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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Effect of slit scan imaging techniques on image quality on radiotherapy electronic portal imaging

Walton, Dean R. January 2008 (has links)
Thesis (M.S.)--University of Toledo, 2008. / "In partial fulfillment of the requirements for the degree of Master of Science in Biomedical Sciences." Title from title page of PDF document. Bibliography: pages 67-72.
2

Estudo da viabilidade do emprego da técnica de subtração radiográfica digital em radiografias periapicais com registro a posteriori

Assis, Afonso Celso Souza de [UNESP] 31 May 2010 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:29:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-05-31Bitstream added on 2014-06-13T19:26:45Z : No. of bitstreams: 1 assis_acs_me_sjc.pdf: 596243 bytes, checksum: fb9783652a81f3cb2ec3e7e3c9337fbc (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Apesar de ser uma técnica limitada, a subtração digital é utilizada na Odontologia. A adição do computador e seus algoritmos para equalização de contraste e também correção geométrica, tornou possível a aplicação da subtração radiográfica digital (SRD), utilizando radiografias intrabucais. Neste estudo foi avaliada a viabilidade da utilização da subtração radiográfica digital pelo programa Regeemy – Image Registration and Mosaicking v.0.2.43-RCB (DPI-INPE, São José dos Campos, SP, Brazil) em radiografias periapicais digitalizadas e obtidas sem utilização de padronização rígida durante as exposições por meio de registro a posteriori. A seleção dos pontos de controle foram realizadas de forma automática e em quantidade múltipla pelo Reggemy. Esses pontos serviram como coordenadas a partir das quais o programa alinhou o par de imagens e gerou uma terceira imagem de acordo com a projeção geométrica da imagem de referência. Com o uso do Adobe Photoshop© foram selecionados os ROI das imagens utilizando guias e coordenadas. Depois de aplicados os testes estatísticos foi verificado que a metodologia do presente estudo não permite concluir que a subtração utilizando-se o programa Regeemy é inviável quando realizada sem padronização / The digital subtraction has been widely used in dentistry. The addition of computer and its algorithms for equalization of contrast and geometric correction also made possible the application of radiographic digital subtraction (SRD) using intraoral radiographs. This study assessed the feasibility of using X-ray digital subtraction of the program Regeemy - Image Registration and mosaicking v.0.2.43-RCB (DPI-INPE, Sao Jose dos Campos, SP, Brazil) in periapical radiographs digitized and obtained without the use of standardized rigid during the exposures by registering the event. The selection of control points were performed automatically and in quantity by multiple Reggemy. These points were used as coordinates from which the program aligned the image pair and a third image generated according to the geometrical projection of the reference image. Using Adobe Photoshop ©, we selected the ROI of the images using guides and coordinates. After applying the statistical tests we can conclude that the methodology of this study does not suggest that the subtraction using the program Regeemy is feasible when performed without standardization. It is suggested further studies to evaluate the impact of subtraction radiography with no standardization in clinical diagnosis
3

Estudo da viabilidade do emprego da técnica de subtração radiográfica digital em radiografias periapicais com registro a posteriori /

Assis, Afonso Celso Souza de. January 2010 (has links)
Orientador: Luiz Cesar de Moraes / Banca: Pedro Luiz de Carvalho / Banca: Cristiane Yumi Koga Ito / Resumo: Apesar de ser uma técnica limitada, a subtração digital é utilizada na Odontologia. A adição do computador e seus algoritmos para equalização de contraste e também correção geométrica, tornou possível a aplicação da subtração radiográfica digital (SRD), utilizando radiografias intrabucais. Neste estudo foi avaliada a viabilidade da utilização da subtração radiográfica digital pelo programa Regeemy - Image Registration and Mosaicking v.0.2.43-RCB (DPI-INPE, São José dos Campos, SP, Brazil) em radiografias periapicais digitalizadas e obtidas sem utilização de padronização rígida durante as exposições por meio de registro a posteriori. A seleção dos pontos de controle foram realizadas de forma automática e em quantidade múltipla pelo Reggemy. Esses pontos serviram como coordenadas a partir das quais o programa alinhou o par de imagens e gerou uma terceira imagem de acordo com a projeção geométrica da imagem de referência. Com o uso do Adobe Photoshop© foram selecionados os ROI das imagens utilizando guias e coordenadas. Depois de aplicados os testes estatísticos foi verificado que a metodologia do presente estudo não permite concluir que a subtração utilizando-se o programa Regeemy é inviável quando realizada sem padronização / Abstract: The digital subtraction has been widely used in dentistry. The addition of computer and its algorithms for equalization of contrast and geometric correction also made possible the application of radiographic digital subtraction (SRD) using intraoral radiographs. This study assessed the feasibility of using X-ray digital subtraction of the program Regeemy - Image Registration and mosaicking v.0.2.43-RCB (DPI-INPE, Sao Jose dos Campos, SP, Brazil) in periapical radiographs digitized and obtained without the use of standardized rigid during the exposures by registering the event. The selection of control points were performed automatically and in quantity by multiple Reggemy. These points were used as coordinates from which the program aligned the image pair and a third image generated according to the geometrical projection of the reference image. Using Adobe Photoshop ©, we selected the ROI of the images using guides and coordinates. After applying the statistical tests we can conclude that the methodology of this study does not suggest that the subtraction using the program Regeemy is feasible when performed without standardization. It is suggested further studies to evaluate the impact of subtraction radiography with no standardization in clinical diagnosis / Mestre
4

