Direct Gamma Research Articles

Can we estimate which colors our participants see? Comparing results from different gamma correction methods

In experimental color research, one must ensure that color is displayed and described reliably. When monitors are involved, colors are displayed through device-dependent color systems. However, these values must be translated into device-independent color systems to interpret what people perceive, often involving techniques such as gamma correction. We sought to explore the feasibility of estimating gamma instead of relying on direct gamma measurements, which typically require specialized equipment like a chromameter. Potential solutions include a computerized perception-based gamma estimation task or adopting the industry-standard gamma value of 2.2. We compared these two solutions against the chromameter measurements in the context of a color-matching task. Thirty-nine participants visually matched red, yellow, green, and blue physical objects using a computerized color picker. Starting from these color choices, we applied two RGB-to-CIE Lab color conversion methods: one using a perception-based gamma estimation and another using the industry-standard gamma. Color values obtained with the chromameter differed from the other two methods by 6–15 JNDs. Small differences existed between the results obtained using the perception-based task and the industry-standard gamma. Thus, we conclude that when standard viewing conditions cannot be assumed, adopting a gamma value of 2.2 should suffice.

In vivo quantitative SPECT imaging of actinium-226: feasibility and proof-of-concept

Objective. 225Ac radiopharmaceuticals have tremendous potential for targeted alpha therapy, however, 225Ac (t 1/2 = 9.9 d) lacks direct gamma emissions for in vivo imaging. 226Ac (t 1/2 = 29.4 h) is a promising element-equivalent matched diagnostic radionuclide for preclinical evaluation of 225Ac radiopharmaceuticals. 226Ac has two gamma emissions (158 keV and 230 keV) suitable for SPECT imaging. This work is the first feasibility study for in vivo quantitative 226Ac SPECT imaging and validation of activity estimation. Approach. 226Ac was produced at TRIUMF (Vancouver, Canada) with its Isotope Separator and Accelerator (ISAC) facility. [226Ac]Ac3+ was radiolabelled with the bioconjugate crown-TATE developed for therapeutic targeting of neuroendocrine tumours. Mice with AR42J tumour xenografts were injected with either 2 MBq of [226Ac]Ac-crown-TATE or 4 MBq of free [226Ac]Ac3+ activity and were scanned at 1, 2.5, 5, and 24 h post injection in a preclinical microSPECT/CT. Quantitative SPECT images were reconstructed from the 158 keV and 230 keV photopeaks with attenuation, background, and scatter corrections. Image-based 226Ac activity measurements were assessed from volumes of interest within tumours and organs of interest. Imaging data was compared with ex vivo biodistribution measured via gamma counter. Main results. We present, to the best of our knowledge, the first ever in vivo quantitative SPECT images of 226Ac activity distributions. Time-activity curves derived from SPECT images quantify the in vivo biodistribution of [226Ac]Ac-crown-TATE and free [226Ac]Ac3+ activity. Image-based activity measurements in the tumours and organs of interest corresponded well with ex vivo biodistribution measurements. Significance. Here in, we established the feasibility of in vivo 226Ac quantitative SPECT imaging for accurate measurement of actinium biodistribution in a preclinical model. This imaging method could facilitate more efficient development of novel actinium labelled compounds by providing accurate quantitative in vivo pharmacokinetic information essential for estimating toxicities, dosimetry, and therapeutic potency.

Biliary Atresia with Cytomegalovirus Infection, Congenital Heart Disease and Pneumonia: A Case Report

Biliary atresia (BA) is a condition of biliary obstruction. Kasai portoenterostomy (KPE) is a treatment option. The aim to determine the success rate of kasai procedure and prognosis in BA patients with other underlying diseases. This is a descriptive case study research. We report a boy, 2 months and 11 days with jaundice all over his body since one week old; putty stool, and dark urine. Old man's face, icteric, rib xylophone, subcostal retraction, rales, continuous heart murmur, and wasting. Total and direct bilirubin, SGOT, SGPT, and gamma GT are increased. A Kasai surgical procedure was carried out, but did not significantly improve his condition because the operation was performed at the age of 4 months and 8 days with liver cirrhosis, sepsis, pneumonia, and malnutrition. Cytomegalovirus (CMV) infection and acyanotic congenital heart disease also worsened his preoperative condition. Kasai portoenterostomy is a method of managing biliary atresia, but our patient was diagnosed with biliary atresia accompanied by CMV infection, congenital heart disease, or pneumonia, so the procedures not enough for this condition, and mortality rate is higher than biliary atresia alone. Age at surgery time also influences the prognosis.

