Abstract Today, the diagnosis of osteoporosis and assessment of fracture risk is based on estimation of bone mineral density (BMD) determined by dual-energy X-ray absorptiometry (DXA). A lack has been shown in the prediction of individual fracture risk using DXA-based BMD (BMDDXA). Digital radiography (DR) has eased the application of dual-energy techniques for separating bone and soft tissue, but the direct application of dual-energy digital radiography (DEDR) to determine BMD has not been investigated. Additionally, with BMD and bone mass, bone geometry affects strongly the mechanical strength of bone. Geometrical parameters can also be determined from the DR images. This study aimed to investigate the ability of DEDR to determine BMD and whether the combination of DEDR-based BMD and geometry improves the prediction of maximal load. Fracture and osteoporosis diagnoses could thus be done with one examination, i.e. with DEDR, whereas in the current routine both DR imaging and DXA examination are needed for diagnoses. Reindeer femora were imaged by DR with two different energies (79 and 100 kVp). The different geometrical parameters were also determined from the 79 kVp images. The BMD measured by DEDR (BMDDEDR) were calculated using the calculation principle of DXA. The ability of BMDDEDR to predict BMDDXA was investigated. The femora were mechanically tested in an axial loading configuration with the shaft in a vertical position to determine mechanical parameters. The best combination of BMDDEDR and geometrical parameters to predict bone maximal load was explored. BMDDXA was used for comparison. Significant moderate to high linear correlations were observed in all regions of the upper femur (femoral neck, Ward’s triangle, trochanter and inter-trochanter) between BMDDEDR and BMDDXA. BMDDEDR of the femoral neck and BMDDXA of the femoral neck predicted maximal load similarly. The best combination of parameters to predict maximal load was BMDDEDR at Ward’s triangle, femoral shaft diameter (FSD) and femoral shaft axis length (FNAL) (r = 0.79, p < 0.05). The study shows that DEDR is a suitable method to determine BMD in vitro and the combination of BMD and geometry improves the prediction of bone maximal load when compared to BMDDEDR of femoral neck or trochanter only. The thesis also includes unpublished data from a preliminary human study. / Tiivistelmä Osteoporoosin diagnosointi ja murtumariskin määrittäminen perustuvat kaksienergisellä röntgenabsorptiometrialla (DXA) mitattavaan luun mineraalitiheyden (BMD) arviointiin. DXA:lla määritetyn luun mineraalitiheyden (BMDDXA) on kuitenkin osoitettu olevan puutteellinen murtumariskin yksilöllisessä ennustamisessa. Digitaalinen röntgenkuvaus (DR) on helpottanut sellaisten kaksienergisten tekniikoiden toteuttamista, joissa luu ja pehmytkudos on eroteltu toisistaan. Kaksienergisen digitaalisen röntgenkuvausmenetelmän (DEDR) soveltamista BMD:n määrittämiseen ei ole tutkittu. BMD:n ja luun massan lisäksi on luun geometrialla vahva vaikutus luun mekaaniseen lujuuteen. Geometriset parametrit voidaan määrittää niin ikään digitaalisista röntgenkuvista. Tässä työssä tutkittiin, pystytäänkö DEDR:llä määrittämään BMD sekä parantaako DEDR:llä mitattujen BMD:n ja geometrian yhdistelmä luun maksimikuormituksen ennustetta. Näin ollen murtuma- ja osteoporoosidiagnoosit voitaisiin tehdä yhdellä tutkimuksella (DEDR), kun nykyisin diagnoosit vaativat sekä digitaalisen röntgenkuvauksen että DXA-tutkimuksen. Poron reisiluut kuvattiin digitaalisen röntgenlaitteen kahdella eri kuvausjännitteellä (79 ja 100 kVp). 79 kVp -kuvista määritettiin myös erilaiset geometriaparametrit. BMD laskettiin DEDR-kuvista (BMDDEDR) DXA:n laskentaperiaatetta käyttäen. BMDDEDR:n kyky ennustaa BMDDXA:a tutkittiin. Maksimikuormituksen selvittämiseksi reisiluut testattiin mekaanisesti aksiaalisuunnassa varren ollessa pystysuorassa asennossa. BMDDEDR- ja geometriaparametreista määritettiin paras yhdistelmä maksimikuorman ennustamiseen. BMDDXA-arvoja käytettiin analysoinnissa vertailun vuoksi. BMDDEDR- ja BMDDXA-arvojen välillä havaittiin merkitsevä keskinkertainen tai korkea korrelaatio kaikissa mielenkiintoalueissa (reisiluun kaula, Wardin kolmio, sarvennoisen alue ja reisiluun varren alue). Wardin kolmiosta mitatun BMD:n (WABMDDEDR), reisiluun varren halkaisijan (FSD) ja reisiluun kaulan kautta kulkevan akselin (FNAL) yhdistelmä ennusti parhaiten luun haurautta (r = 0.79, p < 0.05). Tutkimus osoittaa, että DEDR on sopiva menetelmä BMD:n määrittämiseen tutkimusolosuhteissa ja että BMD:n ja geometrian yhdistelmä parantaa maksimikuormituksen ennustetta pelkästään reisiluun kaulasta tai sarvennoisesta mitattuun BMDDEDR:iin verrattuna. Väitöskirja sisältää myös julkaisemattomia tuloksia alustavista ihmistutkimuksista.

