Background
Uterine fibroids (UFs) are the most common neoplasm affecting women that can cause significant morbidity and may adversely impact fertility.
Objectives
To examine UF epidemiology and to ...evaluate the relative strengths of putative risk factors.
Search strategy
MEDLINE and Embase were searched for studies published in English between January 1995 and April 2015.
Selection criteria
Publications reporting relevant data from registries and other observational studies with over 1000 patients and single‐centre studies with over 100 patients were selected.
Data collection and analysis
Data on UF incidence, prevalence and associated risk factors were extracted from 60 publications.
Main results
Wide ranges were reported in both UF incidence (217–3745 cases per 100 000 women‐years) and prevalence (4.5–68.6%), depending on study populations and diagnostic methods. Black race was the only factor that was recurrently reported to increase UF risk, by two–threefold compared with white race. Eleven other factors affected UF risk to a magnitude similar to or greater than race. Age, premenopausal state, hypertension, family history, time since last birth, and food additive and soybean milk consumption increased UF risk; use of oral contraceptives or the injectable contraceptive depot medroxyprogesterone acetate, smoking in women with low body mass index and parity reduced UF risk.
Conclusions
We identified 12 risk factors that play an important role in UF epidemiology. The UF risk factor with the strongest evidence is black race. High‐quality prospective observational data are needed to improve our understanding of UF epidemiology, and thus its aetiology and optimal management.
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Uterine fibroids occur in about 70% of women. Black race and 11 other factors affect uterine fibroid risk.
Tweetable
Uterine fibroids occur in about 70% of women. Black race and 11 other factors affect uterine fibroid risk.
Spatial resolution is one of the most important parameters objectively defining image quality, particularly in dental imaging, where fine details often have to be depicted. Here, we review the ...current status on assessment parameters for spatial resolution and on published data regarding spatial resolution in CBCT images. The current concepts of visual line-pair (lp) measurements and automated modulation transfer function (MTF) assessment of spatial resolution in CBCT images are summarized and reviewed. Published measurement data on spatial resolution in CBCT are evaluated and analysed. Effective (i.e. actual) spatial resolution available in CBCT images is being influenced by the two-dimensional detector, the three-dimensional reconstruction process, patient movement during the scan and various other parameters. In the literature, the values range between 0.6 and 2.8 lp mm(-1) (visual assessment; median, 1.7 lp mm(-1)) vs MTF (range, 0.5-2.3 cycles per mm; median, 2.1 lp mm(-1)). Spatial resolution of CBCT images is approximately one order of magnitude lower than that of intraoral radiographs. Considering movement, scatter effects and other influences in real-world scans of living patients, a realistic spatial resolution of just above 1 lp mm(-1) could be expected.
Cone-beam computed tomography (CBCT) was first used in dental and maxillofacial radiology (DMFR) at the end of the 1990s. Since then, it has been successfully established as the standard ...three-dimensional radiographic imaging technique in DMFR, with a wide variety of applications in this field. This manuscript briefly reviews the background information on the technology and summarises available data on effective dose and dose optimisation. In addition, typical clinical applications and indications of the technique in DMFR are presented.
Acceleration of particles by intense laser–plasma interactions represents a rapidly evolving field of interest, as highlighted by the recent demonstration of laser-driven relativistic beams of ...monoenergetic electrons. Ultrahigh-intensity lasers can produce accelerating fields of 10 TV m-1 (1 TV = 1012 V), surpassing those in conventional accelerators by six orders of magnitude. Laser-driven ions with energies of several MeV per nucleon have also been produced. Such ion beams exhibit unprecedented characteristics—short pulse lengths, high currents and low transverse emittance—but their exponential energy spectra have almost 100% energy spread. This large energy spread, which is a consequence of the experimental conditions used to date, remains the biggest impediment to the wider use of this technology. Here we report the production of quasi-monoenergetic laser-driven C5+ ions with a vastly reduced energy spread of 17%. The ions have a mean energy of 3 MeV per nucleon (full-width at half-maximum ∼0.5 MeV per nucleon) and a longitudinal emittance of less than 2 × 10-6 eV s for pulse durations shorter than 1 ps. Such laser-driven, high-current, quasi-monoenergetic ion sources may enable significant advances in the development of compact MeV ion accelerators, new diagnostics, medical physics, inertial confinement fusion and fast ignition.
