Radioisotope Measurements Research Articles

Computed tomography imaging analysis of a fused filament fabrication (FFF) 3D printed neck-thyroid phantom for multidisciplinary purposes

The application of the 3D printing technique for the development of low-cost phantoms is being investigated recently and requires a complex study of the interaction of printed materials with different types and qualities of radiation, as well as the characterization of printing filaments to correctly simulate human tissue attenuation. This study aims to present the Computed Tomography (CT) Imaging analysis of a fused filament fabrication (FFF) 3D printed anthropomorphic neck-thyroid phantom. The commercial phantom ATOM MAX 711 from CIRS was used as anatomy of reference for the 3D modeling base of the neck-thyroid phantom. Commercially available PLA and ABS XCT-A validated at IPEN were used in the 3D printing process in order to simulate soft and bone tissues respectively. The printing process was done using the RAISE3D PRO 2 FFF printer from IPEN. The imaging study of the phantom was performed through the analysis of images from a CT acquisition, comparing the Hounsfield Units (HU) numbers of the tissues between both CIRS and 3D printed phantoms. The developed phantom is a feasible alternative and presents some desirable characteristics for applications in radiation protection, measurements of radioisotopes incorporated in the thyroid (both contamination counters and nuclear medicine detectors) and training of techniques of acquisition of images with X rays.

Uranium Isotope Characterization in Volcanic Deposits in a High Natural Background Radiation Area, Mamuju, Indonesia

Mamuju is an area of high natural radiation in Indonesia with high natural radiation levels (average 613 nSv h−1). Mamuju is anomalous due to its high average 238U and 232Th concentrations of 22,882 and 33,549 Bq kg−1, respectively, in laterite and rock. High natural radionuclide concentrations of 238U, 232Th, and 40K have also been reported in soil samples from several locations in Mamuju, including Botteng, Northern Botteng, Takandeang, Ahu, and Taan. High radiation levels are related to radioactive mineral occurrences in the Adang volcanic complex, comprised of phonolitoid and foiditoid lithologies. According to the International Atomic Energy Agency (IAEA), uranium deposits can be classified into several types, among them a volcanic-related deposits, which include three sub-types: stratabound, structure-bound, and volcano-sedimentary deposits. This study aims to characterize volcanic rock deposit sub-types in the Mamuju area based on uranium radioisotope measurements. The uranium isotopes were measured using a tandem quadrupole inductively coupled plasma mass spectrometer combined with chemical separation by extraction chromatography using UTEVA resin. The analytical results for the 234U/238U ratios are used to determine the formation characteristics of minerals in each deposit sub-type based on mineral formation age, post-formation processes, and disturbances that affected the formation processes. Based on geochronological calculations using 234U/238U mineralization age, the deposits in the Mamuju area are 0.914–1.11 million years old and are classified as recent mineralization. These data have important implications for tracing uranium source rocks in the Mamuju area and may explain the anomalously high radiation levels in the Mamuju area.

Cross-section measurement of thulium radioisotopes with an 18 MeV medical PET cyclotron for an optimized 165Er production

165Er is a pure Auger-electron emitter with promising characteristics for therapeutic applications in nuclear medicine. The short penetration path and high Linear Energy Transfer (LET) of the emitted Auger electrons make 165Er particularly suitable for treating small tumor metastases. Several production methods based on the irradiation with charged particles of Er and Ho targets can be found in the literature. In this paper, we report on the study of 165Er indirect production performed via the 166Er(p,2n)165Tm →165Er reaction at the 18 MeV Bern medical cyclotron. Despite the use of highly enriched 166Er2O3 targets, several Tm radioisotopes are produced during the irradiation, making the knowledge of the cross sections involved crucial. For this reason, a precise investigation of the cross sections of the relevant nuclear reactions in the energy range of interest was performed by irradiating Er2O3 targets with different isotopic enrichment levels and using a method based on the inversion of a linear system of equations. For the reactions 164Er(p, γ)165Tm, 166Er(p,n)166Tm, 166Er(p, γ)167Tm, 167Er(p,3n)165Tm, 167Er(p, γ)168Tm, 168Er(p,2n)167Tm and 170Er(p,3n)168Tm, the nuclear cross section was measured for the first time. From the results obtained, the production yield and purity of the parent radioisotope 165Tm were calculated to assess the optimal irradiation conditions. Several production tests with solid targets were performed to confirm these findings.

