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Irvine, Michael Alan, and thebovus@yahoo com. "Image Quality and Radiation Dose Comparison of a Computed Radiography System and an Amorphous Silicon Flat Panel System in Paediatric Radiography: A Phantom Study." RMIT University. Applied Sciences, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20091019.122013.
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This purpose of this work was to investigate the patient radiation doses and image quality of a Philips/Agfa computed radiographic (CR) system and a Philips indirect-capture digital radiographic (DR) system in a paediatric setting. A CDRAD digital radiographic contrast-detail phantom was used to assess radiographic image quality. Perspex slabs of three different thicknesses (6, 11 and 16 cm) were used to simulate paediatric patients of three arbitrary ages. These phantoms, in conjunction with the CDRAD digital radiographic contrast-detail phantom, were imaged under three different conditions. The CDRAD Analyser software package was used to assess the quality of each image. The first experiment conducted was a comparison of the two systems under standard conditions, with beam filtration of aluminium and copper, as recommended in European Guidelines on Quality Criteria for Diagnostic Radiographic Images in Paediatrics (European Commission 1996b). Image quality was compared for each phantom size at three doses with the same entrance exposure used for both systems. A visual comparison of the resulting contrast detail curves showed the DR system generally outperformed the CR system, especially at the lowest two doses. A chi-square analysis of the targets detected generally confirmed this visual impression. The second experiment performed was to compare the two systems under the conditions used in routine clinical practice at PMH. As a result of additional beam filtration not generally being employed, the image quality of the CR system was similar to the DR system for the two smaller phantom sizes but with a major dose cost - effective doses higher by between 38% and 100%. A chi-square analysis of the targets detected showed the CR system to be significantly better than the DR system at two of three doses for the thinnest phantom and no significant difference at any doses for the intermediate phantom size. For the largest phantom size, additional filtration - although different - was used for the CR and DR systems and so the X-ray beam spectra were more similar. Consequently, the results for this phantom size reflected those from the experiment conducted under standard conditions, ie the effective doses for both systems were similar and the image quality of the DR system superior. The chi-square analysis s howed the DR system to be significantly better than the CR at all three dose levels. A third experiment was undertaken to compare doses between the two systems at 'equal' image quality. The CDRAD Analyser software specific image quality parameter, IQFinv, was held constant for both systems. The entrance exposures required to achieve this image quality were measured and then converted to effective doses using the dose calculation software package PCXMC 1.5. The DR system offered effective dose savings of between 28 and 42% for the three phantom sizes. Overall, this work suggests that a Philips flat-panel system is superior to an Agfa CR system in paediatric radiography. This result generally reflects the findings of other authors who have conducted similar studies in adult patient settings.
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Polinsky, Adam S. "Evaluation and Comparison of Periapical Healing Using Periapical Films and Cone Beam Computed Tomography: Post-Treatment Follow Up." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/5767.
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Purpose: The purpose of this study was to assess the radiographic changes in periapical status and analysis of healing determined using periapical radiographs (PA) versus cone beam computed tomography (CBCT) pre-operatively and at 3-64 months following endodontic treatment.
Methods: Pre/post treatment radiograph and CBCT scans of patients who had NSRCT, NSReTx, or SRCT from July 2011-December 2018 at VCU Graduate Endodontic clinic were included in this study. Volumetric and linear measurements of periapical lesions on initial and recall PA and CBCT images were performed using three calibrated examiners. Changes and differences in the estimated area from PA to CBCT were compared using the Wilcoxon signed-rank test. McNemar’s chi-squared test was used to determine agreement in the proportion of lesions that were absent (0x0) between the PA and corresponding view of CBCT. This data was used to calculate the sensitivity, specificity, positive predictive value (PPV), and negative predicative value (NPV).
Results: A total of 51 patients with a median healing time of 13 months were included in the analysis. Significant healing was observed on both PA and CBCT images (p-value
Conclusion: Assessment using CBCT revealed a lower healing rate for all treatment categories compared with periapical radiographs. CBCT was more likely to detect the presence of a PARL, whereas a periapical radiograph would be less sensitive to detection of a PARL. Significant healing cannot be detected at an earlier point in time with PA radiographs or CBCT.
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Pitcher, Christopher D. "Quantitative metrics to evaluate image quality for computed radiographic images." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0007362.
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Bergh, Mary Sarah. "Radiographic, Computed Tomographic, And Histologic Study Of Central Tarsal Bone Fractures In Racing Greyhounds." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1211974471.
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Kong, Xiang. "Optimization of image quality and minimization of radiation dose for chest computed radiography." Oklahoma City : [s.n.], 2006.
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Abofatira, Mohamed Farag. "A radiographic analysis of the anterior palate as a donor site for bone harvesting." University of the Western Cape, 2015. http://hdl.handle.net/11394/5040.
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Magister Scientiae Dentium - MSc(Dent)<br>Autologous bone grafting in conjunction with dental implant therapy is a well-accepted procedure in oral and maxillofacial rehabilitation. A variety of intraoral donor sites, such as the mandibular symphysis, the mandibular ramus and the maxillary tuberosity have been used in oral and maxillofacial reconstruction. However these sites are associated with complications. In order to reduce these complications, the anterior palate has been proposed as a potential donor site. However, the scientific literature in this regard is sparse, and larger studies are required to investigate the clinical potential of this proposed site. Aim: To determine the volume and density of available bone in the anterior palate that may be used for bone harvesting using cone-beam computed tomography (CBCT) in a select South African population. Materials and methods: One hundred previously acquired CBCT scans taken at the Diagnostic and Radiology Department of Tygerberg Oral Health Centre were analyzed for the required data. These were all acquired from a single CBCT machine (Newtom VGI®, Verona, Italy). The study sample included 52 females and 48 males ranging from ages 20 years to 80 years. The CBCT scans were divided into 3 different age groups. The first age group was between the ages of 20 and 39 years, the second age group was from 40 to 59 years and the third age group was ≥ 60 years. The volume and density of the anterior palate of the different age groups were analyzed using specific criterion. CBCT specific software (Simplant Pro Crystal®) Dentsply implants, Mannheim, Germany was used to standardize the data collection. All data was stored in a Microsoft Excel spreadsheet (Microsoft Corporation, Washington, USA). Results: The mean volume of the anterior palate in this study was 2.11 ± 0.55 cm3, with a minimum volume of 1.04 cm3 and a maximum volume of 3.82 cm3. There was no significant difference in the volume and density of the anterior palate between different age groups and no significant difference in the volume between males and females (p value = 0.227). Conclusions: The anterior palate affords a considerable amount of bone volume which is similar or even more than other intraoral donor sites. The anterior palate is a potential donor site for bone harvesting and CBCT may be regarded as an ideal tool to analyze the amount of bone available for harvesting.
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Li, Geng, and 李耕. "Magnetic resonance, computed tomographic, radiographic and anatomical correlation of dimensions of the metacarpal and proximal phalanx ofthe little finger." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31969641.
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Li, Geng. "Magnetic resonance, computed tomographic, radiographic and anatomical correlation of dimensions of the metacarpal and proximal phalanx of the little finger." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21105960.
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Jamjoom, Faris Zainalabedeen. "Positional Accuracy of Prosthetic Treatment Plan Incorporation Into Cone-beam Computed Tomography Scans Using Surface Scan Superimposition." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1498241824233391.
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Adam, Ryan J. "Radiographic assessment of lung anatomy, physiology, and disease in a porcine model of cystic fibrosis and people with cystic fibrosis." Diss., University of Iowa, 2017. https://ir.uiowa.edu/etd/5692.
