When the United States Air Force completed a multi-million dollar transition to digital dental radiography in 2010 there was no quantitative method available for establishing the appropriate balance of image quality and radiation dose. The objective of this research was to devise a process to fill this need. Through computer simulation and clinical validation the effect of technical parameters on digital dental radiographic image quality was investigated and an optimization method was devised. The Monte Carlo N-Particle Extended (MCNPX) radiation transport code was used to model the DC Planmeca Intra and AC Gendex 770 dental intraoral radiographic units and a unique anthropomorphic phantom simulating dental bitewing anatomy. The Carestream 6100 RVG sensor signal response, noise response, dose rate dependence and reproducibility were determined experimentally, as were their uncertainties and the inter- and intra- radiographic unit variabilities. The experimental measurements were used to calibrate and scale the MCNPX generated data for the optimization analysis. The technical parameters modified in the simulation were peak kilovoltage, (50 through 90) and tube filtration (inherent, 0.1 mm and 0.2 mm added copper). The entrance air KERMA (~720 microGy) at the current clinical technique (63 kVp at 1 milliAmpere-seconds) was used to establish the reference image quality metrics for comparison. Four figures of merit (FOM) were chosen to encompass the impact of variations in the adjustable parameters. With equal weighting of all FOMs and given no limitations on the equipment, the optimal combination of kVp and tube filtration for dental bitewing imaging identified was 90 kVp with 0.1 mm added copper filtration. The optimal technique in the radiographic units' operating range was 70 kVp and 0.1 mm added copper filtration, which could be immediately adopted for a ~50% (+/-17%) entrance dose and ~40% effective dose savings (Planmeca units). In general, the optimization method facilitates image quality standardization across different radiographic units and sensors in a dental clinic. The unique computer model and optimization method used could be easily customized to evaluate any adult or pediatric intraoral imaging task. The results underscore the importance of tailoring the technical parameters to the particular imaging devices in service. / text

Thesis (M.S.)--University of Michigan, Ann Arbor, 1978. / Typescript (photocopy). Includes bibliographical references (leaves 23-24). Also issued in print.

Thesis (M.S.)--University of Michigan, Ann Arbor, 1978. / Typescript (photocopy). eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 23-24).

No description available.

Orientador: Francisco Jose de Souza Filho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-04T10:07:50Z (GMT). No. of bitstreams: 1 Santos_JulioCesarBentodos_D.pdf: 777651 bytes, checksum: ead9155fe00aa49ebe36b753c9c89d8a (MD5) Previous issue date: 2005 / Resumo: A presente pesquisa teve por finalidade avaliar, in vitro, a eficácia dos localizadores apicais, Bingo 1020, Novapex e Root ZX, nas posições 1mm aquém do ápice e na posição 0 (zero). Comparar a odontometria eletrônica na posição 0 com a medida real dos dentes. Comparar a odontometria radiográfica com a odontometria eletrônica utilizando o Bingo 1020 na posição 1mm aquém do ápice e na posição 0. Para tanto foram utilizadas 71 raízes de molares humanos, extraídos, com rizogênese completa e sem sinais de fratura apical. Dos molares inferiores utilizou-se raízes mesiais e dos molares superiores as raízes vestibulares. Foi realizada a abertura coronária . Após a radiografia, sendo essa o segundo critério de seleção, os dentes foram colocados em uma plataforma para a odontometria eletrônica. Essa plataforma teve a finalidade de manter os dentes em posição, com os respectivos ápices em contato com uma solução salina . A exploração do canal foi realizada com as limas 10 e 15 e a odontometria com a lima 20, sendo que a medida real foi obtida com lupa de aumento de 2,5 vezes , considerando a posição em que a lima emergia da constrição apical. A primeira medida eletrônica foi realizada na posição em que o localizador apical marcou 1mm aquém do ápice. A segunda medida, na posição 0. Esse procedimento foi realizado com os três localizadores apicais, perfazendo um total de 213 medidas na posição 1mm e 213 medidas na posição 0. Quarenta e quatro canais foram utilizados para avaliação radiográfica. O cálculo estatístico demonstrou que os localizadores apicais Bingo 1020, Novapex e Root ZX não foram significativamente diferentes entre si, nas medidas 1mm aquém do ápice e na posição 0mm, nas condições da pesquisa. Na comparação com a medida real o Root ZX apresentou uma maior porcentagem de aproximação, embora não significante, nos desvios de 0,5 mm e 0,75mm. Na odontometria radiográfica, considerando três avaliadores, houve diferença estatisticamente signicante em dois, em relação à odontometria eletrônica com o localizador apical Bingo 1020 / Abstract: The aim of this study was to evaluate, in vitro, the measurement efficiency of the apex locators known as Bingo 1020, Novapex and Root ZX, at the positions of 1mm and 0mm from the apex; compare the electronic measurement at 0mm with the real measurement of the teeth; and compare the radiographic root canal measurement to the electronic measurement obtained by the Bingo 1020. For this, 71 extracted human molar roots, presenting complete root formation and no signs of apical fracture were selected and only the mesial roots of the inferior molars and the buccal roots of the superior molars were included in the study. The teeth were embedded in a resin ring and coronary access and radiographs were performed. After tooth radiography, considered the second criteria for selection, these were placed upon a platform for electronic root measurement. Such platform had the finality to maintain the teeth in position, with the respective apexes in contact with saline solution. Canal exploration was accomplished using files #10 and 15#, root measurement was performed with a file #20, and the real root measurement was determined when file emergence from the apical constriction was observed using a 2.5X magnifying glass. The first electronic measurement was made when the apex locator marked 1mm from the apex. The second measurement was noted at 0mm. Such sequence was performed using the three apex locators, adding up to a total of 213 measurements at 1mm and at 0mm from the apex. Forty-four root canals were used for radiographic evaluation. Statistic evaluation demonstrated that the apex locators Bingo 1020, Novapex and Root ZX were not statistically different among each other at the measurements of 1mm and 0mm from the apex under the conditions of this experiment. During the comparison with real root measurements, Root ZX presented the highest percentage approximation, although not statistically significant during deviation of 0.5mm and 0.75mm. Three different evaluators revealed significant statistical difference among two, when radiographic root measurement were compared to the Bingo 1020 apex locator / Doutorado / Endodontia / Doutor em Clínica Odontológica