Estimation of Late Postmortem Interval: Where Do We Stand? A Literature Review.

Estimating time since death can be challenging for forensic experts, and is one of the most challenging activities concerning the forensic world. Various methods have been assessed to calculate the postmortem interval on dead bodies in different stages of decomposition and are currently widely used. Nowadays, the only well-recognized dating technique is carbon-14 radioisotope measurement, whereas other methods have been tested throughout the years involving different disciplines with different and sometimes not univocal results. Today, there is no precise and secure method to precisely determine time since death, and late postmortem interval estimation remains one of the most debated topics in forensic pathology. Many proposed methods have shown promising results, and it is desirable that with further studies some of them might become acknowledged techniques to resolve such a difficult and important challenge. The present review aims at presenting studies about the different techniques that have been tested in order to find a valuable method for estimating time since death for skeletal remains. By providing a comprehensive overview, the purpose of this work is to offer readers new perspectives on postmortem interval estimation and to improve current practice in the management of skeletal remains and decomposed bodies.

Proposed Lunar Measurements of r-Process Radioisotopes to Distinguish the Origin of Deep-sea 244Pu

244Pu has recently been discovered in deep-sea deposits spanning the past 10 Myr, a period that includes two 60Fe pulses from nearby supernovae. 244Pu is among the heaviest r-process products, and we consider whether it was created in supernovae, which is disfavored by nucleosynthesis simulations, or in an earlier kilonova event that seeded the nearby interstellar medium with 244Pu that was subsequently swept up by the supernova debris. We discuss how these possibilities can be probed by measuring 244Pu and other r-process radioisotopes such as 129I and 182Hf, both in lunar regolith samples returned to Earth by missions such as Chang’e and Artemis, and in deep-sea deposits.

A New Approach for NaI(Tl) Detector Efficiency Calibration Using 41Ar Radionuclide for Air Exhaust Systems

Argon-41 is an essential gaseous radionuclide that must be monitored in gaseous effluents from nuclear facilities. Therefore, a precise evaluation of 41Ar activity is highly desired. Gamma spectroscopy with a NaI(Tl) scintillation detector coupled with a multichannel analyzer (MCA) is one of the widely used techniques for the identification and activity measurements of radioisotopes. However, the efficiency calibration of these kinds of monitoring systems highly depends on the source-detector geometry, and a large amount of uncertainty may complicate the calibration. This paper presents the evaluation of the full peak efficiency of a 2 × 2-in. NaI(Tl) scintillation detector coupled with a stable MCA for a 41Ar source with 1293.5 keV energy in two different source-detector geometries, duct and Marinelli beaker, using the FLUKA code. A new experimental technique is considered to produce 41Ar in a controlled geometry, like a Marinelli beaker, through neutron irradiation of natural argon inside a cyclotron bunker. The simulation data were compared with the experimental results for Marinelli beaker geometry, and the ratio was evaluated as 0.99 ± 0.07. The ratio was considered a scaling factor for the final efficiency calibration of duct geometry.

Paleoenvironmental evolution and evidence of marine submersion events from mid-to late Holocene in northwestern Morocco: The case of the Tahaddart lower estuary

The present study aims at reconstructing mid-to late Holocene paleoenvironmental evolution of the Tahaddart lower estuary (NW of Morocco) and to find possible sedimentary evidence of past marine submersion events (storm surges and tsunamis). This is achieved through the study of four sedimentary cores and by using a multiproxy approach that combines sedimentological, geochemical and foraminiferal analyses. Radioisotope measurements of 210Pbex, 137Cs and 14C were used to provide a chronological framework of the studied cores. The results show that the Tahaddart lower estuary has evolved from a bay-like environment characterized by very shelly sandy facies (i.e., marine phase) between ∼6800 and ∼625 cal BP, to an estuarine system after ∼625 cal BP, with a dominance of fine-grained sediments (i.e., estuarine phase). We further identified several sedimentary deposits that we interpret as possible marine submersion events. Two events were identified in the marine phase at ∼3800 cal BP and ∼2700 cal BP, in coherence with previously documented marine high-energy deposits located on the Atlantic Iberian coast. In the estuarine phase of the cores, two other events were detected and dated at ∼625 cal BP and ∼200 cal BP. The latter coincides with the 1755 CE Lisbon tsunami (195 cal BP).

