Search

Cobalt-59 nuclei are known for extremely thermally sensitive chemical shifts (δ), which in the long term could yield novel magnetic resonance thermometers for bioimaging applications. In this manuscript, we apply extended X-ray absorption fine-structure spectroscopy (EXAFS) for the first time to probe the exact variations in physical structure that produce the exceptional thermal sensitivity of the (59)Co NMR chemical shift. We apply the technique to five Co(III) complexes: [Co(NH(3))(6)]Cl(3) (1), [Co(en)(3)]Cl(3) (2) (en = ethylenediamine), [Co(tn)(3)]Cl(3) (3) (tn = trimethylenediamine), [Co(tame)(2)]Cl(3) (4) (tame = 1,1,1-tris(aminomethyl)ethane), and [Co(diNOsar)]Cl(3) (5) (diNOsar = dinitrosarcophagine). The solution-phase EXAFS data reveal increasing Co─N bond distances for these aqueous complexes over a ~50 °C temperature window, expanding by Δr((Co─N)) = 0.0256(6) Å, 0.0020(5) Å, 0.0084(5) Å, 0.0006(5) Å, and 0.0075(6) Å for 1-5, respectively. Computational analyses of the structural changes reveal that increased connectivity between the donor atoms encourages complex structural variations. These results imply that rich temperature-dependent structural variations define the (59)Co NMR thermometry in macrocyclic complexes.

This manuscript details the first investigation of ligand encapsulation on thermometry by cobalt-59 nuclear spins., Thermometry via magnetic resonance imaging (MRI) would provide a powerful noninvasive window into physiological temperature management. Cobalt-59 nuclear spins demonstrate exceptional temperature dependence of their NMR chemical shifts, yet the insight to control this dependence via molecular design is lacking. We present the first systematic evidence that encapsulation of this spin system amplifies the temperature sensitivity. We tested the temperature dependence of the 59Co chemical shift (Δδ/ΔT) in a series of five low-spin cobalt(iii) complexes as a function of increasing encapsulation within the 1st coordination sphere. This study spans from [Co(NH3)6]Cl3, with no interligand connectivity, to a fully encapsulated dinitrosarcophagine (diNOsar) complex, [Co(diNOsar)]Cl3. We discovered Δδ/ΔT values that span from 1.44(2) ppm °C–1 in [Co(NH3)6]Cl3 to 2.04(2) ppm °C–1 in [Co(diNOsar)]Cl3, the latter among the highest for a molecular complex. The data herein suggest that designing 59Co NMR thermometers toward high chemical stability can be coincident with high Δδ/ΔT. To better understand this phenomenon, variable-temperature UV-Vis, 59Co NMR relaxation, Raman spectroscopic, and variable-solvent investigations were performed. Data from these measurements highlight an unexpected impact of encapsulation – an increasingly dynamic and flexible inner coordination sphere. These results comprise the first systematic studies to reveal insight into the molecular factors that govern Δδ/ΔT and provide the first evidence of 59Co nuclear-spin control via vibrational means.

The flux-weighted average cross-sections for the 59Co($ \gamma$, xn)58-55Co reactions have been measured with the bremsstrahlung end-point energies of 65 and 75 MeV by using the activation method in combination with the off-line $ \gamma$-ray spectrometry. The measured cross-sections for the $ (\gamma,\mathrm{n})$, $ (\gamma,2\mathrm{n})$, $ (\gamma,3\mathrm{n})$ and $ (\gamma,4\mathrm{n})$ reactions of 59Co at 65 MeV are $ 15.828\pm 0.491$, $ 5.003\pm 0.206$ , $ 0.408\pm 0.047$ and $ 0.039\pm 0.008$ mb, whereas at 75 MeV are $ 15.653\pm 0.361$, 4.965±0.289, $ 0.389\pm 0.062$ and $ 0.036\pm 0.007$ mb, respectively. The 59Co($ \gamma$, xn) reaction cross-sections as a function of photon energy were also theoretically simulated by using TALYS 1.9 code. Then the flux-weighted average cross-sections at different bremsstrahlung energies were obtained from the theoretical values and the literature data at lower energy based on mono-energetic photons. The present data are measured for the first time and are found to be in good agreement with the theoretical flux-weighted average values. It was found that the 59Co($ \gamma$, xn)58-55Co reaction cross-sections increase from their threshold values to a certain bremsstrahlung energy. After a certain energy, the individual 59Co($ \gamma$, xn) reaction cross-sections decrease with the increase of bremsstrahlung energy due to opening of other reaction channels. These two observations indicate the role of excitation energy and its partition in different reaction channels. All the four cobalt isotopes produced from the 59Co($ \gamma$, xn) reactions have medical and other applications.

Based on the Shell-Model, and the linear response theory, we discuss the influence of strong electron screening (SES) on the $\gamma$ -ray heating rates (GRHR) by beta decay for several typical iron group nuclei. We calculate the screening potential caused by the relativistically degenerate electron. We also investigate the effect of SES on beta decay Q-value, electron chemical potential, as well as the shell and pair effects. We find that the GRHR increase by several orders magnitude and the screening enhancement factor can get to 76.83 due to SES.

The direct whole core calculation is applied on Cobalt-59 activation calculation. The coupled neutronics, thermal hydraulics and depletion calculation is conducted, where the neutronics is solved by the Monte Carlo code JMCT and the thermal hydraulics is treated with sub-channel method. In the neutronics calculation, the reactor core is pin-by-pin modeled and the cobalt rods are modeled without approximation in geometry. The first reactor cycle is calculated with and without cobalt rods. The power distribution, coolant temperature and boron concentration curve are shown. And the boron concentration curve is compared with the reference value provided by the power plant. The effect of loading cobalt rod on power distributions and critical boron concentration is investigated. With the direct whole core solution, the average specific activity of cobalt rods and their distribution are obtained. In the end, the sensitivity study on number of tracking particles, the coupling strategy and the position of cobalt rods are conducted respectively. And the optimization to enhance the specific activity of cobalt rods is discussed as well.

