Continuous-wave optically stimulated luminescence properties of Guajillo chilli polyminerals exposed to gamma radiation.

In this investigation, the Continuous-Wave Optically Stimulated Luminescence (CW-OSL) properties of polyminerals extracted from Mexican and Peruvian Guajillo chilli were studied using a source of cesium-137 (Cs-137) gamma radiation. The Guajillo chilli polyminerals were stimulated with blue light for 120 s, and their luminescence was detected in the UV region. The General Order Kinetics (GOK) deconvolution analysis of the CW-OSL curves was carried out using three individual components. The CW-OSL dose response from 10 to 5000 Gy was analysed in Guajillo chilli polyminerals. After different storage periods, the polyminerals show an increase in the CW-OSL intensity. A strong and moderate effect of the sunlight (60 min) and artificial (6 h) light is observed on the CW-OSL response. Therefore, the CW-OSL properties of polyminerals could be used in the identification of Mexican and Peruvian Guajillo chilli exposed to Cs-137 gamma radiation.

MCHP (Monte Carlo + Human Phantom): Platform to facilitate teaching nuclear radiation physics.

Some concepts in nuclear radiation physics are abstract and intellectually demanding. In the present paper, an "MCHP platform" (MCHP was an acronym for Monte Carlo simulations + Human Phantoms) was proposed to provide assistance to the students through visualization. The platform involved Monte Carlo simulations of interactions between ionizing radiations and the Oak Ridge National Laboratory (ORNL) adult male human phantom. As an example to demonstrate the benefits of the proposed MCHP platform, the present paper investigated the variation of the absorbed photon dose per photon from a 137Cs source in three selected organs, namely, brain, spine and thyroid of an adult male for concrete and lead shields with varying thicknesses. The results were interesting but not readily comprehensible without direct visualization. Graphical visualization snapshots as well as video clips of real time interactions between the photons and the human phantom were presented for the involved cases, and the results were explained with the help of such snapshots and video clips. It is envisaged that, if the platform is found useful and effective by the readers, the readers can also propose examples to be gradually added onto this platform in future, with the ultimate goal of enhancing students' understanding and learning the concepts in an undergraduate nuclear radiation physics course or a related course.

Uncertainties in Radiation Doses for a Case-control Study of Thyroid Cancer among Persons Exposed in Childhood to 131 I from Chernobyl Fallout.

Uncertainties in thyroid doses due to I intake were evaluated for 2,239 subjects in a case-control study of thyroid cancer following exposure to Chernobyl fallout during childhood and adolescence carried out in contaminated regions of Belarus and Russia. Using new methodological developments that became available recently, a Monte Carlo simulation procedure was applied to calculate 1,000 alternative vectors of thyroid doses due to I intake for the study population of 2,239 subjects accounting for sources of shared and unshared errors. An overall arithmetic mean of the stochastic thyroid doses in the study was estimated to be 0.43 Gy and median dose of 0.16 Gy. The arithmetic mean and median of deterministic doses estimated previously for 1,615 of 2,239 study subjects were 0.48 Gy and 0.20 Gy, respectively. The geometric standard deviation of individual stochastic doses varied from 1.59 to 3.61 with an arithmetic mean of 1.94 and a geometric mean of 1.89 over all subjects of the study. These multiple sets of thyroid doses were used to update radiation-related thyroid cancer risks in the study population exposed to I after the Chernobyl accident.

Gamma radiation-induced preparation of chitosan-acrylic acid-1-vinyl-2-vinylpyrrolidone/multiwalled carbon nanotubes composite for removal of 152+154Eu, 60Co and 134Cs radionuclides.

Removal behaviors of 152+154Eu, 60Co, and 134Cs radionuclides onto Chitosan-acrylic acid-1-vinyl-2-vinylpyrrolidone/oxidized multi-walled carbon nanotubes (CTS-AA-VP/o-MWCNTs) composite has been investigated by batch adsorption technique. CTS-AA-VP/o-MWCNTs composite has been synthesized by copolymerization of acrylic acid (AA) and 1-vinyl-2-vinylpyrrolidone (VP) onto the surface of chitosan/oxidized multi-walled carbon nanotubes (CTS/o-MWCNTs) using gamma radiation. SEM, TGA, and FTIR were applied to characterize the morphology, thermal stability, and structure of the composite. The composite shows high removal capacity of 321.77, 369.91, and 456.46 mg/g towards 152+154Eu, 60Co, and 134Cs radionuclides, respectively.

