4,536 research outputs found

    Characterization of photomultiplier tubes in a novel operation mode for Secondary Emission Ionization Calorimetry

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    Hamamatsu single anode R7761 and multi-anode R5900-00-M16 Photomultiplier Tubes have been characterized for use in a Secondary Emission (SE) Ionization Calorimetry study. SE Ionization Calorimetry is a novel technique to measure electromagnetic shower particles in extreme radiation environments. The different operation modes used in these tests were developed by modifying the conventional PMT bias circuit. These modifications were simple changes to the arrangement of the voltage dividers of the baseboard circuits. The PMTs with modified bases, referred to as operating in SE mode, are used as an SE detector module in an SE calorimeter prototype, and placed between absorber materials (Fe, Cu, Pb, W, etc.). Here, the technical design of different operation modes, as well as the characterization measurements of both SE modes and the conventional PMT mode are reported

    Mass distributions for nuclear disintegration from fission to evaporation

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    By a proper choice of the excitation energy per nucleon we analyze the mass distributions of the nuclear fragmentation at various excitation energies. Starting from low energies (between 0.1 and 1 MeV/nucleon) up to higher energies about 12 MeV/n, we classified the mass yield characteristics for heavy nuclei (A>200) on the basis of Statistical Multifragmentation Model. The evaluation of fragment distribution with the excitation energy show that the present results exhibit the same trend as the experimental ones.Comment: 5 pages, 3 figure

    A rare cause of congenital portosystemic shunt: type 2 Abernethy malformation

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    The Abernethy malformation is characterised by congenital extrahepatic portosystemic shunts and is divided into two groups according to the type of anastomosis. In type 1, all portal venous blood is discharged into the inferior vena cava and there is no intrahepatic portal vein. In type 2, the portal vein is partially discharged to the inferior vena cava via side-by-side anastomoses. Imaging has an important role in the diagnosis and follow-up of this malformation. Magnetic resonance imaging should be preferred to demonstrate both vessel anatomy and associated anomalies. The aim of this study was to present a 17-year-old male patient and to discuss the imaging findings of Abernethy malformation

    Determination of anomalous pulmonary venous return with high-pitch low-dose computed tomography in paediatric patients

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    Background: In this study, we aimed to image pulmonary venous return anomalies and associated cardiovascular and pulmonary abnormalities by high-pitch low-dose computed tomography (CT) in children. Materials and methods: Forty-one patients with total or partial anomalous pulmonary venous return anomalous between May 2012 and June 2019 were retrospectively reviewed. The anomalies were determined using high-pitch low-dose CT. The patients’ mean age was 3 years (6 months to 15 years), and 24 of them were female. Results: There were 10 patients with total pulmonary venous return anomalies (TPVRA) and 31 patients with partial pulmonary venous return anomalies (PPVRA). Six (60%) patients with TPVRA had the supracardiac type, 2 (20%) had the cardiac type, and 2 (20%) had the mixed type. All patients with TPVRA had a large atrial septal defect (ASD), 1 patient also had patent ductus arteriosus, and 1 patient had right cardiac hypertrophy. Forty cases of PPVRA were found in 31 patients. Twenty-seven (67%) of them were right-sided, and 13 were left-sided (33%). Twenty (65%) patients also had an additional cardiovascular anomaly (ASD in 12 patients, persistent superior vena cava in 4 patients, patent ductus arteriosus in 3 patients, and aortic coarctation in 2 patients). Of the 27 patients with right-sided PPVRA, it drained into the superior vena cava in 19 patients, the right atrium in 5 patients, and the inferior vena cava in 3 patients. In left-sided cases, the anomalous pulmonary vein drained into the left innominate vein in 9 patients, and in 4 patients, there were accessory pulmonary veins that drained into the left innominate vein. Many of the patients had additional lung anomalies, including pneumonic infiltration (n = 12), atelectasis (n = 8), and lobar emphysema (n = 5), and some of these findings coexisted. Conclusions: Anomalous pulmonary venous drains and associated cardiac and extra-cardiac anomalies can be detected reliably and quickly with high-pitch low-dose CT without sedation in paediatric patients