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Despite affecting many organ systems, the leading cause of morbidity and mortality in the cystic fibrosis (CF) population is lung disease. For the current studies we investigated elements of CF lung disease in a porcine model of CF and in people with CF. Our primary analysis tool was chest computed tomography (CT).
To investigate early CF lung disease we examined three week old CF and non-CF pigs. We found three week old CF pigs to have large, irregular tracheal smooth muscle bundles, airways of reduced size, airways of irregular shape, and airways of abnormal distensibility.
Three week old CF pig lung parenchyma was more heterogenous in density than three week non-CF pigs, especially in the right cephalad lung. The degree of lung tissue heterogeneity in CF pigs correlated with the degree of lung infection. Three week old CF pigs also had significantly more air trapping upon exhalation, evidence of airflow obstruction, than non-CF pigs. The degree of air trapping correlated with the degree of mucus accumulation in the airways. These data show that CF pigs spontaneously develop hallmark features of CF lung disease within weeks of birth, and that abnormal airway growth and development in CF may contribute to lung disease. This study helped set the foundation for future comparative studies involving CF therapeutics, for example, antibiotics and mucolytics.
In adults with CF we performed a before drug, after drug study. The drug was ivacaftor, and it restores the basic underlying defect in a subset of people with CF: impaired function of a particular anion channel. We hypothesized that abnormal airway smooth muscle behavior in people with CF, known as “CF asthma,” is, in part, a primary pathogenic mechanism of CF lung disease. We tested our hypothesis by assaying smooth muscle tone before and after administration of ivacaftor. We limited the time duration to two days. We reasoned two days was long enough for ivacaftor to become effective, but not long enough to reverse long standing lung infection and inflammation which could affect smooth muscle function independently. The implication being, that observed changes would be directly due to restoration of the CF defect. We found evidence suggesting relaxation of airway and vascular smooth muscle tone. And, the change in airway smooth muscle tone correlated with the change in vascular smooth muscle tone. These data suggest that impaired smooth muscle function is a primary element of CF lung disease.
Many of the people in our two day ivacaftor study returned for follow up after one year of ivacaftor therapy. We hypothesized that radiographic features of lung disease would improve following one year of ivacaftor therapy. We observed no change in lung volume upon inspiration, but a reduction in expiratory lung volume, approximately half of which occurred within two days. Our airway measurements were confounded by errors in scan reconstruction, however, other published studies report airway wall thinning over long term ivacaftor administration. Taken together, these studies of pigs with CF and people with CF, help us understand this disease.
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Knuppel, Julie M. "Correlation of Neurologic Status As Evaluated By Neurologic Examination And Brainstem Auditory Evoked Response Test With Computed Tomographic And Radiographic Morphometric Analysis Of The Caudal Skull In Cavalier King Charles Spaniels." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243866074.
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Malusek, Alexandr. "Calculation of scatter in cone beam CT : Steps towards a virtual tomograph." Doctoral thesis, Linköping : Department of Medical and Health Sciences, Linköping University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11275.
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Vaz, Sergio Lins de Azevedo 1984. "Detection of periimplant fenestration and dehiscence using CBCT - an in vitro study = Diagnóstico tomográfico de fenestração e deiscência peri-implantar - estudo in vitro." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/289080.
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Orientador: Francisco Haiter Neto<br>Tese (Doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba<br>Made available in DSpace on 2018-08-22T00:06:43Z (GMT). No. of bitstreams: 1
Vaz_SergioLinsdeAzevedo_D.pdf: 2097588 bytes, checksum: 48e378674d749eb9b8ea2a05042e21a4 (MD5)
Previous issue date: 2013<br>Resumo: O presente estudo se propôs a avaliar a influência do tamanho de voxel e giro de escaneamento na detecção tomográfica de fenestração e deiscência peri-implantar, além do uso de filtros de imagem na detecção da deiscência peri-implantar. Em fragmentos de costelas bovinas, foi criado defeitos que simulariam fenestração e deiscência peri-implantar após a instalação de 100 implantes de titânio. As imagens foram adquiridas no tomógrafo computadorizado de feixe cônico i-CAT Next Generation, empregando FOV de 8 x 8 cm e três protocolos: A- voxel de 0,2 mm, giro de escaneamento de 180°; B- voxel de 0,2 mm, giro de 360°; C- voxel de 0,12 mm, giro de 360°. Cinco filtros do programa XoranCat foram testados: Angio Sharpen High 5x5, Shadow, Sharpen 3×3, Sharpen Mild e Smooth. Três cirurgiões-dentistas radiologistas identificaram a presença ou ausência dos defeitos. Curvas ROC foram criadas e os valores de área sob a curva (Az) comparados utilizando a Análise de Variância (ANOVA), com teste post hoc de Bonferroni (alfa de 5%). O teste de McNemar foi utilizado para comparar imagens (originais e com filtros) versus padrão ouro, bem como imagens originais versus imagens com filtros. Os resultados mostraram diferenças estatisticamente significantes entre os valores de Az dos protocolos B e C em relação ao protocolo A (p < 0,01) para deiscência. Houve diferenças estatisticamente significantes (p < 0,01) entre as imagens originais e o filtro Shadow em relação ao padrão ouro, bem como entre todos os filtros testados em relação às imagens originais. Concluiu-se que os tamanhos de voxel testados não influenciaram no diagnóstico de ambos os defeitos, enquanto que o giro de escaneamento completo (360°) foi melhor para deiscência. Diante da maior dificuldade no diagnóstico tomográfico de deiscência peri-implantar, o uso dos filtros de imagem testados é aconselhado, com exceção do filtro Shadow<br>Abstract: This study set out an assessment of the effects of two voxel sizes and scan modes of cone-beam computed tomography (CBCT) in periimplant fenestration and dehiscence detection. It also aimed to investigate whether CBCT filters would enhance the diagnosis of periimplant dehiscence. One hundred titanium implants were placed in bovine ribs in which periimplant fenestration and dehiscence were simulated. The images were acquired using the i-CAT Next Generation CBCT unit, with a FOV of 8 x 8 cm and the following protocols: A- 0.2 mm voxel size half-scan (180°); B- 0.2 mm voxel size full-scan (360°); and C- 0.12 mm voxel size full-scan (360°). Five filters of the XoranCat software were tested: Angio Sharpen High 5x5, Shadow, Sharpen 3×3, Sharpen Mild and Smooth. Three oral radiologists performed a dynamic evaluation of the presence/absence of the defects and ROC curves were created. The values of the area under the curve (Az) were compared with ANOVA and Bonferroni post-hoc test. The significance level was adopted at 5%. The McNemar test was applied to perform two comparisons in order to identify disagreements. All the enhanced and the original images were compared with the gold-standard and the original images were compared to the enhanced ones. The protocol A had significantly lower Az values than those obtained with the protocols B and C (p < 0.01) for dehiscence. The original images and the Shadow filter were statistically different from the gold-standard (p < 0.01). All the enhanced images also had statistically significant differences from the original images (p < 0.01). In conclusion, the voxel sizes did not influence in periimplant fenestration and dehiscence detection but the full-scan (360°) performed better than the half-scan for dehiscence. The use of enhancement CBCT filters for dehiscence detection is advised, with the exception of the Shadow filter<br>Doutorado<br>Radiologia Odontologica<br>Doutor em Radiologia Odontológica
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Vidor, Michele Machado. "Avaliação da interface osso e implantes dentários em exames por imagem e suas implicações no diagnóstico." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/130152.
