498 research outputs found

    Proton-Ion Medical Machine Study (PIMMS), 1

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    The Proton-Ion Medical Machine Study (PIMMS) group was formed following an agreement between the Med-AUSTRON (Austria) and the TERA Foundation (Italy) to combine their efforts in the design of a cancer therapy synchrotron. CERN agreed to host this study in its PS Division and a close collaboration was set up with GSI (Germany). The study group was later joined by Onkologie-2000 (Czech Republic). Effort was first focused on the theoretical understanding of slow extraction and the techniques required to produce a smooth beam spill for the conformal treatment of complex-shaped tumours with a sub-millimetre accuracy by active scanning with proton and carbon ion beams. Considerations for passive scanning were also included. The more general and theoretical aspects of the study are recorded in Part I and the more specific technical design considerations are presented in a second volume Part II. The PIMMS team started their work in January 1996 in the PS Division and continued for a period of three years

    Synchrotrons for hadron therapy, part 1

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    The treatment of cancer with accelerator beams has a long history with linacs, cyclotrons and now synchrotrons being exploited for this purpose. Treatment techniques can be broadly divided into the use of spread-out beams and scanned 'pencil' beams. The Bragg-peak behaviour of hadrons makes them ideal candidates for the latter. The combination of precisely focused 'pencil' beams with controllable penetration (Bragg peak) and high, radio-biological efficiency (light ions) opens the way to treating the more awkward tumours that are radio-resistant, complex in shape and lodged against critical organs. To accelerate light ions (probably carbon) with pulse-to-pulse energy variation, a synchrotron is the natural choice. The beam scanning system is controlled via an on-line measurement of the particle flux entering the patient and, for this reason, the beam spill must be extended in time (seconds) by a slow-extraction scheme. The quality of the dose intensity profile ultimately depends on the uniformity of the beam spill. This is the greatest challenge for the synchrotron, since slow-extraction schemes are notoriously sensitive. This paper reviews the extraction techniques, describes methods for smoothing the beam spill and outlines the implications for the extraction line and beam delivery system

    New Cretaceous empidoids and the Mesozoic dance fly revolution (Diptera: Empidoidea)

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    Dance flies and relatives (Empidoidea) are a diverse and ecologically important group of Diptera in nearly all modern terrestrial ecosystems. Their fossil record, despite being scattered, attests to a long evolutionary history dating back to the early Mesozoic. Here, we describe seven new species of Empidoidea from Cretaceous Kachin amber inclusions, assigning them to the new genus Electrochoreutes gen.n. (type species: Electrochoreutes trisetigerus sp.n.) based on unique apomorphies among known Diptera. Like many extant dance flies, the males of Electrochoreutes are characterized by species-specific sexually dimorphic traits, which are likely to have played a role in courtship. The fine anatomy of the fossils was investigated through high-resolution X-ray phase-contrast microtomography to reconstruct their phylogenetic affinities within the empidoid clade, using cladistic reasoning. Morphology-based phylogenetic analyses including a selection of all extant family- and subfamily-ranked empidoid clades along with representatives of all extinct Mesozoic genera, were performed using a broad range of analytical methods (maximum parsimony, maximum-likelihood and Bayesian inference). These analyses converged in reconstructing Electrochoreutes as a stem-group representative of the Dolichopodidae, suggesting that complex mating rituals evolved in this lineage during the Cretaceous

    Practical application of AAPM Report 270 in display quality assurance: A report of Task Group 270

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    Published in January 2019, AAPM Report 270 provides an update to the recommendations of the AAPM\u27s TG18 report. Report 270 provides new definitions of display types, updated testing patterns, and revised performance standards for the modern, flat-panel displays used as part of medical image acquisition and review. The focus of the AAPM report is on consistent image quality and appearance, and how to establish a quality assurance program to achieve those two goals. This work highlights some of the key takeaways of AAPM Report 270 and makes comparisons with existing recommendations from other references. It also provides guidance for establishing a display quality assurance program for different-sized institutions. Finally, it describes future challenges for display quality assurance and what work remains

    Incidencia de un nuevo signo fenotípico en el síndrome de Down : la desviación cubital

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    El diagnóstico del síndrome de Down ha dejado de pertenecer a la observación clínica, sustituidacon ventaja por la exactitud y accesibilidad del diagnóstico genético. Por lo que agregar un datomás a la larga serie de signos ya descritos no tendría mayor valor ´Sin embargo el valor del signo propuesto tendría otras ventajas : 1) facilitar el diagnósticoinicial en el período neonatal inmediato al ser fácilmente visible por implicar de hecho a todoel cuerpo. 2 ) señalar un camino para la superación del retraso psicomotor característico delsíndrome , ya que el signo se integra en un patrón motor de simetría que obstaculiza eldesarrollo de los primeros años.

    The use of pocket-size imaging devices: a position statement of the European Association of Echocardiography.