Exploratory radioisotope measurements suggest that in-stream erosion represents the main sediment source in a pristine, tropical rainforest in Costa Rica

Exploratory radioisotope measurements suggest that in-stream erosion represents the main sediment source in a pristine, tropical rainforest in Costa Rica

Hydrogeological Survey, Radiometric Analysis and Field Parametric Measurements: A Combined Tool for the Study of Porous Aquifers

The use of isotopic geochemistry for hydrogeological studies is growing internationally. The use of isotopic geochemistry methodologies on hydrogeological survey data, integrated with the use natural tracers, is helpful when defining the hydrogeological model of the aquifer. In particular, the use of radioisotope concentration measurements as natural tracers and the detection of the temperature, redox potential and dissolved oxygen in groundwater in the field provide information on underground water circulation, which is useful for identifying recharge areas and groundwater drainage. Variations in these parameters in the aquifer allow for information about its hydrodynamics to be obtained. The application of this method in a sample area showed how the uranium and radon concentrations, temperature, redox potential and dissolved oxygen vary in the different sectors of the aquifer, depending on water mobility. This information, integrated with the results of a hydrogeological survey of the static levels, distinguished the recharge and drainage areas of the aquifer and the preferential directions in terms of water flow and allowed for information on the mobility of the aquifer in the various sectors to be obtained. The method presented in this paper was tested in a larger hydrogeological study in the southern sector of the shallow aquifer of the S. Eufemia Lamezia plain (Calabria, Italy).

Cross section measurement of terbium radioisotopes for an optimized 155Tb production with an 18 MeV medical PET cyclotron

155Tb [t1/2 = 5.32 d, Eγ = 87 keV (32%); 105 keV (25%) (IAEA, 2021)] is a novel promising radionuclide for theranostic applications in nuclear medicine. Its physical properties make it suitable for single photon emission computed tomography (SPECT) imaging, while its chemistry allows it to be used as a diagnostic partner for therapeutic radiolanthanides or pseudo-radiolanthanides, such as 177Lu and 90Y. Moreover, 155Tb could be used as a precise diagnostic match for the β−-emitter 161Tb, opening doors for the true theranostics concept. The availability of 155Tb in quantity and quality suitable for medical applications is an open issue and its production with medical cyclotrons via the 155Gd(p,n)155Tb and 156Gd(p,2n)155Tb nuclear reactions represents a possible but challenging solution. For this purpose, an accurate knowledge of the production cross sections is mandatory. In this paper, we report on the measurement of the production cross sections of 155Tb and other terbium radionuclides formed by proton irradiation of natGd2O3, 155Gd2O3 and 156Gd2O3 enriched targets, performed at the Bern University Hospital cyclotron laboratory. On the basis of the obtained results, the production yield and purity were calculated to assess the optimal irradiation conditions. The results of several production tests are also presented.

Agreement between serum estimates of glomerular filtration rate (GFR) and a reference standard of radioisotopic GFR in children with cancer.

Accurate assessment of renal function is important in the care of children with cancer because renal function has implications for anti-tumor medication dosing and eligibility for clinical trials. To characterize agreement between serum estimates of glomerular filtration rate (GFR) and a reference standard of radioisotopic GFR in a large pediatric oncology cohort. We conducted a retrospective cross-sectional study of children who had both radioisotopic GFR (99mTc-diethylenetriaminepentaacetic acid, or 99mTc-DTPA) and serum labs (creatinine, cystatin C) obtained <7days apart between January 2017 and August 2019. We calculated estimated GFR from serum labsusing published equations and calculated agreement using intraclass correlation coefficient (ICC) and Bland-Altman analysis with univariate regression to define predictors of agreement. We included 272 pairs of data. Mean patient age was (mean ± standard deviation) 7.8±5.7years. Mean radioisotopic GFR was 112±33mL/min/1.73m2. Absolute agreement between radioisotopic GFR and serum estimates was only fair (ICC=0.46-0.58) with a mean difference of -26.6 to +0.12mL/min/1.73m2. For radioisotopic GFR measurements <60mL/min/1.73m2, mean differences were greater, with serum estimates overestimating GFR by a mean of 21.5-39.6mL/min/1.73m2. In multivariable modeling, significant predictors of agreement included age, height, acute kidney injury and tumor type. Sensitivity of serum estimates was 14-29% for a GFR <60mL/min/1.73m2. Agreement between radioisotopic GFR and serum estimates of GFR is only fair and serum estimates of GFR have poor sensitivity for clinically relevant GFR <60mL/min/1.73m2. Radioisotopic measurement of GFR likely remains necessary to assess renal function in pediatric oncology patients with decreased renal function.