In vivo removal of radioactive cesium compound using Prussian blue-deposited iron oxide nanoparticles.

Aim: To mitigate the side effects of medical treatment by Prussian blue (PB), a well-known adsorbent for radioactive cesium (Cs), PB-deposited magnetic nanoparticles (MNPs), were prepared and analyzed on the adsorbent capacity for Cs removal. Materials & methods: The PB-deposited MNPs were prepared by photo-deposition method and investigated for their Cs adsorption properties in vitro and in vivo. The distribution of the adsorbents was also evaluated in C57BL/6 mice. Results: PB-deposited MNPs provided an improved adsorbent capacity for Cs removal and reduced toxicity to blood cells compared with those of bulk PB. Conclusion: PB-deposited MNPs could be considered as an alternative of PB-based medicine to reduce the possible hazards caused by high dose of PB intake.

Cesium-137 Contaminated Roads and Health Problems in Residents: an Epidemiological Investigation in Seoul, 2011.

BACKGROUND: In 2011, two roads in a residential area in Seoul were found to be contaminated with the radionuclide cesium-137 (137Cs). In response to public concerns, an epidemiological study was conducted. METHODS: The standardized cancer incidence ratios in the affected and neighboring regions were calculated based on the central cancer registry. Households in the region were sampled using the random stratified sampling technique, and questionnaires were administered to family members, via home visit and via students in elementary to high schools. Information on duration of residency and frequency of use of the roads was applied to calculate cumulative radiation exposure dose from the roads, alongside with the reported 137Cs contamination amounts. Information on past medical history, perceived risk, anxiety and psychological stress was also obtained. Of the 31,053 residents, 8,875 were analyzed. To examine possible associations between radiation exposure and health problems, logistic regression adjusted for covariates were performed with consideration of the sampling design, population weight and stratification. RESULTS: No significant association was found between self-informed diseases, including cancers, and estimated radiation exposure dose. According to an increase of radiation level, a significant increase in anxiety in all and a decline in the psychosocial wellbeing of the adults was noted. The risk perception level was higher in the elderly, females, the less educated, and the highest exposed individuals. CONCLUSION: This study provides a basis for risk communication with residents and community environmental health policy.

Chronic irradiation with low-dose-rate 137Cs-γ rays inhibits NGF-induced neurite extension of PC12 cells via Ca2+/calmodulin-dependent kinase II activation.

Chronic irradiation with low-dose-rate 137Cs-γ rays inhibits the differentiation of human neural progenitor cells and influences the expression of proteins associated with several cellular functions. We aimed to determine whether such chronic irradiation influences the expression of proteins associated with PC12 cells. Chronic irradiation at 0.027 mGy/min resulted in inhibition of NGF-induced neurite extension. Furthermore, irradiation enhanced the nerve growth factor (NGF)-induced increase in the phosphorylation of extracellular signal-regulated kinase (ERK), but did not affect the phosphorylation of NGF receptors, suggesting that irradiation influences pathways unassociated with the activation of ERK. We then examined whether irradiation influenced the Akt-Rac1 pathway, which is unaffected by ERK activation. Chronic irradiation also enhanced the NGF-induced increase in Akt phosphorylation, but markedly inhibited the NGF-induced increase in Rac1 activity that is associated with neurite extension. These results suggest that the inhibitory effect of irradiation on neurite extension influences pathways unassociated with Akt activation. As Ca2+/calmodulin-dependent kinase II (CaMKII) is known to inhibit the NGF-induced neurite extension in PC12 cells, independent of ERK and Akt activation, we next examined the effects of irradiation on CaMKII activation. Chronic irradiation induced CaMKII activation, while application of KN-62 (a specific inhibitor of CaMKII), attenuated increases in CaMKII activation and recovered neurite extension and NGF-induced increases in Rac1 activity that was inhibited by irradiation. Our results suggest that chronic irradiation with low-dose-rate γ-rays inhibits Rac1 activity via CaMKII activation, thereby inhibiting NGF-induced neurite extension.