Quantitative ultrasonography in regional anesthesia. / CUHK electronic theses & dissertations collection

January 2009 (has links)
Li, Xiang. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 161-184). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract and appendix also in Chinese.
5

Quantifying image quality in diagnostic radiology using simulation of the imaging system and model observers /

Ullman, Gustaf, January 2008 (has links) (PDF)
Diss. (sammanfattning) Linköping : Linköpings universitet, 2008. / Härtill 6 uppsatser. Includes bibliographical references.
6

Calculation of scatter in cone beam CT : steps towards a virtual tomograph /

Malusek, Alexandr, January 2008 (has links)
Diss. (sammanfattning) Linköping : Linköpings universitet, 2008. / Härtill 5 uppsatser.
7

Quantifying image quality in diagnostic radiology using simulation of the imaging system and model observers /

Ullman, Gustaf, January 2008 (has links) (PDF)
Diss. (sammanfattning) Linköping : Linköpings universitet, 2008. / Härtill 6 uppsatser.
8

Дигитална мамографија и томосинтеза у детекцији и радиолошкој БИ РАДС категоризацији туморских лезија дојке / Digitalna mamografija i tomosinteza u detekciji i radiološkoj BI RADS kategorizaciji tumorskih lezija dojke / Digital mammography and tomosynthesis in BIRADS lesions characterization

