo revealed a long tumor retention time and effective tumor treatment during the radiotherapy. The results indicate that radioiodine-labeled PEG-COF-Ag could be potentially applied in brachytherapy with a promising therapeutic effect.

Study of coincidence summing effect using Monte Carlo simulation to improve large samples measurement for environmental applications

A new measurement model composed of High Purity Germanium detector HPGe including Lead Shield with a mixed source of Am-241, Cd-109, …in a soil matrix packed in a cylindrical container was developed by Monte Carlo N-Particles code MCNP5. The Monte Carlo models being largely used for efficiencies calculations in routine environmental radioactivity measurements of high volume soil samples.In order to validate the simulation, a multi-radionuclides soil matrix source in a cylindrical container is prepared. Comparing the simulated results to the experimental ones, allows us to correct coincidence summing in the soil standard and study its effect in activity measurements where a good agreement is found between corrected activities and results found by another geometry and show how uncorrected efficiency curves lead to erroneous activity calculation.Finally, the developed model is applied to study the distribution of natural and artificial radioactivity in a forest site in Bainem, northern of Algeria, these results are invested for radiological impact and soil erosion studies in the study Area.

3D position and radioactivity estimation of radiation source by a simple directional radiation detector combined with structure from motion

It is important to visualize radioactive substances' position and distribution and estimate their radioactivity levels to reduce the exposure dose of workers in radioactive areas (such as decommissioning worksites of nuclear power stations) and improve nuclear security functions. To visualize the radioactive substance's three-dimensional (3D) location, a directional radiation detector with a cylindrical shield on a simple single-pixel gamma-ray detector was applied to the structure from motion (SfM) technology using an ordinary digital camera. Verification was performed by a system that combines SfM with a CdTe sensor probe having narrow directivity. 241Am radiation source's position was visualized by drawing the radiation source's image acquired by the gamma-ray detector on the work area 3D model reconstructed through SfM. Furthermore, as SfM is a simultaneous localization and mapping technology, the system measures the gamma rays while measuring the gamma-ray detector's dynamic position and posture information. The measurements can be acquired while the gamma-ray detector is freely moving in the work area. These methods visualized the radiation source's position and quantitatively estimated the radiation source's radioactivity.

The Effect of Circumstellar Matter on the Double-peaked Type Ic Supernovae and Implications for LSQ14efd, iPTF15dtg, and SN 2020bvc

Abstract Double-peaked light curves are observed for some Type Ic supernovae (SNe Ic), including LSQ14efd, iPTF15dtg, and SN 2020bvc. One possible explanation of the first peak would be shock-cooling emission from massive extended material around the progenitor, which is produced by mass eruption or rapid expansion of the outermost layers of the progenitor shortly before the supernova explosion. We investigate the effects of such circumstellar matter (CSM) on the multiband optical light curves of SNe Ic using the radiation hydrodynamics code STELLA. Two different SNe Ic progenitor masses at the pre-SN stage (3.93 M ⊙ and 8.26 M ⊙) are considered in the SN models. The adopted parameter space consists of the CSM mass of M CSM = 0.05–0.3M ⊙, the CSM radius of R CSM = 1013–1015 cm, and the explosion energy of E burst = (1.0–12.0) × 1051 erg. We also investigate the effects of the radioactive nickel distribution on the overall shape of the light curve and the color evolution. Comparison of our SN models with the double-peaked SNe Ic LSQ14efd, iPTF15dtg, and SN 2020bvc indicates that these three SNe Ic had a similar CSM structure (i.e., M CSM ≈ 0.1–0.2M ⊙ and R CSM = 1013–1014 cm), which might imply a common mechanism for their CSM formation. The implied mass-loss rate of M ̇ ≳ 1.0 M ⊙ yr − 1 is too high to be explained by the previously suggested scenarios for pre-SN eruption, which calls for a novel mechanism.

Preparation of Technetium Labeled-Graphene Quantum Dots and Investigation of Their Bio Distribution

The novel radiotracer has been studied with the title of Graphene quantum dots (GQDs) and decorated by the usage of selenium (Se), while surface modification has been carried out in the following through the utilization of Polyethylene glycol (PEG) and labeled with 99mTechnetium (99mTc). Moreover, 99mTc has been eluted from a 99Mo/99mTc producer, and Graphene quantum dots have been synthesized with high photoluminescence (PL) intensity throughout the range of 600 to 900 nm. We have also evaluated the labeling stability percentages of GQDs and 99mTc in double-distilled water and human serum through the application of the Instant Thin Layer Chromatography (ITLC) method in different time intervals; it should be noted that methanol and acetone have been applied as the mobile phase. Radioactivity of 99mTc-GQDs have been injected into nine designated rats through their tail, while the bio distribution of radioactivity was being surveyed through a Gamma counter and had the percent of Injected Dose per gram (%ID/g) calculated for each organ. In addition, the process of capturing static posterior and anterior images by the application of a gamma camera has been done in vivo. In accordance with the observations, there has been a higher GQDs (Se-PEG) distribution throughout the kidneys when compared to the other organs. There is the possibility of exerting these quantum dots for the labeling of kidneys since they can almost completely escape the body within 24 h.

