Amorphous selenium based digital radiography has attracted much attention because of selenium's high X-ray absorption and excellent charge transport properties, and the ability to be created thick (typically 100 to 1000 micron) uniform layers over a large area (typically 30 cm X 30 cm) at low processing temperatures (typically at around 50 degree C substrate temperature). In this work, the excess noise in amorphous selenium has been studied. A number of device parameters were altered to study the noise characteristics, such as the metal of the electrodes, bulk material composition, device volume, surface conditions and substrate temperature. All the samples had a transverse geometry with 20 to 200- micron thick layers of amorphous selenium electroded with metal at the top and at the bottom. Sample devices were fabricated by conventional vacuum deposition.<p> Noise power was measured over a limited bandwidth of 1 kHz. The fluctuations for one sample amounted to 1% of the bias current. The excess noise was mainly 1/<i>f</i> noise with the slope ranging from -0.77 to -1.4. Interpretation of the noise spectra was complicated due to the samples' highly non-linear I-V relation and long time transients.<p> The metals of the electrode clearly showed a large effect on both the magnitude and shape of the noise spectrum. Of the metals studied, aluminum produced the least normalized noise and platinum the most. The addition of arsenic caused a decrease in the normalized noise. An additional 0.2% (% wt.) arsenic decreased the 1/<i>f</i> noise magnitude by more than a decade, but did not change the slope. The addition of chlorine did not affect the noise magnitude. Amorphous selenium is quite vulnerable to stress and in particular, external mechanical stress causes crystallization. The surface of the sample was gently abraded, applying the least possible amount of stress to the selenium layer. A change in the surface condition before the top electrode was deposited showed that a roughened surface decreased the noise magnitude substantially. These results strongly indicate that the noise is controlled by the metal-semiconductor interface.<p> Noise characteristics in multilayered samples were examined. The p-i-n and n-i-p structures consisted of 200 micron i-layer with 2 to 6 micron p- and n-like layers. The noise fluctuation in the current are typical of 1/<i>f</i> noise showing a power-law spectrum with slopes between -0.9 to -1.1. These samples showed a substantial decrease in the noise power compared to single layer samples; the additional n-like and p-like layers acted as carrier sources so that the current was not controlled by the metal interface. Hence, the measurements are closer to the intrinsic noise of a-Se. After exposure to 14 R (Roentgen) of X-rays, the normalized noise decreased by a factor of 1.6 for the n-i-p structure.

Amorphous selenium based digital radiography has attracted much attention because of selenium's high X-ray absorption and excellent charge transport properties, and the ability to be created thick (typically 100 to 1000 micron) uniform layers over a large area (typically 30 cm X 30 cm) at low processing temperatures (typically at around 50 degree C substrate temperature). In this work, the excess noise in amorphous selenium has been studied. A number of device parameters were altered to study the noise characteristics, such as the metal of the electrodes, bulk material composition, device volume, surface conditions and substrate temperature. All the samples had a transverse geometry with 20 to 200- micron thick layers of amorphous selenium electroded with metal at the top and at the bottom. Sample devices were fabricated by conventional vacuum deposition.<p> Noise power was measured over a limited bandwidth of 1 kHz. The fluctuations for one sample amounted to 1% of the bias current. The excess noise was mainly 1/<i>f</i> noise with the slope ranging from -0.77 to -1.4. Interpretation of the noise spectra was complicated due to the samples' highly non-linear I-V relation and long time transients.<p> The metals of the electrode clearly showed a large effect on both the magnitude and shape of the noise spectrum. Of the metals studied, aluminum produced the least normalized noise and platinum the most. The addition of arsenic caused a decrease in the normalized noise. An additional 0.2% (% wt.) arsenic decreased the 1/<i>f</i> noise magnitude by more than a decade, but did not change the slope. The addition of chlorine did not affect the noise magnitude. Amorphous selenium is quite vulnerable to stress and in particular, external mechanical stress causes crystallization. The surface of the sample was gently abraded, applying the least possible amount of stress to the selenium layer. A change in the surface condition before the top electrode was deposited showed that a roughened surface decreased the noise magnitude substantially. These results strongly indicate that the noise is controlled by the metal-semiconductor interface.<p> Noise characteristics in multilayered samples were examined. The p-i-n and n-i-p structures consisted of 200 micron i-layer with 2 to 6 micron p- and n-like layers. The noise fluctuation in the current are typical of 1/<i>f</i> noise showing a power-law spectrum with slopes between -0.9 to -1.1. These samples showed a substantial decrease in the noise power compared to single layer samples; the additional n-like and p-like layers acted as carrier sources so that the current was not controlled by the metal interface. Hence, the measurements are closer to the intrinsic noise of a-Se. After exposure to 14 R (Roentgen) of X-rays, the normalized noise decreased by a factor of 1.6 for the n-i-p structure.