An approach for the indirect determination of 238U and 232Th content in ceramic products based on gross alpha and gross beta measurement

The aim of this work was the development of a procedure for the indirect characterization of 238U and 232Th in ceramic products using the quantification of gross alpha and gross beta activities in a low background proportional counter, which is less time consuming and cheaper than the direct radiochemical methods and gamma spectrometry. The procedure was applied, first, to a reference material used to fine-tune the procedure and statistical techniques, and then, for two types of ceramic products: micronized zircon and zircon flour samples, and spray-dried ceramic powders (atomized).This procedure requires obtaining linear regression models for estimating the activity of 238U and 232Th as a function of specific gross alpha and gross beta measurements. Regression models must be obtained for each type of ceramic material together with the range of application of the model, which depend primarily on the ratio between 238U and 232Th activities. The applications to micronized zircon and zircon flours, and spray-dried ceramic powders demonstrated that the models obtained for the indirect characterization of 238U and 232Th activities explain more than 95% of the variability in the data.In addition, those models were used for predicting the results of new validation samples. Regarding the micronized zircon and zircon flours, predictions were good for the 238U activity with a relative bias of less than 10%, while they were not so accurate for the 232Th activity, with a relative bias of less than 15% for most of the samples. For spray-dried ceramic powders, the predictions were quite good for the 238U activity with a relative bias of less than 20% irrespective of the cluster to which the validation sample belongs, and similarly for the 232Th activity.

Multi-pixel photon counter-based gamma camera with pinhole collimator to locate Cs-137 sources at high dose rates for the Fukushima nuclear power plant

The Fukushima Daiichi Nuclear Power Plant was severely damaged during the 2011 Great East Japan Earthquake. However, the ongoing decommissioning work has been limited by the complexity of the reactor's internal structure and very high radiation levels; locating radioactive sources is essential for efficient decommissioning. Conventional gamma cameras are mainly designed for low radiation dose (∼mSv/h) and using them under high radiation conditions is difficult (>Sv/h). Therefore, we developed a pinhole gamma camera with a gamma radiation detector consisting of a high-speed YGAG scintillator array and multi-pixel photon counters to locate radioactive sources at high dose rates. The gamma-ray photon signals captured by the developed two-dimensional detector array can be processed at a speed as high as >1 MHz/pixel using the developed large scale integrated circuit. Herein, we report the measurement results of an extremely high radioactivity of 137Cs (∼34 TBq) using the developed gamma camera. The gamma-ray source position was determined using an angular size of ∼4.6°, with images obtained at 2 m from the radioactive source and at a dose rate of 0.3 Sv/h. The direct gamma rays with a photoelectric peak at 662 keV and scattered component of gamma rays can be distinguished from the measured spectrum. We also characterize the imaging capability of the 137Cs depending on the detected gamma-ray energies and discuss related details.

Direct gamma dose rate measurement and assessment of excess lifetime cancer risk.

In this study, in some neighborhoods in Kahramanmaraş province of Turkey, indoors and outdoors direct gamma dose rate measurements have been done. All of the gamma dose rate measurements have been made at ground level and at the height of 1m from the ground. The median values of the gamma dose rates on the ground and 1m above the ground indoors are 70.34±7.74 and 49.53±5.39nGy h-1, respectively. Outdoor measurements have been carried out on both soil and asphalt floors. The average values of gamma dose rate on the ground and at a height of 1m outdoors (soil floor) are 68.16±7.49 and 53.50±5.88nGy h-1, respectively. The mean values of gamma dose rate on the ground and 1m above the ground outdoors (asphalt floor) are 61.63±6.77 and 48.69±5.35nGy h-1, respectively. Indoor and outdoor average gamma dose rates are below the mean world. In addition, using the measured gamma dose rate values, annual effective dose equivalent (AEDE) and excess lifetime cancer risk (ELCR) for adults have been calculated. The total AEDE and ELCR (on soil floors and indoors at 1m above ground level) are 0.31±0.03mSv y-1 and 1.08±0.10×10-3, respectively. The total AEDE and ELCR (on asphalt floors and indoors at 1m above ground level) are 0.30±0.03mSv y-1 and 1.06±0.10×10-3, respectively. The AEDE and ELCR for adults living in the neighborhoods within the scope of the study in Kahramanmaraş city center within 1y are lower than the average world.