Prvulović Bunović Nataša 28 April 2015 (has links)
<p>Циљ ове студије је да се упореди дијагностичкa значајност 2Д и 2Д+3Д мамографије у детектовању тумора дојке. Испитивали смо 864 дојки у 740 пацијенткиња. Студија је спроведена у току рутинског рада у Центру за имиџинг дијагностику Институту за онкологију Војводине. 2Д + 3Д мамографија су начињене појединачно или у истом акту снимања као комбо опција на Selenia Dimensions апарату произвођача фирме Холоџик. Радиолошки извешатаји су класификовани у категорије 1-5 према АЦР БИ РAДС-у. Патохистолошка верификација је вршена у свих суспектних промена или у току њиховог праћења . Све пацијенткиње са уредним налазом или мамографски уочених бенигних промена су радиолошки праћене најкраће током 2 године. Уочено је 103 малигне лезије у дојкама класификованих као БИ РАДС 4, 5 на дигиталној мамографији и у 22 дојке чије су промене класификоване као БИ РАДС 1-3, током праћења или прегледа дојки помоћу других модалитета. На 2Д + 3Д мамографији малигните је потврђен у 125 дојке од којих је 118 класификовано као БИ РАДС 4,5 и у 7 дојки чује су промене категорисане у БИРАДС 1-3. Постоји статистички значајна разлика у дистрибуцији малигних налаза у односу на подгрупе Студија је показала 20% лажно негативних налаза на 2Д, а 5,6% на 2Д + 3Д модалитету прегледа дојки. Осетљивост у откривању рака у овој студији износи 82,4% на 2Д и 94,4% на 2Д+3Д методи прегледа, док је специфичност 90,5% и 92,0%, респективно. ППВ је већа за 2Д + 3Д технику прегледа , износи 66,7%, као и негативна предиктивна вредност која износи 99,0%. У 172 случаја (19, 9%) налази 2Д мамографије се не уочавају на 3Д техници прегледа и сматрају се последицом структурне или анатомске &bdquo;буке&ldquo;. Већина не -сталних налаза (85%) је класификовано као фокална асиметрија. У овој студији 500 дојки је класификовано према АЦР структури у масне (АЦР 1) или дифузне фибро-гландуларне (АЦР 2), а преосталих 264 је било хетеродензно (АЦР 3) и значајно дензно (АЦР 4). Статистички значајна разлика није показана приликом дистрибуције малигних налаза у поређењу са подгрупама дојки начињеним према њиховој густини - складу са правилима АЦР-а. Укупна тачност теста износи 89,4% за 2Д и 92,4% за 2Д + 3Д мамографију. Предиктивне вредности добијене за 2Д + 3Д мамографију су боље од оних које се односе само на 2Д мамографију, што је резултат њене веће осетљивости и шире могућности карактеризације промена. Варијабилност у интерпретацији налаза међу два радиолога је је ниска, показано је слагање у интершпретавцији евалуираних мамограма у 94.1% случајева.</p> / <p>Cilj ove studije je da se uporedi dijagnostička značajnost 2D i 2D+3D mamografije u detektovanju tumora dojke. Ispitivali smo 864 dojki u 740 pacijentkinja. Studija je sprovedena u toku rutinskog rada u Centru za imidžing dijagnostiku Institutu za onkologiju Vojvodine. 2D + 3D mamografija su načinjene pojedinačno ili u istom aktu snimanja kao kombo opcija na Selenia Dimensions aparatu proizvođača firme Holodžik. Radiološki izvešataji su klasifikovani u kategorije 1-5 prema ACR BI RADS-u. Patohistološka verifikacija je vršena u svih suspektnih promena ili u toku njihovog praćenja . Sve pacijentkinje sa urednim nalazom ili mamografski uočenih benignih promena su radiološki praćene najkraće tokom 2 godine. Uočeno je 103 maligne lezije u dojkama klasifikovanih kao BI RADS 4, 5 na digitalnoj mamografiji i u 22 dojke čije su promene klasifikovane kao BI RADS 1-3, tokom praćenja ili pregleda dojki pomoću drugih modaliteta. Na 2D + 3D mamografiji malignite je potvrđen u 125 dojke od kojih je 118 klasifikovano kao BI RADS 4,5 i u 7 dojki čuje su promene kategorisane u BIRADS 1-3. Postoji statistički značajna razlika u distribuciji malignih nalaza u odnosu na podgrupe Studija je pokazala 20% lažno negativnih nalaza na 2D, a 