Synthesis of titanium phosphates from unconventional solid precursor and their ion-exchange and electrochemical properties

A new low-cost and simple synthesis of titanium phosphate functional materials of desired composition has been developed. The route of material transformation is unconventional solid precursor-sorbent-anode material. The synthesis is based on the heterogeneous interaction between phosphoric acid and the solid (NH4)2TiO(SO4)2·H2O precursor. The influence of the synthesis conditions on the titanium phosphate composition has been thoroughly studied using NMR, FTIR spectroscopy, XRD, and DTA techniques, and mechanism of TiP formation has been established. Optimal synthesis conditions to provide obtaining of a pure TiO(OH)(H2PO4)·H2O (TiHP) phase have been found. In contrast to existing methods that require rigid synthesis conditions and high reagent consumption, the new synthesis lasts 4 h and no special equipment is needed. The sorption and electrochemical capabilities of TiHP have been investigated. The obtained material exhibits the highest sorption capacity toward Cs+ and Sr2+ ions among other TiP-based ion exchangers. Furthermore, TiHP has been tested as a sorbent for treatment of multicomponent liquid radioactive waste and distribution coefficients of the radionuclides have been found to be 105 mL·g–1. New approach to the synthesis of precursor for Li-ion batteries has been proposed. The substitution of protons of the dihydrogen phosphate group in TiHP by lanthanum (III) cations and subsequent calcination at 900 °C result in formation of nanoparticles of the final powder and provide the good electrochemical characteristics of obtained electrode material.

Teknik Pemeriksaan Kedokteran Nuklir Bone Scan di Instalasi Radiologi RSUP Dr. Kariadi Semarang

Background: A bone scan or commonly referred to as bone print is nuclear medicine examination using a radioactive substance or radiopharmaceutical that is inserted into the body through intravenous injection which aims to help diagnose abnormalities that occur in the bone. This imaging procedure uses a radiopharmaceutical 99mTc-MDP (methylenediphosphonate) is the most commonly used radiopharmaceutical.Methods: The patient will be injected with this radiopharmaceutical at a dose of 15-20 mCi, through the vein in the hand. Imaging can be done as soon as the radiopharmaceutical is injected or after a while to wait for the radiopharmaceutical to be distributed and absorbed by the bone, about 3-5 hours later. Imaging is done by three-phase method, namely the first phase (Vascular phase), the second phase (Blood Pool phase), and the third phase (Total body phase) l.Results: The bone scan method is an efficient examination because in 1x the imaging can provide a complete picture from the head to the foot. Evaluation of results, under normal conditions the distribution of radioactivity in the bone appears symmetrical.Conclusion: In the process of bone metastasis, it can be seen that typical pathological radioactivity can be multiple (multiple hot spots). Malignant tumors can be distinguished from benign tumors by blood pool examination.

Gamma Spectrometry of Inhomogeneous Samples Using Peak-Ratio Method

In gamma spectrometry of voluminous samples, inhomogeneous distribution of radioactivity caused by the presence of hot particles can create significant Bias in the results of activity determinations. We developed a novel method to reduce this Bias using the gamma-peak ratio. We show that the peak area ratio of two gamma peaks of different energies, emitted by the same radionuclide, is a sensitive measure of emitting source location and thus the inhomogeneity. A new calibration formula was then derived for true gamma efficiency pi as a function of efficiency ratio pi/pj of two peaks. This approach was verified by Monte Carlo simulations for a sample of 1-L volume containing from 1 up to 2048 of hot particles randomly distributed in a soil matrix. A 152Eu radionuclide was selected for calculations and we used various combinations of two gamma spectral peaks selected from three gamma energies of 121.8, 344.3, and 1408.0 keV. This new method is shown to reduce the Bias range and Bias standard deviation by several times when compared with the traditional homogeneous calibration applied to measuring hot particles. The method is independent of the number, location, and distribution of hot particles in the samples, and can be applied to a mixture of radionuclides. It complements our previous calibration model based on the peak-to-total ratio.

