Design and Validation of Synchronous QCT Calibration Phantom: Practical Methodology

Introduction: Quantitative computed tomography (QCT) can supplement dual x-ray absorptiometry by enabling geometric and compartmental bone assessments. Whole-body spiral CT scanners are widely available and require a short scanning time of seconds, in contrast to peripheral QCT scanners, which require several minutes of scanning time. This study designed and evaluated the accuracy and precision of a homemade QCT calibration phantom using a whole-body spiral CT scanner. Materials and Methods: The QCT calibration phantom consisted of K 2 HPO 4 solutions as reference. The reference material with various concentrations of 0, 50, 100, 200, 400, 1000, and 1200 mg/cc of K 2 HPO 4 in water were used. For designing the phantom, we used the ABAQUS software. Results: The phantoms were used for performance assessment of QCT method through measurement of accuracy and precision errors, which were generally less than 5.1 for different concentrations. The correlation between CT numbers and concentration were close to one (R 2 = 0.99). Discussion: Because whole-body spiral CT scanners allow central bone densitometry, evaluating the accuracy and precision for the easy to use calibration phantom may improve the QCT bone densitometry test. Conclusion: This study provides practical directions for applying a homemade calibration phantom for bone mineral density quantification in QCT technique. © 201

Effects of variations of flow and heart rate on intra-aneurysmal hemodynamics in a ruptured internal carotid artery aneurysm during exercise

Background: Hemodynamics is thought to play an important role in the mechanisms responsible for initiation, growth, and rupture of intracranial aneurysms. Computational fluid dynamic (CFD) analysis is used to assess intra-aneurysmal hemodynamics. Objectives: This study aimed to investigate the effects of variations in heart rate and internal carotid artery (ICA) flow rate on intra-aneurysmal hemodynamics, in an ICA aneurysm, by using computational fluid dynamics. Patients and Methods: Computed tomography angiography (CTA) was performed in a 55 years old female case, with a saccular ICA aneurysm, to create a patient-specific geometrical anatomic model of the aneurysm. The intra-aneurysmal hemodynamic environments for three states with different flow and heart rates were analyzed using patient-specific image-based CFD modeling. Results: Results showed significant changes for the three simulated states. For a proportion of the states examined, results were counterintuitive. Systolic and time-averaged wall shear stress and pressure on the aneurysm wall showed a proportional evolution with the mainstream flow rate. Conclusion: Results reinforced the pivotal role of vascular geometry, with respect to hemodynamics, together with the importance of performing patient-specific CFD analyses, through which the effect of different blood flow conditions on the aneurysm hemodynamics could be evaluated

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Search for black holes and other new phenomena in high-multiplicity final states in proton-proton collisions at root s=13 TeV

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Measurements of differential production cross sections for a Z boson in association with jets in pp collisions at root s=8 TeV

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Search for high-mass diphoton resonances in proton-proton collisions at 13 TeV and combination with 8 TeV search

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Search for heavy resonances decaying into a vector boson and a Higgs boson in final states with charged leptons, neutrinos, and b quarks

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