1,720,979 research outputs found
Pediatric vs adult dosimetry in CBCT: a challenge?
No full textConcern about the radiation dose to children from diagnostic radiology examinations has recently been popularly expressed, particularly as related Computed Tomography (CT) procedures. This involves the idea that children can receive higher doses compared to adults. Since the dosimetric quantities are essentially defined for adult patients, if related to effective dose, it becomes important to study and derive methods applicable also to pediatric cases. In fact, the “commonly” statement implies that size, shape, and data for pediatric organs will be derived from adult ones, numerically reducing dosimetric problems to the definition of scaling algorithms. The aim of this study is to analyze the differences in pediatric vs adult dosimetry, starting from measured organ doses in Cone-Beam Computed Tomography (CBCT) procedures for maxilla-facial region. Two different anthropomorphic phantoms (child vs adult phantoms) were scanned, acquiring all data: results will be presented in terms of organ and derived doses, discussing the approach and differences
XXII International Conference on Mechanics in Medicine and Biology - Abstracts Book
No full textThis book contain the abstracts presented the XXII ICMMB, held in Bologna in September 2022. The abstracts are divided following the sessions scheduled during the conference
Using Cone Beam Computed Tomography for Radiological Assessment Beyond Dento-maxillofacial Imaging: A Review of the Clinical Applications in other Anatomical Districts
Full text linkBackground: Cone Beam Computed Tomography (CBCT) represents the optimal imaging solution for the evaluation of the maxillofacial and dental area when quantitative geometric and volumetric accuracy is necessary (e.g., in implantology and orthodontics). Moreover, in recent years, this technique has given excellent results for the imaging of lower and upper extremities. Therefore, significant interest has been increased in using CBCT to investigate larger and non-traditional anatomical districts. Objective: The purpose of this work is to review the scientific literature in Pubmed and Scopus on CBCT application beyond head districts by paying attention to image quality and radiological doses. Method: The search for keywords was conducted in Pubmed and Scopus databases with no back-date restriction. Papers on applications of CBCT to head were excluded from the present work. From each considered paper, parameters related to image quality and radiological dose were extracted. An overall qualitative evaluation of the results extracted from each issue was done by comparing the conclusive remarks of each author regarding doses and image quality. PRISMA statements were followed during this process. Results: The review retrieved 97 issues from 83 extracted papers; 46 issues presented a comparison between CBCT and Multi-Detector Computed Tomography (MDCT), and 51 reviewed only CBCT. The radiological doses given to the patient with CBCT were considered acceptable in 91% of cases, and the final image quality was found in 99%. Conclusion: CBCT represents a promising technology not only for imaging of the head and upper and lower extremities but for all the orthopedic districts. Moreover, the application of CBCT derived from C-arms (without the possibility of a 360 ° rotation range) during invasive investigations demonstrates the feasibility of this technique for non-standard anatomical areas, from soft tissues to vascular beds, despite the limits due to the incomplete rotation of the tube
Optimization of gas injection in CO2 Angiography
No full textThe use of programmable gas injectors has demonstrated how it is necessary to adapt the parameters (gas pressure and flow) in the particular diagnostic context to obtain the best imaging result with minimum radiological exposure. Imaging of a big vascular cavity, or medium size artery or small peripheral artery is a completely different game, which requires different regulations and management of the instruments. In this paper the focus will be on small peripheral arteries imaging (BTK), where the required low injection gas flow interferes with the low hydraulic resistance of the catheter and the wide arterial pressure pulsatility, producing an irregular gas injection, with reflow and pain. To overcome this problem, a calibrated adjunctive resistance in series of the catheter is proposed, with theoretical analysis and optical simulation
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
Radioprotection in CO2 Angiography
No full textWhy to focus on radioprotection in a Conference of biomechanics? Because a deep analysis of the radioprotective problem of this quite new diagnostic procedure, demonstrates that the optimization of radioprotection is strictly related to the optimization of gas injection, which changes in the different biomechanical conditions. A particular attention is focused to the differences, in terms of radiological dose between iodine and CO2, and some protocols are on course to clarify this aspect, frequently with incoherent results. In this paper the radioprotection problem of CO2 angiography will be clearly outlined, with procedural references to vascular biomechanics. It will be demonstrated that the radioprotection problem and imaging results depend only and how the clinicians manage the diagnostic procedure: it depends only a little on the contrast medium, it mostly depends on the scientific knowledge of clinical staff: doctors, technicians and physicists. If everyone plays his role in the best way, knowing that the imaging result is strictly related to the vascular biomechanics, (which has to be deeply known), a global positive result is achieved
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
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