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Introdução: O desenvolvimento da radiologia digital e da tomografia computadorizada de feixe cônico (TCFC) permitiu aos profissionais diferentes formas de avaliação das imagens. Entretanto, frente a materiais metálicos, é observada a formação de artefatos tanto na imagem tomográfica, quanto nas radiografias digitais após a aplicação de filtros de processamento. Objetivo: Esta pesquisa objetivou investigar a interferência provocada por materiais metálicos na avaliação da interface osso/implante em radiografias periapicais convencional e digital, e em TCFC. Materiais e Métodos: Foram inseridos implantes de titânio em 74 blocos de costelas bovina frescas. Em 37, a inserção foi em íntima relação com as paredes ósseas (Grupo Controle-GC) e nos outros 37 com um espaço de 0.125 mm (Grupo Teste-GT). As radiografias periapicais foram realizadas com filme convencional e dois sistemas digitais de placa de fósforo. As imagens volumétricas foram adquiridas em dois equipamentos de TCFC. Nos sistemas digitais as imagens foram investigadas com e sem a utilização dos filtros e, nas tomografias, com diferentes protocolos de aquisição. Três examinadores treinados e cegados realizaram a avaliação utilizando uma escala Likert de cinco pontos. Foram utilizados testes de sensibilidade, especificidade e acurácia (área sob a curva ROC) e teste de concordância de Kendall (W). Resultados: Na avaliação radiográfica (ARTIGO I), foi observada maior acurácia do exame convencional e das imagens do sistema VistaScan com filtros Caries2 e Endo e do sistema Express com filtro Sharpen3 na detecção da justaposição entre osso e implante. Na avaliação tomográfica (ARTIGO II), somente as imagens do tomógrafo i-Cat com a resolução de voxel de 0.125mm não apresentaram diferença significativa com a radiografia convencional na acurácia diagnóstica. Conclusão: Na avaliação radiográfica da justaposição entre o osso e o implante, preferência deve ser dada às radiografias convencionais ou às digitais com filtros de realce (Caries2, Endo e Sharpen3). Em caso da existência de exames de TCFC com voxel 0.125 mm, tal avaliação também pode ser realizada.<br>Introduction: The development of digital radiology and computed tomography cone beam (CBCT) enabled professionals different possibilities of images evaluation. However, when metallic materials are present, artifacts formation can be observed in tomographic images and in digital radiography after processing fiters. Objective: This study investigated the interference caused by metallic materials in bone/implant interface evaluation with conventional and digital periapical radiographs, and CBCT. Materials and Methods: Titanium implants were placed into 74 fresh bovine ribs. In 37, the implants were in close relation with the bone walls (Control Group-CG) and the remaining 37 ribs preparations promoted a 0.125 mm space (Test Group-GT) .The periapical radiographs were taken with conventional film and digital photostimulable phosphor plate (PSP) system of two commercial brands. The volumetric images were acquired in two CBCT equipment. The digital images were investigated with and without the use of processing filters available and the tomographic with different acquisition protocol. Three trained and blinded examiners performed the evaluation using a five points Likert scale. Sensitivity, specificity and accuracy (area under the ROC curve) tests were used and Kendall´s coefficient of concordance (W). Results: In the radiographic evaluation (Article I), there was a higher accuracy to detect the juxtaposition between bone and implant with the conventional radiography and the images of VistaScan system using the Caries2 and Endo filters, and Express system with Sharpen3 filter. In the tomographic evaluation (Article II), only the images with 0.125mm of voxel resolution from i-Cat CBCT showed no significant difference with conventional radiography in the diagnostic accuracy. Conclusion: In radiographic evaluation of juxtaposition between bone and implant preference should be given to conventional radiographs or in digital radiographs to Caries2, Endo and Sharpen3 enhancement filters. In case of the existence of CBCT exams (voxel 0.125mm), such evaluation can also be performed.
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Jacome, Victor Roland. "Evaluation of dose and image quality parameters for cone-beam CT localization protocols in radiation therapy." Oklahoma City : [s.n.], 2009.
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Liedke, Gabriela Salatino. "Influência da presença de materiais metálicos na capacidade diagnóstica de diferentes métodos por imagem - radiografia convencional, radiografia digital e tomografia computadorizada de feixe cônico - investigação in vitro." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/102539.
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O objetivo desta tese foi avaliar a interferência da presença de materiais metálicos na imagem radiográfica e tomográfica por meio da análise da adaptação marginal de restaurações e coroas metálicas. Esta investigação resultou em 3 artigos: uma revisão sistemática da literatura para identificar o estado da arte com relação ao uso dos métodos radiográficos; um estudo in vitro comparando o desempenho do filme radiográfico convencional e dos sistemas digitais VistaScan Dürr Dental, Digora Classic Soredex e Express Instrumentarium – com e sem o emprego de filtros para o pós processamento da imagem; e um estudo in vitro avaliando o processamento das imagens da TCFC – utilizando diferentes espessuras de reconstrução. Na revisão sistemática foram incluídos 14 estudos, sendo classificados de baixa ou moderada qualidade, de acordo com os critérios QUADAS de classificação. Na investigação radiográfica (artigo 2), os maiores valores de sensibilidade (0,67 0,83), especificidade (0,81 0,92) e acurácia (0,73 0,86) foram obtidos com radiografias convencionais e imagens digitais originais. Na avaliação tomográfica (artigo 3), os valores da aucROC variaram de 0,60 a 0,72, sendo que o limite inferior do intervalo de confiança mostrou-se abaixo ou muito próximo da linha de referencia. Frente aos resultados, conclui-se que imagens radiográficas originais (convencionais ou digitais) devem ser preferidas para a avaliação de dentes com restaurações metálicas. Quanto à TCFC, mesmo quando se aumenta a espessura de reconstrução da imagem e diminui-se o artefato, ainda assim não há melhora na acurácia do diagnóstico.<br>The aim of this thesis was to evaluate the interference of the presence of metallic materials on radiographic and tomographic image by assessing misfits tooth and restoration in metal-restored teeth. This investigation resulted in three articles: a systematic review of the literature to identify the state of the art on the use of radiographic methods; an in vitro study comparing the performance of conventional film and digital phosphor plate systems Vistascan Dürr Dental, Digora Classic Soredex and Instrumentarium Express – exported as original images and with the use of post processing filters; and an in vitro study evaluating the post-processing of CBCT images – using diverse reconstruction thicknesses. The systematic review retrived 14 studies, classified as low- / moderate quality based on QUADAS criteria. For radiographic evaluation (article II), higher sensitivity (0.67 0.83), specificity (0.81 0.92) and accuracy (0.73 0.86) values were obtained with conventional and digital original images. For tomographic evaluation (article III), mean aucROC ranged from 0.60 to 0.72, and the analysis of the 95% CI showed the lower bound of the curve bellow or very close to the reference line. Based on the results, it is concluded that original images (conventional or digital) should be preferred for the assessment of teeth with metal restorations. Considering CBCT images, even thought increased reconstruction thickness decreased perceived artifact, it did not improve diagnosis accuracy.
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Yao, Min. "Computed radiography system modeling, simulation and optimization." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0128/document.