Measurement and spatial distribution pattern of natural radioactivity in a uranium tailings pond in Northwest China

ABSTRACT Numbers of radioactive tailings were produced in the process of uranium mining and milling.In this study,radiation environment monitoring was carried out on a decommissioned uranium mining and milling tailings pond in northwest China, and the governance effect and operation status of the tailings pond was investigated. The soil radionuclide activity concentration and ambient dose equivalent rate (H*(10)) were measured, and soil surface radon exhalation rate was calculated. The results shown that in the tailings pond and its surrounding area, the average soil radionuclide activity concentration was respectively 238U: 42.64±11.17 Bq·kg-1, 226Ra: 45.47±13.56 Bq·kg-1, 232Th: 33.30±7.33 Bq·kg-1, 40K: 631.33±72.05 Bq·kg-1, the average H*(10) was 63.32±6.46 nSv·h-1, and the average radon exhalation rate was 40.46±11.29 mBq·m-2·s-1.Radionuclide activity concentration, H*(10) and radon exhalation rate were within the range of world natural background. Spatial distribution of radioactivity was analyzed by OK interpolation based on the investigated data. According to the measured results and spatial interpolation analysis,the decommissioning governance effect of the uranium tailings reservoir is good, the operation is normal, and there is no migration or diffusion situation of radionuclides in the pond has been found.

A prototype of SiPM-based scintillator Compton camera with capacitive multiplexing readout

Compton camera is capable of visualizing the distribution of radioactivity based on the Compton scattering kinematics, and can be applied in nuclear accident emergency response, radioactivity decontamination, homeland security and etc. A prototype of Compton camera has been constructed consisting of two 4×4 SiPM-Ce: GAGG scintillator arrays. The signals of a SiPM array were converted into 4 position-weighted outputs with capacitive network circuit and collected by a CAEN digitizer. Two-dimensional flood images and energy responses of two detector modules were obtained. The average energy resolution of single elements of the two detector modules was 6.6% FWHM at 662 keV. Imaging performance of the prototype camera was evaluated with a 137Cs point source and a 22Na point source. Efficiency of the prototype for the 137Cs point source located right in front was measured to be 0.09%. The angular resolution of a 137Cs point source placed right in front of the camera was 7.2° FWHM. Isotopic images of the two gamma-ray sources were obtained with spatial resolutions of 8.2° FWHM for 137Cs and 8.8° FWHM for 22Na.

Temperature Field Variation Law of Low Exothermic Polymer Grouting Material in Repairing Void Damage of Frozen Soil Subgrade

In this study, the self‐developed grouting mold was used to study the heat release characteristics of different density polymer grouting material under different temperature conditions. The spatial distribution characteristics of the frozen soil subgrade temperature field under the effect of polymer grouting repair were analyzed. Further, the rules governing the temperature change of a frozen soil subgrade monitoring point under the effect of polymer grouting repair were studied. The heat transfer mechanism of polymer grouting material in frozen soil subgrade was revealed. The results showed that in the void region of the frozen soil subgrade, a discontinuity zone appeared in the temperature field distribution isotherm due to the effect of voids; this zone exhibited a layered radioactive distribution along the two sides of the void area. Furthermore, during the exothermic stage of the curing reaction, the temperature distribution isotherms changed from a layered radioactive distribution to a ring distribution that decreased from the inside to outside. During the natural cooling process, the peripheral temperature of the ring isotherm first decreased and a negative temperature ring‐shaped isotherm gradually formed. Finally, the upper boundary of the influence of the heat energy released by the curing reaction on the frozen soil subgrade temperature field was determined to be 30 cm, and the lower boundary was 20 cm.

Image Reconstruction Based on Total Variation Minimization for Radioactive Wastes Tomographic Gamma Scanning From Sparse Projections

Tomographic Gamma Scanning (TGS) is one of the most important non-destructive analyzed techniques for radioactive waste drums. By reconstructing the radioactivity distribution image, it can accurately realize the qualitative, quantitative, and positioning analysis of the radionuclides in the drum. However, the time consuming of the scanning is long and the reconstructed image is rough, which limits its good application in the practical assay of the waste drum. In this work, the total variational minimization (TVM) method was applied to improve the iterative process of the conventional algorithms of maximum likelihood expectation maximization (MLEM) and algebraic reconstruction technique (ART), then the MLEM-TVM and ART-TVM reconstruction methods were developed. The transmitted experiments were carried out where four kinds of materials were arranged in a segment whose densities ranging from 1.04 g/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> to 2.02 g/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> and a <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">152</sup> Eu isotope was set up as a transmission source. Compared with the traditional algorithms MLEM and ART, the MLEM-TVM and the ART-TVM algorithms have a better performance on the accuracy and the signal-to-noise ratio, and the MLEM-TVM algorithm achieves the best results, which means the quality of the reconstructed image is improved. The accuracy and effectiveness of the TVM method used in the TGS image reconstruction are verified in the work, and moreover, it can save the scanning time and enhance the TGS image resolution through sparse projection sampling.