Anti-radiation protection of astronauts in the process of working on the surface of the Moon in a short-term mission

Introduction. The issue of assessing the types of ionizing radiation characteristic of the lunar surface, the anti-radiation properties of various materials, and factors ensuring the anti-radiation safety of astronauts when placed on the lunar surface, taking into account the radiation safety standards for personnel, remains insufficiently studied.
 The study aims to analyze the factors that determine the features of anti-radiation protection of astronauts in future lunar settlements.
 Materials and methods. During the study, experts used analytical methods to generalize and systematize materials on the levels of dose load on astronauts at the stages of space flight and on the surface of the Moon. The researchers also used computational methods taking into account the anti-radiation properties of various materials, depending on the type of ionizing radiation, to develop approaches to the organization of anti-radiation protection of astronauts in conditions of short-term (up to 14 days) stay on the surface of the Moon.
 Results. The researchers have carried out the analysis of the factors determining the radiation hazard for astronauts during their stay and work in lunar settlements. It is proved that when developing anti-radiation protection, it is necessary to use the housing of the lunar module (aluminum frame), lunar regolith and polyethylene. With the multilayer protection of the lunar module, it is necessary to take into account the attenuation coefficients of materials for various types of ionizing radiation, which will reduce the doses from both direct gamma radiation, protons and neutrons, and from scattered secondary radiation.
 Conclusion. Various design options for the protection of the lunar station modules by the thickness of their constituent layers will provide anti-radiation protection of premises for various purposes, depending on the possible options for solar activity and the required levels for residential, working, emergency compartments.
 Ethics. The study was conducted in compliance with Ethical standards.

COMPARISON OF GAMMA–RAYS ATTENUATION MEASURED BY DIRECT AND COINCIDENCE SPECTRA

Measurements of gamma –rays attenuation in lead and iron sheets were carried out using direct spectrum and gamma- gamma fast slow coincidence spectrometer composed of two 3"×3"NaI(Tl) detectors and Na-22 source. Measurements of mass attenuation coefficient at 511keV were carried out and its values (in cm²/g units) for lead from direct spectrum for the cases of without and with using a collimator (1cm diameter and 5 cm length) were 0.12029 and 0.13591and from coincidence spectrum were 0.10721 and 0.10602 respectively. For iron sheets the mass attenuation coefficient values from direct spectrum for the cases of without and with using a collimator were 0.0780 and 0.0766 andfrom coincidence spectrum were 0.0593 and 0.0616 respectively. The present results registered by direct measurement are little lower than the standard values due to making only photoelectric absorption needed for comparison with coincidence results where the latter showed lower values.
 The build-up factor were also measured as function of thickness using lead and iron sheets and found fluctuating around unity for lead and iron coincidence spectra and iron direct spectrum, whereas its increases gradually for lead direct spectrum for the measured thickness range. The coincidence spectrometer greatly reduces scatteringevents in the measured material, and thus its results somewhat resemble that of direct measurements with using the collimator.

In-line measurement of multiphase flow viscosity

The transportation modes depend entirely on the viscosity of the oil. To date, none of the viscometric methods are able to provide measurements to meet all the requirements of oil flow, features of main oil pipelines, and trends in the oil industry, such as decarbonization and digitalization. The method of inline viscosity measurement of multiphase flow through a metal pipeline can be based on direct gamma ray measurement. It is stipulated by the ability of gamma-radiation to penetrate through the pipeline material without destroying it, as well as by the ability to work with flows containing free gas and the high capability to be introduced into automatic control systems. The authors consider the physical forces acting on the gas inclusions in the oil flow. They determine the physical dependence between the parameters determined by the radioisotope method and the viscosity of oil in the three-phase flow. These studies show good agreement with the work of other scientists. The prospect of further research will be to clarify the mathematical model of gas-oil flow, to increase the accuracy by reducing the number of assumptions made.