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Depuis plus d’un siècle, la radiographie sur film est utilisée pour le contrôle non destructif (CND) de pièces industrielles. Avec l’introduction de méthodes numériques dans le domaine médical, la communauté du CND industriel a commencé à considérer également les techniques numériques alternatives au film. La radiographie numérique (en anglais Computed radiography -CR) utilisant les écrans photostimulables (en anglais imaging plate -IP) est une voie intéressante à la fois du point de vue coût et facilité d’implémentation. Le détecteur (IP) utilisé se rapproche du film car il est flexible et réutilisable. L’exposition de l’IP aux rayons X génère une image latente qui est ensuite lue et numérisée grâce à un système de balayage optique par laser. A basse énergie, les performances du système CR sont bonnes ce qui explique son utilisation importante dans le domaine médical. A haute énergie par contre, les performances du système CR se dégradent à la fois à cause de la mauvaise absorption de l’IP mais également de la présence de rayonnement diffusé par la pièce qui, étant d’énergie plus faible, est préférentiellement absorbée par l’IP. Les normes internationales préconisent l’utilisation d’écrans métalliques pour améliorer la réponse des systèmes CR à haute énergie. Néanmoins, la nature et l’épaisseur de ces écrans n’est pas clairement définie et la gamme des configurations possibles est large. La simulation est un outil utile pour prévoir les performances d’une expérience et déterminer les meilleures conditions opératoires. Les méthodes Monte Carlo sont communément admises comme étant les plus précises pour simuler les phénomènes de transport de rayonnement, et ainsi comprendre les phénomènes physiques en jeu. Cependant, le caractère probabiliste de ces méthodes implique des temps de calcul importants, voire prohibitifs pour des géométries complexes. Les méthodes déterministes au contraire, peuvent prendre en compte des géométries complexes avec des temps de calcul raisonnables, mais l’estimation du rayonnement diffusé est plus difficile. Dans ce travail de thèse, nous avons tout d’abord mené une étude de simulation Monte Carlo afin de comprendre le fonctionnement des IP avec écrans métalliques à haute énergie pour le contrôle de pièces de forte épaisseur. Nous avons notamment suivi le trajet des photons X mais également des électrons. Quelques comparaisons expérimentales ont pu être menées à l’ESRF (European Synchrotron Radiation Facility). Puis nous avons proposé une approche de simulation hybride, qui combine l'utilisation de codes déterministe et Monte Carlo pour simuler l'imagerie d'objets de forme complexe. Cette approche prend en compte la dégradation introduite par la diffusion des rayons X et la fluorescence dans l'IP ainsi que la diffusion des photons optiques dans l'IP. Les résultats de différentes configurations de simulation ont été comparés<br>For over a century, film-based radiography has been used as a nondestructive testing technique for industrial inspections. With the advent of digital techniques in the medical domain, the NDT community is also considering alternative digital techniques. Computed Radiography (CR) is a cost-efficient and easy-to-implement replacement technique because it uses equipment very similar to film radiography. This technology uses flexible and reusable imaging plates (IP) as a detector to generate a latent image during x-ray exposure. With an optical scanning system, the latent image can be readout and digitized resulting in a direct digital image. CR is widely used in the medical field since it provides good performance at low energies. For industrial inspection, CR application is limited by its poor response to high energy radiation and the presence of scattering phenomena. To completely replace film radiography by such a system, its performance still needs to be improved by either finding more appropriate IPs or by optimizing operating conditions. Guidelines have been addressed in international standards to ensure a good image quality supplied by CR system, where metallic screens are recommended for the case of using high energy sources. However, the type and thickness of such a screen are not clearly defined and a large panel of possible configurations does exist. Simulation is a very useful tool to predict experimental outcomes and determine the optimal operating conditions. The Monte Carlo (MC) methods are widely accepted as the most accurate method to simulate radiation transport problems. It can give insight about physical phenomena, but due to its random nature, a large amount of computational time is required, especially for simulations involving complex geometries. Deterministic methods, on the other hand, can handle easily complex geometry, and are quite efficient. However, the estimation of scattering effects is more difficult with deterministic methods. In this thesis work, we have started with a Monte Carlo simulation study in order to investigate the physical phenomena involved in IP and in metallic screens at high energies. In particular we have studied separately the behavior of X-ray photons and electrons. Some experimental comparisons have been carried out at the European Synchrotron Radiation Facility. Then, we have proposed a hybrid simulation approach, combining the use of deterministic and Monte Carlo code, for simulating the imaging of complex shapes objects. This approach takes into account degradation introduced by X-ray scattering and fluorescence inside IP, as well as optical photons scattering during readout process. Different simulation configurations have been compared
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Marshall, Nicholas W. "Optimisation of digital image intensifier and computed radiography systems." Thesis, University of Newcastle Upon Tyne, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246136.
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Johnson, Kennita A. "Quantifying computed radiography (CR) and digital radiography (DR) image quality and patient dose for pediatric radiology." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0001030.
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Guzman, Dawn Nella. "Curriculum guide to teach computed radiography at El Camino College." CSUSB ScholarWorks, 2002. https://scholarworks.lib.csusb.edu/etd-project/2147.
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The purpose of the project was to design a curriculum guideline for educators to teach computed radiography. This project can be used as a stand-alone course, or integrated into existing radiologic technology courses.
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Abdelrahman, Magdy Shehata. "Scattering correction and image restoration in neutron radiography and computed tomography." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3025066.
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Ekert, Thomas [Verfasser]. "Machine learning techniques for computer aided classification of dental radiographic images / Thomas Ekert." Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2020. http://d-nb.info/1206183144/34.
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Li, Gang. "Visual linearization of image data for the display of digital intraoral radiographs." Stockholm, 2004. http://diss.kib.ki.se/2003/91-85910-36-8.
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Hazey, Michael A. "Sensitivity comparison evaluation of computer-generated three dimensional surface topography to conventional maxillofacial radiographic imagery." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4481.
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Thesis (M.S.)--West Virginia University, 2006.<br>Title from document title page. Document formatted into pages; contains x, 220 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 69-74).
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Lawrence, Herenia Procopio. "Computer-assisted radiographic analysis of caries progression in fluoridated and fluoride-deficient areas in Brazil." Thesis, Queen Mary, University of London, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341124.
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Kano, Hiroshi, Tokiko Endo, Mitsuru Ikeda, Mikinao Oiwa, and Takeo Ishigaki. "Evaluation of New Image Processing Conditions for Digital Mammograms from FUJI Computed Radiography." Nagoya University School of Medicine, 2006. http://hdl.handle.net/2237/6906.
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Hagag, Usama. "Radiography, ultrasonography and computed tomography of the dromedary camel tarsus (One humped camel)." Doctoral thesis, Universitätsbibliothek Leipzig, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-112585.
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The dromedary camel has a very high economic importance in the Arabic countries. Nevertheless, there is a very little background literature on the use of ultrasound (US) and computed tomography (CT) in dromedaries in comparison to other domestic and farm animal species. Therefore, the tarsal region of six cadaver limbs, obtained from three orthopedic disease free dromedary camels, was evaluated via radiography, US and CT. The limbs were frozen and sectioned transversely, sagittaly and dorsally. The anatomic structures were identified and correlated to the analogous structures on the corresponding CT slices and US images and published in two manuscripts. Radiography was performed in both standard (0º and 90º) oblique (45º and 135º) radiographic projections. The tarsus was investigated via US in four planes (dorsal, medial, lateral and plantar) and each plane was scrutinized in four levels (calcaneal tuber, tibial
malleoli, base of calcaneus and proximal head of metatarsus) in both transverse and longitudinal views. Radiography provided a good representation of the bony structures and articulations with little information on the soft tissues of the tarsus and superimposition of the tarsal bones. Ultrasonography furnished adequate delineation of the peri-articular tissues of the tarsus and was limited to the bone surface. Computed tomography provided cross sectional imaging of the dromedary tarsus without bone and soft tissue overlap and allowed
visualization and differentiation of tissues in almost every situation.
This work was undertaken to document the normal appearance of the dromedary camel tarsus via radiography, ultrasonography, and computed tomography which may be used as a resource for interpretation of dromedary tarsal pathology using various diagnostic imaging modalities.