    Common coeliacomesenteric trunk: a computed tomography radiological study

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    Background: There is an increasing trend for administration of invasive radiological interventions, laparoscopic surgery, and transplantation procedures in recent years, and determining the vascular variations prior to these procedures is crucially important. Coeliacomesenteric trunk (CMT) is among these variations. This study aimed to retrospectively evaluate this rare anomaly by computed tomography (CT). Materials and methods: A total of 1000 CT angiography images were analysed retrospectively, and the patients with mesenteric and coeliac arteries arising from the abdominal aorta with a single root were identified. The level that CMT arose, and its branching patterns were determined individually for all patients. Results: Ten patients (6 males and 4 females) with a mean age of 50.2 years (17–87 years) had CMT in CT images. Conclusions: The knowledge of variations in the CMT prior to vascular or laparoscopic interventions will contribute to early intervention in case of a complication, or to avoid from a potential damage

    The utility of multidetector computed tomography for evaluation of congenital heart disease

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    Background: Congenital heart diseases (CHD) are the leading cause of birthdefect-related deaths. Multidedector computed tomography (MDCT) plays animportant role for imaging CHD in addition to echocardiography and providesa comprehensive evaluation of complex heart malformations for the referringcardiologist. The aim of the study was to evaluate the utility of MDCT in theassessment of CHD.Materials and methods: A 102 patients with CHD were investigated after initialassessment by echocardiography. The information obtained by MDCT and findingsof echocardiography were reviewed together by paediatric cardiologistsand cardiac radiologists. Perioperative anatomic descriptions, wherever available(n = 34) formed the gold standard for the comparison.Results: The clinical consensus diagnosis defined 154 cardiovascular lesions inthe patients. The results were classified in groups. We present the appearanceof various congenital cardiac lesions seen in clinical practice.Conclusions: MDCT provides important information about anatomic details ofCHD for the referring cardiologist. The evaluation of different anatomic structuressuch as heart, great vessels, lungs and abdomen is possible in one acquisitionwith this technique

    Non-invasive detection of biliary leaks using Gd-EOB-DTPA-enhanced MR cholangiography: Comparison with T2-weighted MR cholangiography

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    Objective: To evaluate the added role of T1-weighted (T1w) gadolinium ethoxybenzyl diethylenetriamine penta-acetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance cholangiography (MRC) compared with T2-weighted MRC (T2w-MRC) in the detection of biliary leaks. Methods: Ninety-nine patients with suspected biliary complications underwent routine T2w-MRC and T1w contrast-enhanced (CE) MRC using Gd-EOB-DTPA to identify biliary leaks. Two observers reviewed the image sets separately and together. MRC findings were compared with those of surgery and percutaneous transhepatic cholangiopancreatography. The sensitivity, specificity and accuracy of the techniques in identifying biliary leaks were calculated. Results: Accuracy of locating biliary leaks was superior with the combination of Gd-EOB-DTPA-enhanced MRC and T2w-MRC (P < 0.05).The mean sensitivities were 79 % vs 59 %, and the mean accuracy rates were 84 % vs 58 % for combined CE-MRC and T2w-MRC vs sole T2w-MRC. Nineteen out of 21 patients with biliary-cyst communication, 90.4 %, and 12/15 patients with post-traumatic biliary extravasations, 80 %, were detected by the combination of Gd-EOB-DTPA-enhanced MRC and T2w-MRC images, P < 0.05. Conclusions: Gd-EOB-DTPA-enhanced MRC yields information that complements T2w-MRC findings and improves the identification and localisation of the bile extravasations (84 % accuracy, 100 % specificity, P < 0.05). We recommend Gd-EOB-DTPA-enhanced MRC in addition to T2w-MRC to increase the preoperative accuracy of identifying and locating extravasations of bile. Key Points: • Magnetic resonance cholangiography (MRC) does not always detect bile leakage and cysto-biliary communications. • Gd-EOB-DTPA-enhanced MRC helps by demonstrating extravasation of contrast material into fluid collections. • Gd-EOB-DTPA-enhanced MRC also demonstrates the leakage site and bile duct injury type. • Combined Gd-EOB-DTPA-enhanced and T2w-MRC can provide comprehensive information about biliary system. • Gd-EOB-DTPA-enhanced MRC is non-invasive and does not use ionising radiation. © 2013 The Author(s)
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