Dose Estimation Model for Terminal Buds in Radioactively Contaminated Fir Trees

Background: After the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, biological alterations in the natural biota, including morphological changes of fir trees in forests surrounding the power plant, have been reported. Focusing on the terminal buds involved in the morphological formation of fir trees, this study developed a method for estimating the absorbed radiation dose rate using radionuclide distribution measurements from tree organs.Materials and Methods: A phantom composed of three-dimensional (3D) tree organs was constructed for the three upper whorls of the fir tree. A terminal bud was evaluated using Monte Carlo simulations for the absorbed dose rate of radionuclides in the tree organs of the whorls. Evaluation of the absorbed dose targeted <sup>131</sup>I, <sup>134</sup>Cs, and <sup>137</sup>Cs, the main radionuclides subsequent to the FDNPP accident. The dose contribution from each tree organ was calculated separately using dose coefficients (DC), which express the ratio between the average activity concentration of a radionuclide in each tree organ and the dose rate at the terminal bud.Results and Discussion: The dose estimation indicated that the radionuclides in the terminal bud and bud scale contributed to the absorbed dose rate mainly by beta rays, whereas those in 1-year-old trunk/branches and leaves were contributed by gamma rays. However, the dose contribution from radionuclides in the lower trunk/branches and leaves was negligible.Conclusion: The fir tree model provides organ-specific DC values, which are satisfactory for the practical calculation of the absorbed dose rate of radiation from inside the tree. These calculations are based on the measurement of radionuclide concentrations in tree organs on the 1-year-old leader shoots of fir trees. With the addition of direct gamma ray measurements of the absorbed dose rate from the tree environment, the total absorbed dose rate was estimated in the terminal bud of fir trees in contaminated forests.

Formula omitted]Pb(p,x)194Hg and 209Bi(p,x)194Hg excitation functions in the energy range 0.04–2.6 GeV

The article presents the excitation functions of 194Hg, which is formed in Pb–Bi eutectic, on lead and bismuth isotopes in deep spallation reactions. The 194Hg production cross sections were measured by direct gamma spectrometry in lead targets enriched in 208Pb, 207Pb, and 206Pb, respectively, as well as in natural lead and bismuth, irradiated with protons of 11 energies from 0.04 to 2.6 GeV. Where possible, the experimental data are compared with the data of other authors, as well as with the simulated excitation functions of this nuclide, obtained using various high-energy transport codes - MCNP6.1 (CEM03.03), PHITS (INCL4.6/GEM), Geant4 (INCL++/ABLA) and the TENDL-2019 data library evaluation.

Reconstruction of Compton Edges in Plastic Gamma Spectra Using Deep Autoencoder.

Plastic scintillation detectors are widely utilized in radiation measurement because of their unique characteristics. However, they are generally used for counting applications because of the energy broadening effect and the absence of a photo peak in their spectra. To overcome their weaknesses, many studies on pseudo spectroscopy have been reported, but most of them have not been able to directly identify the energy of incident gamma rays. In this paper, we propose a method to reconstruct Compton edges in plastic gamma spectra using an artificial neural network for direct pseudo gamma spectroscopy. Spectra simulated using MCNP 6.2 software were used to generate training and validation sets. Our model was trained to reconstruct Compton edges in plastic gamma spectra. In addition, we aimed for our model to be capable of reconstructing Compton edges even for spectra having poor counting statistics by designing a dataset generation procedure. Minimum reconstructible counts for single isotopes were evaluated with metric of mean averaged percentage error as 650 for 60Co, 2000 for 137Cs, 3050 for 22Na, and 3750 for 133Ba. The performance of our model was verified using the simulated spectra measured by a PVT detector. Although our model was trained using simulation data only, it successfully reconstructed Compton edges even in measured gamma spectra with poor counting statistics.

