137Cs Source Research Articles

Determination of Calibration Factors and Uncertainties Associated with the Irradiation of MTS-N (LiF: Mg, Ti) Chips with Cesium-137 and X-ray Sources Under Low Doses for Personal Dosimetry in Diagnostic Radiology

Purpose: The purpose of this study was to compare calibration factors for deep dose equivalent Hp (10) and shallow dose equivalent Hp (0.07) between Cesium (Cs)-137 and X-ray sources when they are exposed to same dose and to determine uncertainties with MTS-N (LiF: Mg, Ti) chips when they are exposed to low dose ≤ 2mGy. Material and Methods: Thermoluminescent (TL) chips were annealed at 400oC for one hour and allowed to cool and were subjected to a temperature of 100oC for another two hours using a TLD Furnace Type LAB-01/400. They were then taken to a Secondary Standard Dosimetry Laboratory (SSDL) for irradiation using a Cs-137 source at known doses (0.2-2mGy). A RadPro Cube 400 manual TLD Reader was used to determine corresponding TL signal. The above process was replicated but with a calibrated X-ray unit as the source for calibration. Results: The calibration factors (CF) from the line graph of dose (mGy) against TL signal (count) for Cs-137 source with Hp (10) and Hp (0.07) were 3.72 x 10-6 and 5.97x10-6 mGy/count respectively. Those with X-ray source for Hp (10) and Hp (0.07) were 3.44x10-6 and 4.05x10-6 mGy/count respectively with an overall coefficient of determination (R2) = 0.99. The adjusted maximum percentage deviation between the actual and calculated dose for both sources was -2.74%. The percent (%) deviation of the mean with both sources for Hp (10) and Hp (0.07) was 3.9% and 19% respectively. Conclusion: Adjusted percent deviation from both sources were within the recommended dose limit of ±30% by the Radiological Protection Institute of Ireland (RPII) and within the International Commission on Radiological Protection (ICRP) limit respectively. Better accuracy was seen for Hp (10) with both sources compared to Hp (0.07). Calibration of the MTS-N chips using both sources was successful and can be used for personal dosimetry.

High count-rate digital gamma-ray spectroscopy using a low-cost COTS digitizer system

A combination of publicly-available digitizers (COTS) has been used in digital gamma-ray spectroscopy in recent years. In this work, a feasibility study was undertaken to use a personal computer (PC) sound card as a digitizer in digital gamma-ray spectroscopy with NaI(Tl) scintillation detector. To this end, the duration of the output pulses of the NaI detector was increased to 300 μs by the preamplifier. Also, the algorithms for correcting and rejecting pile-up events at a low sample rate (96 kHz) were investigated. A new method based on a high-pass filter was developed to detect the pulse start time. Moreover, a new fast-fitting method based on the Integrodifferential equation was introduced, which represented a good performance at a low sample rate. An approximate method of applying the MLE method of long waveforms was also implemented. Wong's method was analytically rewritten assuming that there were more neighbors and it was shown that this result was independent of the assumption of a different number of close neighbors. The performance of these three methods in correcting the energy spectrum of the Cs-137 source, which was disturbed due to the presence of pile-up events and achieving high energy resolution, was compared. Finally, a new method based on the full width at half maximum of preamplifier pulses was also introduced to reject pile-up events.

Low cost radiation shielding material for low energy radiation applications: Epoxy/Yahyali Stone composites

