1,720,983 research outputs found
コンピュータ支援カテーテルガイドシステムの開発
Get PDF本研究では,脳動脈瘤に対するコイリング手技などのInterventional Radiology(IVR)を,Magnetic Resonance Angiography(MRA)データを用い,カテーテルやガイドワイヤの先端位置をMRAデータの3次元画像内に表示することで,IVRの術者にカテーテルなどのデバイスの3次元的位置情報を提供するシステムを開発中してきた.
昨年度までは,透視画像内のカテーテル先端位置を自動的に検出追跡する手法やその2次元的なカテーテル先端位置をMRA画像上の位置へマッピングする手法の開発および評価を行った.本年度は,カテーテルと同様にIVR手技においてカテーテルを目的位置まで導くガイドワイヤ,特にマイクロガイドワイヤを透視画像において自動的に認識・追跡する手法と,脳血管MRA内の脳血流信号をそれぞれの脳血管に自動的に分類する手法を開発した.
開発したマイクロガイドワイヤ自動認識・追跡手法では,透視画像中のマイクロカテーテルを1フレームあたり94.8%の精度で認識できた.
カテーテルやガイドワイヤの透視画像中の2次元的位置をMRA上の3次元的位置にマッピングする際MRAと透視画像の代わりのDigital Subtraction Angiography (DSA)画像との間の,いわゆる2D/3Dレジストレーションが必要となる.そのレジストレーションでは,2つの画像に写っている血管が異なると失敗する可能性が高い.MRAの血流信号をそれぞれの脳血管に分類する手法は,MRA画像からDSA画像に写っている血流信号のみをMRAデータ内から選び出すために用いられる.またその精度は,pixelベースで79.4%であった.研究課題/領域番号:15790656, 研究期間(年度):2003 – 2005出典：「コンピュータ支援カテーテルガイドシステムの開発」研究成果報告書 課題番号15790656
（KAKEN：科学研究費助成事業データベース（国立情報学研究所））
（https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-15790656/)を加工して作成金沢大学医薬保健研究域医学系research repor
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
New metric, Local Uncertainty for assessment of dose accumulation in radiation therapy
Get PDF本研究課題では,まず変形レジストレーションの特性を評価するためデジタルファントムを作成した. 更に,変形レジストレーションの結果を評価する新たな評価指標である部分的・信頼性指標(Local Uncertainty)を開発し, 作成したデジタルファントムを用いてLocal Uncertaintyの評価を行った. また, 直接線量積算を想定した評価を行うためその実験に適切なゲル開発を行った.そのゲル線量計を用いて実際に積算された線量と変形レジストレーションを用いて計算された積算線量を比較する実験を行う予定である.In this study, first, degital phantoms were created to evaluate the characteristics of a deformable image registration method. Then, the Local Uncertainty, a new metric for the assessment of deformable image registration results, was developed. The Local Uncertainty was validated by using the degital phantoms. To assess accuracy of accumulated dose, an applicable type of a polymer gel dosimeter was developed. The Local Uncertainty for dose accumulation will be validated by using the polymer gel dosimeter.研究課題/領域番号:26460724, 研究期間(年度):2014-04-01 - 2017-03-31出典：「変形画像照合による積算線量分布の有用性を向上させる新たな部分的精度・信頼性の開発」研究成果報告書 課題番号26460724
（KAKEN：科学研究費助成事業データベース（国立情報学研究所））
（https://kaken.nii.ac.jp/report/KAKENHI-PROJECT-26460724/26460724seika/）を加工して作成金沢大学医薬保健研究域保健学系research repor
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Development of a respiratory motion suppressed three dimensional catheter/guide-wire navigation system for endovascular interventions of upper abdominal artery
Get PDF脳血管を対象とした3次元カテーテルガイドシステムの開発をもとに,腹部血管内手術用三次元カテーテルガイドシステムを開発するにあたり,腹部血管の呼吸性移動を補正する手法の開発が必要であった.そのため,上腹部血管の呼吸性移動の解析とその解析結果をもとに,その呼吸性移動の補正手法の開発を行い,かつ,その信頼性を検証した.横隔膜位置を用いた補正手法の信頼性は3症例中2症例で90%以上と高い信頼性を示し,本システムとして有用な手法を開発できた.The respiratory motion suppressed three dimensional catheter/guide-wire navigation system has been developed based on three dimensional catheter guiding system for cerebral artery which we had developed before. To apply the guiding system to abdominal artery a respiratory motion suppression technique was necessary. We analyzed respiratory motions of abdominal arteries, and a respiratory motion suppression technique was developed based on the results of the analysis. Additionally, we evaluated reliability of the technique. We found that motions of abdominal artery were correlative well with diaphragm motions and the reliability of the respiratory motion suppression technique was over 90 % in two of the three cases. Thus, this respiratory motion suppress technique is effective for the respiratory motion suppressed three dimensional catheter/guide-wire navigation system.研究課題/領域番号:19700417, 研究期間(年度):2007-2009出典：研究課題「呼吸性移動に対応した腹部血管内手術用三次元カテーテルガイドシステムの開発」課題番号19700417
（KAKEN：科学研究費助成事業データベース（国立情報学研究所））
（https://kaken.nii.ac.jp/report/KAKENHI-PROJECT-19700417/19700417seika/）を加工して作成金沢大学医薬保健研究域保健学系research repor
Quality assurance method for the accumulation of radiotherapy dose with deformable image registration
Get PDFIn this study, we challenged to develop a method for verifying the accuracy of the accumulated dose distribution calculated with the deformable image registration (DIR) in radiotherapy. We use a gel dosimeter that can be measured three-dimensionally and can be deformed. We irradiated the gel dosimeter before and after the deformation, also scanned it by CT scanner and build each treatment plan, then the accu,ulated dose distribution by DIR was calculated. The accumulated dose distribution was compared with the dose distribution read from the gel dosimeter. Since the sensitivity of the gel dosimeter decreases when gel dosimeter is exposed to oxygen, an oxygen blocking method for the verification method could be developed. And it was found that the gelatin of the gel dosimeter collapsed due to the deformation of the gel dosimeter and the sensitivity of the collapsed part decreased.本研究では, 放射線治療におけるDeformable image registration(DIR)を用いた合算線量分布の精度検証方法開発のために,3次元的に測定でき変形可能なゼリー状のゲル線量計を用いることを検討した.ゲル線量計を変形前と変形後に照射し, それぞれのCT撮影とそれぞれの治療計画を立てDIRによる合算線量分布をえてゲル線量計から読み出した線量分布を比較する評価方法を検討した.ゲル線量計は酸素に触れると感度が低下するため,検証方法に用いる酸素遮断方法が開発できたが,ゲル線量計の変形によってゲル線量計のゼラチンが崩れ,崩れた部分の感度が低下することがわかった.研究課題/領域番号:19K12818, 研究期間(年度):2019-04-01 – 2022-03-31出典：研究課題「放射線治療における変形画像照合技術を用いた線量合算精度の評価手法確立」課題番号19K12818
（KAKEN：科学研究費助成事業データベース（国立情報学研究所））
（https://kaken.nii.ac.jp/ja/report/KAKENHI-PROJECT-19K12818/19K12818seika/）を加工して作成金沢大学医薬保健研究域保健学系research repor
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