Background and motivation: While small molecules can be used in cancer diagnosis there is a need for imageable diagnostic NanoParticles (NPs) that act as surrogates for the therapeutic NPs. Many NPs are composed of hydrophobic materials so the challenge is to formulate hydrophobic imaging agents. To develop individualized medical treatments based on NP, a first step should be the selection of patients who are likely responders to the treatment as judged by imaging tumor accumulation of NPs. This requires NPs with the same size and structure as the subsequent therapeutic NPs but labelled with a long-lived radionuclide. Cobalt isotopes are good candidates for NP labelling since 55Co has half-life of 17.5 h and positron energy of 570 keV while 57Co (t 1/2 271.6 d) is an isotope suited for preclinical single photon emission tomography (SPECT) to visualize biodistribution and pharmacokinetics of NPs. We used the hydrophobic octaethyl porphyrin (OEP) to chelate cobalt and to encapsulate it inside hydrophobic liquid NPs (LNPs). We hypothesized that at least two additional hydrophobic axial ligands (oleylamine, OA) must be provided to the OEP-Co complex in order to encapsulate and retain Co inside LNP. Results: 1. Cobalt chelation by OEP and OA. The association constant of cobalt to OEP was 2.49 × 10 5 M −1 and the formation of the hexacoordinate complex OEP-Co-4OA was measured by spectroscopy. 2. NP formulation and characterization: LNPs were prepared by the fast ethanol injection method and were composed of a liquid core (triolein) surrounded by a lipid monolayer (DSPC:Cholesterol:DSPE-PEG 2000). The size of the LNPs loaded with the cobalt complex was 40 ± 5 nm, 3. Encapsulation of OEP-Co-OA: The loading capacity of OEP-Co-OA in LNP was 5 mol%. 4. Retention of OEP- 57Co-4OA complex in the LNPs: the positive effect of the OA ligands was demonstrated on the stability of the OEP- 57Co-4OA complex, providing a half-life for retention in PBS of 170 h (7 days) while in the absence of the axial OA ligands was only 22 h. 5 Biodistribution Study: the in vivo biodistribution of LNP was studied in AR42J pancreatic tumor-bearing mice. The estimated half-life of LNPs in blood was about 7.2 h. Remarkably, the accumulation of LNPs in the tumor was as high as 9.4% ID/g 24 h after injection with a doubling time for tumor accumulation of 3.22 h. The most important result was that the nanoparticles could indeed accumulate in the AR42J tumors up to levels greater than those of other NPs previously measured in the same tumor model, and at about half the values reported for the molecular agent 57Co-DOTATATE. Conclusions: The additional hydrophobic chelator OA was indeed needed to obtain a stable octahedral OEP-Co-4OA. Cobalt was actually well-retained inside LNP in the OEP-Co-4OA complex. The method described in the present work for the core-labelling of LNPs with cobalt is now ready for labeling of NPs with 55Co, or indeed other hexadentate radionuclides of interest for preclinical in vivo PET-imaging and radio-therapeutics.

Este trabalho consiste no desenvolvimento de um detector composto por um calorímetro com núcleo de água para dosimetria de feixes de 60Co e 137Cs com média intensidade. Além do calorímetro, foi também dimensionada a instrumentação, a metodologia de calibração e a medição de temperatura. O trabalho foi dividido em 4 etapas distintas: escolha do melhor projeto como base para desenvolvimento do calorímetro, dimensionamento de parâmetros e ajuste fino do projeto, construção e calibração. Durante o desenvolvimento deste trabalho foi construída uma Unidade de Tratamento de Água que permite a produção da água que o calorímetro emprega. Em seguida foi construído o calorímetro em sí com os conceitos das etapas anteriores. O equipamento foi testado tanto nas instalações da GMR quanto no CTR do IPEN, obtendo taxas de dose na água com fontes de 137Cs e 60Co com diversas atividades (3,3 TBq, 15,54 TBq e 7 TBq) e em algumas distâncias. Foram obtidas taxas de dose que variavam de 2 mGy/s até 15 mGy/s, dependendo do tipo de fonte e SDD escolhida. O projeto contou com simulações de códigos como MCNP5 e FLUENT 14 e foram essenciais na construção do equipamento. O objetivo deste trabalho foi aprimorar a infraestrutura do LCI, desenvolvendo um detector que deverá aumentar a gama dos serviços prestados pelo LCI com um tipo de medição dosimétrica ainda inexistente no país. This work aims to develop a radiation detector composed by a water calorimeter for beam dosimetry of 60Co and 137Cs gamma radiation with medium intensity. Besides the calorimeter itself, all the instrumentation, methodology, calibration and testing protocols were established. This work was divided into 4 parts: the choice of the best design; simulation and setting of the ideal operation parameters; adaptation of the project; construction and calibration. During the development of this work a water treatment unit was built which allows the production of distilled water for the calorimeter. Then the calorimeter itself was built with the concepts from the previous steps. The equipment has been tested both in the facilities of GMR as the CTR at IPEN, obtaining dose rates ( from 2 mGy/s up to 15 mGy/s) in water for 137Cs and 60Co sources in some activities (3,3 TBq, 15,54 TBq e 7 TBq) and distances. The MCNP5 and FLUENT 14 have been used and proved essential in the development of the prototype. The main goal was to improve the LCI infrastructure with a new radiation detector that will increase the calibration laboratory service range with a still absent kind of dosimetric measurement in Brazil.

Purpose: Magnetic fields are known to alter radiation dose deposition. Before patients receive treatment using an MRI-linear accelerator (MRI-Linac), preclinical studies are needed to understand the biological consequences of magnetic-field-induced dose effects. In the present study, the authors sought to identify a beam energy and magnetic field strength combination suitable for preclinical murine experiments. Methods: Magnetic field dose effects were simulated in a mouse lung phantom using various beam energies (225 kVp, 350 kVp, 662 keV [Cs-137], 2 MV, and 1.25 MeV [Co-60]) and magnetic field strengths (0.75, 1.5, and 3 T). The resulting dose distributions were compared with those in a simulated human lung phantom irradiated with a 6 or 8 MV beam and orthogonal 1.5 T magnetic field. Results: In the human lung phantom, the authors observed a dose increase of 45% and 54% at the soft-tissue-to-lung interface and a dose decrease of 41% and 48% at the lung-to-soft-tissue interface for the 6 and 8 MV beams, respectively. In the mouse simulations, the magnetic fields had no measurable effect on the 225 or 350 kVp dose distribution. The dose increases with the Cs-137 beam for the 0.75, 1.5, and 3 T magnetic fields were 9%, 29%, and 42%, respectively. The dose decreases were 9%, 21%, and 37%. For the 2 MV beam, the dose increases were 16%, 33%, and 31% and the dose decreases were 9%, 19%, and 30%. For the Co-60 beam, the dose increases were 19%, 54%, and 44%, and the dose decreases were 19%, 42%, and 40%. Conclusions: The magnetic field dose effects in the mouse phantom using a Cs-137, 3 T combination or a Co-60, 1.5 or 3 T combination most closely resemble those in simulated human treatments with a 6 MV, 1.5 T MRI-Linac. The effects with a Co-60, 1.5 T combination most closely resemble those in simulated human treatments with an 8 MV, 1.5 T MRI-Linac.