Digital radiography systems are important diagnostic tools for modern medicine. The images are produced when x-ray sensitive materials are coupled directly onto the sensing element of the detector panels. As a result, the size of the detector panels is the same size as the x-ray image. An alternative to the modern DR system is to image the x-ray phosphor screen with a lens onto a digital camera. Potential advantages of this approach include rapid readout, flexible magnification and field of view depending on applications. We have evaluated lens-coupled DR systems for the task of signal detection by analyzing the covariance matrix of the images for three cases, using a perfect detector and lens, when images are affected by blurring due to the lens and screen, and for a signal embedded in a complex random background. We compared the performance of lens-coupled DR systems using three types of digital cameras. These include a scientific CCD, a scientific CMOS, and a prosumer DSLR camera. We found that both the prosumer DSLR and the scientific CMOS have lower noise than the scientific CCD camera by looking at their noise power spectrum. We have built two portable low-cost DR systems, which were used in the field in Nepal and Utah. We have also constructed a lens-coupled CT system, which included a calibration routine and an iterative reconstruction algorithm written in CUDA.

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.

Thesis (M.S.D.)--Indiana University School of Dentistry, 2009. / Title from PDF t.p. (viewed Aug. 11, 2009) Advisors: Mychel Vail, Chair of the Research Committee, Susan Zunt, Ted Parks, Kenneth Sponik, Joseph Legan. Curriculum vitae. Includes abstract. Includes bibliographical references (leaves 103-119).

Submitted by Suelen Reis (suziy.ellen@gmail.com) on 2013-04-23T17:02:51Z No. of bitstreams: 1 Dissertacao Eugenio Leite.pdf: 1280278 bytes, checksum: f23be710eb7acbb9dbe2cb1e282c5193 (MD5) / Approved for entry into archive by Rodrigo Meirelles(rodrigomei@ufba.br) on 2013-05-08T12:12:19Z (GMT) No. of bitstreams: 1 Dissertacao Eugenio Leite.pdf: 1280278 bytes, checksum: f23be710eb7acbb9dbe2cb1e282c5193 (MD5) / Made available in DSpace on 2013-05-08T12:12:19Z (GMT). No. of bitstreams: 1 Dissertacao Eugenio Leite.pdf: 1280278 bytes, checksum: f23be710eb7acbb9dbe2cb1e282c5193 (MD5) Previous issue date: 2006 / A fenda alveolar é um distúrbio congênito que afeta crianças em todas as partes do mundo, trazendo comprometimentos funcional, estético e social. Diversos estudos têm avaliado as diferentes técnicas cirúrgicas para a reabilitação destes pacientes, sendo que a maioria utiliza critérios clínicos ou a radiografia convencional para analisar seu resultado terapêutico. Este trabalho teve como objetivo avaliar longitudinalmente o enxerto de crista ilíaca no tratamento de fenda alveolar unilateral, empregando análises quantitativas do tecido ósseo em radiografias digitalizadas. A amostra foi constituída por dez (10) indivíduos (seis (6) do gênero masculino e quatro (4) do gênero feminino), com idade entre 5 e 15 anos, operados por um mesmo cirurgião, no Hospital Santo Antônio (HSA) – Obras Sociais Irmã Dulce (OSID) (SSA-BA), utilizando a crista ilíaca como área doadora dos enxertos. Foram obtidas radiografias periapicais pré e pós-operatórias imediatas e tardias, que foram digitalizadas e corrigidas no programa Photoshop®, e posteriormente analisadas no programa ImageTool®. Os resultados mostraram que a técnica utilizada preencheu adequadamente a área da fenda e que este preenchimento manteve-se estável no pós-operatório tardio. / Salvador

Made available in DSpace on 2014-06-11T19:33:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-08-29Bitstream added on 2014-06-13T20:05:24Z : No. of bitstreams: 1 sakakura_ce_dr_arafo.pdf: 1061463 bytes, checksum: 369280e6910c622911b9659ba1e551ac (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Agentes imunossupressores provocam alterações severas no metabolismo ósseo mineral podendo resultar em osteopenia. Tais alterações podem ser prejudiciais no processo e manutenção da osseointegração. Este estudo teve o objetivo de avaliar a influência da administração de ciclosporina-A (CSA) na osseointegração de implantes de titânio, através da avaliação: durante a cicatrização óssea ao redor de implantes dentais (Estudo I); da densidade óssea ao redor implantes dentais (Estudo II); da retenção do implante após a cicatrização óssea de implantes dentais (Estudo III) e radiográfica da qualidade óssea ao redor de implantes dentais já osseointegrados (Estudo IV). Os resultados permitiram concluir que a administração de CSA durante a cicatrização óssea resulta em diminuição da osseointegração e da densidade óssea ao redor do implante dental. Ainda, a administração de CSA após o período de cicatrização óssea ao redor do implante reduz a sua retenção mecânica ao tecido ósseo e promove a diminuição da qualidade e da densidade óssea radiográfica ao redor do implante dental. / Immunosupressive agents may induce severe changes on bone mineral metabolism resulting in osteopenia. These alterations may impair the osseointegration processes. The purposes of this study were evaluate the cyclosporin-A (CSA) influence: on bone healing around dental implants (Study I); on bone density around dental implants (Study II); on mechanical retention of dental implants integrated to the bone (Study III) and on radiographic bone density and quality around dental implants integrated to the bone (Study IV). The CSA administration may impair the osseointegration and bone density during the bone healing. Besides, the administration of CSA after bone healing may impair the dental implant mechanical retention and decrease the radiographic bone density and bone quality around dental implants integrated to the bone.

