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[en] Pressurized Heavy Water Reactor (PHWR), CANadian Deuterium-Uranium (CANDU), Operating Experience (OPEX) provides evidence that performing post-refurbishment Primary Heat Transport System (PHTS) Hot Conditioning (HC) with fuel in core presents a risk that the fuel bundles may become coated with iron-based, primarily magnetite and hematite, deposits during the evolution. This OPEX also provide evidence that these deposits remain on the fuel sheath for a period of approximately three to six months into the subsequent operation of the plant before the deposit material is redistributed into the PHTS coolant and removed from the system through the PHTS purification system. Such deposits, while present on the sheath, are thought to contribute to fuel sheath corrosion and impact fuel element heat transfer properties. OPG commissioned a series of laboratory testing to investigate the factors that contribute to the phenomena of fuel sheath deposit formation. These tests included comparative studies of HC evolutions, which emulated recent CANDU post-refurbishment OPEX in a laboratory setting. These investigations provided clarity on the parameters relevant to this adverse condition and on controls that can be implemented to minimize deposition on fuel bundle sheath surfaces. Sensitive parameters and associated controls include; (1) use of a “conventional” HC process as compared to a chelating-agent type HC, that use forms of Ethylenediaminetetraacetic Acid (e.g. Li2EDTA), (2) HC prior to reactor first approach-to-critical (i.e. no fuel heat), (3) maintenance of PHTS pH per current industry expert recommendations, and (4) careful control of other dissolved materials in the PHTS during PHT cold flush. OPEX observations suggest that the surface condition of fuel sheathing may also be a contributing factor related to the probability of deposition. This indicates that fuel sheaths that have been “polished” following tube production may be less susceptible to deposition of magnetite on sheath surfaces during HC. While OPG has considered this observation to be interesting, it was not further investigated, and thus requires validation. (author)
[en] The quality of welded joints depends on the most optimal welding parameters and the selection of shielding gas type. The shielding gas was selected for joining stainless steels through gas metal arc welding methods by considering properties such as chemical-metallurgical interaction of shielding gas and the molten weld metal during the welding process, heat transmission capability of the gas and cost. In this study, the effect of different shielding gas combinations on the mechanical and microstructural properties of 316 austenitic stainless steel joined by the metal inert gas (MIG) welding method was investigated. In the welding process, pure argon (100 % Ar), 98.5 % Ar + 1.5 % H and 95 % Ar + 5 % H were used as shielding gases. Tensile, hardness, and bending tests were conducted to determine mechanical properties of the welded samples. In addition, metallographic examinations were carried out to detect the macrostructural and microstructural properties of weld zones. According to the results obtained from the study, the highest tensile strength was obtained from the joints welded using 100 % Ar shielding gas. When the addition of H into the Ar gas increased, the tensile strength of the welded samples decreased. As a result of the tensile test, fractures occurred in the base metal in all welded samples. In all welding parameters, the hardness of the weld metal was lower as compared to the heat affected zone (HAZ) and the base metal. As a result of the bending test, crack and tearing defects were found in the weld zone.
[en] Dynamic PET (dPET) studies have been used until now primarily within research purposes. Although it is generally accepted that the information provided by dPET is superior to that of conventional static PET acquisitions acquired usually 60 min post injection of the radiotracer, the duration of dynamic protocols, the limited axial field of view (FOV) of current generation clinical PET systems covering a relatively small axial extent of the human body for a dynamic measurement, and the complexity of data evaluation have hampered its implementation into clinical routine. However, the development of new-generation PET/CT scanners with an extended FOV as well as of more sophisticated evaluation software packages that offer better segmentation algorithms, automatic retrieval of the arterial input function, and automatic calculation of parametric imaging, in combination with dedicated shorter dynamic protocols, will facilitate the wider use of dPET. This is expected to aid in oncological diagnostics and therapy assessment. The aim of this review is to present some general considerations about dPET analysis in oncology by means of kinetic modeling, based on compartmental and noncompartmental approaches, and parametric imaging. Moreover, the current clinical applications and future perspectives of the modality are outlined.
