Influence of anatomical location on CT numbers in cone beam computed tomography

Objective: To assess the influence of anatomical location on computed tomography (CT) numbers in mid- and full field of view (FOV) cone beam computed tomography (CBCT) scans. Study Design: Polypropylene tubes with varying concentrations of dipotassium hydrogen phosphate (K2HPO4) solutions (50-1200 mg/mL) were imaged within the incisor, premolar, and molar dental sockets of a human skull phantom. CBCT scans were acquired using the NewTom 3G and NewTom 5G units. The CT numbers of the K2HPO 4 phantoms were measured, and the relationship between CT numbers and K2HPO4 concentration was examined. The measured CT numbers of the K2HPO4 phantoms were compared between anatomical sites. Results: At all six anatomical locations, there was a strong linear relationship between CT numbers and K2HPO4 concentration (R 2 > 0.93). However, the absolute CT numbers varied considerably with the anatomical location. Conclusion: The relationship between CT numbers and object density is not uniform through the dental arch on CBCT scans. © 2013 Elsevier Inc.

Changes during chilled storage of whole tilapia and short-term frozen storage of tilapia fillets

This study evaluated the physicochemical changes in Nile tilapia (n = 82, 373.71 ± 61.91 g) refrigerated for up to 92 h and in the frozen fillets. The tilapias were captured with nets, slaughtered by ice and water shock (1:1) in a temperature of approximately 2°C for 30 min, and stored refrigerated at 4°C in polystyrene boxes containing ice. The fish were filleted, and filets were weighed and frozen. The drip loss and protein were determined after 23 days of frozen storage. After 4 h of storage, all fish were in full rigor mortis. The pH of the muscles decreased for up to 45 h of the storage period. The fillets obtained from tilapia stored for more than 72 h lost more weight and protein. Thus, the filleting or processing of tilapia should be done before 72 h of cold storage, since deterioration of the fish starts to occur after this period. Copyright © Taylor & Francis Group, LLC.

Otimização de imagem de torax para radiografia computadorizada

Pós-graduação em Biologia Geral e Aplicada - IBB

Estudo experimental do escoamento em torno de cilindros circulares em movimento de rotação

Pós-graduação em Engenharia Mecânica - FEIS

Análise de multirresolução baseada em polinômio potência de Sigmóide - Wavelet

Pós-graduação em Ciência da Computação - IBILCE

Perfil de índices de refração do cristalino humano: simulação computacional

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Otimização de imagens de mamografia computadorizada

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Arcabouço para aprovisionamento de QoS e QoE em redes sem fio heterogêneas WiMAX/Wi-Fi com garantia de equidade entre vazões

Recentemente a sociedade está vivendo em meio a um aglomerado de dispositivos móveis com múltiplas interfaces sem fio que permitem que clientes móveis domésticos e corporativos solucionem problemas rotineiros no menor espaço de tempo e em diversas localizações. Por outro lado, a disponibilidade de diversas tecnologias de acesso sem fio como: Wi-Fi (Wireless Fidelity), WiMAX (Worldwide Interoperability for Microwave Access) e LTE (Long Term Evolution), proporcionam um cenário heterogêneo com diversas oportunidades de conectividade para o usuário de dispositivos com múltiplas interfaces. Alguns dos desafios atuais no contexto da concepção da então denominada NGN (Next Generation Networks) são o desenvolvimento de arcabouços e mecanismos que viabilizem tanto o suporte adequado à Qualidade de Serviço (QoS – Quality of Service) e à Qualidade de Experiência (QoE – Quality of Experience) para aplicações multimídia, quanto a garantia de equidade entre vazões de diferentes aplicações em ambiente heterogêneo. Esta dissertação propõe um arcabouço para o aprovisionamento de QoS e QoE em redes sem fio heterogêneas formada por redes WiMAX e Wi-Fi. Especificamente, nossa solução provê mapeamento estático de QoS entre as classes de serviços WiMAX e categorias de acesso Wi-Fi. Além disso, nossa proposta também combina funcionalidades de equidade entre vazões com a solução de mapeamento, a fim de alcançar um bom compromisso tanto para o operador da rede, quanto para o usuário, através de uma nova metodologia de coleta e calculo de vazão agregada e algoritmo de decisão de handover vertical. A avaliação quantitativa da proposta foi realizada através de modelos de simulação no ns-2 (Network Simulator). Os resultados de desempenho demonstram a eficiência da arquitetura em termos de métricas de QoS (vazão, vazão média e atraso) e QoE (PSRN - Peak Signal to Noise Ratio, SSIM - Structural Similarity Index e VQM - Video Quality Metric).

Avaliação de Técnicas de Interpolação de Imagens Digitais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

conventional radiography and computed tomography to cervical spine study of adult horses - review

The imaging is essential to aid the diagnosis of horses that have performance decrease associated with any pain or clinical signs related to the vertebral column. Radiography is the first imaging examination performed in these cases, particularly for disorders affecting the cervical region. However, this technique has limitations when the study of subtle changes due to the overlapping of adjacent structures. Computed tomography is a new diagnostic method in Brazil for the study of bone disorders in horses, but it is of great diagnostic value associate with the radiographic examination in order to provide an accurate assessment of the study area, owing to superiority in image quality when compared to conventional radiography. The aim of this study is increase and update knowledge of diagnostic imaging available to investigate cervical disorders in horses.