Ενώ υπάρχουν πολλές μελέτες που ασχολούνται με ένα συγκεκριμένο ακτινολογικό σύστημα ή συγκρίνουν δύο παρόμοια, η διαφορά στην μελέτη μας είναι ότι μετρούνται πέντε διαφορετικά συστήματα με τα ίδια ακριβώς δοσίμετρα και το ίδιο ακριβώς phantom. Ο σκοπός της έρευνας αυτής είναι να συγκρίνει τις δόσεις τις οποίες λαμβάνει ο εξεταζόμενος από διαφορετικά οδοντιατρικά ακτινολογικά συστήματα. Τα ακτινολογικά συστήματα που προτιμήθηκαν για να συμμετάσχουν στην μελέτη είναι τα παρακάτω: 1) Οδοντιατρικό Σύστημα (Οπισθοφατνιακό) 2) Κεφαλομετρικό Σύστημα 3) Πανοραμικό Σύστημα 4) Υπολογιστικός Τομογράφος (CT) 5) Υπολογιστικός Τομογράφος Κωνικής Δέσμης (Cone Beam CT) Για να μπορέσουμε να έχουμε ακριβείς μετρήσεις στα ευαίσθητα σημεία, όπως π.χ στον εγκέφαλο, στο εσωτερικό του οισοφάγου ή στους υπογνάθιους αδένες προτιμήθηκε αντί να γίνουν οι μετρήσεις απευθείας σε ασθενείς να τοποθετήσουμε τα δοσίμετρα σε ένα RANDO phantom. Με τον τρόπο αυτό πετύχαμε μέτρηση της δόσης στο ακριβές σημείο ενδιαφέροντος. Τα δοσίμετρα που χρησιμοποιήθηκαν ήταν δοσίμετρα θερμοφωταύγειας (TLD), τα οποία προτιμήθηκαν καθώς, όπως θα δούμε στην συνέχεια, διαθέτουν στοιχεία που βοήθησαν πολύ στην διαδικασία των μετρήσεων. Τα δοσίμετρα που χρησιμοποιήθηκαν ανήκουν στο Πανεπιστημιακό Γενικό Νοσοκομείο «Αττικόν». Το phantom που χρησιμοποιήθηκε διατέθηκε από το Διαγνωστικό και Θεραπευτικό Κέντρο «Υγεία» και οι μετρήσεις πραγματοποιήθηκαν τόσο στην Πάτρα όσο και στην Αθήνα. Οι ακτινοβολήσεις για το οπισθοφατνιακό, το πανοραμικό σύστημα και τον υπολογιστικό τομογράφο πραγματοποιήθηκαν στο «Ολύμπιον Θεραπευτήριο» στην Πάτρα, για το κεφαλομετρικό στο Ακτινοδιαγνωστικό Κέντρο Ψηφιακής Απεικόνισης του κ. Σωτήρη Α. Αποστολόπουλου ενώ οι μετρήσεις του Cone Beam CT έγιναν στην Αθήνα, στο Ακτινοδιαγνωστικό Κέντρο της κ. Καρέλη. Η εργασία είναι χωρισμένη σε 4 Κεφάλαια, τα οποία ασχολούνται με τα εξής: Στο Κεφάλαιο 1 θα γίνει μία συνοπτική παρουσίαση των αποτελεσμάτων άλλων μελετών που έχουν πραγματοποιηθεί και είναι σχετικές με την έρευνα που πραγματοποιήσαμε. Στο Κεφάλαιο 2 θα γίνει μία αναλυτική παρουσίαση των υλικών που χρησιμοποιήθηκαν στην έρευνα καθώς και της διαδικασίας που ακολουθήθηκε για να φτάσουμε στα αποτελέσματά μας. Στο Κεφάλαιο 3 θα γίνει η παρουσίαση των αποτελεσμάτων μας. Στο Κεφάλαιο 4 θα πραγματοποιηθεί σχολιασμός των αποτελεσμάτων και σύγκριση με τα δεδομένα που παρουσιάστηκαν στο Κεφάλαιο 1, έτσι ώστε να διαπιστωθεί η πιστότητά τους. / Dose comparison for different dental radiology units using RANDO Phantom.