[en] In about 30% of patients treated with neoadjuvant chemoradiotherapy (nCRT) followed by surgical resection for locally advanced oesophageal cancer no vital tumour is found in the resection specimen. Accurate clinical response assessment is critical if deferral from surgery is considered in complete responders. Our study aimed to compare the performance of MRI and of FDG-PET/CT for the detection of residual disease after nCRT. Patients with oesophageal cancer eligible for nCRT and oesophagectomy were prospectively included. All patients underwent FDG-PET/CT and MRI before and between 6 and 8 weeks after nCRT. Two radiologists scored the MRI scans, and two nuclear medicine physicians scored the FDG-PET/CT scans using a 5-point score for residual disease. Histopathology after oesophagectomy represented the reference standard. Sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) were calculated for detection of residual tumour (ypT+), residual nodal disease (ypN+), and any residual disease (ypT+Nx/ypT0N+). Seven out of 33 (21%) patients had a pathological complete response. The AUCs for individual readers to detect ypT+ were 0.71/0.70 on diffusion-weighted (DW)-MRI and 0.54/0.57 on FDG-PET/CT, and to detect ypN+ were 0.89/0.81 on DW-MRI and 0.75/0.71 on FDG-PET/CT. The AUCs/sensitivities/specificities for the individual readers to detect any residual disease were 0.74/92%/57% and 0.70/96%/43% on MRI; these were 0.49/69%/29% and 0.60/69%/43% on FDG-PET/CT, respectively. MRI reached higher diagnostic accuracies than FDG-PET/CT for the detection of residual tumour in oesophageal cancer patients at 6 to 8 weeks after nCRT.
[en] Cancer has a multitude of phenotypic expressions and identifying these are important for correct diagnosis and treatment selection. Clinical molecular imaging such as positron emission tomography can access several of these hallmarks of cancer non-invasively. Recently, hyperpolarized magnetic resonance spectroscopy with [1-C] pyruvate has shown great potential to probe metabolic pathways. Here, we investigate simultaneous dual modality clinical molecular imaging of angiogenesis and deregulated energy metabolism in canine cancer patients. Canine cancer patients (n = 11) underwent simultaneous [Ga]Ga-NODAGA-E[(cRGDyK)] (RGD) PET and hyperpolarized [1-C]pyruvate-MRSI (hyperPET). Standardized uptake values and [1-C]lactate to total C ratio were quantified and compared generally and voxel-wise. Ten out of 11 patients showed clear tumor uptake of [Ga]Ga-NODAGA-RGD at both 20 and 60 min after injection, with an average SUV of 1.36 ± 0.23 g/mL and 1.13 ± 0.21 g/mL, respectively. A similar pattern was seen for SUV values, which were 2.74 ± 0.41 g/mL and 2.37 ± 0.45 g/mL. The [1-C]lactate generation followed patterns previously reported. We found no obvious pattern or consistent correlation between the two modalities. Voxel-wise tumor values of RGD uptake and lactate generation analysis revealed a tendency for each canine cancer patient to cluster in separated groups. We demonstrated combined imaging of [Ga]Ga-NODAGA-RGD-PET for angiogenesis and hyperpolarized [1-C]pyruvate-MRSI for probing energy metabolism. The results suggest that [Ga]Ga-NODAGA-RGD-PET and [1-C]pyruvate-MRSI may provide complementary information, indicating that hyperPET imaging of angiogenesis and energy metabolism is able to aid in cancer phenotyping, leading to improved therapy planning.
[en] The detection of lymph-node metastases (N1) with conventional imaging such as magnetic resonance imaging (MRI) and computed tomography (CT) is inadequate for primarily diagnosed prostate cancer (PCa). Prostate-specific membrane antigen (PSMA) PET/CT is successfully introduced for the staging of (biochemically) recurrent PCa. Besides the frequently used gallium-labelled PSMA tracers, fluorine-labelled PSMA tracers are available. This study examined the diagnostic accuracy of F-DCFPyL (PSMA) PET/CT for lymph-node staging in primary PCa. This was a prospective, multicentre cohort study. Patients with primary PCa underwent F-DCFPyL PET/CT prior to robot-assisted radical prostatectomy (RARP) with extended pelvic lymph-node dissection (ePLND). Patients were included between October 2017 and January 2020. A Memorial Sloan Kettering Cancer Centre (MSKCC) nomogram risk probability of ≥ 8% of lymph-node metastases was set to perform ePLND. All images were reviewed by two experienced nuclear physicians, and were compared with post-operative histopathologic results. A total of 117 patients was analysed. Lymph-node metastases (N1) were histologically diagnosed in 17/117 patients (14.5%). The sensitivity, specificity, positive predictive value and negative predictive value for the F-DCFPyL PET/CT detection of pelvic lymph-node metastases on a patient level were 41.2% (confidence interval (CI): 19.4–66.5%), 94.0% (CI 86.9–97.5%), 53.8% (CI 26.1–79.6%) and 90.4% (CI 82.6–95.0%), respectively. F-DCFPyL PET/CT showed a high specificity (94.4%), yet a limited sensitivity (41.2%) for the detection of pelvic lymph-node metastases in primary PCa. This implies that current PSMA PET/CT imaging cannot replace diagnostic ePLND. Further research is necessary to define the exact place of PSMA PET/CT imaging in the primary staging of PCa.
