The aim of this study was to validate the computed tomography dose index (CTDI) and organ doses evaluated by Monte Carlo simulations through comparisons with doses evaluated by in-phantom dosimetry. ...Organ doses were measured with radio-photoluminescence glass dosemeter (RGD) set at various organ positions within adult and 1-y-old anthropomorphic phantoms. For the dose simulations, the X-ray spectrum and bow-tie filter shape of a CT scanner were estimated and 3D voxelised data of the CTDI and anthropomorphic phantoms from the acquired CT images were derived. Organ dose simulations and measurements were performed with chest and abdomen-pelvis CT examination scan parameters. Relative differences between the simulated and measured doses were within 5 % for the volume CTDI and 13 % for organ doses for organs within the scan range in adult and paediatric CT examinations. The simulation results were considered to be in good agreement with the measured doses.
Secondary to the previous development of age-specific Japanese head phantoms, the authors designed Japanese torso phantoms for dose assessment in infant computed tomography (CT) examinations and ...completed a Japanese 3-y-old head-torso phantom. For design of age-specific torso phantoms (0, 0.5, 1 and 3 y old), anatomical structures were measured from CT images of Japanese infant patients. From the CT morphometry, it was found that rib cages of Japanese infants were smaller than those in Europeans and Americans. Radiophotoluminescence glass dosemeters were used for dose measurement of a 3-y-old head-torso phantom. To examine the validity of the developed phantom, organ and effective doses by the in-phantom dosimetry system were compared with simulation values in a web-based CT dose calculation system (WAZA-ARI). The differences in doses between the two systems were <20 % at the doses of organs within scan regions and effective doses in head, chest and abdominopelvic CT examinations.
Abstract
The aim of this study is to estimate tube current modulation (TCM) profiles in paediatric computed tomography (CT) examinations with a TCM scheme (Volume-EC) and evaluate the estimation ...accuracy of TCM profiles. Another aim is to validate organ doses calculated using Monte Carlo-based CT dosimetry software and estimated TCM profiles by comparing them with those measured using 5-year-old and 10-year-old anthropomorphic phantoms and radio-photoluminescence glass dosemeters. Dose calculations were performed by inputting detailed descriptions of a CT scanner, scan parameters and CT images of the phantoms into the software. Organ doses were evaluated from the calculated dose distribution images. Average relative differences (RDs) between the estimated and actual TCM profiles ranged from −3.6 to 5.6%. RDs between the calculated and measured organ doses ranged from −4.2 to 13.0% and −18.1 to 4.9% for 5-year-old and 10-year-old phantoms, respectively. These results validate dose calculations for paediatric CT scans using TCM.
Status of balloon production for KamLAND-Zen 800kg phase Obara, S.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2017, Letnik:
845
Journal Article
Recenzirano
KamLAND-Zen is an experiment for neutrinoless double beta decay (0ν2β) search with 136Xe, based on the large liquid scintillator detector KamLAND. KamLAND-Zen includes 16.5m3 xenon loaded liquid ...scintillator in a 3.16m diameter nylon balloon (inner-balloon) with 25μm wall thickness.
KamLAND-Zen 400 (383kg 136Xe used) released a lower limit on the 0ν2β half-life of 136Xe. However, the sensitivity is limited by the contamination of radioactive backgrounds from the inner-balloon. Then, we planned KamLAND-Zen 800, upgrading the detector with a new inner-balloon of 3.84m diameter with 800kg 136Xe and 31.4m3 liquid scintillator.
We present the current status of KamLAND-Zen, the new mini-balloon construction and methods to avoid background contaminations. In addition, the development of a scintillating balloon for future upgrades in order to remove the radioactive decay chain daughter nuclei bismuth is also introduced.
Abstract
A high-pressure xenon gas time projection chamber, with a unique cellular readout structure based on electroluminescence, has been developed for a large-scale neutrinoless double-beta decay ...search. In order to evaluate the detector performance and validate its design, a 180 L size prototype is being constructed and its commissioning with partial detector has been performed. The obtained energy resolution at 4.0 bar is 1.73 $\pm$ 0.07% (FWHM) at 511 keV. The energy resolution at the $^{136}$Xe neutrinoless double-beta decay $Q$-value is estimated to be between 0.79 and 1.52% (FWHM) by extrapolation. Reconstructed event topologies show patterns peculiar to the track endpoint that can be used to distinguish $0\nu\beta\beta$ signals from gamma-ray backgrounds.