Gamma spectrometry technique for the determination of residence time in Submarine Groundwater Discharges

The evaluation of time period that meteoric water remains in the ground (residence time) before exiting in the open sea can be a valuable information for the submarine groundwater discharges (SGD) in the costal zones. Coastal waters contain elevated dissolved activities of radium isotopes compared to the open ocean, where excess activities are zero. Lately it has been shown by Moore et al., that residence time can be estimated by a model based on radium radioisotopes ratio reduction throughout the coast. However the standard methods for the estimation of radium isotopes concentration in the water are sophisticated, time consuming or require big amount of sample. Hereby, a method based on the direct gamma ray spectrometry of untreated water samples from coastal areas is applied to determine the residence time of the SGD. Efficiency calibration of the spectrometry set up has been performed for two different volumetric sample geometries, using 152Eu/154Eu solution as reference source. In order to ensure the reliability of the method, the background courting rate magnitude and variance through time have been defined for the radioisotopes of interest. Additionally, the minimum detectible activity (MDA) of the measuring system was determined, in Becquerel per cubic meter, as a function of energy in water samples. The developed method was applied and validated for water samples from the submarine spring in Stoupa Bay, southwestern Peloponnesus. The defined residence time varies from 3 to 6 days, being in good agreement with the results of the standard geological pigment-tracer method.

Natural and anthropogenic radionuclides in urban soil around non-nuclear industries (Northern Al Jubail), Saudi Arabia: assessment of health risk.

The residential areas are located around one of the oldest and largest non-nuclear industrial cities in Saudi Arabia, Arabian Gulf. Therefore, it is important to study the radioactivity levels in the urban soil in order to estimate the potential risk of radiation in environment and for public. The activity concentrations of 226Ra, 232Th, 40K, and 137Cs in urban soil around non-nuclear industries were measured using gamma ray spectrometric technique. The mean values of activity concentrations were found to be 7.64 ± 0.4, 3.76 ± 0.2, 174 ± 3.7, and 0.391 ± 0.03 (Bq/kg) for 226Ra, 232Th, 40K, and 137Cs, respectively. Radium equivalent activity (Raeq), gamma absorbed dose rate in air (D), and annual effective dose equivalent (E) for outdoor were calculated. The mean values of these radiological parameters were found to be less than the allowed limits in soil. The obtained results were compared with other studies from Arabian Gulf and other regions of the world. Consequently, the direct gamma radiation exposure from the urban soil in the study area was found to be safe for public. Additionally, the present study is the first in this area which could be used as a baseline for radioactivity levels in soil nearby industrial areas of the Arabian Gulf region.

Direct PPARγ Activation by L-Thyroxin and TETRAC Links Thyroid Hormone and PPAR Signaling

Thyroid hormones (THs) operate numerous physiological processes through the nuclear thyroid hormone receptors and several other proteins. Here we report direct peroxisome proliferator-activated receptor gamma (PPARγ) and retinoid X receptor (RXR) activation by the T4 metabolite TETRAC at nanomolar affinity. We demonstrate that TETRAC is a highly active PPARγ agonist promoting PPARγ signaling in cell-free, cellular and in vivo settings suggesting that TETRAC and other THs are activators of PPARγ linking TH and PPAR signaling.

Space-based GAMMA-400 mission for direct gamma- and cosmic-ray observations

The future space-based GAMMA-400 mission is intended for direct gamma- and cosmic-ray observations in the highly elliptic orbit during 7-10 years. GAMMA-400, currently developing gamma-ray telescope, will observe in the energy range from ∼20 MeV to several TeV some regions of the Universe (such as Galactic Center, Fermi Bubbles, Crab, Cygnus, etc.) with the unprecedented angular (∼0.01° at Eγ = 100 GeV) and energy (∼1% at Eγ = 100 GeV) resolutions better than the Fermi-LAT, as well as ground gamma-ray telescopes, by a factor of 5-10. GAMMA-400 will also study cosmic rays in the energy range of up to ∼20 TeV due to deep calorimeter (22 r.l. and 53 r.l. for vertical and lateral events, respectively). GAMMA-400 will permit to resolve gamma rays from dark matter particles, identify many discrete sources (many of which are variable), to clarify the structure of extended sources, to specify the data on the diffuse emission. GAMMA-400 will also specify the sources and the spectra of cosmic-ray electrons + positrons.