Made available in DSpace on 2014-06-11T19:24:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-03-24Bitstream added on 2014-06-13T19:52:06Z : No. of bitstreams: 1 carvalho_fb_me_arafo.pdf: 565333 bytes, checksum: 1218d203c1a346abccf56852aac282d9 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo desse estudo foi avaliar as alterações radiográficas de lesões periapicais, nos períodos de proservação de 0, 2, 4 e 6 meses após o tratamento endodôntico, por meio da subtração radiográfica digital realizada pelo programa Adobe Photoshop 6.0, e da demarcação de seus limites externos na tela do computador utilizando o programa VixWin 2000. E em seguida, fazer uma comparação entre as áreas de reparação ou perda óssea visualizadas nos dois programas. Foram utilizados 13 dentes anteriores de humanos com necrose pulpar e lesão periapical crônica, que foram tratados endodonticamente. Após o tratamento endodôntico, para realização da radiografia final, foi utilizada uma técnica para padronização das imagens que consistiu no uso de um posicionador para filmes radiográficos, o qual foi estabilizado com material de impressão (silicona) colocado sobre os bordos incisais dos dentes radiografados. Para as radiografias de proservação realizadas 2, 4 e 6 meses após o tratamento endodôntico foi utilizado o mesmo método. Os filmes radiográficos foram processados automaticamente, digitalizados por meio de um scanner, e em seguida feita a subtração digital. As imagens digitalizadas de 0, 2, 4 e 6 meses, foram importadas para o programa VixWin 2000 para que os limites externos das lesões periapicais nos diferentes períodos de proservação fossem delimitados por dois examinadores. As imagens geradas pela subtração digital também foram levadas para o programa VixWin 2000 para que as áreas das alterações radiográficas fossem delimitadas pelos examinadores. Os resultados mostraram uma correlação não significante entre as medidas das áreas de reparação ou perda óssea detectadas pelos dois programas (o coeficiente de correlação intraclasse variou de 0,02 a 0,45)... / The aim of this study was to evaluate the radiographics changes of periapical lesions in the follow-up periods of 0, 2, 4 and 6 months after endodontic treatment using digital subtracted radiography in the software Adobe Photoshop 6.0 and by delimiting yours edges with a pointing device in the software VixWin 2000. The comparison of the areas of repair or bone loss visualized in the two softwares was also evaluated. It were used 13 human teeth with no pulp vitality and chronic periapical lesion that were root canal treated. After the root canal treatment standardized periapical radiographs were obtained immediately postoperatively and at 2, 4, and 6 months using individualized silicone bit blocks and Rinn XCP film holder. Each periapical radiographs were automatic processing, digitized by a scanner and then subtracted. The digitized radiographic images of 0, 2, 4 and 6 months after root canal treatment were imported to the software VixWin 2000 in order to the edges of the periapical lesions were drawn with a pointing device for two examiners. The subtracted digital images were also imported to the software VixWin 2000 in order to the areas of repair or bone loss were drawn by the examiners. The results showed no significant correlation between the measure of the areas of repair or bone loss visualized in the two softwares (the intraclass correlation coefficient varied from 0,02 to 0,45). The results of interexaminer assessment demonstrated a significant correlation between the measure of the areas of repair or bone loss detected by the two examiners in the softwares (the intraclass correlation coefficient varied from 0,82 to 0,99). The bone repair was detected in all periodos of follow-up, been more evident in the period from the final of root canal tretament and two months of follow-up.