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Moore, Craig Steven. "Optimisation of computed radiography chest imaging utilising a novel simulation technique derived from real patient computed tomography data sets." Thesis, University of Hull, 2011. http://hydra.hull.ac.uk/resources/hull:5762.
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To optimise any medical digital imaging system for chest radiography, it is vital that the images used for optimisation contain projected anatomy, or in other words, anatomical noise. In this thesis, a method to produce and validate a digitally reconstructed radiograph (DRR) computer algorithm that utilises real patient computed tomography (CT) data sets is presented. The algorithm uses a ray casting DRR calculation method to project X-ray pencil beams through CT data and derive the photon energy absorbed in a virtual computed radiography (CR) phosphor. Radiation scatter and CR system noise are added post DRR calculation. Quantitative and qualitative validation has shown the algorithm simulates chest CR images of average and obese patients with realistic anatomical and system noise. This has allowed images to be generated using various X-ray exposure parameters, i.e. tube potential, scatter rejection and receptor dose, which can then be used in the optimisation exercise. However, the algorithm is not without limitations; the impact of these on the resulting images is discussed. Simulated images reconstructed at the various X-ray exposure parameters and techniques were scored by experienced image evaluators; optimum tube potential, scatter rejection technique and receptor doses for clinical CR chest radiography have been derived. At the outset of this work, CR chest exposure factors across the Hull & East Yorkshire Hospitals NHS Trust (HEY) were not standardised, and therefore not optimised; this thesis concludes with recommendations to the HEY Radiology Department for optimum exposure factors and technique for chest radiography. These were implemented across the Trust as a result of this work. In summary, a DRR computer algorithm has been produced (and validated) that adequately simulates anatomical and system noise; image evaluators are able to grade simulated chest images presented at different X-ray exposure parameters in order to optimise radiographic technique for clinical CR chest radiography, without the need for repeat patient exposures.
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Gunes, E. evren. "Computerized Test Procedure For Industrial Radiographic Examination Of Metallic Welded Joints." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/2/12605553/index.pdf.
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Radiography is an extensively used NDT method, especially in nuclear, aerospace and automotive industries where optimal designs call for greater reliability. The rules corresponding to industrial radiography are defined in a system of radiographic standards. The standards related to the radiographic testing of metallic welded joints had been harmonised in all over the Europe and at the end in 1997, the standard "<br>EN 1435"<br>was established and published. Since then, this standard has become the most widely used standard where the radiographic applications are necessary. To eliminate the person based errors during application of the standard, moreover to save time, cost and effort in radiographic exposures, in this study it was aimed to write a computer program which is able to calculate all necessary parameters for a radiographic exposure related to this standard EN 1435.
In the programming stage, Visual Basic 6.0 &<br>#61651<br>was used. The program consists of many windows, each giving and controlling separate parameters related to the exposure. Besides giving all the needed parameters, the evolved program is able to prepare a report with these parameters. So, both radiography technicians and experts can use it. It is believed that this study constructs a basis for developing other computerised test procedures for any kind of non-destructive testing methods used in industry today.
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Manning, David J. "Applications of signal detection theory to the performance of imaging systems, human observers and artificial intelligence in radiography." Thesis, Lancaster University, 1998. http://eprints.lancs.ac.uk/11591/.
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An investigation was carried out to evaluate diagnostic performance in medical radiology. A critical review of methods available for the assessment of image quality in terms of physical objective measurements and quantitative observer performance was followed by a series of experiments which applied the techniques of Receiver Operating Characteristics (ROC) to radiographic problems. An appraisal of the performance of six currently available imaging systems designed for chest radiography was performed using expert observers and an anthropomorphic phantom. Results showed a range of abilities to demonstrate pulmonary nodules (ROC areas of 0.866 to 0.961). The ROC outcomes for the imaging systems were shown to correlate well with signal to noise ratio (SNR) measurements for the images (0.78, p< 0.05) although comparisons of ROC and threshold detection indices (HT) gave a lower level of agreement (0.6, p<0.05). The SNR method of image evaluation could probably be used as an alternative to ROC techniques in routine quality assurance procedures when time is short. Observers from a group of undergraduate radiography students were tested by an ROC study into their ability to detect pulmonary lesions in chest images. Their ROC areas (Az) ranged from 0.616 to 0.857 (mean 0.74) compared with an expert mean score of 0.872. The low score for the students was investigated in terms of the cognitive task and their search strategy training. Their (Az ) scores showed no significant correlation with simple psychometric tests. A neural network was tested against radiologists, radiographers and student radiographers in its ability to identify fractures in wrist radiographs. All observers performed to a similar level of ROC Az score but the artificial intelligence showed higher specificity values. This attribute was used to filter some of the normals from the test population and resulted in changes to the mean Az score for the human observers.
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Butler, Anthony Philip Howard. "Eigenimage Processing of Frontal Chest Radiographs." Thesis, University of Canterbury. Electrical and Computer Engineering, 2007. http://hdl.handle.net/10092/2780.
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The goal of this research was to improve the speed and accuracy of reporting by clinical radiologists. By applying a technique known as eigenimage processing to chest radiographs, abnormal findings were enhanced and a classification scheme developed. Results confirm that the method is feasible for clinical use. Eigenimage processing is a popular face recognition routine that has only recently been applied to medical images, but it has not previously been applied to full size radiographs. Chest radiographs were chosen for this research because they are clinically important and are challenging to process due to their large data content. It is hoped that the success with these images will enable future work on other medical images such as those from CT and MRI. Eigenimage processing is based on a multivariate statistical method which identifies patterns of variance within a training set of images. Specifically it involves the application of a statistical technique called principal components analysis to a training set. For this research, the training set was a collection of 77 normal radiographs. This processing produced a set of basis images, known as eigenimages, that best describe the variance within the training set of normal images. For chest radiographs the basis images may also be referred to as 'eigenchests'. Images to be tested were described in terms of eigenimages. This identified patterns of variance likely to be normal. A new image, referred to as the remainder image, was derived by removing patterns of normal variance, thus making abnormal patterns of variance more conspicuous. The remainder image could either be presented to clinicians or used as part of a computer aided diagnosis system. For the image sets used, the discriminatory power of a classification scheme approached 90%. While the processing of the training set required significant computation time, each test image to be classified or enhanced required only a few seconds to process. Thus the system could be integrated into a clinical radiology department.
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Barallat, Sendagorta Lucía. "Histologic and radiographic evaluation of different bone grafts in ridge preservation procedures." Doctoral thesis, Universitat Internacional de Catalunya, 2016. http://hdl.handle.net/10803/392633.
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The main goal of this PhD project was to better understand how different types of bone
grafts behave in ridge preservation procedures. There is clear evidence that, after tooth
removal, a healing process takes place in which the blood clot that fills the socket is
gradually substituted with new bone. This process is accompanied by a reduction in height and width of the alveolar ridge. These events may result in limited bone
availability, which may compromise an adequate implant placement in order to replace the missing teeth.
For this reason, the insertion of different graft materials into the extraction socket has been reported. From the available evidence, it may be concluded that ridge preservation procedures do not completely prevent, but minimize loss of horizontal and vertical ridge alterations.
From an histological point of view, several studies have analyzed the histological
composition of previously preserved areas in order to determine the amount of vital bone formed. Since the additional benefits of different graft materials in terms of newly formed bone compared to natural healing of the extraction socket was still unknown, we conducted a systematic review in order to answer this question. Calcium sulfate, magnesium enriched hydroxyapatite (MHA) and porcine-derived bone grafts resulted in a significant greater amount of newly formed bone than natural healing sites. Studies evaluating allografts, autologous bone and bioactive glass showed no statistical significant differences between treatment groups. Due to the great variability of the included studies, no firm conclusions could be drawn.