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    Pocket-size imaging devices are a completely new type of echo machines which have recently reached the market. They are very cheap, smartphone-size hand-held echo machines with limited technical capabilities. The aim of this European Association of Echocardiography (EAE) position paper is to provide recommendations on the use of pocket-size imaging devices in the clinical arena by profiling the educational needs of potential users other than cardiologists experts in echo. EAE recommendations about pocket-size imaging devices can be summarized in: (1) pocket-size imaging devices do not provide a complete diagnostic echocardiographic examination. The range of indications for their use is therefore limited. (2) Imaging assessment with pocket-size imaging devices should be reported as part of the physical examination of the patient. Image data should be stored according to the applicable national rules for technical examinations. (3) With the exception of cardiologists who are certified for transthoracic echocardiography according to national legislation, specific training and certification is recommended for all users. The certification should be limited to the clinical questions that can potentially be answered by pocket-size devices. (4) The patient has to be informed that an examination with the current generation of pocket-size imaging devices does not replace a complete echocardiogram.Peer reviewe

    Spin-Splitter Studies: Polarization Stability Measurements at IUCF

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    This research was sponsored by the National Science Foundation Grant NSF PHY-931478

    Dark blood ischemic LGE segmentation using a deep learning approach

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    The extent of ischemic scar detected by Cardiac Magnetic Resonance (CMR) with late gadolinium enhancement (LGE) is linked with long-term prognosis, but scar quantification is time-consuming. Deep Learning (DL) approaches appear promising in CMR segmentation. Purpose: To train and apply a deep learning approach to dark blood (DB) CMR-LGE for ischemic scar segmentation, comparing results to 4-Standard Deviation (4-SD) semi-automated method. Methods: We trained and validated a dual neural network infrastructure on a dataset of DB-LGE short-axis stacks, acquired at 1.5T from 33 patients with ischemic scar. The DL architectures were an evolution of the U-Net Convolutional Neural Network (CNN), using data augmentation to increase generalization. The CNNs worked together to identify and segment 1) the myocardium and 2) areas of LGE. The first CNN simultaneously cropped the region of interest (RoI) according to the bounding box of the heart and calculated the area of myocardium. The cropped RoI was then processed by the second CNN, which identified the overall LGE area. The extent of scar was calculated as the ratio of the two areas. For comparison, endo- and epi-cardial borders were manually contoured and scars segmented by a 4-SD technique with a validated software. Results: The two U-Net networks were implemented with two free and open-source software library for machine learning. We performed 5-fold cross-validation over a dataset of 108 and 385 labelled CMR images of the myocardium and scar, respectively. We obtained high performance (> ∼0.85) as measured by the Intersection over Union metric (IoU) on the training sets, in the case of scar segmentation. With regards to heart recognition, the performance was lower (> ∼0.7), although improved (∼ 0.75) by detecting the cardiac area instead of heart boundaries. On the validation set, performances oscillated between 0.8 and 0.85 for scar tissue recognition, and dropped to ∼0.7 for myocardium segmentation. We believe that underrepresented samples and noise might be affecting the overall performances, so that additional data might be beneficial. Figure1: examples of heart segmentation (upper left panel: training; upper right panel: validation) and of scar segmentation (lower left panel: training; lower right panel: validation). Conclusion: Our CNNs show promising results in automatically segmenting LV and quantify ischemic scars on DB-LGE-CMR images. The performances of our method can further improve by expanding the data set used for the training. If implemented in a clinical routine, this process can speed up the CMR analysis process and aid in the clinical decision-making

    Proton-Ion Medical Machine Study (PIMMS), 2

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    The Proton-Ion Medical Machine Study (PIMMS) group was formed following an agreement between the Med-AUSTRON (Austria) and the TERA Foundation (Italy) to combine their efforts in the design of a cancer therapy synchrotron capable of accelerating either light ions or protons. CERN agreed to support and host this study in its PS Division. A close collaboration was also set up with GSI (Germany). The study group was later joined by Onkologie-2000 (Czech Republic). Effort was first focused on the theoretical understanding of slow extraction and the techniques required to produce a smooth beam spill for the conformal treatment of complex-shaped tumours with a sub-millimetre accuracy by active scanning with proton and carbon ion beams. Considerations for passive beam spreading were also included for protons. The study has been written in two parts. The more general and theoretical aspects are recorded in Part I and the specific technical design considerations are presented in the present volume, Part II. An accompanying CD-ROM contains supporting publications made by the team and data files for calculations. The PIMMS team started its work in January 1996 in the PS Division and continued for a period of four years

    Análisis de variantes de HPV-16 como marcador molecular antropólogico

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    El Virus Papiloma Humano tipo 16 (HPV16) es el principal responsable del desarrollo del cáncer de cuello uterino. Además de su significado clínico, el estudio de la variación genética en las regiones E6, L1 y LCR de este virus ha permitido identificar variantes específicas de diferentes áreas geográficas. Este descubrimiento sugiere una antigua propagación del HPV16 y su coevolución con el género humano. En este contexto, las variantes podrían servir como marcador molecular antropológico, aportando nuevos datos al análisis de patrones migratorios humanos. El objetivo del trabajo fue determinar las variantes de HPV16 en las regiones genéticas E6 y L1 que infectan mujeres guaraníes de Misiones. Para ello se analizaron 39 muestras de cepillados cervicales de mujeres guaraníes infectadas con HPV16. Las variantes en E6 y L1 se identificaron por PCR e hibridación en dot blot. Los resultados obtenidos fueron: el 77% de las variantes Europeas, 20% Africanas y 3% Asiático Americanas. La baja prevalencia de variantes Asiático Americanas coincide con lo reportado por Picconi y col, 2002 para mujeres quechuas, y haría suponer una limitada diseminación del HPV16 durante la época prehispánica. El predominio de las variantes Europeas podría ser resultado de la colonización española y la inmigración europea, mientras que el tráfico de esclavos negros explicaría la presencia de variantes Africanas. Por otra parte, la hipótesis de competencia viral tampoco puede ser descartada.Sesión de posterAsociación de Antropología Biológica de la República Argentina (AABRA
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