1,721,079 research outputs found
Experimental evaluation of MCDTK, the Monte Carlo DICOM Tool-Kit
No full textThe Monte Carlo DICOM Tool-Kit (MCDTK) is a software suite designed for treatment plan dose verification, using the BEAMnrc and DOSXYZnrc Monte Carlo codes. MCDTK converts DICOM-format treatment plan information into Monte Carlo input files and compares the results of Monte Carlo treatment simulations with conventional treatment planning dose calculations. In this study, a treatment is planned using a commercial treatment planning system, delivered to a pelvis phantom containing ten thermoluminescent dosimeters and simulated using BEAMnrc and DOSXYZnrc using inputs derived from MCDTK. The dosimetric accuracy of the Monte Carlo data is then evaluated via comparisons with the dose distribution obtained from the treatment planning system as well as the in-phantom point dose measurements. The simulated beam arrangement produced by MCDTK is found to be in geometric agreement with the planned treatment. An isodose display generated from the Monte Carlo data by MCDTK shows general agreement with the isodose display obtained from the treatment planning system, except for small regions around density heterogeneities in the phantom, where the pencil-beam dose calculation performed by the treatment planning systemis likely to be less accurate. All point dose measurements agree with the Monte Carlo data obtained using MCDTK, within confidence limits, and all except one of these point dose measurements show closer agreement with theMonte Carlo data than with the doses calculated by the treatment planning system. This study provides a simple demonstration of the geometric and dosimetric accuracy ofMonte Carlo simulations based on information from MCDTK
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Desaturation delay, parameter for evaluating severity of sleep disordered breathing
No full textSleep apnea hypopnea syndrome (SAHS) is considered as a major health problem causing increased risk of cardiovascular problems. One of the most often used parameters to assess the severity of SAHS is apnea hypopnea index (AHI). It is calculated as the average amount of total cessations of breathing (apnea events) and partial reductions in breathing (hypopnea events) per hour of sleep. AHI only takes into account the total number of events regardless of their true nature. In this paper ambulatory polygraphic recordings of 19 male patients were analysed and the blood oxygen desaturation delay (BODD) studied in estimating the cardiovascular stress associated with sleep disordered breathing. The delay of the desaturation event occurring after apnea and hypopnea events were studied. Correlation with AHI and the delay parameter is modest and it shows variation between patients with similar AHI. This suggests that the delay parameter may provide additional information about the probably varying car-diovascular stress in patients with similar AHI and in the diagnostics of sleep disordered breathing in general
Calibration of radiochromic film for electron radiotherapy dosimetry
No full textRadiochromic film has the potential to provide accurate in vivo measurements of the skin dose received by radiotherapy patients; this is especially important for superficial treatments such as electron radiotherapy. This study examines the use of Gafchromic EBT2 radiochromic film for dosimetry of megavoltage electron radiotherapy beams. 80 pieces of film are irradiated to different doses, using 6, 9, 12, 16 and 20 MeV electron beams delivered using a medical linear accelerator, in order to derive a dose-response relationship for each of these standard electron beam energies. These five calibration relationships are then evaluated and compared. When red-channel data are used to calibrate the film, the use of a single calibration curve obtained at one energy to evaluate dose from films irradiated to doses above 50 cGy using the other electron beam energies introduces a maximum inaccuracy of 5%. If red-and blue-channel data are used, the additional inaccuracy arising from using one calibration relationship to evaluate dose from films irradiated to doses above 50 cGy using the other electron beam energies was found to increase to 20%. This study establishes that red-channel data calibrations made at standard megavoltage electron energies can be used interchangeably, with an acceptable level of uncertainty
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