[en] During recent field surveys, a new Ceylon iron wood (Manilkara hexandra) population was discovered in the Upper Ganga Ramsar Site, Uttar Pradesh (UP), India. The largest specimen located at Van Khan-deshwar partially collapsed in 2012, which led to a canopy impairment. The rupture enabled direct extraction of samples close to the pith of the main stem. The radiocarbon date of the oldest sample was 361 ± 23 BP, which corresponds to a calibrated age of 525 ± 25 cal yr. The results indicate the Ceylon iron wood of Narora, UP is the oldest dated extant M. hex-andra with a calculated age of 550 ± 50 yr. Several protection measures are presented and urgent action is required to prevent the total collapse of this ancient tree. (author)
[en] After a decade of PET/MR, the case of attenuation correction (AC) remains open. The initial four-compartment (air, water, fat, soft tissue) Dixon-based AC scheme has since been expanded with several features, the latest being MR field-of-view extension and a bone atlas. As this potentially changes quantification, we evaluated the impact of these features in PET AC in prostate cancer patients. Two hundred prostate cancer patients were examined with either F- or Ga-prostate-specific membrane antigen (PSMA) PET/MR. Qualitative and quantitative analysis (SUV, SUV, correlation, and statistical significance) was performed on images reconstructed using different AC schemes: Dixon, Dixon+MLAA, Dixon+HUGE, and Dixon+HUGE+bones for F-PSMA data; Dixon and Dixon+bones for Ga-PSMA data. Uptakes were compared using linear regression against standard Dixon. High correlation and no visually perceivable differences between all evaluated methods (r > 0.996) were found. The mean relative difference in lesion uptake of F-PSMA and Ga-PSMA remained, respectively, within 4% and 3% in soft tissue, and within 10% and 9% in bones for all evaluated methods. Bone registration errors were detected, causing mean uptake change of 5% in affected lesions. Based on these results and the encountered bone atlas registration inaccuracy, we deduce that including bones and extending the MR field-of-view did not introduce clinically significant differences in PSMA diagnostic accuracy and tracer uptake quantification in prostate cancer pelvic lesions, facilitating the analysis of serial studies respectively. However, in the absence of ground truth data, we advise against atlas-based methods when comparing serial scans for bone lesions.
[en] Automatic translation: When raising sheep for production lamb should follow the same requirements as well as before feeding cattle. It should be borne in mind that y lamb passes much more radionuclides, than in cattle, so before slaughtering animals is necessary feed for one to two months on clean feed. Wool can become surface contaminated radionuclides, but it is easily washed away ordinary detergents. Currently, sheep breeding is possible: c 4 and the zone without restrictions; in the 3rd zone on pastures with content of Cs 137 in the grass 600 Bq / kg. Pollution sheep wool is 8 9 times higher than meat.
[uk]При вирощуванні овець для виробництва баранини слід дотримуватися таких же самих вимог як і до годівлі худоби. Слід мати на увазі, що у баранину переходить набагато більше радіонуклідів, ніж у ВРХ, тому перед забоєм тварин необхідно годувати на протязі одного двох місяців на чистих кормах. Вовна може поверхнево забруднюватись радіонуклідами, але вона легко відмивається звичайними миючими засобами. В теперішній час ведення вівчарства можливе: в 4 й зоні без обмежень; в 3 й зоні на пасовищах з вмістом Cs 137 в траві 600 Бк/кг. Забруднення вовни овець у 8 9 разів вище, ніж м’яса.
[en] Nowadays plant origin compounds with anti-cancer properties come into prominence, among them is curcumin (CUR) with a remarkable anti-cancer activity against various cancers. CUR was nanoformulated (CUR-PLGA) by the polymer based poly(lactic-co-glycolic acid) (PLGA) and both CUR and CUR-PLGA were radiolabeled with iodine-131 radionuclide for investigation of their in vitro behaviour on Human cervix adenocarcinoma (HeLa) and Ovarian endometrioid adenocarcinoma (MDAH-2774) cell lines. The newly described radiolabeled CUR and CUR-PLGA may be initiative discovery of novel potential imaging and therapeutic agents. (author)