Low quenched samples containing 241Am, 137Cs, or 60Co have been investigated by liquid scintillation counting using two-vial configuration, with the aim to study the effect of incidental radiations on the counting efficiency of α or β particles. For β determination, the effect of incidental radiations mainly depends on whether they are in coincidence with the β particles. While for α determination, the counting efficiency of α particles can hardly be affected by the incidental radiations if a proper α/β discrimination parameter is applied. When coincidence exists, summation effect can offset the effect of incidental radiations.

This study investigated the human gastrointestinal uptake (f1) and subsequent whole-body retention of orally administered inorganic radioactive cobalt. Of eight adult volunteers aged between 24 and 68 years, seven were given solutions of (57)Co (T1/2 = 272 d) containing a stable cobalt carrier, and six were given carrier-free (58)Co (T1/2 = 71 d). The administered activities ranged between 25 and 103 kBq. The observed mean f1, based on 6 days accumulated urinary excretion sampling and whole-body counting, was 0.028 ± 0.0048 for carrier-free (58)Co, and 0.016 ± 0.0021 for carrier-associated (57)Co. These values were in reasonable agreement with values reported from previous studies involving a single intake of inorganic cobalt. The time pattern of the total retention (including residual cobalt in the GI tract) included a short-term component with a biological half-time of 0.71 ± 0.03 d (average ± 1 standard error of the mean for the two nuclides), an intermediate component with a mean half-time of 32 ± 8.5 d, and a long-term component (observed in two volunteers) with half-times ranging from 80 to 720 d for the two isotopes. From the present data we conclude that for the short-lived (57)Co and (58)Co, more than 95% of the internal absorbed dose was delivered within 7 days following oral intake, with a high individual variation influenced by the transit time of the unabsorbed cobalt through the gastro-intestinal tract.

In this article, the in vivo study performed to evaluate the uniformity of biological doses within an hypothetical target volume and calculate the values of relative biological effectiveness (RBE) at different depths in the spread-out Bragg peak (SOBP) of the new CNAO (National Centre for Oncological Hadrontherapy) carbon beams is presented, in the framework of a typical radiobiological beam calibration procedure. The RBE values (relative to (60)Co γ rays) of the CNAO active scanning carbon ion beams were determined using jejunal crypt regeneration in mice as biological system at the entrance, centre and distal end of a 6-cm SOBP. The RBE values calculated from the iso-effective doses to reduce crypt survival per circumference to 10, ranged from 1.52 at the middle of the SOBP to 1.75 at the distal position and are in agreement with those previously reported from other carbon ion facilities. In conclusion, this first set of in vivo experiments shows that the CNAO carbon beam is radiobiologically comparable with the NIRS (National Institute of Radiological Sciences, Chiba, Japan) and GSI (Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany) ones.

Two most common types of LiF-based thermoluminescent (TL) detectors LiF:Mg,Ti (natural Li: MTS-N) and LiF:Mg,Cu,P (natural Li: MCP-N) have been studied for sensitivity loss after 60 MeV proton and gamma rays (60Co) doses ranging between 0.5 and 30 Gy. The sensitivity (main peak area) of LiF:Mg,Ti was found to be reduced by almost 10% after the highest proton dose of 30 Gy with respect to the lowest dose of 0.5 Gy. The sensitivity loss was noticeable even after 5 Gy of protons. After gamma-ray exposures the sensitivity loss of LiF:Mg,Ti was smaller than after protons. LiF:Mg,Cu,P detectors show opposite effect: gamma-rays cause a stronger sensitivity loss than protons. The high-temperatures peaks of LiF:Mg,Ti decreased much more significantly than the main peak (by 40%). The decreased sensitivity may be partly (depending on the dose radiation type) recovered by application the extended annealing procedures: 400 °C/20 h for MTS-N and 10 min at 270 °C followed by 1 h at 240 °C for MCP-N. The observed changes of sensitivity are of importance for dosimetry in proton radiotherapy.

High energy γ-rays can be used in many fields, such as nuclear waste transmutation, flash photographics, and astrophysics. The 13C( p , γ )14N resonance reaction was used to generate high energy and mono-energetic γ-rays in this work. The thick-target yield of the 9.17-MeV γ-ray from the resonance in this reaction was determined to be (4.7±0.4) × 10 − 9 γ /proton, which was measured by a HPGe detector. Meanwhile, the angular distribution of 9.17-MeV γ-ray was also determined. The absolute efficiency of HPGe detector was calibrated using 56Co and 152Eu sources with known radioactive activities and calculated by GEANT4 simulation.

International audience; The estimation of the dose and the irradiated fraction of the body is important information in the primary medical response in case of a radiological accident. The PCC-R assay has been developed for high-dose estimations, but little attention has been given to its applicability for partial-body irradiations. In the present work we estimated the doses and the percentage of the irradiated fraction in simulated partial-body radiation exposures at high doses using the PCC-R assay. Peripheral whole blood of three healthy donors was exposed to doses from 0-20 Gy, with 60Co gamma radiation. To simulate partial body irradiations, irradiated and nonirradiated blood was mixed to obtain proportions of irradiated blood from 10-90%. Lymphocyte cultures were treated with Colcemid and Calyculin-A before harvest. Conventional and triage scores were performed for each dose, proportion of irradiated blood and donor. The Papworth's u test was used to evaluate the PCCR distribution per cell. A dose-response relationship was fitted according to the maximum likelihood method using the frequencies of PCC-R obtained from 100% irradiated blood. The dose to the partially irradiated blood was estimated using the Contaminated Poisson method. A new D0 value of 10.9 Gy was calculated and used to estimate the initial fraction of irradiated cells. The results presented here indicate that by PCC-R it is possible to distinguish between simulated partial- and whole-body irradiations by the u-test, and to accurately estimate the dose from 10-20 Gy, and the initial fraction of irradiated cells in the interval from 10-90%. © The Author 2013. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Therapeutic Radiology and Oncology.