Development of advanced rigorous two-step code system for evaluation of radioactive waste with high-resolution activation calculation

Nowadays, evaluation of amounts and distributions of radioactive waste is an important preparatory step in the process of nuclear reactor decommissioning. For tentative estimation of radioactive waste, a cell-based rigorous 2 step (R2S) method usually is used; however, a poor resolution caused by the averaged flux and spectrum in a cell is still a great challenge because of leading to underestimated or overestimated results. To overcome the poor resolution, several systems were introduced. Neither system, however, provides any function for evaluation of radioactive waste amount and distribution. Thus, it is additionally required to classify radioactive waste based on the results of activation calculation. In this study, the advanced R2S (AR2S) system was developed. To verify the performance of the system, its results for a verification problem were compared with those of the cell-based R2S method. The results showed good agreement, which is to say, within 2.0% relative error. Also, several characteristics of fine/coarse mesh were analyzed. To demonstrate the performance of the AR2S system, the radioactive waste from the Japan Power Demonstration Reactor (JPDR) was estimated, and the result indicated a high-resolution distribution. Therefore, it is expected that the AR2S system will prove useful for precise evaluation of radioactive waste.

COCOSYS analysis on aerosol wash-down of THAI-AW3 experiment and generic containment

During severe accidents, fission products as aerosols are released into the containment and consequently deposited on walls. The condensate flow on walls could wash the deposited aerosols downwards to the sump. Therefore, the aerosol wash-down process on walls is significant to evaluate radioactive source term distribution in nuclear containment. In this paper, the containment code COCOSYS coupled with aerosol wash-down model AULA and condensate coverage model CONRAG is used to analyze the aerosol wash-down process of THAI-AW3 experiment and ‘Generic Containment’. THAI-AW3 experiment was conducted by Becker Technologies to investigate insoluble aerosol wash-down behavior from the vertical, quasi-horizontal surfaces, and a small puddle. The COCOSYS calculated results shows the aerosol wash-down is predicted well, as well as the thermal-hydraulics in THAI-AW3 experiment. There are no significant differences of aerosol wash-down efficiency between the calculation and measurement. The acceptable COCOSYS is to enable further analysis on the aerosol wash-down process of the Generic Containment within SARNET2 activity under a full severe accident scenario in order to test the aerosol wash-down model. The evolutions of the containment’ thermal-hydraulics are analysed. The calculation offers the aerosol distribution, the aerosol wash-down mass, and the aerosol distribution inside containment over time. The comparisons with previous COCOSYS simulations indicate that the modification of COCOSYS, e.g. the coupling with condensate coverage model CONRAG, is necessary to investigate the aerosol wash-down.

Kidney dosimetry in 777 patients during 177Lu-DOTATATE therapy: aspects on extrapolations and measurement time points

PurposeFractionated peptide receptor radionuclide therapy (PRRT) with 177Lu-DOTATATE is increasingly applied as an effective treatment for patients with disseminated neuroendocrine tumors. In parallel to dose planning before external beam radiation therapy, dosimetry is also needed to optimize PRRT to the individual patient. Accordingly, absorbed doses to organs at risk need to be calculated during PRRT, based on serial measurements of radioactivity distribution utilizing SPECT/CT. The dosimetry should be based on as few measurements as possible, while still retaining reliable results. The main aim of the present work was to calculate the fractional contribution of the extrapolations of the curve fits for the absorbed dose calculations to the kidneys. The secondary aim was to study agreement between absorbed dose (AD) and the effective half-life (teff) for the kidneys, estimated by means of measurements at one or two time points, in comparison to our current method employing three time points.MethodsIn 777 patients with disseminated neuroendocrine tumors undergoing PRRT, SPECT/CT over the abdomen was acquired at 1, 4, and 7 days after 177Lu-DOTATATE infusion. The absorbed dose to the kidneys was calculated from SPECT/CT radioactivity distribution data, and the teff and fractional contributions of the extrapolations were estimated, utilizing data from one, two, and three time points, respectively.ResultsThe fractional contributions from extrapolations before day 1 measurement and after day 7 measurement were approximately 26% and 11%, respectively. The mean differences in absorbed dose, based on one, two, and three time points were small, but with high method dependence for individual patients. The differences in estimated teff were small when it was based on measurements at days 1 and 7, but high for days 1 and 4 time points.ConclusionWhen assessing simplifications of methods for calculation of the absorbed dose to the kidneys, it was of the uttermost importance to incorporate the fractional contribution for the extrapolations included in the reference method. Measurements at an early and a late time point were found most important. An intermediate measurement contributes with an idea of the goodness of the fit.