In the present study, the gamma-ray shielding performance of the epoxy polymer matrix has been tried to develop by loading the matrix with a natural stone named as Yahyali Stone (YS), The YS has been collected from the Fairy Chimneys of Kayseri, Turkey. The chemical composition of the YS, which has been analyzed by X-Ray Fluorescence (XRF) spectroscopy, revealed that the main components of the stone are Fe2O3 (75.28 wt%), SiO2 (17.21 wt%), and Al2O3 (4.24 wt%). The Epoxy/YS composites that include 5 wt%, 10 wt%, 20 wt% and, 30 wt% YS have been prepared by mechanical mixing technique. The experimental setup contained a133Ba, 137Cs, and 60Co point radioactive sources, which emit 81 keV, 356 keV, 662 keV, 1173 keV, and 1332 keV photons, and a NaI(Tl) detector. The gamma-ray shielding capability of the samples has been discussed in the context of mass attenuation coefficient (μ/ρ), half-value layer (HVL), and mean free path (MFP). The mass attenuation coefficient, HVL, and MFP have also been calculated by WinXCom software. The experimental and WinXCom software results have been compared and good consistency has been established between these results. Finally, the effective atomic number (Zeff) and effective electron density (Neff) have been calculated by using the interpolation method. In conclusion, it can be suggested that low cost, natural and non-toxic reinforcing YS material has a promising role in enhancing the radiation shielding ability of the epoxy matrix for low energy radiation applications.

Development of Gamma-Ray Position-Sensitive Transition-Edge-Sensor Microcalorimeters

Position-sensitive transition-edge sensor (TES) microcalorimeters (PoSTs) were developed to detect gamma rays up to a few MeV. Each gamma-ray PoST comprised a 0.5 mm × 0.5 mm × 19 mm lead absorber with a TES on each end and worked as a 1D imaging spectrometer. Only one TES worked at low temperature and its results are reported herein. We irradiated the PoST device with gamma rays from a Cs-137 source, and the resultant pulses showed strong correlations between the pulse height and the rise time. To determine effective pixels, we separately divided the photopeak and lead-K escape peak pulses into 19 groups after sorting them by their rise times. From the pulse shape distributions, we concluded that the TES was sensitive to the gamma-ray interaction position as long as it was not located too far away from the TES, and that it was probably possible to determine the interaction positions of the entire absorber, if both TESs were working. The PoST device was then modeled and the average pulses of the 19 effective pixels were compared to those of numerical simulations, where the rise time distributions of the actual pulses and simulated pulses were in good agreement.

An intelligent gamma-ray technique for determining wax thickness in pipelines

Measuring the wax deposition inside pipelines is one of the critical parameters in the oil, gas and petrochemical industries to control the flow through the pipelines. This paper presents a novel method using artificial neural networks to measure the thickness of the wax. This method was based on counting the backscattered gamma-ray from different thicknesses of the wax inside the pipes with different diameters. For this purpose, the system was simulated by MCNPX code and the designed setup was optimized. The main analyses were based on the simulation results but the verification was performed using a real experimental setup. The results showed a good agreement between the simulation results and the experimental data with a root mean square error less than 1%. Response of the detector was simulated for a standard industrial nominal pipe ranged from 2 to 4.5 inches and for radiation sources 137Cs and 60Co. Using these data, a multilayer perceptron for different energy sources was trained. The best prediction of the wax thickness was obtained for the case of using two radiation sources, simultaneously. The output of the trained neural network showed that the proposed method is capable of measuring the wax thickness inside the pipe with a good accuracy.

Study on the lower absolute measurement limit of air kerma from 137Cs source using a large-size cavity chamber

For the purpose of obtaining the lower absolute measurement limit of the air kerma in 137Cs γ-ray reference fields, a cavity chamber with a volume of 301.936(19) cm3 was designed and fabricated. The absolute measurement of the air kerma was performed at the minimum effective dose rate of the large-size cavity chamber in our 137Cs γ-ray reference field. With the help of the detailed Monte-Carlo (MC) simulations of the large-size cavity chamber and our 137Cs irradiation facility, the conversion coefficient from the cavity dose to the reference air kerma was calculated. And the obtained air kerma rate with the MC simulation method was 1.429(13) mGy/h. At the same condition, the measured air kerma rates with the cavity theory method and the substitute method were 1.428(13) mGy/h and 1.419(53) mGy/h, respectively. The measurement result with the full MC simulation method agrees with the other two measurement results within 0.07% and 0.70%, respectively. The combination of the large-size chamber and the full MC simulation method can help calibration laboratories achieve the absolute measurement of the low air kerma rate (such as 1.5 mGy/h) in the 137Cs γ-ray reference field.