Demineralized bovine bone mineral (DBBM) and demineralized bone bovine mineral embedded in 10% collagen matrix (DBBM-C) have been widely used in regenerative therapies and particularly in ridge preservation procedures. However, the possible differences between both grafting materials had not previously been analysed.
Therefore, a double blind randomized clinical trial comparing DBBM and DBBM-C in ridge preservation procedures was conducted. A reduction in height and width was observed 5 months after tooth extraction in sites preserved either with DBBM or DBBM-C, but no significant differences were encountered between treatment groups. On the other hand, the histomorphometric analysis resulted in a similar composition in terms of new bone formation, non-mineralized connective tissue and residual graft particles in both treatment groups.
From the above mentioned research projects it may be concluded that there is no
consensus on which graft material offers the best outcomes from an histological point of view. More specifically, the results of the randomized clinical trial suggest that there are no statistically significant differences between DBBM and DBBM-C neither in height and width reduction of the alveolar ridge nor in their histological composition after a healing period of 5 months.<br>El objetivo final de este proyecto de tesis doctoral era conocer mejor el comportamiento de distintos materiales de injerto en la técnica de preservación alveolar. Hay evidencia de que, después de la extracción dental, comienza un proceso de cicatrización durante el cual el coágulo sanguíneo es progresivamente reemplazado por hueso nuevo. Además, se produce una reducción en altura y anchura de la cresta alveolar, que puede a su vez dar lugar a una disponibilidad ósea limitada pudiendo comprometer la posterior colocación de implantes.
Por este motivo, se ha propuesto la introducción de distintos materiales de injerto en el alveolo postextracción. La literatura científica sugiere que los procedimientos de preservación alveolar minimizan estas alteraciones dimensionales de la cresta en sentido horizontal y vertical .
Desde un punto de vista histológico, múltiples estudios han evaluado la composición histológica de áreas donde previamente se había realizado una preservación alveolar para determinar la cantidad y calidad del hueso nuevo formado. Como el beneficio adicional a nivel histológico de la preservación alveolar con distintos materiales de injerto respecto a la cicatrización natural del alveolo postextracción no se conocía, realizamos una revisión sistemática para responder esta cuestión. El sulfato de calcio, la hidroxiapatita enriquecida con magnesio (MHA) y los xenoinjertos de origen porcino resultaron en un porcentaje de hueso nuevo formado significativamente mayor que las áreas control. Otros estudios que utilizaron autoinjertos, aloinjertos o biovidrios no observaron diferencias significativas entre grupos. Sin embargo, debido a la gran variabilidad de los estudios incluídos, no se pudieron sacar conclusiones definitivas.
El injerto bovino desproteneizado (DBBM) y el injerto bovino desproteneizado en una matriz de colágeno (DBBM-C) han sido ampliamente utilizados en terapias regenerativas y, particularmente, en preservación alveolar aunque aún no se han analizado las posibles diferencias entre ambos materiales. Por eso se realizó un ensayo clínico randomizado a doble ciego comparando DBBM y DBBM-C en preservación alveolar. Cinco meses después de la extracción, se observó una reducción en anchura y altura de la cresta alveolar en ambos grupos de tratamiento, pero no se encontraron diferencias estadísticamente significativas entre ambos. Por otro lado, el análisis histomorfométrico demostró una composición histológica similar en áreas tratadas con DBBM y áreas tratadas con DBBM-C.
De los estudios mencionados previamente, se puede concluir que no hay un consenso sobre qué material de injerto ofrece los mejores resultados en cuanto a composición histológica. Particularmente, los resultados del ensayo clínico randomizado sugieren que no existen diferencias estadísticamente significativas entre DBBM y DBBM-C en cuanto a cambios dimensionales ni en cuanto a composición histológica 5 meses después de realizar la preservación alveolar.
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Jo, Young Gyun. "Development of a thermal neutron imaging facility for real time neutron radiography and computed tomography /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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McCann, Aaron Jude. "Computed radiography in the quantification of bone content and morphology in the healing tibial shaft." Thesis, Queen's University Belfast, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492030.
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Image processing techniques have been devised which allow quantitative measurements of bone mineral density (BMD) and soft tissue content from clinical, single-energy Computed Radiography (CR) radiographs. Impediments to quantitative data extraction and serial comparison have been addressed, specifically the physical phenomena associated with X-ray irradiation (scatter, beam hardening, spatial beam inhomogeneity), the automated processing and digitization of the image by the CR processing unit, and variation in patient positioning between visits. Interactive image processing software has been developed which allows automated processing of clinical lower leg radiographs and extraction of serial BMD measurements at user defined regions of clinical interest. Output may be visualized in the form of absolute BMD images, colour subtraction images, time-lapse animations and parametric images. The techniques have been applied to a group of tibial shaft fracture patients treated with intramedullary nailing and llizarov frame fixation. Analysis of BMD and soft tissue content in serial images has identified significant differences in the quantities and patterns of tissue generation and loss at the fracture site and local regions. The technique has the potential to complement existing radiological methods in fracture review and other areas of study, and for use in clinical research.
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Nataša, Prvulović Bunović. "Дигитална мамографија и томосинтеза у детекцији и радиолошкој БИ РАДС категоризацији туморских лезија дојке". Phd thesis, Univerzitet u Novom Sadu, Medicinski fakultet u Novom Sadu, 2015. http://www.cris.uns.ac.rs/record.jsf?recordId=92756&source=NDLTD&language=en.
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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 „буке“. 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.<br>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 „buke“. 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.<br>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<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<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.
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Silva, Francisco Wanderley Garcia de Paula e. "Métodos de avaliação e mecanismos envolvidos no reparo apical e periapical após tratamento endodôntico em dentes com lesão induzida experimentalmente." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/58/58135/tde-19032010-111831/.