NMR spectroscopy (solution and solid state) of group 3d metals is described, including some applications in biology and material sciences. Most nuclei are difficult to observe because they have large nuclear quadrupole moments and/or low receptivities. The ranges of typical parameters (chemical shift and shift anisotropy, coupling constants, quadrupolar interactions) are surveyed, and factors influencing these parameters are discussed.

Cobalt is a chemical element with symbol Co and atomic number 27 and atomic weight 58.93. 59 Co is the only stable cobalt isotope and the only isotope to exist naturally on Earth. Cobalt is the active center of coenzymes called cobalamin or cyanocobalamin the most common example of which is vitamin B12. Vitamin B12 deficiency can potentially cause severe and irreversible damage, especially to the brain and nervous system in the form of fatigue, depression and poor memory or even mania and psychosis. In order to study the degree of deficiency of the population with Co or the correctness of treatment with vitamin B12, a modern optoelectronic method for the determination of metals and metalloids from biological samples has been developed, Graphite Furnace – Atomic Absorption Spectrometer (GF– AAS) method is recommended. The technique is based on the fact that free atoms will absorb light at wavelengths characteristic of the element of interest. Free atoms of the chemical element can be produced from samples by the application of high temperatures. The system GF-AAS Varian used as biological samples, blood or urine that followed the digest of the organic matrix. For the investigations was used a high – performance GF-AAS with D2 – background correction system and a transversely heated graphite atomizer. As result of the use of the method are presented the concentration of Co in the blood or urine of a group of patient in Bucharest. The method is sensitive, reproducible relatively easy to apply, with a moderately costs.

The 600 MeV synchro-cyclotron (SC) was the first accelerator that came into operation at CERN in 1957.It provided beams for CERN’s first particle and nuclear physics experiments and operated for 33 yearsuntil it was shut down in 1990. In view of a planned partial decommissioning of the facility, a range ofmeasurements were carried out to evaluate the levels of residual radioactivity in the accelerator and itssurrounding after about 20 years of cooling time. Gamma spectrometry measurements were performedon 113 samples collected inside the three floors of the accelerator vault, on the cyclotron itself and onconcrete samples taken from various parts of the building walls, up to a depth of 50 cm in the shield.About 40% of all samples contain traces of neutron-induced radionuclides, mainly 60 Co (in metals), 133 Ba, 137 Cs, 152 Eu and 154 Eu (in concrete). Values of specific activities range from 5 mBq/g to 781 Bq/g.The maximum activity induced in concrete was observed at the depth of 40 cm in the wall near thecyclotron extraction channel. The laboratory measurements were supplemented by in-situ gammaspectrometry performed with the ISOCS system. A complete dose rate survey was also performedyielding isodose maps of the three levels of the building. The isotope production and the residualradioactivity in the barite walls of the SC bunker were simulated with the FLUKA and JEREMY codes inuse at CERN for predicting residual radioactivity in activated accelerator components, and the resultscompared with the gamma spectrometry data. A detailed comparison of calculated and measuredspecific activities shows generally good agreement, to within a factor 2 in most cases. These resultsserve as indirect validation of the capabilities of these codes to correctly predict residual radioactivitywith only a very approximate knowledge of the irradiation profile and after a very long (20 years)cooling time. Overall the results provided in this paper may be of use for estimating residualradioactivity in proton accelerators of comparable energy and for benchmarking computer codes.& 2012 Elsevier B.V. All rights reserved.

Samples of soil and epigeic lichens were collected from the "Taiga" peaceful nuclear explosion site (61.30°N 56.60°E, the Perm region, Russia) in 2009 and analyzed using high resolution γ-ray spectrometry. For soil samples obtained at six different plots, two products of fission ((137)Cs and (155)Eu), five products of neutron activation ((60)Co, (94)Nb, (152)Eu, (154)Eu, (207)Bi) and (241)Am have been identified and quantified. The maximal activity concentrations of (60)Co, (137)Cs, and (241)Am for the soils samples were measured as 1650, 7100, and 6800 Bq kg(-1) (d.w.), respectively. The deposit of (137)Cs for the top 20 cm of soil on the tested plots at the "Taiga" site ranged from 30 to 1020 kBq m(-2); the maximal value greatly (by almost 3 orders of magnitude) exceeded the regional background (from global fallout) level of 1.4 kBq m(-2). (137)Cs contributes approximately 57% of the total ground inventory of the man-made γ-ray emitters for the six plots tested at the "Taiga" site. The other major radionuclides -(241)Am and (60)Co, constitute around 40%. Such radionuclides as (60)Co, (137)Cs, (241)Am, and (207)Bi have also been determined for the epigeic lichens (genera Cladonia) that colonized certain areas at the ground lip produced by the "Taiga" explosion. Maximal activity concentrations (up to 80 Bq kg(-1) for (60)Co, 580 Bq kg(-1) for (137)Cs, 200 Bq kg(-1) for (241)Am, and 5 Bq kg(-1) for (207)Bi; all are given in terms of d.w.) have been detected for the lower dead section of the organisms. The air kerma rates associated with the anthropogenic sources of gamma radiation have been calculated using the data obtained from the laboratory analysis. For the six plots tested, the kerma rates ranged from 50 to 1200 nGy h(-1); on average, 51% of the dose can be attributed to (137)Cs and 45% to (60)Co. These estimates agree reasonably well with the results of the in situ measurements made during our field survey of the "Taiga" site in August 2009.

Gamma-ray irradiation is a very useful tool to improve the physicochemical properties of various biodegradable polymers without the use of a heating and crosslinking agent. The purpose of this study was to investigate the degradation behavior of poly ( l -lactide-co-glycolide) (PLGA) depending on the applied gamma-ray irradiation doses. PLGA films prepared through a solvent casting method were irradiated with gamma radiation at various irradiation doses. The irradiation was performed using 60Co gamma-ray doses of 25–500 kGy at a dose rate of 10 kGy/h. The degradation of irradiated films was observed through the main chain scission. Exposure to gamma radiation dropped the average molecular weight ( M n and M w ), and weakened the mechanical strength. Thermograms of irradiated film show various changes of thermal properties in accordance with gamma-ray irradiation doses. Gamma-ray irradiation changes the morphology of the surface, and improves the wettability. In conclusion, gamma-ray irradiation will be a useful tool to control the rate of hydrolytic degradation of these PLGA films.

