Percorrer por autor "Ruben, Rui B."
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- Automatic reconstruction of dental CT images using optimizationPublication . Amorim, Paulo H. J.; Moraes, Thiago F. de; Silva, Jorge V. L. da; Pedrini, Helio; Ruben, Rui B.Computed Tomography (CT) is, in several cases, important in dental diagnosis. In fact, the panoramic reconstruction is commonly used in order to have a longitudinal view of the dental arch. Nowadays, dental CT equipments emit lower-dose radiation compared with other CT machines. Thus, dental CT became popular. However, there are some equipments that are not able to make the panoramic reconstruction of the dental arch. In this work, a new method for automatically reconstructing the dental arch based in CT images is developed and discussed. The technique uses optimization methods in order to find the best B-spline that approaches the dental arch.
- Chemical characterization of fungal chitosan for industrial applicationsPublication . Cruz, Pedro; Vaz, Daniela C.; Ruben, Rui B.; Avelelas, Francisco; Silva, Susana; Campos, Maria
- Comparative analysis of mandibular symphysis platesPublication . Dinis, Jairson C.; Kemmoku, Daniel T.; Noritomi, Pedro Y.; Silva, Jorge V. L.; Ruben, Rui B.Mandibular symphysis plates, used to heal fractures, can be made from different materials, normally titanium or CoCr alloys. In this work these two materials are tested and compared in order to study the plate's performance in fracture stabilization. This is a computational work performed with the advice of Brazilian maxoillofacial surgeons.
- Does Printing Orientation Matter in PolyJet 3D Printed Teeth for Endodontics? A Micro-CT AnalysisPublication . Barbosa, Cláudia; Reis, Tiago; Reis, José B.; Franco, Margarida; Batista, Catarina; Ruben, Rui B.; Martín-Biedma, Benjamín; Martín-Cruces, JoseThis study aimed to identify the optimal printing orientation (X, Y, or Z axis) and positioning of a mandibular molar presenting an isthmus using PolyJet™ technology. The influence of these parameters on dimensional accuracy and on the behavior of 3D-printed teeth (3DPT) during endodontic preparation with ProTaper Gold® system was evaluated. Six groups (XA, XB, YA, YB, ZA, ZB; n = 10) were printed with different axis orientations and distinct isthmus positions relative to the build platform. All samples underwent micro-computed tomography scanning before and after endodontic preparation. Regarding preoperative analyses—canal volume, centroids, and total tooth volume and area—no significant differences were found between groups XA–YA or XB–YB (p > 0.05), supporting their comparability. In contrast, groups ZA and ZB differed significantly from all others (p < 0.05), failing to meet equivalence required for further comparison, and were therefore excluded. Postoperative evaluation—volume change, centroid displacement, transportation, and unprepared areas—revealed no significant differences between XA–YA and XB–YB. Within the limitations of this study, both printing orientation and position affected the accuracy and repeatability of 3DPT, with positioning exerting the greatest influence, while their behavior towards endodontic preparation remained consistent across orientations.
- Medical devices: from design to productionPublication . Almeida, Henrique de Amorim; Ruben, Rui B.
- An open-source GUI application for segment foetal ultrasound imagesPublication . Dinis, J. C.; Moraes, T. F.; Amorim, P. H. J.; Amorim, O. H. J.; Silva, J. V. L.; Ruben, Rui B.There are several commercial software for medical image dataset segmentation. However, most of them are expensive and not user-friendly. With our proposal of a new opensource software with a simple and specific graphical user interface (GUI), it is easy to segment a foetus from a 3D ultrasound medical image dataset. The segmented portion of images can be converted into a stereolithography (STL) file format for 3D print technologies in order to obtain an accurate physical reproduction of the model segmented. Despite the large number of segmentation algorithms available, this new GUI has three specific possibilities (threshold, region growing and Chan-Vese) in order to keep it simple and efficient. For the same reason, the GUI has just three noise filters available in order to reduce speckle. Besides GUI simplicity, a good segmentation quality was achieved. The main purpose of our proposal is to segment foetal 3D ultrasound images and to make this task quick, easy and efficient.
- Reconstruction of panoramic dental images through Bézier function optimizationPublication . Amorim, Paulo H. J.; Moraes, Thiago F.; Silva, Jorge V.L.; Pedrini, Helio; Ruben, Rui B.Computed tomography (CT) and X-ray images have been extensively used as a valuable diagnostic tool in dentistry for surgical planning and treatment. Nowadays, dental cone beam CT has been extensively used in dental clinics. Therefore, it is possible to employ three-dimensional (3D) data from the CT to reconstruct a two-dimensional (2D) panoramic dental image that provides a longitudinal view of the mandibular region of the patient, avoiding an additional exposure to X-ray. In this work, we developed a new automatic method for reconstructing 2D panoramic images of the dental arch based on 3D CT images, using Bézier curves and optimization techniques. The proposed method was applied to five patients, some of them with missing teeth, and smooth panoramic images with good contrast were obtained.
- Sebenta de BiofísicaPublication . Macedo, Cidália; Ruben, Rui B.Biomecânica é a mecânica aplicada à biologia. Por outras palavras, é o estudo de fenómenos biológicos através das teorias da mecânica. A palavra “mecânica” foi usada pela primeira vez por Galileu Galilei no livro Discorsi e dimostrazioni, intorno à due scienze attenenti alla mecanica & movimenti local (1638), para descrever força, movimento e resistência dos materiais. Com o decorrer dos anos o seu significado foi estendido, abrangendo o estudo do movimento de todo o tipo de partículas e meios contínuos, incluindo átomos, moléculas, gases, líquidos, sólidos, estrelas e galáxias. De um modo geral, a mecânica é aplicada à análise de qualquer sistema dinâmico. A termodinâmica, a transferência de calor e massa e os métodos computacionais também são disciplinas da mecânica. A biologia, como parte do mundo físico, também é objecto de estudo da mecânica.