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Considerando-se a localização intra-óssea das lesões periapicais, o diagnostico clinico e dificultado e a avaliação radiográfica não fornece informações suficientes para o diagnostico de um periodonto apical sadio pós-tratamento. Dessa maneira, o objetivo deste estudo foi comparar os achados radiográficos e por tomografia computadorizada de feixe cônico com a avaliação microscópica após tratamento de canais radiculares em dentes de cães e avaliar a participação das metaloproteinases da matriz (MMPs) na lesão periapical e nos tecidos em processo de reparação, assim como em cistos e granulomas periapicais obtidos de humanos. A seguir, os mecanismos envolvidos na cementogênese apical foram investigados utilizando células do ligamento periodontal de humanos. Foram induzidas lesões periapicais em dentes de cães e o tratamento endodôntico foi realizado em sessão única ou apos utilização de um curativo de demora a base de hidróxido de cálcio [Ca(OH)2]. Avaliações radiográficas e tomográficas foram realizadas previamente, após a indução das lesões periapicais e 180 dias apos o tratamento endodôntico. Os tecidos periapicais foram avaliados por meio de microscopia de luz, imunofluorescência, imunoistoquímica e RT-PCR em tempo real. In vitro, células do ligamento periodontal foram utilizadas para avaliar os efeitos da estimulação com Ca(OH)2 nos processos de migração, proliferação, diferenciação celular e mineralização. As vias de sinalização envolvidas na diferenciação cementoblastica foram investigadas por meio de inibidores bioquímicos da via das proteínas quinases ativadoras de mitose (MAPK), bloqueadores de canais de cálcio e silenciadores de RNA para proteínas quinases reguladas por sinal extracelular (ERK-1 / ERK-2). De acordo com os resultados obtidos, a tomografia computadorizada permitiu a detecção de lesões periapicais com maior sensibilidade e acuracia que a radiografia periapical convencional, utilizando-se a avaliação microscópica como padrão-ouro. Histologicamente, as lesões periapicais experimentalmente induzidas apresentaram bactérias distribuídas pelo sistema de canais radiculares e lacunas de reabsorção do cemento e estavam associadas a desorganização das fibras colágenas e alta expressão de MMPs. A presença das MMPs em processos inflamatórios periapicais de humanos (cistos e granulomas) foi confirmada. Nos dentes com lesão periapical submetidos ao tratamento endodôntico em sessão única o desfecho do tratamento endodôntico foi caracterizado pela manutenção ou progressão da lesão periapical e alta expressão de MMPs. Por outro lado, nos dentes submetidos ao tratamento endodôntico utilizando o Ca(OH)2 como curativo de demora, maior numero de espécimes apresentaram regressão da lesão periapical e houve modulação da expressão de MMPs pelo tratamento. Neste grupo foi evidenciada neoformação de cemento no forame apical. Células do ligamento periodontal estimuladas com Ca(OH)2 expressaram proteínas especificas de cementoblastos (CEMP-1, CAP) e foram capazes de sintetizar nódulos de mineralização, mediados via ERK MAPK. A ação do Ca(OH)2 ocorreu via canais de cálcio, uma vez que o bloqueio destes canais inibiu a fosforização de ERK-1 e ERK-2 e, portanto, a expressão de CEMP-1 e CAP. CEMP-1 estimulou a migração, proliferação e mineralização mediada por células, exercendo um papel central na cementogenese, uma vez que o bloqueio de CEMP-1 inibiu a migração celular e mineralização. Juntos, estes resultados permitem concluir que a tomografia computadorizada e superior a radiografia periapical convencional para detecção de lesões periapicais refratarias ao tratamento de canais radiculares. Ainda, o tratamento endodôntico realizado utilizando o hidróxido de cálcio como curativo de demora propiciou um reparo apical e periapical mais favorável do que o tratamento endodôntico em sessão única, possivelmente devido a capacidade do Ca(OH)2 induzir a diferenciação de células do ligamento em células com um fenótipo cementoblastico e posterior mineralização.<br>Clinical diagnosis of apical periodontitis is difficult due to the intraosseous nature of the disease and radiographic evaluation does not provide sufficient information to determine a healthy apical periodontium following root canal therapy. Therefore, the aim of this study was to compare the radiographic and cone beam computed tomographic findings with microscopic evaluation following root canal treatment in dogs teeth. Then, the presence of matrix metalloproteinases (MMPs) in apical periodontitis and during the healing phase following treatment was evaluated and compared to the expression of MMPs in periapical cysts and granulomas obtained from human. Finally, the mechanisms involved in apical cementogenesis were investigated using human periodontal ligament cells. Apical periodontitis was induced in dogs teeth and then root canal treatment was performed in a single visit or using calcium hydroxide [Ca(OH)2] as the root canal dressing. Tomographic and radiographic evaluations were performed prior to and following induction of apical periodontitis, and 180 days following root canal therapy. Periapical tissues were evaluated by conventional light microscopy, immunofluorescence, immunohistochemistry, and real time RT-PCR. In vitro, periodontal ligament cells were used to evaluate the effects of Ca(OH)2 treatment on cell migration, proliferation, differentiation, and mineralization. The signaling pathways triggered by treatment with Ca(OH)2 were investigated using mitogen activated protein kinase (MAPK) biochemical inhibitors, calcium channel blockers, and extracellular regulated protein kinase (ERK-1 / ERK-2) silencing RNAs. Based on the results obtained, apical periodontitis was detected with higher sensitivity and accuracy by means of cone beam computed tomography compared to conventional periapical radiographs, using microscopic evaluation as the gold standard. Histological evaluation revealed that teeth with apical periodontitis presented microorganisms throughout the root canal system and in areas with resorption of cementum. Apical periodontitis was characterized by collagen fiber disorganization and high expression of MMPs. The presence and activity of MMPs was confirmed in periapical inflammatory diseases (cysts and granulomas) obtained from humans. Root canal treatment outcome was characterized by maintenance or progression of apical periodontitis and high expression of MMPs in teeth submitted to root canal treatment in a single visit, whereas root canal treatment outcome in teeth submitted to root canal treatment using Ca(OH)2 as the root canal dressing, higher number of teeth presented reduced apical periodontitis and lower expression of MMPs. In this group, cementum neogenesis was evident in the apical foramina. Periodontal ligament cells stimulated with Ca(OH)2 expressed cementoblastic specific proteins (CEMP-1, CAP) and were able to synthesize mineralized nodules via ERK MAPK. The effects of Ca(OH)2 occurred via calcium channels, since their blockade prevented ERK-1 and ERK-2 phosphorylation and therefore expression of CEMP-1 and CAP. CEMP-1 stimulated cell migration, proliferation, and mineralization and it was central to cementogenesis because blockade of activity of CEMP-1 prevented cell migration and mineralization. Taken together, these findings demonstrate that cone beam computed tomography is superior to conventional periapical radiography for detection of refractory apical periodontitis. Furthermore, the root canal treatment using Ca(OH)2 as the root canal dressing permitted a more favorable outcome than the root canal treatment performed in a single visit, probably due to the ability of Ca(OH)2 induce cementoblastic differentiation of periodontal ligament cells and mineralization.
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ISHIGAKI, TAKEO, MITSUHIKO HIROSE, KIYOKO NAKAMURA, MITSURU IKEDA, KENGO ITO, and NICOLAS MILLA. "FUNDAMENTAL AND CLINICAL EVALUATION OF CHEST COMPUTED TOMOGRAPHY IMAGING IN DETECTABILITY OF PULMONARY NODULE." Nagoya University School of Medicine, 1994. http://hdl.handle.net/2237/16074.
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Waraporn, Aumarm [Verfasser]. "Comparative diagnosis of Canine Elbow Dysplasia between Radiography, Computer Tomography and Arthroscopy / Waraporn Aumarm." Berlin : Freie Universität Berlin, 2008. http://d-nb.info/1022599852/34.
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Leung, Chung-Chu, and 梁中柱. "Use of generalized fuzzy operator in digital subtraction radiography." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B31245614.
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Narayanan, Barath Narayanan. "New Classifier Architecture and Training Methodologies for Lung Nodule Detection in Chest Radiographs and Computed Tomography." University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1508237793168873.
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Ved, Hetal R. "A computer-based cascaded modeling and experimental approach to the physical characterization of a clinical full-field mammography system." Link to electronic thesis, 2002. http://www.wpi.edu/Pubs/ETD/Available/etd-0920102-144012.
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Ni, Zhihong. "Computer-based Skeletal Age Assessment Using Hand/Wrist Radiographs in Children 8-18 Years Old." Wright State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=wright1284988394.
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Rohleder, Jacob John. "A comparison of radiography versus computed tomography in the diagnosis of middle ear disease in the dog." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/31965.