Radiation shielding properties of mortars containing heavyweight particles

Abstract In this study the radiation shielding properties of mortar samples were investigated. The samples were created by replacing heavyweight particles of iron, steel and chromium waste by calcareous sand in different volume percentages. Additionally, the effects of the physical properties of particles and samples on shielding properties is also discussed. In the scope of this work, the radiation shielding properties of mortar samples were measured by determining the values of mass attenuation coefficients by means of an experimental setup consisting of 133Ba, 137Cs and 60Co standard point sources and high purity germanium (HPGe) detector. It’s concluded that the highest mass attenuation coefficient values among the heavy particles were achieved by chromium particles. However, all the high-density particles used in the study improved the radiation shielding properties of the mortars considerably compared to ordinary mortars.

Dosimetric characterization of 3D printed for 137Cs gamma rays

The aim this paper is characterize materials for 3D printed with different infill percentages for 137Cs gamma rays. The RAISE 3D PRO2 printer was used to print PLA and ABS plates. Using a 137Cs source, the attenuation coefficient was obtained by the transmission method and results compared with PMMA. The readings were performed by a Radcal ionization chamber, model 10X6-6. The results of attenuation coefficients show that the PLA filament demonstrated a equivalent behavior to PMMA. The PLA plates exhibits an increase in radiation transmission when reduces the infilling, and ABS printing achieved same results for all infills.

Thermal expansion of lanthanum and neodymium oxides from 300–1000 K from measurements of attenuation of gamma rays

The present communication is a study of the linear attenuation coefficients, density and thermal expansion of oxides of lanthanum and neodymium as a function of temperature from 300–1000 K. The values of thermal expansion have been determined from linear attenuation coefficient of gamma rays and density in the range 300–1000 K. Measurements on the attenuation of gamma rays have been made with an experimental set up assembled in our laboratory using narrow beam geometry method. Radioactive gamma source 137Cs (0.662 MeV) has been used for making measurements. The results on the linear gamma ray attenuation (μ l), density (ρ) and the coefficient of linear thermal expansion (α) of Lanthanum oxide (La2O3)and Neodymium oxide (Nd2O3) as a function of temperature have been fit to a second degree polynomial equation. The linear attenuation coefficient (μ l) of La2O3 shows a decrease from 50.87 m−1 at 350 K to 49.96 m−1 at 1000 K. The linear attenuation coefficient (μ l) of Nd2O3 shows a decrease from 59.04 m−1 at 350 K to 58.07 m−1 at 1000 K. The decrease in density for lanthanum and neodymium oxides from 350–1000 K is 1.79% and 1.64% respectively. The present results on the thermal expansion of La2O3 and Nd2O3 have been compared with the results obtained from x-ray diffraction method.

Factors affecting the cesium transfer factor to shiitake (Lentinula edodes) cultivated in sawdust medium

The transfer factor (TF) of radioactive cesium-137 (137Cs) to shiitake (Lentinula edodes) cultivated on bed logs varies greatly. Therefore, the present study investigated which factors affect the TF using stable cesium-133 (133Cs) and sawdust medium with 5% rice bran as a model, which had similar 133Cs TFs to bed-log cultivation. It was found that the Cs concentration and nutrient concentration (represented by the nitrogen concentration) concerned with the TF in the model sawdust medium. In addition, the TFs calculated using total 137Cs and 133Cs concentrations differed in both bed-log cultivation and the model sawdust medium cultivation, while the TFs calculated using exchangeable 137Cs and 133Cs concentrations were the same in sawdust medium cultivation, indicating that exchangeable Cs in the medium is the source of Cs for the fruiting body and the former difference was due to the presence of other chemical speciation of Cs that could not be absorbed. One purpose of the TF on the mushroom farm is to determine the fruiting body 137Cs concentration at the start of bed-log cultivation, therefore the prediction method of TF are discussed considering the future changes of 137Cs concentrations in trees.