[pt] Ensaios não-destrutivos são técnicas utilizadas na inspeção de materiais e equipamentos sem danificá-los, sendo executados nas etapas de fabricação, construção, montagem e manutenção. Constituem uma das principais ferramentas do controle e garantia da qualidade de materiais e produtos, sendo largamente utilizados nos setores petróleo/petroquímico, químico, aeronáutico, aeroespacial, siderúrgico, naval, eletromecânico, papel e celulose, entre outros. Representam métodos capazes de proporcionar informações sobre defeitos, características tecnológicas do material, ou ainda, monitoração da degradação em serviço de componentes, equipamentos e estruturas, o que permite o uso de ações de extensão de suas vidas úteis. O objetivo desta pesquisa foi comparar a adequação de diferentes técnicas não destrutivas na detecção e estimativa da dimensão de trincas de fadiga, nucleadas e propagadas intencionalmente, em material estrutural. Para tal, corpos de provas cilíndricos do aço 42CrMo4 com um entalhe em V sofreram carregamentos cíclicos até diferentes números de ciclos, o que proporcionou diferentes tamanhos de trinca. O comprimento das trincas passantes foi monitorado por meio de lupa posicionada na lateral do corpo de prova. Após a etapa de nucleação e propagação das trincas de fadiga, todos os corpos de prova foram inspecionados com emprego das técnicas de Ultrassom Convencional, Ultrassom Phased Array e Radiografia Digital, para permitir a indicação das trincas de fadiga e o estabelecimento de suas dimensões. Terminada as inspeções, os corpos de prova foram resfriados em nitrogênio líquido e fraturados com aplicação de uma carga de flexão, o que permitiu a visualização das superfícies das trincas. Em seguida, as trincas foram medidas visualmente com o auxílio de uma lupa, o que permitiu comparar as indicações (virtual) de defeitos nos corpos de prova com a existência (real) dos mesmos e, ainda correlacionar as dimensões indicadas nas inspeções com aquelas medidas nas superfícies das trincas. Neste contexto, todas as técnicas se mostraram adequadas para a indicação de defeitos. Além disso, para trincas curtas, o Ultrassom Phased Array foi a técnica que apresentou a melhor suscetibilidade para o dimensionamento de descontinuidades, enquanto que a Radiografia Digital se mostrou mais eficiente para trincas mais longas. / [en] Non-destructive tests are techniques used in material and equipment inspection without permanent damage, applied in the stages of manufacture, construction, assembly and maintenance. They are one of the main tools to control and insure the quality of materials and products, with widely applications in oil / petrochemical, chemical, aeronautical, aerospace, steel industry, naval, electromechanical industries. They represent with capacity of providing information about defects, technological characteristics of the material, or monitoring the degradation in service of components, equipment and structures, which allows the use of useful live extensions in service. The objective of this research was to compare the application of different non-destructive techniques in the detection and size estimation of fatigue cracks, nucleated and propagated intentionally, in structural material. For this purpose, cylindrical specimens of 42CrMo4 steel with a V-notch were subjected to cyclic loading with different cycle numbers, which provided different crack sizes. The length of the cracks was monitored by a magnifying glass positioned on the specimen surface. After the crack nucleation and propagation, all specimens were subjected to non-destructive tests making use of Conventional Ultrasound, Phased Array Ultrasound and Digital Radiography, in order to provide crack indications and crack dimensions. After the inspections, the specimens were cooled down in nitrogen and fractured in three point bending to promote opened crack surfaces. In the sequence, the cracks were measured using a magnifying glass, which allowed a comparison between the indicated and measured defects. In this context, all techniques were adequate for crack indications. On the other hands, for short cracks, the Phased Array Ultrasound was the technique that presented the best susceptibility for estimate the discontinuity dimensions, while Digital Radiography proved to be more efficient for longer cracks.