The experimental results from the various reaction and radioactive decay studies leading to nuclides in the A = 68 mass chain have been reviewed. Nuclides ranging from Cr (Z = 24) to Br (Z = 35) are included. For these nuclei, level and decay schemes, as well as tables of nuclear properties, are given. This work supersedes the previous evaluation of the data on these nuclides (2002Bu29).

The total mass attenuation coefficients for natural beryl, corundum, garnet, pearl, and tourmaline gemstones were measured at 81, 356.5, 661.6, 1173.2, and 1332.5 keV photon energies. The samples were irradiated with 133Ba, 137Cs and 60Co radioactive point sources using gamma ray transmission method. Total atomic and electronic cross-sections, effective atomic numbers and electron densities were determined experimentally and theoretically. The experimental values were compared with the calculated values for all samples. The calculations were extended for total photon interactions in a wide energy range (1 keV–100 GeV) using WinXCom program of the most commonly irradiated gemstones with different sources of ionized radiation. The values of these parameters have been found to vary with photon energy and chemical composition of the gemstones. All variations of these parameters against energy are shown graphically for total photon interactions.

Radioactivation of Zircaloy-4 (Zry-4) and Zirlo cladding hulls after 55 GWD/tU burn-up and 10 years of cooling was simulated using the ORIGEN-S code. The simulation results revealed that 125Sb and 60Co are major contributors of both radioactivity and decay heat in the case of the Zry-4 hulls. For the Zirlo hulls, 93mNb and 125Sb consisted 82.2% of radioactivity while 125Sb and 60Co emitted 77.9% of decay heat. Although the radioactivity between the Zry-4 (1.17 Ci for 1 kg of fresh Zry-4) and Zirlo (1.38 Ci for 1 kg of fresh Zirlo) hulls was not significantly different, decay heat of the activated Zry-4 hulls (8.58 mW) was much larger than 1.62 mW of the activated Zirlo hulls. This gap might have come from the different major constituents of Zry-4 (Zr, Sn, Fe, and Cr) and Zirlo (Zr, Sn, Nb, and Fe) resulting in different radioactive nuclides after radioactivation. Chlorination reaction behavior of the activated Zry-4 and Zirlo hulls was performed using the HSC chemistry code. Constituents of recovered ZrCl4 were investigated via changes of Gibbs free energy and boiling points of resulting chlorides. The calculation results suggested that radioactivity and decay heat might decrease by 49.0 and 81.8%, respectively, in the ZrCl4 recovered from the activated Zry-4 hulls. In the case of Zirlo, it was expected that radioactivity and decay heat might decrease by 11.6 and 13.0%, respectively, after the chlorination reaction. Effect of cooling time on radioactivity and decay heat was also investigated.

In the framework of a systematic study on light ion (p, d) induced reaction on different targets of medical, industrial, etc. importance, natural cobalt has been investigated by using stacked-foil technique. In these measurements C-55,C-56,C-57,C-58,C-60 isotopes have been identified. Beyond the Cobalt isotopes we have also presented Ni-57 and Mn-52 from the proton experiment. For the above isotope the excitation functions in the measured energy range were determined and compared with the literature data and with the results of model calculations. The agreement with previous measurements was good and we have also measured new cross-section data.

Production cross-sections of the residual radionuclides for the natNi(p,x)55,56,57,58 m + gCo, 56,57Ni nuclear reactions were measured up to 40 MeV by using a stacked-foil activation technique at the MC-50 cyclotron of the Korea Institute of Radiological and Medical Sciences. The results were compared with the reported experimental data as well as the theoretical calculations based on the TALYS and the ALICE-IPPE codes. The present results are in general good agreement with the other experimental data and calculated results. The integral yields for thick target were also deduced from the measured excitation functions of the produced radionuclides. The present experimental results will play an important role in enrichment of the literature data base for proton-induced reactions on natural nickel leading to various applications.

The radioactivation of linear accelerator components for radiation therapy is interest for radiation protection in general, and particularly, when decommissioning these structures. The energy spectra of gamma rays emitted from the heads of two accelerator models, EXL-15SP and Clinac iX, after 10-MeV X-ray irradiation, were measured using a high-purity germanium semiconductor survey meter. After spectrum analyses, activities of (24)Na, (28)Al, (54)Mn, (56)Mn, (57)Ni, (58)Co, (60)Co, (64)Cu, (65)Zn, (122)Sb, (124)Sb, (181)W, (187)W, (196)Au, and (198)Au were detected. One centimetre deep dose-equivalent rate of the heads of the linear accelerator was measured using the survey meter. The dose rate decreased to ∼10 % of its initial rate after 1 week. Long-term activations were few, the radioactivity level was low, and a cooling time of several days was effective for reducing dose rate to an acceptable level for decommissioning.

The experimental nuclear structure and decay data are evaluated for all the known nuclides of mass 50 (Cl, Ar, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni). Detailed evaluated nuclear structure information are presented in individual decay and reaction datasets and the best values are recommended in the Adopted dataset for level properties, γ and β radiations, and other spectroscopic information. No excited states are known in 50Cl and 50Ni, and limited information is available for 50Ar, 50K, 50Fe and 50Co. This work supersedes earlier evaluations of A=50 by 2011El01, 1995Bu09, 1990Bu18, 1984Al29, and 1976Au07.

The cross sections for the production of the radioactive isotopes 74As, 68Ge, 65Zn, and 60Co in metallic germanium irradiated with 100-MeV protons were measured, the experiments being performed both with germanium of natural isotopic composition and germanium enriched in the isotope 76Ge. The targets were irradiated with a proton beam at the facility for the production of radionuclides at the accelerator of the Institute for Nuclear Research (INR, Moscow). The data obtained will further be used to calculate the background of radioactive isotopes formed by nuclear cascades of cosmic-ray muons in new-generation experiments devoted to searches for the neutrinoless double-beta decay of 76Ge at underground laboratories.