Compact lightweight imager of both gamma rays and neutrons based on a pixelated stilbene scintillator coupled to a silicon photomultiplier array

Dual particle imaging, in which both neutrons and gamma-rays in the environment can be individually characterized, is particularly attractive for monitoring mixed radiation emitters such as special nuclear materials (SNM). Effective SNM localization and detection benefits from high instrument sensitivity so that real-time imaging or imaging with a limited number of acquired events is enabled. For portable applications, one also desires a dual particle imager (DPI) that is readily deployable. We have developed a hand-held type DPI equipped with a pixelated stilbene-silicon photomultiplier (SiPM) array module and low sampling-rate analog-to-digital converters (ADCs) processed via a multiplexed readout. The stilbene-SiPM array (12 × 12 pixels) is capable of effectively performing pulse shape discrimination (PSD) between gamma-ray and neutron events and neutron/gamma-ray source localization on the imaging plane, as demonstrated with 252Cf neutron/gamma and 137Cs gamma-ray sources. The low sampling rate ADCs connected to the stilbene-SiPM array module result in a compact instrument with high sensitivity that provides a gamma-ray image of a 137Cs source, producing 6.4 μR/h at 1 m, in less than 69 s. A neutron image for a 3.5 × 105 n/s 252Cf source can also be obtained in less than 6 min at 1 m from the center of the system. The instrument images successfully with field of view of 50° and provides angular resolution of 6.8°.

Development of New High Transparency Pb-Free Radiation Shielding Glass

This experimental research aimed to development of new high transparency non-lead radiation shielding properties of the borosilicate glasses in the composition of xBaO: (40-x)SiO2: 25ZnO: 30B2O3: 5Al2O3 where x is the percent by mol of barium oxide of borosilicate glasses. All of glasses were prepared by melt quenching technique. The glasses were investigated physical properties, optical properties, and radiation shielding properties. The density of the glasses was measured by Archimedes’ principle. The optical property was measured by the UV-spectrometer, the XRD analysis have been used to confirm the phase (crystalline or amorphous). The mass attenuation coefficients, the effective atomic number, and the effective electron densities were measured at 662 keV of the energy by using the gamma-ray transmission technique from the 137Cs source. The theoretical values of radiation shielding were calculated by WinXCom program and compared with the experimental values. The results showed that the density and molar volume of the glasses were increased with the increasing of percent by mol of BaO. The results of optical properties found out that the sample glass is shown to have turned transparent yellow at the higher wavelength. The results of radiation shielding properties showed that mass attenuation coefficients, effective atomic numbers, effective electron densities, and lead equivalence thickness have trivial increases when the BaO is added. The half value layers (HVL) were decreases with the increasing of BaO content and also the energy absorption buildup factor coefficients (EABF) and exposure buildup factor (EBF) were studied.

Simulations and Experimental Verifications of an Algorithm for Radiation Source Mapping and Navigational Path Generation.

Accurate and efficient mapping and localization of both ionizing and non-ionizing radiation sources are important across many different fields. As such, a versatile mapping and navigational path generation algorithm, which can be applied to any point source measurements that follow an inverse-square characteristic, was developed using non-linear least squares methods. Forty thousand simulations were performed on the algorithm, which located sources successfully in a 10 m × 10 m × 10 m three-dimensional space with a success rate of over 80% across different noise functions, given a proportional constant of 10 to 1,000. The algorithm was also verified experimentally with small-scale radioactive decontamination of a 70 cm × 70 cm surface and localization of a lost Wi-Fi router in a 70 m × 70 m open field. One hundred twenty-one measurements were taken from each experiment, which were then fed into the algorithm for navigation. For the radioactive 137Cs source, the estimated locations were within 7 cm × 7 cm of the answer in 79.3% of the scenarios, while the Wi-Fi router was located to within 7 m × 7 m in 57.9% of the tests. In general, the method requires much less information and data than a geographically comprehensive survey and thus shows a lot of potential for practical applications, such as lost source retrieval with unmanned aerial vehicles, small-scale decontamination, mapping undocumented Wi-Fi routers or radio towers, and radiation simulation with radio signals. Different failure modes, desirable features, and potential improvements were also identified but remain as future work.