Thesis (M.S.)--University of Michigan, 1983.

Thesis (M.S.)--University of Michigan, 1983.

Orientador: Marcelo Gonçalves / Banca: Mário Tanomaru Filho / Banca: Carlos Alberto Herrero de Morais / Resumo: O objetivo deste estudo foi analisar radiograficamente a modelagem de canais radiculares ovalados realizada com três sistemas rotatórios de níqueltitânio. Foram utilizados 60 incisivos inferiores inseridos em blocos acrílicos, que acoplados a um sistema de plataforma radiográfica, permitiu a obtenção de imagens antes e após o preparo biomecânico, em sentido mésio-distal e vestíbulo-lingual. Um meio de contraste radiológico foi utilizado para preenchimento dos canais radiculares, proporcionando visualização mais adequada destes nas imagens radiográficas. Para o preparo biomecânico, os dentes foram divididos em três grupos (n=20), numericamente equivalentes, de acordo com o sistema rotatório utilizado. O grupo I foi instrumentado com o sistema Protaper Universal, tendo os instrumentos modeladores acionados em brushing motion e como último instrumento empregado para o preparo apical o F3. O grupo II foi instrumentado com o sistema Race, tendo os instrumentos Pré-Race acionados em brushing motion e como último instrumento empregado no preparo apical o #30/0,06. O grupo III foi instrumentado com o sistema K3, tendo todos os instrumentos acionados em pecking motion e como último instrumento utilizado no preparo apical o #30/0,06. As radiografias periapicais, contendo as imagens antes e após o preparo biomecânico, em ambos os sentidos, foram processados automaticamente e digitalizados em um scanner de plataforma. As imagens resultantes foram arquivadas no programa Adobe Photoshop 7.0 e importadas para o software Image tool 3.0. Avaliou-se o aumento percentual de área dos canais radiculares nos terços cervical, médio e apical, resultante em cada grupo experimental, nos sentidos mésio-distal e vestíbulo-lingual. / Abstract: The aim of this study was radiographically analyze the shaping of oval root canals obtained by utilization of three nickel-titanium rotary systems. It was conducted on 60 mandibular incisors embedded in acrylic blocks and connected to a radiographic platform system for achievement of images, before and after biomechanical preparation, in mesiodistal and buccolingual directions. A radiographic contrast medium was used for root canal filling, which allowed more adequate visualization on the radiographic films. For biomechanical preparation, the teeth were divided into three numerically equivalent groups according to the rotary system employed. Group I was instrumented with the system Protaper Universal, by utilization of shaping instruments in brushing motion and apical preparation finalized with an instrument F3. Group II was instrumented with the system Race, by utilization of Pre-Race instruments in brushing motion and apical preparation finalized with an instrument #30/0,06. Group III was instrumented with the system K3, by utilization of all instruments in pecking motion and apical preparation finalized with an instrument #30/0,06. The periapical radiographies containing the images before and after biomechanical preparation in both views were automatically developed and digitized on a platform scanner. The resulting images were stored in the software Adobe Photoshop 7.0 and imported to the software Image Tool 3.0. The percent increase in the root canal area was analyzed at the cervical, middle and apical thirds, for each study group, in both mesiodistal and buccolingual directions. Occasional changes in the original proportion between the buccolingual and mesiolingual areas, caused by biomechanical preparation, were also analyzed for each third. Data were analyzed by analysis of variance one-way and Tukey test at a significance level of 5% (p<0.05). / Mestre