The zinc injection technique has been applied to many PWRs (Pressurized Water Reactors) around the world as one of the most effective countermeasures against a radiation source reduction. More than 10 years have passed since the first application of the zinc injection technique mainly in Europe and the US, and its dose reduction effect has been confirmed in each nuclear power plant. The Japan Atomic Power Company has applied the zinc injection technique to Tsuruga nuclear power plant unit 2 (PWR, 1,160 MWe, Commercial operation started in 1987) since 2005. Zinc concentration in primary coolant had been controlled around 5ppb by not more than 10 ppb. Dose equivalent rates on primary equipment and pipes were reduced about 20-30% after zinc injection. Although the dose reduction effect of 20-30% is included the various factors, it was estimated that the effect of about 10% is due to the zinc injection technique. There were no negative effects caused by the zinc injection for the plant operation, water chemistry and fuel integrity in the case of Tsuruga unit 2.

α -Decay half-lives and α -capture cross sections are evaluated in the framework of a unified model for α -decay and α -capture. In this model α -decay and α -capture are considered as penetration of the α -particle through the potential barrier formed by the nuclear, Coulomb, and centrifugal interactions between the α -particle and nucleus. The spins and parities of the parent and daughter nuclei as well as the quadrupole and hexadecapole deformations of the daughter nuclei are taken into account for evaluation of the α -decay half-lives. The α -decay half-lives for 344 nuclei and the α -capture cross sections of 40Ca, 44Ca, 59Co, 208Pb, and 209Bi agree well with the experimental data. The evaluated α -decay half-lives within the range of 10 - 9 ⩽ T 1 / 2 ⩽ 10 38 s for 1246 α -emitters are tabulated.

Characteristics of clear PMMA dosimeter (Radix W) were studied for electron irradiation and compared with the response for gamma irradiation. The dose–response curves were nearly linear up to 30 kGy and become sublinear at higher doses. The radiation-induced absorbance was reduced with 6% within 4 h after irradiation. Dose comparisons were performed for 2, 3, 4 and 5 MeV electron irradiation using cellulose triacetate dosimeter (CTA) (FTR-125) and Radix W dosimeters which were independently calibrated for 2 MeV electrons and 60 Co gamma-rays using calorimeter and ionizing chamber, respectively. The doses estimated by CTA and Radix W were different by about 20%. The magnitude of this difference was, however, independent of electron energy.

International audience; In order to investigate the biological effects of galactic rays on astronaut cerebral functions after space flight, mice were exposed to different heavy ions (HZE) in whole-body conditions at doses comparable to the galactic flux: 12C, 16O and 20Ne (95 MeV/u, at 42– 76 mGy). Animals were also exposed to 42 mGy of 60Co radiation for comparison with HZE. The neuroimmune response, evaluated by interleukin-1 (IL-1) measurement, showed that this cytokine was produced 3 h after irradiation by 16O or 60Co. In contrast, neither 12C (56.7 mGy) nor 20Ne (76 mGy) induced IL-1 production. However, immunohistochemical staining of 12C-irradiated mouse brain tissue showed 2 months later a marked inflammatory reaction in the hippocampus and a diffuse response in parenchyma. Sleep studies were realized before and after exposure to 42 mGy of 16O and 76 mGy of 20Ne: only the 20Ne radiation displayed a small effect. A slight decrease in paradoxical sleep, corresponding to a reduction in the number of episodes of paradoxical sleep, was manifested between 8 and 22 days after exposure. Exposure to 12C and 16O induced no changes either in cellularity of spleen or thymus, or in caspase 3 activity (as much as four months after irradiation). Taken together, these data indicate that the CNS could be sensitive to heavy ions and that responses to HZE impact depend on the nature of the particle, the dose threshold and the time delay to develop biological processes. Differences in responses to different HZE highlight the complex biological phenomena to which astronauts are submitted during space flight.

Mutagenesis and retrotransposons have a close relationship, but little attention has been paid yet to the activity of retrotransposons produced by physical mutagens. The variation of retrotransposon WIS 2–1A activity in wheat (Triticum aestivum L.) embryos at three different growth times (30 h, 45 h and 60 h) was investigated after they had been treated with N+ implantation in a vacuum of 5 × 10−2 Pa and irradiation by 60Coγ-ray respectively. For each of the three growth times the expression of WIS 2–1A showed almost entirely a same trend of downregulation, upregulation, then downregulation, and upregulation again with the increase in dose of N+ implantation, but the expression appeared irregular with the increase in irradiation of 60Coγ-ray. In conclusion, the acutely activating effect of WIS 2–1A stimulated by vacuum and high dose N+ implantation within a shorter incubation time may provide a convenient tool to advance the research on mutagenic breeding and function genes.

The effects of varying the concentrations of cross-linker N, N ′ -methyelene-bis-acrylamide (BIS) from 2% to 4%, and 2-hydroxyethylacrylate (HEA) monomer from 2% to 4% at 5% gelatin on the dose response of BIS–HEA–gelatin (BHEAG) aqueous polymer gel dosimeters have been studied using magnetic resonance imaging (MRI) for relaxation rate ( R 2 ) of water proton. The dosimeters were irradiated with 60Co teletherapy γ -ray source at a constant dose rate, receiving doses up to 30 Gy. The radiation polymerization occurs and increases with increasing initial dose. R 2 is found to decrease mono-exponentially with depth inside the polymer gel and depend strongly upon the initial concentrations of co-monomers (HEA and BIS). Dose–depth map for BHEAG gel was determined for different concentrations of co-monomer (HEA and BIS). The percentage dose depth was also evaluated which leads to a good agreement with the ionization chamber measurements.

The radioisotope concentrations in stainless steel for the cryostat of the GERDA experiment at the Laboratori Nazionali del Gran Sasso (LNGS) have been measured. A total of 13 different stainless steel batches have been screened by low-level γ -ray spectrometry with germanium detectors located at two underground laboratories. The article reports the discovery of commonly available stainless steel with very low concentrations of primordial and cosmogenic radionuclides. The concentrations are in the range of 1 mBq/kg and below. Only the manmade 60Co-isotope is present in all samples with a higher concentration of around 19 mBq/kg. Further, deviations from secular equilibrium in the natural decay chains of U and Th have been observed in some cases.