Implementation of electronic health records by the Health Information Technology for Economic and Clinical Health has led to the implementation of electronic dental records (EDRs) and digital radiography in dental offices. The purpose of this study was to determine the state of the implementation and usage of EDRs and digital radiographs by the private general and pediatric dental practices in Mississippi as well as reasons why the dental practices are not moving forward with the advanced technology. A survey was emailed to 712 dental practices: 116 responded (16% response rate), and 104 consented to participate (89.66%). Results indicated dental practices in Mississippi using EDRs was 46.07%, EDRs with paper records was 42.70%, and only paper records was 11.24%. Results indicated dental practices using digital radiography was 76.40%, conventional radiography was 13.48%, and both was 10.11%. Common reasons for not advancing were cost, insufficient training, computer/software issues, and “too old.”

This paper describes a MATLAB application with the main purpose of the simulation of noise components and noise elimination methods of Digital Radiography. The main parts of simulator are the model of a scene, procedures for loading the noise components to image data and methods for image processing. Various methods are employed depending on the type of noise. Subtraction techniques are used for the elimination of structural noise. The physical noise suppression is obtained using several methods of cumulation and Pixel Shift is used to reduce motion artifacts caused by the existence of moving noise. The techniques of superposition highlight the areas of interest in an image. Included are also auxiliary procedures for simulator running and presentation of final data. The model and the presented application can be used mainly for educational purposes as a powerful didactic tool.

Indiana University-Purdue University Indianapolis (IUPUI) / Accurate determination of working length during endodontic therapy is a crucial step in achieving a predictable outcome. This is determined by the use of electronic apex locators, tactile perception, and knowledge of average tooth lengths and/or dental radiography whether digital or conventional is utilized. It is the aim of this study to determine if there is a difference between Schick digital radiography and Kodak Insight conventional film in accurately determining working lengths when modifying exposure time and source-film/sensor distance. Twelve teeth with size 15 K-flex files at varying known lengths from the anatomical apex were mounted in a resin-plaster mix to simulate bone density. Each tooth was radiographed while varying the source-film/sensor distance and exposure 122 time. Four dental professionals examined the images and films independently. Ten images and 10 films were selected at random and re-examined to determine each examiner?s repeatability. The error in working length was calculated as the observed value minus the known working length for each tooth type. A mixed-effects, full-factorial analysis of variance (ANOVA) model was used to model the error in working length. Included in the ANOVA model were fixed effects for type of image, distance, exposure time, and all two-way and three-way interactions. The repeatability of each examiner for each film type was assessed by estimating the intra-class correlation coefficient (ICC). The repeatability of each examiner on digital film was good with ICCs ranging from 0.67 to 1.0. Repeatability on the conventional film was poor with ICCs varying from -0.29 to 0.55.We found there was an overall difference between the conventional and digital films (p < 0.001). After adjusting for the effects of distance and exposure time, the error in the working length from the digital image was 0.1 mm shorter (95% CI: 0.06, 0.14) than the error in the working length from the film image. There was no difference among distances (p = 0.999) nor exposure time (p = 0.158) for film or images. Based on the results of our study we conclude that although there is a statistically significant difference, there is no clinically significant difference between digital radiography and conventional film when exposure time and source-film/sensor distance are adjusted.

