Search results for "volumetric"
showing 10 items of 175 documents
Evaluation of enamel pearls by cone-beam computed tomography (CBCT)
2011
Objective: The aim of this study was to evaluate the frequency of enamel pearls according to population, sex and tooth groups on Cone-Beam Computed Tomography (CBCT) or Dental Volumetric Tomography (DVT) scans of patients, retrospectively. Study Design: In this study, 15185 teeth belonging to 768 patients, 430 female and 338 male, was performed cross-sectional examination by CBCT. The volumetric Computed Tomography used in the study is Newton FP based on flat-panel. The data were analyzed with Pearson chi-squared test. Results: Enamel pearls were detected in 36 subjects (4.69%). Of these enamel pearls, 19 were detected in male and 17 were in male. There was no statistically a significant as…
Assessment of left ventricular function by breath-hold cine MR imaging: Comparison of different steady-state free precession sequences
2005
Purpose To compare steady-state free precession (SSFP) sequence protocols with different acquisition times (TA) and temporal resolutions (tRes) due to the implementation of a view sharing technique called shared phases for the assessment of left ventricular (LV) function by breath-hold cine magnetic resonance (MR) imaging. Materials and Methods End-diastolic and end-systolic volumes (EDV, ESV) were measured in contiguous short-axis slices with a thickness of 8 mm acquired in 10 healthy male volunteers. The following true fast imaging with steady-state precession (TrueFISP) sequence protocols were compared: protocol A) internal standard of reference, segmented: tRes 34.5 msec, TA 18 beats pe…
Hippocampal dose during Linac-based stereotactic radiotherapy for brain metastases: An observational study
2017
Abstract Introduction Aim of the present study is to evaluate homolateral and contralateral hippocampus (H-H, C-H, respectively) dose during Fractionated Stereotactic Radiotherapy (FSRT) or Radiosurgery (SRS) for brain metastases (BM). Materials & methods Patients with BM 3 months, were considered for SRS/FSRT (total dose 15–30 Gy, 1–5 fractions). For each BM, a Flattening Filter Free (FFF) Volumetric Modulated Arc Therapy (VMAT) plan was generated with one or two arcs. Hippocampi were not considered during optimizations phase and were contoured and evaluated retrospectively in terms of dose: the Dmedian, Dmean, D0.1cc and the V1Gy, V2Gy, V5Gy and V10Gy were analyzed. Results From April 2…
Studio di segmentazione morfovolumetrica in pazienti con declino cognitivo lieve amnestico (aMCI) e demenza di Alzheimer (AD) rispetto ad un gruppo d…
2016
SCOPO: Presentare i risultati preliminari di un’analisi di segmentazione morfovolumetrica (VBM) eseguita in pazienti con aMCI ed AD rispetto ad una popolazione di controllo (NAB). Tali dati saranno in futuro correlati ad altri parametri clinico-psicologici raccolti (età, sesso, scolarità, MMSE, ADL, IADL). MATERIALI E METODI: Sono stati sottoposti ad esame RM encefalo 103 soggetti, utilizzando uno scanner RM GE Signa HDxt da 1,5T ed acquisendo, tra le altre, una sequenza Sag 3D T1 FSPGR IR preped ASSET che è stata utilizzata per l’analisi VBM eseguita con il tool sienax (FSL). I risultati sono stati valutati in termini di valori medi e deviazioni standard mediante applicazione del t-test…
Determination of the Herbicide Fluometuron by Photo‐induced Chemiluminescence in a Continuous‐flow Multicommutation Assembly
2007
Abstract This study was dealing with the chemiluminometric determination of the selective herbicide Fluometuron or 1,1‐dimethyl‐3‐(α,α,α‐trifluoro‐m‐tolyl)urea, (C10H11F3N2O) with a molecular weight 232.29 belongs to the phenyl urea herbicides family. The analytical strategy is based on the continuous‐flow manifold, multicommutation and the analyte pre‐treatment, the photo‐degradation. The optimization of chemical (pH, medium, temperature, and organized media) and hydrodynamic parameters (volume of reagents and flow rate) was performed by univariant and multiparametric simplex procedure respectively. Analytical figures of merit and the effect of foreign substances were studied. The method r…
Determination of the herbicide benfuresate by its photo-induced chemiluminescence using flow multicommutation methodology.
2007
The present paper deals with an analytical strategy based on coupling photo-induced chemiluminescence in a multicommutation continuous-flow methodology for the determination of the herbicide benfuresate. The solenoid valve inserted as small segments of the analyte solution was sequentially alternated with segments of the NaOH solution for adjusting the medium for the photodegradation. Both flow rates (sample and medium) were adjusted to required time for photodegradation, 90 s; and then, the resulting solution was also sequentially inserted as segments alternated with segments of the oxidizing solution system, hexacyanoferrate (III) in alkaline medium. The calibration range from 1 microg L(…
The Smith-Robinson Approach to the Subaxial Cervical Spine: A Stepwise Microsurgical Technique Using Volumetric Models From Anatomic Dissections.
2020
BACKGROUND: The Smith-Robinson1 approach (SRA) is the most widely used route to access the anterior cervical spine. Although several authors have described this approach, there is a lack of the stepwise anatomic description of this operative technique. With the advent of new technologies in neuroanatomy education, such as volumetric models (VMs), the understanding of the spatial relation of the different neurovascular structures can be simplified. OBJECTIVE: To describe the anatomy of the SRA through the creation of VMs of anatomic dissections. METHODS: A total of 4 postmortem heads and a cervical replica were used to perform and record the SRA approach to the C4-C5 level. The most relevant…
Reactor model for fast reactions in the micro-bubble column and validation
2007
A simple reactor model for predicting conversions in a micro-bubble column is described. It assumes fast reactions so that the gaseous component is readily consumed at the gas-liquid interface. Then, gas-liquid mass transfer becomes determining. As input parameters for the model, the hydrodynamics, specific interfacial area, and mass transport need to be described. Two fast model reactions, the catalytic oxidation of butyraldehyde and the absorption of CO2 in aqueous NaOH, show the applicability of the model but also its limits. The model was used for predicting reaction performance in dependence of operating conditions, in particular to get maximum conversion with the antagonistic paramete…
A calcined clay fixed bed adsorption studies for the removal of heavy metals from aqueous solutions
2021
Abstract A natural clay material from southern Tunisia was used as a low cost sorbent in a column-wise removal of metal pollutants. This is fundamentally important for a sustainable wastewater treatment strategy. This work has been performed within the framework of a project aiming to the valorization of natural geomaterials, from Tunisia, in several environmental applications. Column adsorption experiments were carried out for a better production of cleaner effluents and further understanding of the main mechanisms involved in the removal process, through a dynamic methodology, that would allow an industrial scale treatment. A calcined clay sample was used as an adsorbent for the removal o…
Documenting carved stones from 3D models. Part II - Ambient occlusion to reveal carved parts.
2021
10 pages; International audience; Revealing carved parts in rock art is of primary importance and remains a major challenge for archaeological documentation. Computational geometry applied to 3D imaging provides a unique opportunity to document rock art. This study evaluates five algorithms and derivatives used to compute ambient occlusion and sky visibility on 3D models of Mongolian stelae, also known as deer stones. By contrast with the previous companion work, models are processed directly in 3D, without preliminary projection. Volumetric obscurance gives the best results for the identification of carved figures. The effects of model resolution and parameters specific to ambient occlusio…