Traces of the Tunguska Event (1908) in Sediments of Zapovednoe Lake Based on SR–XRF Data

An anomalous layer enriched with chemical elements indicating the presence of terrigenous matter was discovered in the sediment core of Zapovednoe Lake located 60 km from the epicenter of the Tunguska event (1908) using synchrotron radiation X-ray fluorescence spectroscopy (SR–XRF). Radioisotope measurements indicate that the age of the layer is consistent with the date of the catastrophe. Apparently, the anomalous layer was formed as a result of an intense terrigenous matter inflow from the water catchment area due to massive forest falls and subsequent wildfires caused by the Tunguska event. Thus, it is established that targeted searches for microparticles of extraterrestrial origin can be carried out in the discovered and dated anomalous bottom sediment layer.

Radiocarbon Dating at Groningen: New and Updated Chemical Pretreatment Procedures

ABSTRACTThe Centre for Isotope Research (CIO) at the University of Groningen has operated a radiocarbon (14C) dating laboratory for almost 70 years. In 2017, the CIO received a major upgrade, which involved the relocation of the laboratory to new purpose-built premises, and the installation of a MICADAS accelerator mass spectrometer. This period of transition provides an opportunity to update the laboratory’s routine procedures. This article addresses all of the processes and quality checks the CIO has in place for registering, tracking and pretreating samples for radiocarbon dating. Complementary updates relating to radioisotope measurement and uncertainty propagation will be provided in other forthcoming publications. Here, the intention is to relay all the practical information regarding the chemical preparation of samples, and to provide a concise explanation as to why each step is deemed necessary.

Upgrades of the GANDALPH photodetachment detector towards the determination of the electron affinity of astatine

The Gothenburg ANion Detector for Affinity measurements by Laser PHotodetachment (GANDALPH) has recently been built for measurements of electron affinities (EA) of radioisotopes. A first measurement campaign is aimed towards the determination of the EA of astatine, the rarest naturally occurring element on earth. In this work we present several upgrades of GANDALPH which have been implemented in order to facilitate EA measurements of radioisotopes where only low intensity ion beams (<1 pA) can be produced.

Signals features extraction in radioisotope liquid-gas flow measurements using wavelet analysis

Knowledge of the structure of a flow is significant for the proper conduct of a number of industrial processes. In this case, a description of a two-phase flow regimes is possible by use of the time-series analysis in time, frequency and state-space domain. In this article the Discrete Wavelet Transform (DWT) is applied for analysis of signals obtained for water-air flow using gamma ray absorption. The presented method was illustrated by use data collected in experiments carried out on the laboratory hydraulic installation with a horizontal pipe, equipped with two Am-241 radioactive sources and scintillation probes with NaI(Tl) crystals. Signals obtained from detectors for slug, plug, bubble, and transitional plug – bubble flows were considered in this work. The recorded raw signals were analyzed and wavelet energy was extracted using multiresolution analysis. It was found that energies of wavelet approximation at 1-5 levels are useful to recognize the structure of the flow.

New and upgraded ionization chambers for AMS at the Australian National University

Three state-of-the-art ionization chambers have recently been designed at the Australian National University (ANU) to further enhance the isotopic and isobaric separation capabilities of the AMS setup at the Heavy Ion Accelerator Facility (HIAF).Two compact split-anode ionization chambers with low noise preamplifiers allow for measurements of actinides and other radioisotopes that do not have atomic isobar interferences. Both assemblies sit inside Dependex-100-Tees and are constructed such that they are retractable from the ion beam under vacuum. A high energy resolution version will be used for Pu, 129I and 55Fe. The second detector serves as the final energy detector in a time-of-flight setup and is employed for 236U and 210Pb detection.The new Flexible-AntiScattering Multi-Anode (FASMA) detector is a 7-anode ionization chamber optimized for the discrimination of 53Mn from 53Cr in the gas-filled magnet setup with the ENGE-split-pole spectrograph. The entire setup was simulated with Raytrace and SRIM. Finally, an existing 8-anode ionization chamber has been upgraded and now provides a 93Zr-93Nb isobar suppression of 5 × 104 resulting in the best limit of detection for 93Zr of any AMS-facility.This article details the various features of these detectors and compares first experimental results to performance values expected from modelling.