In einer initialen Studie verglichen wir das XQi Revolution, welches auf indirektem CsI (Cäsium Iodit) /a: Si (amorphes Silizium) basiert mit einem direkten Digitalröntgengerät a: SE (amorphes Selen) an einem CDRAD-Phantom bei vier unterschiedlichen Eintrittsdosen und an einem TRG-Phantom bei zwei unterschiedlichen Eintrittsdosen. Mittels des berechneten Bildqualitätsfaktors des CDRAD-Phantoms konnten wir zeigen, daß das indirekte im Vergleich zum direkten System bei niedrigeren Dosen eine bessere Detailerkennungsrate aufweist. Ein positiver Trend läßt sich auch beim TRG-Phantom darstellen. In einer weiteren Studie untersuchten wir anhand von Patientenbildern die Bildqualität des Dual Energy Systems bei zwei unterschiedlichen Dosisniveaus, der Standarddosis sowie einer doppelten Dosis, was einem Speed-Äquivalent von 400/1000 bzw. 200/500 entspricht. Bei hoher Dosis konnten wir eine signifikante Reduktion des Rauschens im Knochen- und Weichteilbild feststellen, gleichzeitig nahmen die Störungen durch Bewegungsartefakte signifikant zu. Im Anschluß verglichen wir die Erkennbarkeit verkalkter Lungenpathologien im Standard P/A Bild mit zusätzlichem Einsatz von Dual Energy. Als Goldstandard erfolgte der sichere Nachweis der Pathologien im CT. Bei zusätzlichem Einsatz von Dual Energy konnten wir eine signifikante Steigerung der Sensitivität erkennen. Dieses Ergebnis wurde durch den Qualitätsfaktor, der die Bildeigenschaften kumulativ beschreibt, bestätigt. Weiterhin untersuchten wir analog die Erkennbarkeit von nichtverkalkten Lungenrundherden. Auch bei diesen Pathologien ließ sich ein positiver Trend der Sensitivität und Spezifität bei zusätzlichem Einsatz von Dual Energy erkennen. Zusätzlich stieg die durchschnittliche Entscheidungssicherheit der Gutachter signifikant an. Damit bietet die Dual Energy Subtraktionstechnik eine wertvolle Ergänzung in der Diagnostik verkalkter und nichtverkalkter Lungenpathologien eine wertvolle Ergänzung zum Standardröntgen. / First study assess and quantify the image quality at two dose levels for an amorphous Silicon (a:Si) Cesium Iodide (CsI) flat panel system compared with a direct amorphous Selenium (a:Se) digital radiography system. Image quality of a:Si flat panel digital radiography proved to be superior to a:Se drum digital radiography using low-dose settings. Second study assess the image quality of subtracted soft tissue and bone images of a CsIdetector-based dual-energy system for chest radiography at varying dose levels. Radiation dose did not significantly influence the perception of dual-energy image quality. Next study assess the value of dual-energy chest radiography obtained using a cesium iodide flat-panel detector in addition to standard posteroanterior chest radiography for the detection of calcified chest abnormalities. When dual-energy images were added, sensitivity increased significantly. Brunner and Langer’s test revealed a highly significant difference between posteroanterior chest radiography and dual-energy imaging in the detection of calcified chest abnormalities. Dual-energy images added to standard posteroanterior chest radiographs significantly improve the detection of calcified chest lesions. Last study compare the sensitivity and specificity of digital chest radiography alone with digital chest radiography combined with dual-energy chest radiography in the detection of small non-calcified pulmonary nodules. Standard and dual-energy radiographs were obtained with a flat-panel digital chest system. The increase of nodule detection overall as well as for different size categories was significant. The increase of the confidence level rating was also significant. Dual energy added to standard posteroanterior chest radiography significantly improves the sensitivity, specificity, and confidence in detection of small non-calcified pulmonary nodules. Dual-energy subtraction has the potential to become a future routine application in chest radiography.