5,6% na 2D + 3D modalitetu pregleda dojki. Osetljivost u otkrivanju raka u ovoj studiji iznosi 82,4% na 2D i 94,4% na 2D+3D metodi pregleda, dok je specifičnost 90,5% i 92,0%, respektivno. PPV je veća za 2D + 3D tehniku pregleda , iznosi 66,7%, kao i negativna prediktivna vrednost koja iznosi 99,0%. U 172 slučaja (19, 9%) nalazi 2D mamografije se ne uočavaju na 3D tehnici pregleda i smatraju se posledicom strukturne ili anatomske &bdquo;buke&ldquo;. Većina ne -stalnih nalaza (85%) je klasifikovano kao fokalna asimetrija. U ovoj studiji 500 dojki je klasifikovano prema ACR strukturi u masne (ACR 1) ili difuzne fibro-glandularne (ACR 2), a preostalih 264 je bilo heterodenzno (ACR 3) i značajno denzno (ACR 4). Statistički značajna razlika nije pokazana prilikom distribucije malignih nalaza u poređenju sa podgrupama dojki načinjenim prema njihovoj gustini - skladu sa pravilima ACR-a. Ukupna tačnost testa iznosi 89,4% za 2D i 92,4% za 2D + 3D mamografiju. Prediktivne vrednosti dobijene za 2D + 3D mamografiju su bolje od onih koje se odnose samo na 2D mamografiju, što je rezultat njene veće osetljivosti i šire mogućnosti karakterizacije promena. Varijabilnost u interpretaciji nalaza među dva radiologa je je niska, pokazano je slaganje u interšpretavciji evaluiranih mamograma u 94.1% slučajeva.</p> / <p>The aim of this study was to compare diagnostic importance of 2D and 2D+3D diagnostic mammography in breast tumor detection. We evaluated 864 breasts in 740 patients. Study was performed in Diagnostic Imaging Center at Oncology Institute of Vojvodina. 2D+3D mammography were performed during single procedure or via combo option at Selenia Dimensions unit, Hologic, BE. Radiological findings were classified in categories 1-5 according to ACR BIRADS. Pathohistologic verification was obtained in all suspicious findings or after follow up studies. All other patients with mammographic normal findings or benign findings were fallowed up during 2 years period or longer. We detected malignant lesions in 103 breasts classified as BIRADS 4,5 at digital mammography, and in 22 breasts classified as BIRADS 1-3 after followed up or diagnosed by other imaging modalities. At 2D+3D mammography malignancy was confirmed in 125 breasts, 118 classified as BIRADS 4,5 and in 7 breasts classified as BIRADS 1-3. There is statistically significant difference (p&lt;0.001) in distribution of malignant findings compared to the subgroups classified according to 2D mammography. There was 20% false negative findings on 2D, and 5.6% on 2D+3D modality. Sensitivity in cancer detection in this study is 82.4% and 94.4% for 2D and 2D+3D mammography, while specificity is 90.5% and 92.0%, respectively. PPV is higher for 2D+3D technique (66.7%), as well as negative predictive value (99.0%). In 172 cases (19, 9%) 2D mammography findings did not persist on 3D mammography and were considered as structural or anatomical noise. The majority of the non-persistent findings (85%) were classified as asymmetric focal density. In this study 500 breast were classified according to ACR as fatty (ACR 1) or scattered fibroglandular densities (ACR 2), and the remaining 264 had heterogeneously (ACR 3) and extremely dense breasts (ACR 4). Statistically significant difference (p&lt;0.001) was not shown in distribution of malignant findings compared to the subgroups of density structure according to ACR. Overall accuracy of the test was 89.4% and 92.4% for 2D and 2D+3D mammography, respectively. Predictive values obtained in 2D+ 3D mammography are better than those for 2D mammography alone, as a result of its higher sensitivity and better possibility of lesion characterization. Interobserver variability is low, there is an agreement between two radiologist between two radiologic interpretations in 94.1% cases.</p>
9