Effect of gold nanoparticles on radiation doses in tumor treatment: a Monte Carlo study.

Radiotherapy is an extensively used treatment for most tumor types. However, ionizing radiation does not discriminate between cancerous and normal cells surrounding the tumor, which can be considered as a dose-limiting factor. This can lead to the reduction of the effectiveness of tumor cell eradication with this treatment. A potential solution to this problem is loading the tumor with high-Z materials prior to radiotherapy as this can induce higher toxicity in tumor cells compared to normal ones. New advances in nanotechnology have introduced the promising use of heavy metal nanoparticles to enhance tumor treatment. The primary studies showed that gold nanoparticles (GNPs) have unique characteristics as biocompatible radiosensitizers for tumor cells. This study aimed to quantify the dose enhancement effect and its radial dose distribution by Monte Carlo simulations utilizing the EGSnrc code for the water-gold phantom loaded with seven different concentrations of Au: 0, 7, 18, 30, 50, 75, and 100 mg-Au/g-water. The phantom was irradiated with two different radionuclide sources, Ir-192 and Cs-137, which are commonly used in brachytherapy, for all concentrations. The results exhibited that gold nanoparticle-aided radiotherapy (GNRT) increases the efficacy of radiotherapy with low-energy photon sources accompanied with high Au concentration loads of up to 30 mg-Au/g-water. Our finding conducts also to the detection of dose enhancement effects in a short average range of 650 µm outside the region loaded with Au. This can indicate that the location determination is highly important in this treatment method.

Adsorptive Property of Food Materials and Chemicals to Cesium and Strontium.

In March, 2011, large amounts of radioactive materials were released from the Fukushima Daiichi nuclear power plant after the nuclear accident. Especially, for humans, internal exposure to ¹³7Cs and 9°Sr radionuclides presents very high risks because of their very long physical half-lives (¹³7Cs: 30.2 years, 9°Sr: 28.9 years). Therefore, it is important to inhibit the absorption of radioactive materials and to promote the excretion of them from the body through feces. The aim of this.study was to explore foods, their components and various chemicals showing adsorption properties to Cs and Sr. Sodium alginate (ALA-Na) strongly adsorbed Cs and Sr compared with other samples. Chondroitin sulfate, carboxymethyl cellulose sodium (CMC-Na), methyl cellulose (MC) and apple polyphenols (AP; high molecule weight) also showed adsorption potency to Cs in that order. For Sr adsorption, kelp, CMC-Na, MC, AP (high molecule weight), laminaran and Jew's mallow exhibited adsorbing effects in that order. These samples might be useful and safe tools to protect from the adverse effects induced by internal exposure to these radioactive materials.

Bactericidal effect of γ-radiation with 137Cesium in platelet concentrates.

INTRODUCTION: γ-radiation is a method that was originally designed for inactivation of T lymphocytes in blood and blood components in order to prevent transfusion associated-graft versus host disease (TA-GVHD). Klebsiella pneumoniae, Escherichia coli, Enterococcus faecium and Staphylococcus epidermidis strains are important pathogens in blood banks since they have been related to post-transfusional sepsis. This study was conducted to demonstrate that γ-radiation is effective in reducing the viability of bacteria in platelet concentrates (PC). MATERIAL AND METHODS: Klebsiella pneumoniae, E. coli, E. faecium and S. epidermidis strains were adjusted at 101 to 106 CFU/ml and used in artificial contamination assays in PC. Contaminated platelet concentrates were subjected to γ-radiation with doses of 2500 cGy in a 137Cesium irradiator. The average of surviving bacteria at different bacterial concentrations, logarithmic reduction values (LRV) and bacterial death after γ-radiation percentage was calculated. RESULTS: Escherichia coli and K. pneumoniae were eliminated in 101 to 103 CFU; in contrast with 104 to 106 CFU, the LRV were 2.4, 2.6 and 2.6 for E. coli and 3.3, 2.7 and 3.0 for K. pneumoniae strains at 104, 105 and 106 CFU respectively. For Gram-positive strains, 101 CFU in PC, the inactivation post γ-radiation was not completed. Logarithmic reduction values post γ-radiation were 0.8 to 1.2 for E. faecium and S. epidermidis strains respectively. CONCLUSION: γ-radiation cannot be an alternative for the inactivation of pathogens in PC, because of the bacterial concentration and pathogen nature - being resistant to γ-radiation, the Gram-positive bacteria.