Impact of gamma-ray irradiation on the electronic structures of PCBM and P3HT organic semiconductor films

Gamma-ray irradiation alters the material properties of organic semiconductors, especially the electronic structure. These changes due to ionization can be useful in dosimetry. Although there are some device-based reports, the effect of gamma-ray irradiation on the electronic structure of organic semiconductors is still unclear. In this study, we investigated the electronic structures of representative organic semiconductor films, namely, n-type [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and p-type poly(3-hexylthiophene-2,5-diyl) (P3HT), after gamma-ray irradiation generated by a Cs-137 source. The X-ray and ultraviolet photoelectron spectra of the PCBM and P3HT films were measured for various gamma-ray doses. In both PCBM and P3HT, chemical interaction with atmospheric oxygen, assisted by high-energy photons, led to significant oxidation. However, the degree of oxidation of PCBM was considerably higher than that of P3HT. The oxidation also affects the valence electronic structures. The possible chemical structures of the oxidized PCBM and P3HT are estimated using density functional theory calculations.

Development and performance evaluation of large-area hybrid gamma imager (LAHGI)

We report the development of a gamma-ray imaging device, named Large-Area Hybrid Gamma Imager (LAHGI), featuring high imaging sensitivity and good imaging resolution over a broad energy range. A hybrid collimation method, which combines mechanical and electronic collimation, is employed for a stable imaging performance based on large-area scintillation detectors for high imaging sensitivity. The system comprises two monolithic position-sensitive NaI(Tl) scintillation detectors with a crystal area of 27 × 27 cm2 and a tungsten coded aperture mask with a modified uniformly redundant array (MURA) pattern. The performance of the system was evaluated under several source conditions. The system showed good imaging resolution (i.e., 6.0–8.9° FWHM) for the entire energy range of 59.5–1330 keV considered in the present study. It also showed very high imaging sensitivity, successfully imaging a 253 μCi 137Cs source located 15 m away in 1 min; this performance is notable considering that the dose rate at the front surface of the system, due to the existence of the 137Cs source, was only 0.003 μSv/h, which corresponds to ∼3% of the background level.

Hematopoietic protection and mechanisms of ferrostatin-1 on hematopoietic acute radiation syndrome of mice

Purpose Baicalein (an anti-ferroptosis drug) was recently reported to synergistically improve the survival rate of mice following a high dose of total body irradiation with anti-apoptosis and anti-necroptosis drugs. At the same time, our group has demonstrated that ferrostatin-1, a ferroptosis inhibitor, improves the survival rate of a mouse model of hematopoietic acute radiation syndrome to 60% for 150 days (p < .001). These phenomena suggest that ferroptosis inhibition can mitigate radiation damage. In this study, we continued to study the mechanisms by which ferrostatin-1 alleviated radiation-induced ferroptosis and subsequent hematopoietic acute radiation syndrome. Materials and methods Male ICR mice (8–10 weeks old) were exposed to doses of 0, 8, or 10 Gy irradiated from a 137Cs source. Ferrostatin-1 was intraperitoneally injected into mice 72 h post-irradiation. Bone marrow mononuclear cells (BMMCs) and peripheral blood cells were counted. The changes in iron-related parameters, lipid metabolic enzymes, lipid peroxidation repair molecules (glutathione peroxidase 4, glutathione, and coenzyme Q10), and inflammatory factors (TNF-α, IL-6, and IL-1β) were evaluated using biochemical or antibody techniques. Results Ferrostatin-1 increased the number of red and white blood cells, lymphocytes, and monocytes in the peripheral blood after total body irradiation in mice by mitigating the ferroptosis of BMMCs. Total body irradiation induced ferroptosis in BMMCs by increasing the iron and lipid peroxidation levels and depleting the acyl-CoA synthetase long-chain family member 4 (ASCL4), lipoxygenase 15, glutathione peroxidase 4, and glutathione levels. Ferroptotic BMMCs did not release TNF-α, IL-6, or IL-1β at the early stage of radiation exposure. Ferrostatin-1 mitigated the lipid peroxidation of radiation-induced ferroptosis by attenuating increases in levels of hemosiderin and liable iron pool and decreases in levels of ASCL4 and glutathione peroxidase 4. Conclusions The onset of total body irradiation-induced ferroptosis in BMMCs involved changes in iron, lipid metabolic enzymes, and anti-lipid peroxidation molecules. Ferrostatin-1 could be a potential radiation mitigation agent by acting on these targets.