Avaliação do processo de raparo de lesões periopicais pós-tratamento endodôntico por meio de subtração digital radiográfica / Evaluation of the process of repair of periapical lesions after endodontic treatment by digital subtraction radiography

SILVA, Janaína Benfica e 30 November 2006 (has links)
Made available in DSpace on 2014-07-29T15:22:00Z (GMT). No. of bitstreams: 1 Parte 1.pdf: 1874528 bytes, checksum: 7e46501ade5b782c1d4f3f9926c18a43 (MD5) Previous issue date: 2006-11-30 / Control of the process of repair or progression of periapical lesions after endodontic treatment is monitored by conventional or digital radiography. In this research digital subtraction radiography (DSR) was used that uses the subtraction of images longitudinally, in which the change in the alveolar bone is visualized against a uniform gray background. The objectives of this study were: (1) to evaluate the repair process of periapical lesions after endodontic treatment by using DSR; (2) to quantify by means of point/pixel (picture element), area (histogram) and linear measures (profile line), the gain or loss of mineral density in the area of the lesion, using the average of the pixel values; (3) to compare the diagnostic information, suggestive of the repair process, obtained through a subjective evaluation of DSR with a conventional radiographic evaluation and digitalized image and (4) to evaluate the contribution of DSR to an early identification of the repair of periapical lesions after endodontic treatment. The sample consisted of twelve patients with a total of seventeen periapical lesions. The x-rays were digitalized and submitted to DSR using DSR&#61650; software. The pixel values of the subtracted images were determined by using Image Tool&#61650; software. Both the conventional x-rays as well as the digitalized and subtracted images were qualitatively evaluated. The results showed a gain in mineral density with a mean&#61617;dp of 133.49&#61617;5.17, 130.27&#61617;5.77 and 129.41&#61617;4.46 for the points/pixel, histogram and profile line tools, respectively. In the evaluation of numerical gain Pearson s Coefficient of Correlation (r) presented these values: mean of points/histogram = 0.746; mean of points/profile line = 0.724 and histogram/profile line = 0.860. When the numerical values were transformed into percentile gain mean&#61617;dp of 0.67&#61617;4.01, 1.21&#61617;4.33 and 1.16&#61617;3.36 were obtained for the points/pixels, histogram and profile line tools, respectively. In the evaluation of the percentile gain Spearman s Coefficient of Correlation (rs) showed the following values: mean of points/histogram = 0.697; mean of the points/profile line = 0.646 and histogram/profile line = 0.844. In the qualitative analysis, the frequency of success in the ordering of the correct sequence of the repair process using conventional radiography, digitalized image and DSR was 37.3%, 31.4% and 31.4%, respectively. One concluded, therefore, that: (1) the process of repair of periapical lesions after endodontic treatment can be evaluated quantitatively by means of longitudinal analysis using DSR; (2) any one of the three tools can be used to quantify the repair, considering that correlation exists between the time of repair and the increase of the value of pixel; (3) the comparative evaluation between the subjective methods using conventional radiography, digitalized image and SDR, it showed that all had been capable to evidence the process of repair of periapical lesions from the first radiography (15 days), not having difference between them and (4) the quantitative evaluation by SDR obtained to after evidence the beginning of the repair with 15 days the beginning of the endodontic treatment, even so this repair was really effective from 105 days after the beginning of the endodontic treatment. / O controle do processo de reparo ou progressão de lesões periapicais pós-tratamento endodôntico é monitorado pelo exame radiográfico convencional ou digital. Nesta pesquisa foi utilizada a subtração digital radiográfica (SDR), que utiliza a subtração de imagens longitudinalmente, na qual a mudança no osso alveolar é visualizada contra um plano de fundo (background) cinza homogêneo. Os objetivos desse estudo foram: (1) avaliar o processo de reparo de lesões periapicais pós-tratamento endodôntico por meio de SDR; (2) quantificar por meio de ponto/pixel (picture element), área (histograma) e medida linear (perfil linha) na área da lesão, o ganho ou perda de densidade mineral por meio da média dos valores dos pixels; (3) comparar as informações diagnósticas, sugestivas do processo de reparo, obtidas por meio da avaliação subjetiva da SDR com a avaliação radiográfica convencional e imagem digitalizada; e (4) avaliar a contribuição da SDR na identificação precoce do reparo de lesões periapicais pós-tratamento endodôntico. A amostra constituiu-se de doze indivíduos totalizando dezessete lesões periapicais. As radiografias foram digitalizadas e submetidas à SDR utilizando o programa DSR&#61650;. As imagens subtraídas tiveram os valores de pixel determinados utilizando o programa Image Tool&#61650;. Tanto as radiografias convencionais quanto as imagens digitalizadas e subtraídas foram avaliadas qualitativamente. Os resultados evidenciaram ganho de densidade mineral com média&#61617;dp de 133,49&#61617;5,17; 130,27&#61617;5,77; 129,41&#61617;4,46 para as ferramentas ponto/pixel; histograma e perfil linha respectivamente. Na avaliação do ganho numérico o Coeficiente de Correlação de Pearson (r) mostrou valores de: média dos pontos/ histograma = 0,746; média dos pontos/ perfil linha = 0,724 e histograma/ perfil linha = 0,860. Quando os valores numéricos foram transformados em ganho percentual foram obtidas média&#61617;dp de 0,67&#61617;4,01; 1,21&#61617;4,33; 1,16&#61617;3,36 para as ferramentas ponto/pixel; histograma e perfil linha respectivamente. Na avaliação do ganho percentual o Coeficiente de Correlação de Spearman (rs) mostrou valores de: média dos pontos/ histograma = 0,697; média dos pontos/ perfil linha = 0,646 e histograma/ perfil linha = 0,844. Na análise qualitativa, a freqüência de acertos na ordenação da seqüência correta do processo de reparo usando radiografia convencional, imagem digitalizada e SDR foi de 37,3%; 31,4% e 31,4% respectivamente. Concluiu-se, portanto, que: (1) o processo de reparo de lesões periapicais pós-tratamento endodôntico pode ser avaliado quantitativamente por meio de análise longitudinal com SDR (2) qualquer uma das três ferramentas pode ser utilizada para quantificar o reparo, considerando que existe correlação entre o tempo de reparo e o aumento do valor de pixel; (3) a avaliação comparativa entre os métodos subjetivos, usando radiografia convencional, imagem digitalizada e a SDR, mostrou que todos foram capazes de evidenciar o processo de reparo de lesões periapicais desde a primeira radiografia (15 dias), não havendo diferença entre eles e (4) a avaliação quantitativa por meio de SDR conseguiu evidenciar o início do reparo com 15 dias após o início do tratamento endodôntico, embora esse reparo fosse realmente efetivo a partir de 105 dias após o início do tratamento endodôntico.

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