Shielding design for a Cs-137 rod-type standard point source for well chamber constancy checks.

Well type chambers are used for radioactive source calibrations in brachytherapy, but do not provide radiation shielding. Routine constancy checks on a well chamber are required between periodic secondary standard laboratory calibrations to ensure consistent device performance, and ultimately to ensure accurate patient dose delivery. In this work, a method is described to provide suitable shielding for a Cs-137 rod-type point source to enable use for constancy checks. A novel plunger-type shielded housing was designed and constructed for the Cs-137 source that when combined with a suitably shielded well-chamber container minimised user exposure during constancy checks. The designed shielding proved effective, and a constancy test routine was established and used for the past 16 months. The well chamber showed consistent performance (0.12 ± 0.18 % from the baseline) and no increased exposure was reported on users' radiation badges.

Evaluating the effect of various intracavitary applicators on dosimetric parameters of (192)Ir, (137)Cs, and (60)Co sources.

The purpose of this research is to study the effect of various applicator compositions on dosimetric parameters and dose distribution of (192)Ir, (137)Cs, and (60)Co sources, using Monte Carlo simulation techniques. To study the effect of applicators on source dosimetry, the dose rate constant, and radial dose function and isodose curves for the above noted sources were calculated in the presence and absence of plastic, titanium, and a stainless steel applicators. The effects of the applicators on the dosimetric parameters and isodose curves of these sources were dependent of the source type and materials of the applicator. The (192)Ir source with the stainless steel applicator has the maximum difference of dose rate (4.2 %) relative to the without applicator case. The (60)Co source with plastic applicator has the minimum dose variation. Moreover, this effect is higher for lower energy sources. Ignoring the effect of applicator composition and geometry on dose distribution may cause discrepancies in treatment planning. Plastic applicators have the least radiation attenuation compared to the other applicators, therefore, they are recommended for use in brachytherapy. A table of correction factors has been introduced for different sources and applicators with different materials for the clinical applications.

Estimates of Radiation Doses and Cancer Risk from Food Intake in Korea.

The aim of this study was to estimate internal radiation doses and lifetime cancer risk from food ingestion. Radiation doses from food intake were calculated using the Korea National Health and Nutrition Examination Survey and the measured radioactivity of (134)Cs, (137)Cs, and (131)I from the Ministry of Food and Drug Safety in Korea. Total number of measured data was 8,496 (3,643 for agricultural products, 644 for livestock products, 43 for milk products, 3,193 for marine products, and 973 for processed food). Cancer risk was calculated by multiplying the estimated committed effective dose and the detriment adjusted nominal risk coefficients recommended by the International Commission on Radiation Protection. The lifetime committed effective doses from the daily diet are ranged 2.957-3.710 mSv. Excess lifetime cancer risks are 14.4-18.1, 0.4-0.5, and 1.8-2.3 per 100,000 for all solid cancers combined, thyroid cancer, and leukemia, respectively.

Chronic Internal Exposure to Low Dose 137Cs Induces Positive Impact on the Stability of Atherosclerotic Plaques by Reducing Inflammation in ApoE-/- Mice.

After Chernobyl and Fukushima Daï Chi, two major nuclear accidents, large amounts of radionuclides were released in the environment, mostly caesium 137 (137Cs). Populations living in contaminated territories are chronically exposed to radionuclides by ingestion of contaminated food. However, questions still remain regarding the effects of low dose ionizing radiation exposure on the development and progression of cardiovascular diseases. We therefore investigated the effects of a chronic internal exposure to 137Cs on atherosclerosis in predisposed ApoE-/- mice. Mice were exposed daily to 0, 4, 20 or 100 kBq/l 137Cs in drinking water, corresponding to range of concentrations found in contaminated territories, for 6 or 9 months. We evaluated plaque size and phenotype, inflammatory profile, and oxidative stress status in different experimental groups. Results did not show any differences in atherosclerosis progression between mice exposed to 137Cs and unexposed controls. However, 137Cs exposed mice developed more stable plaques with decreased macrophage content, associated with reduced aortic expression of pro-inflammatory factors (CRP, TNFα, MCP-1, IFNγ) and adhesion molecules (ICAM-1, VCAM-1 and E-selectin). Lesions of mice exposed to 137Cs were also characterized by enhanced collagen and smooth muscle cell content, concurrent with reduced matrix metalloproteinase MMP8 and MMP13 expression. These results suggest that low dose chronic exposure of 137Cs in ApoE-/- mice enhances atherosclerotic lesion stability by inhibiting pro-inflammatory cytokine and MMP production, resulting in collagen-rich plaques with greater smooth muscle cell and less macrophage content.

