Résumé
Objectif
Le but de cette étude randomisée multicentrique était d’évaluer le pourcentage de fistules anastomotiques symptomatiques chez les patients opérés d’une résection antérieure du bas ...rectum, randomisés avec ou sans stomie de protection.
Introduction
L’introduction de l’exérèse totale du mésorectum pour les cancers du moyen et bas rectum, comme la technique chirurgicale de référence, a permis de diminuer le taux de récidive locale et d’améliorer les résultats oncologiques.
Malgré cette avancée, la morbidité péri-opératoire reste un souci majeur, et la complication la plus redoutée est la fistule anastomotique symptomatique. L’intérêt de la stomie de protection afin de prévenir la fistule anastomotique reste controversé et n’a été démontré dans aucune étude randomisée d’effectif suffisant.
Méthodes
De décembre 1999 à juin 2005, 234 patients ont été randomisés « avec stomie » ou « sans stomie de protection ». Le choix entre l’iléostomie ou la colostomie transverse dépendait du chirurgien. Les critères d’inclusion pour la randomisation étaient une survie attendue > 6 mois, un consentement éclairé, une anastomose < ou = à 7 cm audessus de la marge anale, un test à l’air négatif, une rangée d’agrafes intacte au niveau de l’anastomose, et l’absence d’évènement indésirable en peropératoire.
Résultats
Le taux global de fistule anastomotique symptomatique était de 19,2% (45 des 234 patients).
Les patients randomisés dans le groupe « avec stomie de protection » (n=116) avaient un taux de fistule de 10,3% (12 sur 116) et ceux randomisés dans le groupe « sans stomie » (n=118) avaient un taux de fistule de 28% (33 sur 118) (odds ratio = 3,4; intervalle de confiance 95% 1,6–1,9; p<0,001). Le taux de réintervention en urgence était de 8,6% (10 sur 116) dans le groupe « avec stomie de protection » et de 25,4% (30 sur 118) pour ceux randomisés « sans stomie » (p<0,001). Après un suivi médian de 42 mois (6–72 mois), 13,8% (16 sur 116) des patients initialement avec une stomie ont gardé une stomie de tous type, en comparaison aux 16,9% (20 sur 118) des patients initialement non protégés (résultats non significatifs). La mortalité à j30 après résection antérieure du rectum était de 0,4% (1 sur 324) et de 0,9% après fermeture de stomie par voie élective (1 sur 111). L’âge médian était de 68 ans (32–86 ans), 45,3% (106 sur 324) étaient des femmes, 79,1% (185 sur 234) avaient reçu une radiothérapie préopératoire, le niveau médian de l’anastomose était de 5 cm, et la médiane de perte sanguine en peropératoire était de 550 mL, sans différence significative entre les groupes.
Conclusion
La stomie de protection diminue le risque de fistule anastomotique symptomatique et est recommandé dans la résection antérieure du rectum avec anastomose colorectale basse et colo-anale.
Background
Gas-Coupled Laser Acoustic Detection (GCLAD) is a non-contact ultrasonic detection technique whose functioning relies on the deviation that a probe laser beam sustains when intersected by ...an acoustic wavefront propagating in a fluid. The maximum sensitivity of the technique is typically obtained when the ultrasound insists on an ample portion of the probe laser beam extension, but such a condition can be unfeasible in several non-destructive testing applications (as in case of limited accessibility to the component).
Objective
In the present work, a solution is provided enabling transformation of the GCLAD device in a point detector. This is based on the use of two mirrors for confining the laser beam in an area with limited width and depth, where reflections however maximize the portion of the probe laser beam subjected to ultrasonic oscillation.
Methods
The characteristics of the obtained GCLAD probe are thoroughly analysed by applying the device to the detection of surface acoustic waves, propagating on a metal bar and refracting into the air. Two different inspection configurations are considered, whose difference lies in the mutual orientation between laser beam and solid surface. The effect on the received signal amplitude of the number of beam reflections, the dimensions of the resulting device, and the bar axisimmetry is investigated in both configurations.