Submitted by Jean Medeiros (jeanletras@uepb.edu.br) on 2016-10-26T11:47:13Z No. of bitstreams: 1 PDF - Vanessa Maria Freire Abílio.pdf: 2920508 bytes, checksum: 9dd2d9baca2d37200df8d4240c629561 (MD5) / Approved for entry into archive by Secta BC (secta.csu.bc@uepb.edu.br) on 2016-11-16T14:20:54Z (GMT) No. of bitstreams: 1 PDF - Vanessa Maria Freire Abílio.pdf: 2920508 bytes, checksum: 9dd2d9baca2d37200df8d4240c629561 (MD5) / Made available in DSpace on 2016-11-16T14:20:54Z (GMT). No. of bitstreams: 1 PDF - Vanessa Maria Freire Abílio.pdf: 2920508 bytes, checksum: 9dd2d9baca2d37200df8d4240c629561 (MD5) Previous issue date: 2013-07-15 / Digital image is a breakthrough in dental radiology characterized by being a quick and easy method of obtaining and evaluating of images. The aim of this study was to compare the semi-direct digital system (Digora Optime®) with the indirect digital system (CCD digital camera) in relation to radiopacity of dental materials indicated as base or liner. In addition, it was proposed to verify the influence of different exposure times and focus-film distances on the degree of radiopacity shown by these materials. A total of 10 specimens (4 X 2 mm) were made for each brand of restorative material employed (KetacTM Molar Easymix, Vidrion F, GC Fugi LiningTM LC, VitrebondTM, FiltekMR Z350 XT Flow and Tetric® N Flow), total of 60 specimens, by using an acrylic matrix. The specimens were radiographed together with an aluminum scale and cross-sections of teeth with 2 mm by both digital systems in four combinations of exposure time / different focus-film distances (0.12 s / 20 cm; 0.12 s /40 cm, 0.25 s /20 cm, 0.25 s /40 cm). The radiopacity of radiographed structures was measured using the tool “analyze histogram” on the software Image J. Data were analyzed using descriptive statistics and non-parametric tests: Wilcoxon, Mann- Whitney and Student’s t test. Only Vidrion F showed radiopacity lower than that of dentin and 2-mm cross-sections with statistically significant difference (p < 0.05) for all cases using the semi-direct digital system and for some cases using the indirect digital system. The radiopacity means for all materials studied were significantly higher (p <0.05) when the semi-direct digital system (Digora Optime®) was used. There was significant difference (p <0.05) in the radiopacity of the materials – except for Vidrion F – when exposure time and focus-film distance changed. It was concluded that the semi-direct digital system (Digora optime®) was more precise for measuring radiopacity compared to the indirect digital system. Thus, the semi-direct procedure is indicated to be used clinically as an auxiliary diagnostic method. / A imagem digital representa um grande avanço na Radiologia Odontológica, uma vez que constitui um método rápido de obtenção de imagem e de fácil avaliação. O objetivo deste trabalho foi comparar o sistema digital semi-direto utilizando o Digora Optime® com o sistema digital indireto que utilizou câmera digital de CCD, frente à radiopacidade dos materiais dentários indicados para base ou forramento, bem como verificar a influência da variação de tempo de exposição e da distância foco- filme no grau de radiopacidade apresentado por estes materiais. Foram confeccionados 10 corpos-de prova (4 X 2 mm) para cada marca de material dentário utilizada (KetacTM Molar Easymix, Vidrion F, GC Fugi LiningTM LC, VitrebondTM, tetricMR Z350 XT Flow e Tetric® N Flow), totalizando 60 espécimes, usando uma matriz acrílica. Os corpos-de-prova foram radiografados junto a uma escala de alumínio e secções transversais de dentes com 2mm, por ambos os sistemas digitais em quatro combinações de tempo de exposição/distância foco-filme diferentes(0,12s/20cm; 0,12s/40cm; 0,25s/20cm e 0,25s/40cm). A radiopacidade das estruturas radiografadas foram mensuradas utilizando a função analyse histogram do programa Image J. O dados foram analisados por meio da estatística descritiva e através dos testes não- paramétrico de Wilcoxon-Mann Whitney e teste T de Sudent. Apenas o Vidrion F apresentou radiopacidade inferior a dentina e ao degrau de 2mm do penetrômetro, sendo esta diferença significativa (p<0,05), para todas as situações utilizando o sistema digital semi-direto e, para algumas situações, utilizando o sistema digital indireto. As médias de radiopacidade para todos os materiais estudados foram significativamente maiores (p<0,05) quando foi utilizado o sistema digital semi-direto (Digora Optime®). Houve diferença significativa (p<0,05) na radiopacidade dos materiais, exceto para o Vidrion F, quando ocorreu variação no tempo de exposição, bem como quando ocorreu variação na distância foco-filme. Conclui-se que o sistema digital semi-direto (Digora optime®) mostrou ser mais preciso para as medições de radiopacidade quando comparado ao sistema digital indireto, sendo nesta situação mais indicado para ser utilizado clinicamente como método auxiliar de diagnóstico.