Returning land contaminated as a result of radiation accidents to farming use.

An assessment is given of the possibility of sorbents based on natural aluminosilicates (glauconite and clinoptilolite) being used for remediation of radioactively contaminated land with the aim of returning it to farming use. A comparative study of selectivity and reversibility of radiocaesium and radiostrontium sorption by natural aluminosilicates as well as by modified ferrocyanide sorbents based on these aluminosilicates was made. It was found that surface modification of aluminosilicates by ferrocyanides increases the selectivity of synthesized sorbents to caesium by 100-1000 times, increases sorption capacity and makes caesium sorption almost irreversible, whereas, selectivity of these sorbents to strontium radionuclides remains approximately the same as for natural aluminosilicates. The caesium distribution coefficient for mixed nickel-potassium ferrocyanide on glauconite is 10((5.0±0.6)) L kg(-1), the static exchange capacity (SEC) is 63 mg g(-1); for mixed nickel-potassium ferrocyanide based on clinoptilolite caesium distribution coefficients in various concentration ranges are 10((7.0±1.0)), 10((5.7±0.4)) and 10((3.2±0.7)) L kg(-1), total SEC was 500 mg g(-1). Caesium leaching by various leaching solutions from saturated mixed nickel-potassium ferrocyanide based on clinoptilolite was lower than 2%; from saturated mixed nickel-potassium ferrocyanide based on glauconite it was 1.5-14.6%. Ferrocyanide sorbents, based on glauconite and clinoptilolite are recommended for remediation of land, contaminated by caesium as a result of the Fukushima accident in Japan. Use of these sorbents should decrease the transfer of caesium to agricultural vegetation up to a factor of 20.

Estimated dietary intake of radionuclides and health risks for the citizens of Fukushima City, Tokyo, and Osaka after the 2011 nuclear accident.

The radionuclides released from the Fukushima Daiichi nuclear power plant in 2011 pose a health risk. In this study, we estimated the 1st-year average doses resulting from the intake of iodine 131 (131I) and cesium 134 and 137 (134Cs and 137Cs) in drinking water and food ingested by citizens of Fukushima City (∼50 km from the nuclear power plant; outside the evacuation zone), Tokyo (∼230 km), and Osaka (∼580 km) after the accident. For citizens in Fukushima City, we considered two scenarios: Case 1, citizens consumed vegetables bought from markets; Case 2, citizens consumed vegetables grown locally (conservative scenario). The estimated effective doses of 134Cs and 137Cs agreed well with those estimated through market basket and food-duplicate surveys. The average thyroid equivalent doses due to ingestion of 131I for adults were 840 µSv (Case 1) and 2700 µSv (Case 2) in Fukushima City, 370 µSv in Tokyo, and 16 µSv in Osaka. The average effective doses due to 134Cs and 137Cs were 19, 120, 6.1, and 1.9 µSv, respectively. The doses estimated in this study were much lower than values reported by the World Health Organization and the United Nations Scientific Committee on the Effects of Atomic Radiation, whose assessments lacked validation and full consideration of regional trade in foods, highlighting the importance of including regional trade. The 95th percentile effective doses were 2-3 times the average values. Lifetime attributable risks (LARs) of thyroid cancers due to ingestion were 1.7-37×10-6 (Case 1) and5.6-79×10-6 (Case 2) in Fukushima City, 0.73-13×10-6 in Tokyo, and 0.04-0.49×10- 6 in Osaka. The contributions of LARs of thyroid cancers due to ingestion were 5.4%-11% of all exposure (Case 1) and 11%-25% (Case 2) in Fukushima City [corrected].

Dosimetry for 131Cs and 125I seeds in solid water phantom using radiochromic EBT film.