Estudo da dose efetiva, razão sinal-ruído e razão contraste-ruído em tomografia computadorizada de múltiplos detetores

Since discovery, computed tomography is a widely used diagnostic modality. However, this modality imparts relatively high doses to the patients and with fast technological advancement, it is necessary optimize the doses used and ensure the quality of the images through a quality assurance program. This work intended to compare Computed Tomography Dose Index (CTDIW) and effective dose with components of image quality: the Contrast-to-Noise Ratio (CNR) and Signal-to-Noise Ratio (SNR), and a quality factor (Q) deduced by the Rose model for two groups of computed tomography units. The first group was composed by equipments with 10 up to 16 slices and the second one presented 40 up to 320 slices detectors, for the protocols of head and abdomen. It was realized a comparison between different selectable parameters in the protocol of a Philips Brilliance 16, too. The results of the first group to CTDIW, effective dose, SNR and CNR showed variations of 28%, 33%, 37% and 32% respectively for head protocol, and 21%, 27%, 43% and 37% respectively for abdomen protocol. The results of the group 2 to CTDIW, effective dose, SNR and CNR showed variations of 15%, 26%, 36% and 34% respectively for the head protocol, and 8%, 13%, 50% and 60% respectively for abdomen protocol. The comparison between both groups demonstrated similar levels of doses impartation to patients though having so many different configurations, if the uncertainties associated with this measurement were considered. The results of the comparison between different parameters in the Philips Brilliance 16 scanner were in agreement with expected

Estudo para determinação da kVp em equipamentos de raios X convencional

The quality assurance control program (QACP) in clinical radiology is very important to acquire, image quality, patient dose reduction and cost for the institution. The verification of the real tension on the x ray tube, it is one of many parameters that may be determined on a QACP. This act on image quality as absorbed dose in patient. Once proved the importance of this fact, this study come up with the determination of tension to any X ray tube used on medical routine, on quick, safe and low cost manner. To reach the aim of this study, the methodology consisted on measuring expose rates (ER) using different thicknesses of copper (Cu) plates like filters and relating these results with Half Layer Value (HLV). Afterwards, the HLV was associated to real tension that was acquired with kilo voltage of peak (kVp) measurers used on clinical routine. So walking in this path, when performed the ER, on any X ray tube, it’s possible acquire the HLV and consequently the real kVp, considering measures obtained before, on the methodology of kVp estimative development

Estudo de doses e otimização de carta técnica na transição de radiologia convencional para computacional em diagnósticos veterinários

This project aims the verification of doses in canines and felines to chest and coxal exams due to the transition from screen-film to computed radiography system. It also seeks a possible optimization of the new techniques employed in this new system. The study was carried out in Diagnostic Imaging service in Hospital Veterinário da Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo using a conventional x-ray equipment. Initially, data about the physical characteristics of animals and the technique currently used in computed radiography was collected for each of 80 chest and 16 coxal X-ray examinations. The animals were divided into different groups according to the body weight. For each group, were calculated the averages of each item: thickness of the region to be imaged, voltage, current, exposure time, current-time product, size of film used, presence or absence of bucky and focus (small or large). The techniques have been reproduced in phantoms (representative of the thickness of the animal) in order to collect the air kerma entrance. Based on the average of intermediate size M group (weights less than 5 kg for cats and from 10.1 kg and 20 kg for dogs) analysis of image quality using three devices test patterns were made consisting of the evaluation of spatial resolution, low-contrast resolution and contrast-detail. In general, the results showed the dose animals decreased with the use of computed radiography and was possible to preliminary optimization of some techniques used currently in CR

Classificação e quantificação de tecidos Biológicos para construção de fantomas pediátricos

Paediatric diagnostic radiology can be considered as a separate specialty and with distinct characteristics of the radiology applied in adult patients. This in reason of the variability in the anatomical structures size and bigger sensitivity of tissues. The literature present in its majority methodologies for segmentation and tissue classification in adult patients, and works on tissue quantification are rare. This work had for objective the development of a biological tissue classifier and quantifier algorithm, from histograms, and that converts the quantified average thickness of these tissues for its respective simulator materials. The results will be used in the optimization process of paediatrics images, in future works, since these patients are frequently over exposed to the radiation in the repeated attempts of if getting considered good quality radiographic images. The developed algorithm was capable to read and store the name of all the archives, in the operational system, to filter artifacs, to count and quantify each biological tissues from the histogram of the examination, to obtain the biological tissues average thicknesses and to convert this value into its respective simulator material. The results show that it is possible to distinguish bone, soft, fat and pulmonary tissues from histograms of tomographic examinations of thorax. The quantification of the constituent materials of anthropomorphic phantom made by the algorithm, compared with the data of literature shows that the biggest difference was of 21,6% for bone. However, the literature shows that variations of up to 30% in bone thickness do not influence of significant form in the radiographic image quality. The average thicknesses of biological tissues, quantified for paediatrics patients, show that one phantom can simulate patients with distinct DAP ranges, since variations... (Complete abstract click electronic access below)

O aprimoramento de um software de estúdio virtual por meio de técnicas de matting digital e registro de objetos virtuais

A virtual studio system can use technologies as augmented reality and digital matting to decrease production costs at the same time it provides the same resources of a conventional studio. With this, it’s possible for the current studios, with low cost and using conventional devices, to create productions with greater image quality and effects. Some difficulties are recurrent in virtual studio applications that use augmented reality and digital matting. The virtual objects registration in augmented reality techniques suffer from problems caused by optical distortions in the camera, errors in the marker tracking system, lack of calibration on the equipments or on the environment (lighting, for example), or even by delays in the virtual objects display. On the other hand, the digital matting’s main problem is the real-time execution to preview the scene, which must have optimized processing speed at the same time while maintain the best image quality possible. Taking the given context into consideration, this work aims to give continuity to a virtual studio system called ARStudio, by enhancing digital matting, virtual objects registration and introducing a segmentation based on depth map, yet adding better control over functionalities previously implemented