To investigate potential correlations between objective CBCT image parameters and accuracy in endodontic working length determination ex vivo. Contrast-to-noise ratio (CNR) and spatial resolution ...(SR) as fundamental objective image parameters were examined using specific phantoms in seven different CBCT machines. Seven experienced observers were instructed and calibrated. The order of the CBCTs was randomized for each observer and observation. To assess intra-operator reproducibility, the procedure was repeated within six weeks with a randomized order of CBCT images. Multivariate analysis (MANOVA) did not reveal any influence of the combined image quality factors CNR and SR on measurement accuracy. Inter-operator reproducibility as assessed between the two observations was poor, with a mean intra-class correlation (ICC) of 0.48 (95%-CI 0.38, 0.59) for observation No. 1. and 0.40 (95%-CI 0.30, 0.51) for observation No. 2. Intra-operator reproducibility pooled over all observers between both observations was only moderate, with a mean ICC of 0.58 (95%-CI 0.52 to 0.64). Within the limitations of the study, objective image quality measures and exposure parameters seem not to have a significant influence on accuracy in determining endodontic root canal lengths in CBCT scans. The main factor of variance is the observer.
Electrospray deposition (ESD) of highly diluted polymers was examined with regard to the deposited surface structure. Only the flight distance (flight time) onto the resulting deposited surface was ...varied from 20 to 200mm.
An apparatus without any additional heating or gas flows was used. Polyacrylic acid (PAA) and polyallylamine (PAAm) in methanol were deposited on Si wafers. The polymer layers were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, derivatization reactions and Fourier transform infrared spectroscopy using a grazing incidence unit.
SEM images illustrated the changing structures of PAA and PAAm. For PAA the deposited structure changed from a smooth film (20mm) to a film with individual droplets on the coated surface (100mm and 200mm), while for PAAm individual droplets can be seen at all distances. The ESD process with cascades of splitting droplets slows down for PAA after distances greater than 40mm. In contrast, the ESD process for PAAm is nearly stopped within the first flight distance of 20mm. Residual solvent analysis showed that most of the solvent evaporated within the first 20mm capillary-sample distance.
•We deposited polyacrylic acid and polyallylamine by electrospray ionization (ESI).•The morphology in dependence of flight distance (20mm to 200mm) was analyzed.•The amount of residual solvent after deposition was determined.•ESI-process slows down for polyacrylic acid after 40mm flight distance.•ESI-Process is complete for polyallylamine within the first 20mm.
Cone beam CT (CBCT) is a relatively new imaging modality, which is now widely available to dentists for examining hard tissues in the dental and maxillofacial regions. CBCT gives a three-dimensional ...depiction of anatomy and pathology, which is similar to medical CT and uses doses generally higher than those used in conventional dental imaging. The European Academy of DentoMaxilloFacial Radiology recognizes that dentists receive training in two-dimensional dental imaging as undergraduates, but most of them have received little or no training in the application and interpretation of cross-sectional three-dimensional imaging. This document identifies the roles of dentists involved in the use of CBCT, examines the training requirements for the justification, acquisition and interpretation of CBCT imaging and makes recommendations for further training of dentists in Europe who intend to be involved in any aspect of CBCT imaging. Two levels of training are recognized. Level 1 is intended to train dentists who prescribe CBCT imaging, such that they may request appropriately and understand the resultant reported images. Level 2 is intended to train to a more advanced level and covers the understanding and skills needed to justify, carry out and interpret a CBCT examination. These recommendations are not intended to create specialists in CBCT imaging but to offer guidance on the training of all dentists to enable the safe use of CBCT in the dentoalveolar region.
Artefacts in CBCT: a review Schulze, R; Heil, U; Gross, D ...
Dento-maxillo-facial radiology
40, Številka:
5
Journal Article
Recenzirano
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Artefacts are common in today's cone beam CT (CBCT). They are induced by discrepancies between the mathematical modelling and the actual physical imaging process. Since artefacts may interfere with ...the diagnostic process performed on CBCT data sets, every user should be aware of their presence. This article aims to discuss the most prominent artefacts identified in the scientific literature and review the existing knowledge on these artefacts. We also briefly review the basic three-dimensional (3D) reconstruction concept applied by today's CBCT scanners, as all artefacts are more or less directly related to it.
The thermal conductivity of uranium dioxide has been studied for over half a century, as uranium dioxide is the fuel used in a majority of operating nuclear reactors and thermal conductivity controls ...the conversion of heat produced by fission events to electricity. Because uranium dioxide is a cubic compound and thermal conductivity is a second-rank tensor, it has always been assumed to be isotropic. We report thermal conductivity measurements on oriented uranium dioxide single crystals that show anisotropy from 4 K to above 300 K. Our results indicate that phonon-spin scattering is important for understanding the general thermal conductivity behaviour, and also explains the anisotropy by coupling to the applied temperature gradient and breaking cubic symmetry.
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