PURPOSE: To measure the 2D dose distributions with submillimeter resolution for (131)Cs (model CS-1 Rev2) and (125)I (model 6711) seeds in a Solid Water phantom using radiochromic EBT film for radial distances from 0.06cm to 5cm. To determine the TG-43 dosimetry parameters in water by applying Solid Water to liquid water correction factors generated from Monte Carlo simulations. METHODS: Each film piece was positioned horizontally above and in close contact with a (131)Cs or (125)I seed oriented horizontally in a machined groove at the center of a Solid Water phantom, one film at a time. A total of 74 and 50 films were exposed to the (131)Cs and (125)I seeds, respectively. Different film sizes were utilized to gather data in different distance ranges. The exposure time varied according to the seed air-kerma strength and film size in order to deliver doses in the range covered by the film calibration curve. Small films were exposed for shorter times to assess the near field, while larger films were exposed for longer times in order to assess the far field. For calibration, films were exposed to either 40kV (M40) or 50kV (M50) x-rays in air at 100.0cm SSD with doses ranging from 0.2Gy to 40Gy. All experimental, calibration and background films were scanned at a 0.02cmpixel resolution using a CCD camera-based microdensitometer with a green light source. Data acquisition and scanner uniformity correction were achieved with Microd3 software. Data analysis was performed using ImageJ, FV, IDL and Excel software packages. 2D dose distributions were based on the calibration curve established for 50kV x-rays. The Solid Water to liquid water medium correction was calculated using the MCNP5 Monte Carlo code. Subsequently, the TG-43 dosimetry parameters in liquid water medium were determined. RESULTS: Values for the dose-rate constants using EBT film were 1.069±0.036 and 0.923±0.031cGyU(-1)h(-1) for (131)Cs and (125)I seed, respectively. The corresponding values determined using the Monte Carlo method were 1.053±0.014 and 0.924±0.016cGyU(-1)h(-1) for (131)Cs and (125)I seed, respectively. The radial dose functions obtained with EBT film measurements and Monte Carlo simulations were plotted for radial distances up to 5cm, and agreed within the uncertainty of the two methods. The 2D anisotropy functions obtained with both methods also agreed within their uncertainties. CONCLUSION: EBT film dosimetry in a Solid Water phantom is a viable method for measuring (131)Cs (model CS-1 Rev2) and (125)I (model 6711) brachytherapy seed dose distributions with submillimeter resolution. With the Solid Water to liquid water correction factors generated from Monte Carlo simulations, the measured TG-43 dosimetry parameters in liquid water for these two seed models were found to be in good agreement with those in the literature.

On the feasibility of polyurethane based 3D dosimeters with optical CT for dosimetric verification of low energy photon brachytherapy seeds.

PURPOSE: To investigate the feasibility of and challenges yet to be addressed to measure dose from low energy (effective energy <50 keV) brachytherapy sources (Pd-103, Cs-131, and I-125) using polyurethane based 3D dosimeters with optical CT. METHODS: The authors' evaluation used the following sources: models 200 (Pd-103), CS-1 Rev2 (Cs-131), and 6711 (I-125). The authors used the Monte Carlo radiation transport code MCNP5, simulations with the ScanSim optical tomography simulation software, and experimental measurements with PRESAGE(®) dosimeters/optical CT to investigate the following: (1) the water equivalency of conventional (density = 1.065 g/cm(3)) and deformable (density = 1.02 g/cm(3)) formulations of polyurethane dosimeters, (2) the scatter conditions necessary to achieve accurate dosimetry for low energy photon seeds, (3) the change in photon energy spectrum within the dosimeter as a function of distance from the source in order to determine potential energy sensitivity effects, (4) the optimal delivered dose to balance optical transmission (per projection) with signal to noise ratio in the reconstructed dose distribution, and (5) the magnitude and characteristics of artifacts due to the presence of a channel in the dosimeter. Monte Carlo simulations were performed using both conventional and deformable dosimeter formulations. For verification, 2.8 Gy at 1 cm was delivered in 92 h using an I-125 source to a PRESAGE(®) dosimeter with conventional formulation and a central channel with 0.0425 cm radius for source placement. The dose distribution was reconstructed with 0.02 and 0.04 cm(3) voxel size using the Duke midsized optical CT scanner (DMOS). RESULTS: While the conventional formulation overattenuates dose from all three sources compared to water, the current deformable formulation has nearly water equivalent attenuation properties for Cs-131 and I-125, while underattenuating for Pd-103. The energy spectrum of each source is relatively stable within the first 5 cm especially for I-125. The inherent assumption of radial symmetry in the TG43 geometry leads to a linear increase in sample points within the 3D dosimeter as a function of distance away from the source, which partially offsets the decreasing signal. Simulations of dose reconstruction using optical CT showed the feasibility of reconstructing dose out to a radius of 10 cm without saturating projection images using an optimal dose and high dynamic range scanning; the simulations also predicted that reconstruction artifacts at the channel surface due to a small discrepancy in refractive index should be negligible. Agreement of the measured with calculated radial dose function for I-125 was within 5% between 0.3 and 2.5 cm from the source, and the median difference of measured from calculated anisotropy function was within 5% between 0.3 and 2.0 cm from the source. CONCLUSIONS: 3D dosimetry using polyurethane dosimeters with optical CT looks to be a promising application to verify dosimetric distributions surrounding low energy brachytherapy sources.