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The purpose of this study was to compare CT and radiography for diagnosing the presence and severity of middle ear disease in dogs with chronic otitis externa. Thirty-one dogs that were presented for a total ear canal ablation and bulla osteotomy were recruited. Three normal dogs served as controls. All dogs were examined using radiography and CT. Three radiologists independently evaluated imaging studies in random order. A visual analog scale method was used for scoring certainty and severity of middle ear disease. Surgical findings were recorded intra-operatively. Bulla lining samples were submitted for histopathology and scored by a single pathologist who also used a visual analog scale system. Findings from both modalities agreed more closely with surgical findings than with histopathology findings. With either surgery or histopathology as the gold standard, CT was more sensitive than and as specific as radiographs for predicting presence and severity of middle ear disease. Overall severity of middle ear disease was lower in the right versus the left ears. For CT, inter-observer variance of middle ear certainty was 217.04 while radiographic variance was 126.14 on the side with lower severity estimates. Both radiography and CT were more accurate for predicting the severity of the disease than its presence. Findings indicate that CT is more accurate and reliable than radiography in diagnosing middle ear disease for dogs with chronic otitis externa, but only when severity of disease is moderate or high. With low severity of disease, reader diagnostic certainty for both modalities becomes more variable.<br>Master of Science
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Harvey, Steven Brian. "Interactive computer methods for morphometric and kinematic measurement of images of the spine." Thesis, University of Aberdeen, 1999. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU116153.
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The aim of this project was to develop robust interactive computer methods for measuring the shape and movement of the lumbar spine vertebrae from lateral radiographs of the spine. In order to achieve this aim, two software packages were written - the Aberdeen Vertebral Morphometry System (AVMS) and the Aberdeen Spinal Videofluoroscopy System (ASVS). AVMS was designed to analyse static images from dual energy x-ray absorptiometry (DXA) imaging densitometers. Comparative precision tests of the ability of AVMS software and Lunar EXPERT-XL software to measure vertebral height were undertaken using four vertebrae from the same lateral spine image (male, 67 years). Two of the vertebrae in this image were abnormal and two were normal. It was concluded that AVMS had higher precision when measuring abnormal and normal vertebrae. The effects of axial rotation and lateral bending, which lead to movement out of the sagittal plane, were investigated by generating a three-dimensional computer model of two adjacent vertebrae and projecting it on to the sagittal plane. The projected model was measured as if it were a radiograph, allowing the effects of out-of-plane movement and errors in reference point placement to be calculated. ASVS was used to acquire and analyse a sequence of images of the spine in motion obtained using videofluoroscopy and incorporated the findings of the computer modelling work. A clinical study for the measurement of intervertebral motion using ASVS during flexion-extension was organised and seven subjects suffering from severe lower back pain were recruited. Analysis of the image sequences using the computerised measurement system in ASVS revealed the apparent effect of analgesia/sedative on the shape and size of centroidal trajectories of vertebrae, and the differences in trajectory shape between subjects. It was concluded that ASVS was able to quantify spinal motion at a minimal radiation dose to the subject.
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Jeffery, Nathan. "Computer assisted tutoring in radiology." Thesis, De Montfort University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391237.
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Wilson, Katharine Joan. "Assessing the accuracy of using biplanar radiography combined with computed tomography to estimate cartilage deformation in the hip." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/37664.
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Excessive or abnormal joint loading that leads to cartilage degeneration has been associated with hip osteoarthritis (OA). Before preventative measures for OA can be designed, such as physiotherapy techniques, braces, or surgical interventions, the connection between load-bearing and cartilage degeneration needs to be validated experimentally. As a first step towards such a validation, a method of measuring the load distribution across the hip joint is needed; ideally that can be used in vivo and can detect changes in the load distribution during an applied load. The objective of this study was to assess the accuracy of using biplanar radiography combined with CT imaging to estimate hip cartilage strain across the joint as an indication of the load distribution.
Estimating cartilage strain using biplanar radiography and CT imaging is a multi-device multi-step measurement protocol that has error associated with each step. While biplanar radiography systems are commonly assessed on their ability to measure radio-opaque bead locations, to the author’s knowledge no studies have quantified errors in the additional steps of estimating cartilage strain. The present study used a phantom hip joint to quantify the errors in measuring bone displacement with biplanar radiography, segmenting 3D joint surfaces from a CT image, and measuring the relative proximity of joint surfaces in the biplanar radiography coordinate frame. The quantified errors were much lower than ex vivo hip cartilage deformation results in the literature, which demonstrated the potential for using this technique to estimate cartilage strain in the hip.
As a proof of concept, cartilage strain was estimated in the ex vivo hip joint during a compressive load. Two hemi-pelvis/proximal femur specimens, with radio-opaque beads inserted in each bone, were loaded in compression in a materials testing machine, with biplanar radiographs acquired throughout. A small amount of cartilage deformation (0.1mm) was detected across the hip joint; however, due to the low load applied the deformation results were not comparable to the literature. The largest cartilage strains were identified in the anterior and superior regions, which was consistent with the literature. Future studies using higher loads are needed to further assess the capabilities of our system.
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Alenazi, Khaled. "Comparison between the alpha angle of the maxillary impacted canines on panoramic radiographs and cone beam computed tomography." University of the Western Cape, 2019. http://hdl.handle.net/11394/7069.
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Magister Chirurgiae Dentium (MChD)<br>There is a paucity of studies that make use of the alpha angle as a diagnostic tool to assist with
the interceptive treatment, prognosis, treatment duration and surgical outcome of possible
maxillary canine impaction in orthodontics. While the literature is replete with studies that
utilise the sector method, the alpha angle is an alternative approach to assess the possible
eruptive outcome of the unerupted canine.
It has been reported that if the alpha angle is greater than 25°, there is the possibility of external
root resorption. However, if the alpha angle is more than 31°, the prospect of canine eruption
decreases even if the deciduous canine is extracted as an interceptive measure.
The dental pantomograph has historically been used to predict canine eruption or possible
impaction. The use of this method, however, is wrought with limitations. These limitations
include magnification, distortion and blurred images. The use of cone-beam computed
tomography has been advocated as a means to overcome these limitations.
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Ullman, Gustaf. "Quantifying image quality in diagnostic radiology using simulation of the imaging system and model observers." Doctoral thesis, Linköping : Department of Medicine and Health, Linköping University, 2008. http://www.bibl.liu.se/liupubl/disp/disp2008/med1050s.pdf.
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Rabbani, Seyedeh Parisa. "Effect of image variation on computer aided detection systems." Thesis, KTH, Skolan för teknik och hälsa (STH), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-123546.
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Computer Aided Detection (CAD) systems are expecting to gain significant importance in terms of reducing the work load of radiologists and enabling the large screening programs. A large share of CAD systems are based on learning from examples, to enables the decision making between the images with or without disease. Images are simplified to numerical descriptors (features vectors) and the system is trained with these features. The common practical problem with CAD systems is training the system with a data from a specific source and testing it on a data from a different source; the variations between sources usually affect the CAD system function. The possible solutions for this problem are (1) normalizing images to make them look more equal, (2) choosing less variation sensitive features and (3) modifying the classifier so that it classifies the data from different sources more accurately. In this project the effect of image variations on the developed CAD system on chest radio graphs for Tuberculosis is studied at Diagnostic Image Analysis Group. Tuberculosis is one of the major healthcare problems in some parts of the world (1.3 million deaths in 2007) [1]. Although the system has a great performance on the train and test data from the same source, using different sub dataset for training and testing the system does not lead to the same result. To limit the effect of image variation of the CAD systems three different approaches are applied for normalizing the images: (1) Simple normalization, (2) local normalization and (3) multi band local normalization. All three approaches enhance the performance of the system in case of various sub datasets for training and testing purposes. According to the improvement achieved by applying normalization it is suggested as a solution for the stated problem above. Although the outcome of this study has satisfactory result, there is always room for further investigations and studies; in specific testing different approaches for finding less variation sensitive features and modifying the classification procedure to a more variation tolerant process.
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Zhang, Hui. "Temporal subtraction of chest radiograph using graph cuts and free-form deformations." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/b40203451.
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