The high energy electrons produced by linear accelerators can generate several radioisotopes by means of photonuclear reactions. The activity produced in the head of a 15 MV Mevatron Siemens 77 medical linear accelerator was measured by high resolution gamma-ray spectrometry, during its decommissioning 1 year after the last clinical use. The activity of 54Mn, 57Co, 60Co, 181W, and 65Zn was measured while the activity of other radioisotopes which emit soft beta or gamma rays such as 59Ni, 63Ni, and 55Fe was inferred by appropriate scaling factors. The number of pieces requiring particular care is limited, their mass does not exceed some tens of kilograms, and their volume is of the order of some thousands of cm3. Moreover, these materials are metals and the emitted radiation can be easily shielded, so that storage should not create particular problems.

This study was carried out to evaluate the effect of gamma irradiation on the physical and structural properties of β- glucan. β- Glucan solution (10%, w/v) was exposed to a cobalt-60 source (10, 30, and 50 kGy). Gel permeation chromatography data showed that the average molecular weight of irradiated β- glucan significantly decreased as the irradiation dose increased. In addition, gamma irradiation improved the solubility and decreased the viscosity of β- glucan by the radiolysis of the glycosidic bonds, and this effect was dependent upon the absorbed dose. Fourier transform infrared spectroscopy results showed that the functional groups of β- glucan were not significantly affected by gamma irradiation. Scanning electron microscopy results showed that the irradiated β- glucan was deformed into smaller granules. Therefore, gamma irradiation could be used in commercial processes as an effective method to resolve the physical problems involved in the use of β- glucan with high viscosity and low solubility.

Dosimetry of the monoenergetic raster-scanned beam of 12C carbon ions at GSI Darmstadt was performed using the LiF:Mg,Cu,P (MCP-N) 2-D thermoluminescence (TL) system. Several of TL foils of sizes 55 × 55 mm 2 and one 200 × 200 mm 2 were exposed to carbon ion beams of energies ranging between 88 and 430 MeV/amu at doses ranging between 5 and 25 Gy. The measured TL efficiency of the TL foil detectors, relative to 60Co γ -rays, varies between 0.30 at 88 MeV/amu and 0.47 at 430 MeV/amu and is well described by the microdosimetric One Hit Detector Model. In the investigated dose range the 2-D TLD system shows a linear dose response. Despite their appreciable energy response the 2-D TL foils based on LiF:Mg,Cu,P can be a useful tool for quality assurance of raster-scanned carbon ion beams.

The LiF:Mg,Cu,P phosphor is the most investigated phosphor in radiation dosimetry. Results on thermoluminescence of the epoxy based LiF:Mg,Cu,P dosimeters irradiated with gamma radiations are presented and compared with results of LiF:Mg,Cu,P powder. The glow curve structure of both LiF powder and dosimeter are same and only difference is found in the glow curve peak temperature. The LiF dosimeters were made from the 5012A and 5012B epoxy. The dosimeters had a mass of about 18 mg, 5.0 mm diameter and 0.5 mm thickness. The sensitivity variation of the dosimeters for exposure to 60Co gamma rays at different angles of incidence of the radiation is found to be within 4%. Its minimum detectable dose is about 3020 µGy. The epoxy based dosimeters withstand different environment and it can be used with general TL reader without need of any special design due to its small size and plane surface.

Changes in the rate of the beta decay of radioactive elements whose periods are about 24 h and 27 d are detected on the basis of long-term investigations performed with the aid of scintillation and germanium-lithium gamma detectors. The use of the scintillation procedure yields results whose level of significance is much higher than 5%, while the procedure based on germanium—lithium detectors gives a more than 1% deviation from the average value of fluxes of gamma rays accompanying, for example, 60Co beta decay. With allowance for the rotation of the laboratory frame together with the Earth, deviations of the change in the rate of beta decay of radioactive elements single out three directions in the physical space.

Thermoluminescence (TL) of LiF:Mg,Cu,P (TLD-700H) phosphor irradiated with 24 MeV 7 Li ions at different fluences in the range 5 × 10 9 – 1 × 10 12 ions / cm 2 (with corresponding doses in the range 620 Gy to 123.96 kGy) has been studied. The samples from the same batch were also exposed to γ -rays from a Co 60 source for comparative studies. It has been found that at low fluences ( 5 × 10 9 – 1 × 10 10 ions / cm 2 ) the TL glow curves of the samples irradiated with 7 Li ions have similar structures to that of γ -irradiated sample, while at higher fluences ( 5 × 10 10 – 1 × 10 12 ions / cm 2 ) the relative intensities and fluence responses of the TL glow peaks were observed to vary with fluences increasing. The TL intensity of the dosimetric peak at 481 K saturates at the fluence 5 × 10 11 ions / cm 2 , while that of the peak at 524 K increases till the maximum fluence 1 × 10 12 ions / cm 2 . All the TL glow peaks show nearly sublinear behavior except the peak at 524 K, which exhibits supralinear. This has been attributed to the formation of more defects (trapping centers (TC)/luminescence centers (LC)) due to 7 Li ions implantation, during ion beam irradiation. The implantation has been confirmed from TRIM calculations. Moreover, on ion beam irradiation, a shift in the peak positions toward lower temperature side by around 10 K was observed, comparing with those induced by Co 60 γ -rays. The TL efficiency of LiF:Mg,Cu,P to 24 MeV 7 Li ion beam has been measured relative to γ -rays of Co 60 . Further, theoretical analysis of the glow curves of the ion beam and γ -irradiated samples was done by glow curve deconvolution (GCD) method to determine trapping parameters of various peaks. As LiF:Mg,Cu,P is highly sensitive and tissue equivalent TLD material and its peak at 524 K does not saturate even at high fluences, this peak may be used for the dosimetry of ion beams in medical and other applications.

The objective of this study was verification of actual doses absorbed by teeth enamel in patients undergoing radiotherapy treatment. The retrospective dosimetry was based on ex vivo measurements of electron paramagnetic resonance (EPR) signals in teeth extracted from six patients during dental treatment within a few years after radiotherapy with 60 Co photons and high-energy photon and electron beams. The measured doses were compared to those calculated by radiotherapy treatment planning (RTP) algorithm (CadPlan 3.1). The total accuracy of dose reconstructions based on EPR measurements was 5–9%. The discrepancy between the planned and measured doses ranged from a few percent (for teeth positioned within the irradiated field) up to about 120% (for teeth located outside the primary beam). Such significant differences between results of RTP calculations and EPR measurement can be explained by changes in geometry of tissues within patient's oral cavity during the treatment, which cannot be accounted for by RTP based on radiotherapy simulation procedure preceding the treatment.