Shielding properties of Cu-Sn-Pb alloy by Geant4, XCOM and experimental data

In this paper, alloy samples consisting of (Pb, Sn, Cu) were prepared in different proportions. The shielding properties of the prepared samples including mass attenuation coefficient (μm), radiation protection efficiency (RPE), half-value layers (HVL), mean free path (MFP), atomic and electronic electron cross-sections (σa and σe), effective atomic number (Zeff), electron density (Ne) were obtained using Monte Carlo simulation code Geant4 and XCOM program form 1 keV to 100 GeV. The experimental measurements were carried out at 356.5, 662 and 1173, 1332 keV of 133Ba, 137Cs, and 60Co isotopes sources, respectively using a gamma spectrometer contains a shielded NaI(Tl) detector. The calculated results of XCOM and Geant4 are consistent and in agreement with the experimental values.

High-performance coded aperture gamma camera based on monolithic GAGG:Ce crystal.

A 50 × 50 × 10mm3 monolithic gadolinium aluminum gallium garnet (Gd3Al2Ga3O12; GAGG):Ce crystal coupled to a 8 × 8 silicon photomultiplier (SiPM) array was developed; it showed very good system uniformity and a high energy resolution of 7.4% at 662 keV. By using a convolutional neural network-based positioning algorithm and a fan-beam calibration method, the detector achieved a position resolution of ∼1.4mm and a depth of interaction resolution of ∼2mm. Based on this high-performance monolithic detector, we developed a coded aperture gamma camera. A 1-mCi Cs-137 source centered at a 2-m distance from the mask could be reconstructed with a signal-to-noise ratio of 6.5 in 1s. Furthermore, the imaging ability of a low-energy Am-241 source and a low-activity Cs-137 source when the background-to-signal ratio was approximately 1:1 and a double low-activity source (Cs-137 and Na-22) was demonstrated. It is shown that the monolithic-crystal-based coded aperture gamma camera can achieve high performance and has a large potential for further improvement.

ТЕХНОГЕННОЕ ВОЗДЕЙСТВИЕ РАДИОАКТИВНОГО ЗАГРЯЗНЕНИЯ ПРОДУКТОВ ПЛАВКИ МЕТАЛЛА НА ОКРУЖАЮЩУЮ СРЕДУ И НАСЕЛЕНИЕ

The analysis of the distribution of radionuclides in the products of blast furnace and steelmaking melting operation processes is carried out. It was shown that the blast furnace melting process is considerably affected by natural radionuclides whereas steelmaking furnace process - by technogenic ones. The main impact on the environment is exerted by the gas-dust fraction, which contaminates the surrounding soil, vegetation and ground water during the settling process. An additional dose of external irradiation of the population and personnel is created by slag and metal fractions. High radiation doses are possible in case of ingestion of high-intensity sources of 60Co and 137Cs into the melt. Internal irradiation of people occurs due to gas and dust emissions.

Comparison of the response of different voltage dividers to low-level measurement using a large plastic scintillator intended for radiation portal monitors

The work deals with the comparison of voltage dividers with different wiring of resistors and capacitors. The voltage divider recommended by the manufacturer of the used photomultiplier (ET Enterprises, GB) was used as a reference. The aim was to assess the influence of different voltage dividers together with the large volume scintillation detector on detection parameters such as the efficiency of the measurement and dose rate linearity using 241Am, 137Cs, and 60Co gamma sources. The experiments showed relatively great differences between 15_10(_C) voltage divider (R1 and R2-R11, 15 MW and 10 MW) and the rest. Furthermore, it was confirmed that the voltage divider recommended by the manufacturer of the used photomultiplier showed the best results, but some of the measured dividers exhibited similar results and therefore can be used in radiation portal monitors as well.