Orientador: Marcelo Gonçalves / Banca: Mário Tanomaru Filho / Banca: Eduardo Kazuo Sannomiya / Resumo: O objetivo desse estudo foi avaliar as alterações radiográficas de lesões periapicais, nos períodos de proservação de 0, 2, 4 e 6 meses após o tratamento endodôntico, por meio da subtração radiográfica digital realizada pelo programa Adobe Photoshop 6.0, e da demarcação de seus limites externos na tela do computador utilizando o programa VixWin 2000. E em seguida, fazer uma comparação entre as áreas de reparação ou perda óssea visualizadas nos dois programas. Foram utilizados 13 dentes anteriores de humanos com necrose pulpar e lesão periapical crônica, que foram tratados endodonticamente. Após o tratamento endodôntico, para realização da radiografia final, foi utilizada uma técnica para padronização das imagens que consistiu no uso de um posicionador para filmes radiográficos, o qual foi estabilizado com material de impressão (silicona) colocado sobre os bordos incisais dos dentes radiografados. Para as radiografias de proservação realizadas 2, 4 e 6 meses após o tratamento endodôntico foi utilizado o mesmo método. Os filmes radiográficos foram processados automaticamente, digitalizados por meio de um scanner, e em seguida feita a subtração digital. As imagens digitalizadas de 0, 2, 4 e 6 meses, foram importadas para o programa VixWin 2000 para que os limites externos das lesões periapicais nos diferentes períodos de proservação fossem delimitados por dois examinadores. As imagens geradas pela subtração digital também foram levadas para o programa VixWin 2000 para que as áreas das alterações radiográficas fossem delimitadas pelos examinadores. Os resultados mostraram uma correlação não significante entre as medidas das áreas de reparação ou perda óssea detectadas pelos dois programas (o coeficiente de correlação intraclasse variou de 0,02 a 0,45)... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this study was to evaluate the radiographics changes of periapical lesions in the follow-up periods of 0, 2, 4 and 6 months after endodontic treatment using digital subtracted radiography in the software Adobe Photoshop 6.0 and by delimiting yours edges with a pointing device in the software VixWin 2000. The comparison of the areas of repair or bone loss visualized in the two softwares was also evaluated. It were used 13 human teeth with no pulp vitality and chronic periapical lesion that were root canal treated. After the root canal treatment standardized periapical radiographs were obtained immediately postoperatively and at 2, 4, and 6 months using individualized silicone bit blocks and Rinn XCP film holder. Each periapical radiographs were automatic processing, digitized by a scanner and then subtracted. The digitized radiographic images of 0, 2, 4 and 6 months after root canal treatment were imported to the software VixWin 2000 in order to the edges of the periapical lesions were drawn with a pointing device for two examiners. The subtracted digital images were also imported to the software VixWin 2000 in order to the areas of repair or bone loss were drawn by the examiners. The results showed no significant correlation between the measure of the areas of repair or bone loss visualized in the two softwares (the intraclass correlation coefficient varied from 0,02 to 0,45). The results of interexaminer assessment demonstrated a significant correlation between the measure of the areas of repair or bone loss detected by the two examiners in the softwares (the intraclass correlation coefficient varied from 0,82 to 0,99). The bone repair was detected in all periodos of follow-up, been more evident in the period from the final of root canal tretament and two months of follow-up. / Mestre

Resumo: Agentes imunossupressores provocam alterações severas no metabolismo ósseo mineral podendo resultar em osteopenia. Tais alterações podem ser prejudiciais no processo e manutenção da osseointegração. Este estudo teve o objetivo de avaliar a influência da administração de ciclosporina-A (CSA) na osseointegração de implantes de titânio, através da avaliação: durante a cicatrização óssea ao redor de implantes dentais (Estudo I); da densidade óssea ao redor implantes dentais (Estudo II); da retenção do implante após a cicatrização óssea de implantes dentais (Estudo III) e radiográfica da qualidade óssea ao redor de implantes dentais já osseointegrados (Estudo IV). Os resultados permitiram concluir que a administração de CSA durante a cicatrização óssea resulta em diminuição da osseointegração e da densidade óssea ao redor do implante dental. Ainda, a administração de CSA após o período de cicatrização óssea ao redor do implante reduz a sua retenção mecânica ao tecido ósseo e promove a diminuição da qualidade e da densidade óssea radiográfica ao redor do implante dental. / Abstract: Immunosupressive agents may induce severe changes on bone mineral metabolism resulting in osteopenia. These alterations may impair the osseointegration processes. The purposes of this study were evaluate the cyclosporin-A (CSA) influence: on bone healing around dental implants (Study I); on bone density around dental implants (Study II); on mechanical retention of dental implants integrated to the bone (Study III) and on radiographic bone density and quality around dental implants integrated to the bone (Study IV). The CSA administration may impair the osseointegration and bone density during the bone healing. Besides, the administration of CSA after bone healing may impair the dental implant mechanical retention and decrease the radiographic bone density and bone quality around dental implants integrated to the bone. / Orientador: Gulnara Scaf / Coorientador: Elcio Marcantonio Junior / Banca: Guilherme Monteiro Tosoni / Banca: Maria Lúcia Rubo de Rezende / Banca: Jamil Awad Shibli / Banca: Francisco Haiter Neto / Doutor