Download or read book Creating and Validating Heterogeneous Tetrahedral Finite Element Models of the Femur from Computed Tomography CT Images written by Tim D. Fawcett and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Finite Element Method and Medical Imaging Techniques in Bone Biomechanics written by Rabeb Ben Kahla and published by John Wiley & Sons. This book was released on 2019-12-05 with total page 165 pages. Available in PDF, EPUB and Kindle. Book excerpt: Digital models based on data from medical images have recently become widespread in the field of biomechanics. This book summarizes medical imaging techniques and processing procedures, both of which are necessary for creating bone models with finite element methods. Chapter 1 introduces the main principles and the application of the most commonly used medical imaging techniques. Chapter 2 describes the major methods and steps of medical image analysis and processing. Chapter 3 presents a brief review of recent studies on reconstructed finite element bone models, based on medical images. Finally, Chapter 4 reveals the digital results obtained for the main bone sites that have been targeted by finite element modeling in recent years.

Download or read book Automated Selection and Entry of Computed Tomography Data in Finite Element Modelling of the Human Femur written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development and Implementation of Subject specific Human Femur Finite Element Models written by Estevan Negrete and published by . This book was released on 2008 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study to develop a procedure for generating human femur finite-element (FE) models from computed tomography (CT) scans of patients, medical imaging software, and finite-element software. Future studies may then use the procedure to quickly produce femur FE models in order to study their response to physiological phenomena, such as loads they experience during lower limb exercises.

Download or read book Tetrahedral Finite Element FE Meshes to Model Femoral Fractures Generated from CT Scans Taken from the Visible Human Project written by Ceri-Anne Pridham and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development and Validation of Statistical Models of Femur Geometry for Use with Parametric Finite Element Models written by Katelyn F. Klein and published by . This book was released on 2015 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Statistical models from a previous study that predict male and female femur geometry as functions of age, body mass index (BMI), and femur length were updated as part of an effort to develop lower-extremity finite element models with geometries that are parametric with subject characteristics. The process for updating these models involved extracting femur geometry from clinical CT scans of an additional 8 men and 36 women (previous models used CT scans from 62 men and 36 women for a new total of 70 men and 72 women), using all of the scans for fitting a template finite element femur mesh to the surface geometry of each patient, and then programmatically determining thickness at each nodal location. Principal component analysis was then performed on the thickness and geometry nodal coordinates, and linear regression models were developed to predict principal component scores as functions of age, BMI, and femur length. The results from the updated models were compared to the previous study, and the only improvement was in the R2 value for the female models (0.74 to 0.82). The largest differences between the original models and the previous models occurred in the ends of the femur, where the largest errors in model predictions occurred.

Download or read book Index to Theses with Abstracts Accepted for Higher Degrees by the Universities of Great Britain and Ireland and the Council for National Academic Awards written by and published by . This book was released on 2006 with total page 660 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of an Automated System for Building a Large Population based Statistical Model of Femur Morphology written by Ju Zhang and published by . This book was released on 2013 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studying femur morphology on a large population of computed-tomography (CT) images requires automatic methods. This thesis presents a fully automatic CT-to- model pipeline that accurately segments and models femur morphology. The pipeline is composed of a training phase, where a statistical shape model is created, and a processing phase, which segments and models cortical bone geometry and cancellous bone mineral density (BMD) distribution. Development and testing of the pipeline was carried out on a set of 262 quantitative-CT images from the Victorian Institute of Forensic Medicine (VIFM). In the training phase, corresponding regions on a training-set of 41 femoral surfaces were automatically partitioned and grouped using region-growing and mean-shift clustering. These regions were used to design a region-based quartic-Lagrange femur mesh, which was fitted region-by-region to manually segmented surfaces, to train the femur statistical shape model. Validation experiments showed that this region-based shape model was more accurate and correspondent than an equivalent non-regional model. Cortical bone geometry was automatically extracted and modelled in the first step of the processing phase, using the shape mode above. Active shape modelling and cortical thickness mapping were adapted and combined to mesh the inner and outer cortical surfaces. Segmented meshes were accurate to 0.9 mm root-mean-square (RMS), and cortical thickness to 0.6 mm RMS. The method achieved a success rate of 83%. Cancellous BMD images were automatically segmented and registered in the second step of the processing phase. BMD values from CT images were mapped to a reference volume by radial basis functions (RBFs), which interpolated the mapping between segmented and reference inner cortical surface meshes. Compared to conventional free- form deformation (FFD) registration, RBF registration followed by FFD led to a four- fold reduction in run time, a surface accuracy of 0.76 mm (versus 3.7 mm), and better alignment of anatomical features. Principal component analysis of registered images showed BMD variations in clinically relevant regions. The development of the CT-to-model pipeline has enabled unsupervised data col- lection from VIFM CT scans for scientific and clinical studies of femur morphology. As a general framework, minor modifications of the pipeline will also allow unsupervised data collection for other bones and other image sets.

