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- 3D shape prior active contours for an automatic segmentation of a patient specific femur from a CT scanPublication . Almeida, D.; Folgado, J.; Fernandes, P.R.; Ruben, RuiThe following paper describes a novel approach to a medical image segmentation problem. The fully automated computational procedure receives as input images from CT scan exams of the human femur and returns a three dimensional representation of the bone. This patient specific iterative approach is based in 3D active contours without edges, implemented over a level set framework, on which the evolution of the contour depends on local image parameters which can easily be defined by the user but also on a priori information about the volume to segment. This joint approach will lead to an optimal solution convergence of the iterative method. The resulting point cloud can be an excellent starting point for a Finite Element mesh generation and analysis or the basis for a stereolitography for example.
- 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.
- 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.
- Controlling Morphology Using Low Molar Mass NucleatorsPublication . Mitchell, Geoffrey; Wangsoub, Supatra; Nogales, Aurora; Davis, Fred J.; Olley, Robert H.Crystallisation is a hugely important process in physical sciences and is crucial to many areas of, for example, chemistry, physics, biochemistry, metallurgy and geology. The process is typically associated with solidification, for example in the purification of solids from a heated saturated solution familiar to all chemistry undergraduates. Crystalline solids are also often the end result of cooling liquids, or in some cases gases, but in order to form require nucleation, in the absence of nucleation supercoiling of liquids well below the melting point is possible (Cava-gna, 2009). The quality of crystals, as gauged by size and levels of order is highly variable, and may depend on factors such as material purity and the rate of cool-ing; rapid cooling may result in poor crystallisation, or even the formation of amorphous materials with no long range order. In geological systems rates of cooling may vary over many orders of magnitude, for example obsidian is a large-ly amorphous material produced when lava is rapidly cooled (Tuffen, 2003), while the gypsum crystals found in the Cueva de los Cristales in Chihuahua, Mexico can reach 10 metres in length (Figure 1) and are formed over hundreds of thousands of years. In this latter case the formation of such large spectacular structures as shown in Figure 1 can only be explained by a low nucleation rate (García-Ruiz, 2007; Van Driessche, 2011).
- Direct Digital Manufacturing: A Challenge to the Artistic Glass ProductionPublication . Felismina, R.; Silva, M.; Mateus, A.; Malça, C.Currently the high hand-labor costs, long production times, lack of automation and high energy consumption associated with the high temperatures required to produce pieces of glass, are identified as the main inhibitors of growth and economic development of the decorative and utility glass industrial sector. Current production processes impose limitations on the complexity of the geometry and shape of the glass pieces to be produced, which in turn greatly restricts the creativity of designers and consequently, the characteristics of differentiation and innovation presented by new products on the market.
- Electrospinning for Medical ApplicationsPublication . Song, Wenhui; Mitchell, Geoffrey R.; Burugapalli, KrishnaThere is a natural connection between a variety of electrospun fibres and biomedical applications. The most commonly quoted application of electrospun fibres is their use as scaffolds in tissue engineering for regenerative medicine. There are also many other applications, which include drug delivery systems, membrane systems and analytical functionality. This chapter identifies the key challenges in each of these topics, as well as the particular role of electrospun fibres in addressing these challenges.
- Geometric and structural comparison of anatomic modelsPublication . Zeibak, R.; Freitas, D.; Almeida, H.A.; Bártolo, P.Computer Aided Design in the medical field helps translating CT and MRI data into anatomical 3D reconstructions. Accurate 3D models are valuable tools in several medical domains, thus finding accurate 3D reconstructions have profound advantages in all of the existing medical fields. The main objective of this research is to compare existing medical imaging processing softwares and evaluating their influence regarding both geometric deviations and numerical structural simulations between the 3D resulting models of both softwares.
- Optimization of a perfusion bioreactor for tissue engineeringPublication . Freitas, D.; Almeida, H.A.; Bártolo, P.Tissue engineering aims to produce artificial tissue in order to create or repair the damage tissue. It is evident that scaffolds are of extreme importance, because they will be the support of the new tissue. This new tissue is cultivated in vitro in a bioreactor in which is placed the scaffold. In order to control the cell culture process inside of a bioreactor it is essential to know the fluid flow inside and around the scaffold and the respective wall shear stress. These wall shear stress must be adequate to the tissue to be cultivated, i.e., bone, muscle, cartilage and it is known that a proper stimulus is necessary to improve the cell proliferation inside the scaffold. This study consider a novel multifunctional bioreactor with a perfusion system module and it is intended to optimize the fluid flow within the scaffold and the respective wall shear stress on the scaffold.
- Photocrosslinkable Materials for the Fabrication of Tissue-Engineered Constructs by StereolithographyPublication . Pereira, Rúben F.; Bártolo, Paulo J.Stereolithography is an additive technique that produces three-dimensional (3D) solid objects using a multi-layer procedure through the selective photoinitiated curing reaction of a liquid photosensitive material. Stereolithographic processes have been widely employed in Tissue Engineering for the fabrication of temporary constructs, using natural and synthetic polymers, and polymer-ceramic composites. These processes allow the fabrication of complex structures with a high accuracy and precision at physiological temperatures, incorporating cells and growth factors without significant damage or denaturation. Despite recent advances on the development of novel biomaterials and biocompatible crosslinking agents, the main limitation of these techniques are the lack number of available photocrosslinkable materials, exhibiting appropriate biocompatibility and biodegradability. This chapter gives an overview of the current state-of-art of materials and stereolithographic techniques to produce constructs for tissue regeneration, outlining challenges for future research.
- Photopolymerizable hydrogels in regenerative medicine and drug deliveryPublication . Pereira, Rúben F.; Bártolo, Paulo J.The use of photopolymerizable hydrogels in biotechnology and medicine has been increasing due to their ability to be introduced into the injured tissue through minimally invasive clinical methods and undergo in situ crosslinking after the exposure to an appropriate light source. These hydrogels can also be formed in the presence of cells and bioactive molecules, allowing the development of bioactive constructs for tissue regeneration, carriers for cell encapsulation, vehicles for drug and growth factor delivery, and cell-laden constructs to investigate both cell–cell and cell–material interactions. This chapter gives a general overview about the applications of photopolymerizable hydrogels for regenerative medicine and drug delivery, presenting the most recent advances and current challenges.