Cenomanian-Turonian flooding cycles: U.S. Gulf Coast and Western Interior

Cenomanian-Turonian ages, 100.5 Ma to 89.8 Ma, represented an extraordinary Cretaceous time interval when continental seaways expanded, tropical waters interchanged with Polar waters, global climates warmed, and at the end of the Cenomanian large amounts of organic carbon were buried. This was a time of major evolutionary changes in marine pelagic and benthic ecosystems, and in terrestrial plant ecosystems. A new comprehensive chronostratigraphic Cretaceous database is built upon reference sections of each Cretaceous stage and is calibrated to the 2016 Geologic Time Scale. This database is composed of bioevents, chemostratigraphic events, radioisotope measurements, and magnetochrons integrated with nearly 3000 species by projecting the section measurements of the events to the numeric time scale.This new database calibrates numerical ages of Cenomanian-Turonian sequence boundaries in Tunisian reference sections. These deep-shelf successions of limestone/marl/shale record biostratigraphically well dated, continuous deposition and serve as a model of Cenomanian-Turonian cycles. The Cretaceous database enables stratigraphic correlation experiments to test the time equivalency of Tunisian depositional cycles with sequences in Europe, in the Eagle Ford Group in Texas and with stratigraphic sequences in the Western Interior. New accurate and precise correlation of Cenomanian-Turonian depositional sequences between the Gulf Coast and the Western Interior test new biostratigraphic and radioisotopic data of the Eagle Ford Group on the Texas Comanche shelf. The Albian-Cenomanian boundary as defined by planktic foraminifers and ammonites in Texas projects between upper Albian shale units and the Dakota Group and associated sandstone units. The Mowry Shale and its endemic ammonites correlate with upper lower Cenomanian zones.

Radioisotope measurements of the liquid-gas flow in the horizontal pipeline using phase method

The paper presents application of the gamma-absorption method to a two-phase liquid-gas flow investigation in a horizontal pipeline. The water-air mixture was examined by a set of two Am-241 radioactive sources and two NaI(Tl) scintillation probes. For analysis of the electrical signals obtained from detectors the cross-spectral density function (CSDF) was applied. Results of the gas phase average velocity measurements for CSDF were compared with results obtained by application of the classical cross-correlation function (CCF). It was found that the combined uncertainties of the gas-phase velocity in the presented experiments did not exceed 1.6% for CSDF method and 5.5% for CCF.

Sonication assisted dissolution of post-detonation nuclear debris using ammonium bifluoride

Abstract There is significant interest in reducing the timeline for post detonation nuclear debris examination. A critical need is rapid dissolution of refractory nuclear debris to facilitate measurement of key radioisotopes and isotope ratios. Field deployable, rapid dissolution and analysis methods could significantly shorten the attribution analysis timeline. The current practice uses HF in combination with other acids to attack silicates and other refractory minerals expected in debris samples. However, techniques requiring HF are not amenable to use in the field. The fluorinating agent ammonium bifluoride (ABF) is a potential field deployable substitute for HF. In this work we report on the use of in-direct sonication with ABF as a means to improve low-temperature acid digestion of seven USGS and NIST geological reference materials. Using this method, elemental recoveries for USGS reference materials DNC-1a Dolerite, QLO-1a Quartz Latite, SDC-1 Mica Schist, and BHVO-2 Hawaiian Basalt were quantitative while the recovery of elements in USGS AGV-2 Andesite and NIST SRM 278 Obsidian and 1413 High Alumina Sand were low.

Improvement of the extraction method of faint signals in $ \gamma$ γ -activity measurements of meteorites⋆

At the underground laboratory of Monte dei Cappuccini (OATo-INAF) in Torino (Italy) we set up selective HPGe-NaI(Tl) spectrometers for measurements of cosmogenic radioisotopes in meteorites in order to study centennial-scale modulation of solar activity. 44 Ti is a suitable proxy for this timescale, but its detection is difficult due to the strong interference by naturally occurring 214 Bi. In order to optimize the extraction of the 44 Ti signal, we have developed software procedures specifically designed to improve selectivity of the Ge-NaI detectors coincidence.