Primary-amine surface functionalization of polytetrafluoroethylene films by radiation grafting of aminated polyacryloyl chloride

Amine-containing surfaces are important in cell adhesion; these surfaces are frequently synthesized using plasma reactions, which come with some disadvantages. Gamma radiation can be used to overcome these disadvantages. In this work, poly(tetrafluoroethylene) functional modification with primary amines was obtained in two steps: grafting acryloyl chloride (AC) using the direct gamma radiation method, followed by a reaction between the grafted AC and ethylenediamine. For PTFE-g-AC, the effects of the monomer concentration, absorbed dose, and reaction time were studied. The grafting percentage was gravimetrically determined using an esterification reaction with methanol, and the density of amine groups on the surface was evaluated by chemical derivatization (CD) with 4-trifluoromethylbenzaldehyde (TFBA) and X-ray Photoelectron Spectroscopy (XPS). The samples were also characterized by Fourier-transform infrared spectroscopy (FTIR), contact angle and Scanning electron microscopy (SEM). The maximum grafting of acryloylchloride obtained was 35%, using a concentration of 70% v/v and 20 kGy. The amine-containing surfaces showed an amine concentration of 3.3 at% in films with 26% of graft as determined by CD-XPS.

Evaluation of potential site for mineral processing plant

Nuclear moisture-density gauge is a type of instrument for measuring density and moisture of the material in a relatively thin zone beneath a surface of the material by using low activity of neutron and gamma radiation source. Density and moisture content data of the compacted layers are needed to determine the degree of compaction of soils, aggregate, concrete, asphalt or other materials used in civil engineering works. A gamma radiation source is mounted inside gauge housing with the source rod vertically extended to various depth positions. Direct transmission gamma radiation technique is used to obtain the count reading for the number of photons emitted before it is converted into density reading by microprocessor. This paper presents the inspection technique and results for the measurement of soil moisture and density carried out at potential site for mineral processing plant, Malaysian Nuclear Agency. Primarily, the experiment was conducted to ensure the compaction of ground is suitable for the plant construction. From the calculation, the percentages of soil wet density compaction (%WD Compact) are within acceptable limits with respect to the standard compacted wet soil density measured in the laboratory.

Removal of toxic heavy metal ions from aqueous solutions using jute fibers grafted with acrylic acid by gamma irradiation

Jute fibers were grafted with acrylic acid by using the direct gamma irradiation technique, which used as an adsorbent substrate for the toxic heavy metal ions such as Hg2+ and Pb2+ from their aqueous solutions. The structure and crystallinity of the grafted jute fibers were characterized by using Fourier‐transform infrared spectroscopy and X‐ray diffraction, respectively. The effect of pH range of the metal ion solutions, contact time, and the adsorption kinetics of the adsorption process were investigated. The effect of the initial concentration of dissolved metal ions and the adsorption isotherm for both Langmuir and Freundlich adsorption models were also investigated. From the results, it can be concluded that the adsorption process obeys the second‐order kinetic reaction and follows the Langmuir adsorption isotherm model, while, about 86 and 80% of Pb2+ and Hg2+, respectively, were adsorbed at pH 5 and 6 after a contact time of 60 min. J. VINYL ADDIT. TECHNOL., 24:339–346, 2018. © 2017 Society of Plastics Engineers

Estimation of the Vertical Distribution of Radiocesium in Soil on the Basis of the Characteristics of Gamma-Ray Spectra Obtained via Aerial Radiation Monitoring Using an Unmanned Helicopter.

After the Fukushima Daiichi Nuclear Power Plant accident, the vertical distribution of radiocesium in soil has been investigated to better understand the behavior of radiocesium in the environment. The typical method used for measuring the vertical distribution of radiocesium is troublesome because it requires collection and measurement of the activity of soil samples. In this study, we established a method of estimating the vertical distribution of radiocesium by focusing on the characteristics of gamma-ray spectra obtained via aerial radiation monitoring using an unmanned helicopter. The estimates are based on actual measurement data collected at an extended farm. In this method, the change in the ratio of direct gamma rays to scattered gamma rays at various depths in the soil was utilized to quantify the vertical distribution of radiocesium. The results show a positive correlation between the abovementioned and the actual vertical distributions of radiocesium measured in the soil samples. A vertical distribution map was created on the basis of this ratio using a simple equation derived from the abovementioned correlation. This technique can provide a novel approach for effective selection of high-priority areas that require decontamination.