The results of experimental measurement and numerical simulation of 979 rates of threshold reactions in 142 samples of 209Bi, 197Au, 181Ta, 169Tm, 115In, 93Nb, 65Cu, 64Zn, 63Cu, 59Co, 27Al, 19F, and 12C placed inside and outside of a “thick” W-Na target irradiated with 0.8-GeV protons are reported. The reaction rates are measured by the method of γ spectrometry using Ge and GeLi semiconductor detectors. The numerical calculations were performed using the LAHET code package together with the EXFOR database and the evaluated data libraries MENDL2N, MENDL2P, and IEAF2001. The experimental and calculated results are compared and the most significant discrepancies are analyzed.

This paper presents an experimental analysis of the effect of dose and dose rate parameters during gamma irradiation of high-density polyethylene (HDPE) samples. Considerations concerning the influence of these parameters on HDPE mechanical strength properties as a result of the predominance of oxidative degradation or of cross-linking are presented. The experimental results show an improvement of HDPE mechanical strength as dose increases, indicating the predominance of cross-linking over oxidative degradation and that lower doses are necessary to obtain a similar change in resistance parameters when radiation is applied at lower dose rates, showing that gamma radiation affects the HDPE in a more efficient way at lower dose rates.

The copper(II) complex of ethylglyoxal bis(thiosemicarbazone) (Cu-ETS) was evaluated as a positron emission tomography (PET) radiopharmaceutical for assessment of regional renal perfusion. Methods: The concordance of renal flow estimates obtained with 11- and 15-Am microspheres was confirmed in four immature farm pigs using co-injected 46 Sc- and 57 Co-microspheres administered into the left ventricle. With the use of both immature farm pigs (n=3) and mature Gfttingen minipigs (n=6), regional renal radiocopper uptake following intravenous [ 64 Cu]Cu-ETS administration was compared to microsphere measurements of renal perfusion. The distribution and kinetics of [ 64 Cu]Cu-ETS were further studied by PET imaging of the kidneys. The rate of [ 64 Cu]Cu-ETS decomposition by blood was evaluated in vitro, employing octanol extraction to recover intact [ 64 Cu]Cu-ETS. Results: The co-injected 11- and 15-Am microspheres provided similar estimates of renal flow. A linear relationship was observed between the renal uptake of intravenous [ 64 Cu]Cu-ETS and regional renal perfusion measured using microspheres. [ 64 Cu]Cu-ETS provided highquality PET kidney images demonstrating the expected count gradient from high-flow outer cortex to low-flow medulla. When incubated with pig blood in vitro at 378C, the [ 64 Cu]Cu-ETS radiopharmaceutical was observed to decompose with a half-time of 2.8 min. Conclusion: Cu-ETS appears suitable for use as a PET radiopharmaceutical for evaluation of regional renal perfusion, affording renal uptake of radiocopper that varies linearly with microsphere perfusion measurements. Quantification of renal perfusion (in ml min � 1 g � 1 ) with [ 60,61,62,64 Cu]Cu-ETS will require correcting the arterial input function for the fraction of blood radiocopper remaining present as the intact Cu-ETS radiopharmaceutical, since the Cu-ETS chelate has limited chemical stability in blood. Rapid octanol extraction of blood samples appears suitable as an approach to capturing the actual blood concentration of [ 60/61/62/64 Cu]Cu-ETS.

This work presents experimental results regarding a new ammonium tartrate blend for ESR dosimetry, with a higher sensitivity and a lower lowest detectable dose (LDD) to Co 60 γ -rays than the recently used pure ammonium tartrate. The blend composed by ammonium tartrate and gadolinium-oxide ( Gd 2 O 3 ) shows a greater sensitivity ( ∼ 2 times) and a smaller LDD than ammonium tartrate. The increased sensitivity was mainly attributed to the great atomic number ( Z = 64 ) of gadolinium, that increases the effective atomic number of the blend; the interaction probability with photons and consequently the radical yield is therefore enhanced. Moreover ammonium tartrate with Gd 2 O 3 has a linear dose response in the investigated dose range (1–50 Gy). We find this blend suitable for use in ESR dosimetry.

NASA Langley Research Center requested a measurement and determination of the ambient gamma dose equivalent rate and kerma at 100 cm from the 252Cf source and determination of the ambient gamma dose equivalent rate and kerma at 200 cm from the 60Co source for the Radiation Budget Instrument Experiment (Rad-X). An Exradin A6 ion chamber with Shonka air-equivalent plastic walls in combination with a Supermax electrometer were used to measure the exposure rate and free-in-air kerma rate of the two sources at the requested distances. The measured gamma exposure, kerma, and dose equivalent rates are tabulated.

Effects of homogeneous radiation were compared to effects of inhomogeneous radiation in uremic patients irradiated in attempts to increase the receptivity of renal homografts. Homogeneous radiation was given by means of an 1800-C /sup 60/Co source, and inhomogeneous radiation from a 250-kv orthovoltage source. The hematologic picture was observed in patients receiving both types of irradiation, and it was concluded that the hematologic response patterns of the platelets, the granulocytes, and the lymphocytes are remarkedly similar in patients exposed to inhomogeneous and homogeneous whole-body irradiation. Further, the similarity was found to prevail despite other variables in physical factors such as differences in quality of radiation, differences in absorbed dose over a range of 240 to 450 rads, and differences in protraction and fractionation over a period of up to one week. (H.M.G.)

BS>The status of radiobiological investigations with fast neutrons is reviewed. The discussion includes the H/sup 3/(p,n)He/sup 3/ reaction as a source of fast neutrons, methods used in the exposure of smail mammals to graduated neutron doses, and the relation of biological effectiveness to the linear energy transfer of radiations. Results are reviewed from studies in mice on the response of thymus weight, spleen weight, spermatogenesis, and nucleic acid synthesis to fast neutrons as a function of energy. Comparisons are made of the relative biological effectiveness of fast neutrons, x, and gamma radiations. The reliability of dose-effect curves is discussed. (33 references.) (C.H.)