For noble gas Time Projection Chambers (TPCs) in the field of rare event searches, operation of high voltage to generate an electric field is a key point. We designed a new structure of electrodes to ...shape a strong and uniform drift field without electric discharge, in which electrodes of two different radius are used. We also developed Cockcroft-Walton voltage multiplier as a high voltage generator inside a pressure vessel. We achieved −30.0 kV output and examined such kind of voltage generator is feasible as a high voltage supplier in a TPC.
Advanced glycation end products (AGEs) participate in the pathogenesis of diabetic nephropathy. We reported earlier that OPB-9195, a synthetic thiazolidine derivative and novel inhibitor of advanced ...glycation, prevented progression of diabetic glomerulosclerosis by lowering serum concentrations of advanced glycation end products and reducing their deposition in the glomeruli. Here, we examined their contribution and that of growth factors, such as transforming growth factor-beta (TGF-beta) and vascular endothelial growth factor (VEGF), to the progression of diabetic nephropathy. We also investigated the expression of type IV collagen in the kidneys of Otsuka-Long-Evans-Tokushima-Fatty (OLETF) rats, a Type II (non-insulin-dependent) diabetes mellitus model, after treatment with OPB-9195.
Using northern blots and immunohistochemical techniques, we determined the renal expression of TGF-beta and type IV collagen mRNAs and proteins in OLETF rats. We also examined OPB-9195's effects on renal expression of VEGF mRNA and protein.
Concomitant increases in TGF-beta and type IV collagen expression were observed at each point in time in OLETF rats not given OPB-9195. In contrast, OPB-9195 treatment greatly suppressed the renal expression of TGF-beta, VEGF and type IV collagen mRNAs and proteins to that seen in non-diabetic rats.
Since OPB-9195, an AGE-inhibitor, prevented the progression of diabetic nephropathy by blocking type IV collagen production and suppressing overproduction of two growth factors, TGF-beta and VEGF, in diabetic rats, this compound warrants further investigation.
Research on the challenges of raising a child with autism is mostly reported from Europe, North America and Australia. There is limited autism spectrum disorder (ASD) research in Kenya and families ...lack support as the etiology is linked to witchcraft and sorcery. Research indicates an increase in ASD prevalence globally and in Africa. Malnutrition and neuro-disability are major public health problems in Africa. Approximately one billion people, 15% of the world’s population, have a disability of some kind and 80% live in Low- and Middle-Income countries (LMICs). Of these, 53 million are children aged below 5 years living in sub-Saharan Africa. In Kenya, 2.2% (0.9 million people) live with some form of disability. Children diagnosed with autism spectrum disorder (ASD) suffer from neuro disabilities eliciting: altered sensory processing, restricted interests, and behavioral rigidity. Autism spectrum disorders have no cure, management is by use of interventional targeting autistic symptoms such as linguistic development, non-verbal cognitive development, and motor development. The objectives of this review were: to identify dietary and nutritional interventions available for the management of ASD symptoms in children and adolescents - Kenya, and to analyze the results of existing research in this area in order to understand and describe the characteristics and results of these studies to enable their use in the management of ASD symptoms. Cochrane Library, PubMed, PMC, Google scholar, and Free Full databases were searched to identify studies published between September 2011 and September 2021. Included were studies on nutrition or dietary interventions given to ASD children and adolescents that assessed autistic behavior and/or gastrointestinal symptoms. Excluded were those articles that evaluated surrogate outcomes as the primary outcome such as urinary peptide excretion and other neuro-disabilities other than ASD. Eighteen articles were included: 12 randomized case-control trials, 3 open-label trials, one 2×2 factorial study, and 2 cross-over trials. The following dietary and nutritional interventions were evaluated: gluten and casein-free diet, ketogenic diets; probiotic supplements, specific carbohydrate diets, polyunsaturated fatty acids, vitamin and mineral supplantation (A, B6, B12, D, magnesium, folic acid), and alternative diets. Authors report improvements in the symptoms associated with ASD individuals receiving nutritional interventions such as vitamin and mineral supplementation however, their safety and efficacy needs to be evaluated. The study findings will help policymakers and implementers to understand the consistency and precision and impact of these interventions. These findings will contribute to improving the safety and efficacy of these interventions, positively impacting the health and nutrition outcomes of children and adolescents with ASD. These study findings indicate that more research targeting ASD dietary and Nutritional Interventions for management of ASD symptoms is required in Kenya and other resource constrained settings. Key words: autism spectrum disorder, nutritional intervention, diet therapy, child, adolescent, Kenya
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