Selective cesium removal from radioactive liquid waste by crown ether immobilized new class conjugate adsorbent.

Conjugate materials can provide chemical functionality, enabling an assembly of the ligand complexation ability to metal ions that are important for applications, such as separation and removal devices. In this study, we developed ligand immobilized conjugate adsorbent for selective cesium (Cs) removal from wastewater. The adsorbent was synthesized by direct immobilization of dibenzo-24-crown-8 ether onto inorganic mesoporous silica. The effective parameters such as solution pH, contact time, initial Cs concentration and ionic strength of Na and K ion concentrations were evaluated and optimized systematically. This adsorbent was exhibited the high surface area-to-volume ratios and uniformly shaped pores in case cavities, and its active sites kept open functionality to taking up Cs. The obtained results revealed that adsorbent had higher selectivity toward Cs even in the presence of a high concentration of Na and K and this is probably due to the Cs-π interaction of the benzene ring. The proposed adsorbent was successfully applied for radioactive Cs removal to be used as the potential candidate in Fukushima nuclear wastewater treatment. The adsorbed Cs was eluted with suitable eluent and simultaneously regenerated into the initial form for the next removal operation after rinsing with water. The adsorbent retained functionality despite several cycles during sorption-elution-regeneration operations.

Aqueous (99)Tc, (129)I and (137)Cs removal from contaminated groundwater and sediments using highly effective low-cost sorbents.

Technetium-99 ((99)Tc), iodine-129 ((129)I), and cesium-137 ((137)Cs) are among the key risk-drivers for environmental cleanup. Immobilizing these radionuclides, especially TcO4(-) and I(-), has been challenging. TcO4(-) and I(-) bind very weakly to most sediments, such that distribution coefficients (Kd values; radionuclide concentration ratio of solids to liquids) are typically <2 mL/g; while Cs sorbs somewhat more strongly (Kd âˆ¼ 50 mL/g). The objective of this laboratory study was to evaluate 13 cost-effective sorbents for TcO4(-), I(-), and Cs(+) uptake from contaminated groundwater and sediments. Two organoclays sorbed large amounts of TcO4(-) (Kd > 1 × 10(5) mL/g), I(-) (Kd ≥ 1 × 10(4) mL/g), and Cs(+) (Kd > 1 × 10(3) mL/g) and also demonstrated a largely irreversible binding of the radionuclides. Activated carbon GAC 830 was effective at sorbing TcO4(-) (Kd > 1 × 10(5) mL/g) and I(-) (Kd = 6.9 × 10(3) mL/g), while a surfactant modified chabazite was effective at sorbing TcO4(-) (Kd > 2.5 × 10(4) mL/g) and Cs(+) (Kd > 6.5 × 10(3) mL/g). Several sorbents were effective for only one radionuclide, e.g., modified zeolite Y had TcO4(-)Kd > 2.3 × 10(5) mL/g, AgS had I(-) Kd = 2.5 × 10(4) mL/g, and illite, chabazite, surfactant modified clinoptilolite, and thiol-SAMMS had Cs(+)Kd > 10(3) mL/g. These low-cost and high capacity sorbents may provide a sustainable solution for environmental remediation.