Results
The optimization of all the analysed standpoints enables obtaining a compact GCLAD probe that features the same signal amplitude of the non-compact alternative. To obtain maximum responsivity of the system, the number of reflections must be maximized, while the distance between the mirrors must be carefully set based on the employed inspection configuration and the eventual axisimmetry of the specimen. The devised GCLAD compact probe is capable of expanding the application range of the technique also to those cases in which the use of point detectors is desirable, without compromising the signal-to-noise ratio of the resulting acquisitions compared to the non-compact alternative.
Introduction:
This paper deals with the class of versatile semiconducting materials called perovskites, which have been deposited for the first time on flexible substrates and then tested for ...radiation detection monitoring applications.
Methods:
Lead halide inorganic perovskite, CsPbCl
3
, 0.4–1 μm-thick films have been grown on plastic flexible substrates equipped with interdigitated electrodes (IDEs) by magnetron sputtering at room temperature.
Results:
First measurements in realtime configuration are reported for a 1–µm thick prototype under proton beams with energy in the range 100–228 MeV and 1–10 nA extraction currents, of interest for protontherapy applications.
Discussion:
Experimental results evidence good performances of our sample as a real-time monitoring device. Current stability under UV and proton beam exposure has been tested in the range 0.1–120 s, as well as reproducibility under multiple exposures. The measured current signal proved to be linearly dependent on the extraction currents at a given proton energy. Linearity of the current signal of the device with proton fluxes was also proved within two order of magnitude range, about 10
7
–10
9
p/s. These promising results, when coupled with easyness of fabrication, low processing costs and high versatility of electrode configurations, all features characterizing the manufacturing process, put into evidence lead halide perovskites as promising candidates for real-time radiation detection in protontherapy.
In the midst of a rich environment for medical device development and manufacturing, universities can play a critical role by developing relevant training programs to produce entrepreneurs who can be ...efficient and successful in creating early stage companies by understanding deeply the issues involved in creating a useful device, how to raise money, designing early clinical studies and locating manufacturing partners.
Ultra-fast silicon detectors Sadrozinski, H. F.-W.; Ely, S.; Fadeyev, V. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2013, Letnik:
730
Journal Article
Recenzirano
Odprti dostop
We propose to develop a fast, thin silicon sensor with gain capable to concurrently measure with high precision the space (∼10μm) and time (∼10ps) coordinates of a particle. This will open up new ...application of silicon detector systems in many fields. Our analysis of detector properties indicates that it is possible to improve the timing characteristics of silicon-based tracking sensors, which already have sufficient position resolution, to achieve four-dimensional high-precision measurements. The basic sensor characteristics and the expected performance are listed, the wide field of applications are mentioned and the required R&D topics are discussed.
•We are proposing thin pixel silicon sensors with 10's of picoseconds time resolution.•Fast charge collection is coupled with internal charge multiplication.•The truly 4-D sensors will revolutionize imaging and particle counting in many applications.
NiTi׳s superelasticity is exploited in a number of biomedical devices, in particular self-expanding endovascular stents. These stents are often laser-cut from textured micro-tubing; texture is the ...distribution of crystallographic grain orientations in a polycrystalline material which has been experimentally shown to have a marked influence on mechanical properties. This study offers a computational examination into the effect of texture on the stress-induced martensite transformation (SIMT) in a micro-dogbone NiTi specimen subject to tensile loading. Finite Element Analysis (FEA) is employed to simulate the transformational behaviour of the specimen on a micro-scale level. To represent a realistic grain structure in the FEA model, grains present in a 200µm×290µm test site located at the centre edge of the specimen were identified using Scanning Electron Microscopy (SEM). Grains are assumed to have homogenous behaviour with properties varying according to their crystallographic orientation to the loading direction. Required material properties were extracted from uniaxial stress–strain curves of single crystals for each crystallographic orientation for input into the in-built UMAT/Nitinol. The orientation of each grain in the test site was identified using Electron Back-Scatter Diffraction (EBSD) techniques. In this way, a quantitative explanation is offered to the effect of crystallographic texture on SIMT. Finally, the evolution of grains in the specimen, during the transformation process, was experimentally investigated by means of an in-situ SEM tensile test.
Display omitted
•FEA employed to study effect of texture on SIMT in a superelastic NiTi specimen.•FE model with a realistic representation of microstructure is created.•Evolution of SIM and localised strain are analysed under various strain levels.•Individual effect of various grain orientations are identified.
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