Download or read book Finite Element Analysis of the Human Femur a Validation Study written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Prediction of Femoral Strength Using Automated Finite Element Modeling written by Joyce Helene Keyak and published by . This book was released on 1996 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Internal Organization of the Hominoid Proximal Femur written by David Bernhard Edelman and published by . This book was released on 1997 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Finite Element Modeling of Soft Tissue Deformation written by Hongjian Shi and published by . This book was released on 2007 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computer-aided minimally invasive surgery (MIS) has progressed significantly in the last decade and it has great potential in surgical planning and operations. To limit the damage to nearby healthy tissue, accurate modeling is required of the mechanical behavior of a target soft tissue subject to surgical manipulations. Therefore, the study of soft tissue deformations is important for computer-aided (MIS) in surgical planning and operation, or in developing surgical simulation tools or systems. The image acquisition facilities are also important for prediction accuracy. This dissertation addresses partial differential and integral equations (PDIE) based biomechanical modeling of soft tissue deformations incorporating the specific material properties to characterize the soft tissue responses for certain human interface behaviors. To achieve accurate simulation of real tissue deformations, several biomechanical finite element (FE) models are proposed to characterize liver tissue. The contribution of this work is in theoretical and practical aspects of tissue modeling. High resolution imaging techniques of Micro Computed Tomography (Micro-CT) and Cone Beam Computed Tomography (CBCT) imaging are first proposed to study soft tissue deformation in this dissertation. These high resolution imaging techniques can detect the tissue deformation details in the contact region between the tissue and the probe for small force loads which would be applied to a surgical probe used. Traditional imaging techniques in clinics can only achieve low image resolutions. Very small force loads seen in these procedures can only yield tissue deformation on the few millimeters to sub-millimeter scale. Small variations are hardly to detect. Furthermore, if a model is validated using high resolution images, it implies that the model is true in using the same model for low resolution imaging facilities. The reverse cannot be true since the small variations at the sub-millimeter level cannot be detected. In this dissertation, liver tissue deformations, surface morphological changes, and volume variations are explored and compared from simulations and experiments. The contributions of the dissertation are as follows. For liver tissue, for small force loads (5 grams to tens of grams), the linear elastic model and the neo-Hooke's hyperelastic model are applied and shown to yield some discrepancies among them in simulations and discrepancies between simulations and experiments. The proposed finite element models are verified for liver tissue. A general FE modeling validation system is proposed to verify the applicability of FE models to the soft tissue deformation study. The validation of some FE models is performed visually and quantitatively in several ways in comparison with the actual experimental results. Comparisons among these models are also performed to show their advantages and disadvantages. The method or verification system can be applied for other soft tissues for the finite element analysis of the soft tissue deformation. For brain tissue, an elasticity based model was proposed previously employing local elasticity and Poisson's ratio. It is validated by intraoperative images to show more accurate prediction of brain deformation than the linear elastic model. FE analysis of brain ventricle shape changes was also performed to capture the dynamic variation of the ventricles in author's other works. There, for the safety reasons, the images for brain deformation modeling were from Magnetic Resonance Imaging (MRI) scanning which have been used for brain scanning. The measurement process of material properties involves the tissue desiccation, machine limits, human operation errors, and time factors. The acquired material parameters from measurement devices may have some difference from the tissue used in real state of experiments. Therefore, an experimental and simulation based method to inversely evaluate the material parameters is proposed and compared with the material parameters measured by devices. As known, the finite element method (FEM) is a comprehensive and accurate method used to solve the PDIE characterizing the soft tissue deformation in the three dimensional tissue domain, but the computational task is very large in implementation. To achieve near real time simulation and still a close solution of soft tissue deformation, region-of-interest (ROI) based sub-modeling is proposed and the accuracy of the simulated deformations are explored over concentric regions of interest. Such a ROI based FE modeling is compared to the FE modeling over the whole tissue and its efficiency is shown and as well as its influence in practical applications such as endoscopic surgical simulation.

Download or read book Elastic Properties of the Human Femur written by Annette Bretin and published by . This book was released on 2019-02-04 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: Patient-specific finite element modelling of bone is a promising method for surgical planning, implant design and the prediction of bone remodelling or fracture risks, yet the assignment of material properties is challenging. Bone is a complicated structure with direction-dependent, inhomogeneous material properties, influenced by compositional, geometrical and architectural aspects. This volume focuses on a density-based assignment of orthotropic bone properties. Elasticity-density relationships in homogenized femoral zones were examined to evaluate the orthotropic density-dependence of the nine elastic material constants locally. Cortical bone samples were tested in compression and torsion tests using videoextensometry to determine the elastic constants. The elastic properties of cancellous bone were predicted by micro finite element analysis. All determined constants were correlated to the radiological bone mineral density of each sample, which was determined by quantitative computed tomography. The trabecular eigensystem was investigated for each cancellous zone to assign the mean directionality of trabecular fabric. The results can be beneficial for density-based orthotropic material assignment in femoral patient-specific finite element models.

Download or read book An Efficient Tissue Classifier for Building Patient specific Finite Element Models from X ray CT Images written by Nandini Shrinidhi and published by . This book was released on 1994 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Finite Element Analysis of a Femur to Deconstruct the Design Paradox of Bone Curvature written by Sameer Jade and published by . This book was released on 2012 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: The femur is the longest limb bone found in humans. Almost all the long limb bones found in terrestrial mammals, including the femur studied herein, have been observed to be loaded in bending and are curved longitudinally. The curvature in these long bones increases the bending stress developed in the bone, potentially reducing the bone's load carrying capacity, i.e. its mechanical strength. Therefore, bone curvature poses a paradox in terms of the mechanical function of long limb bones. The aim of this study is to investigate and explain the role of longitudinal bone curvature in the design of long bones. In particular, it has been hypothesized that curvature of long bones results in a trade-off between the bone's mechanical strength and its bending predictability. This thesis employs finite element analysis of human femora to address this issue. Simplified human femora with different curvatures were modeled and analyzed using ANSYS Workbench finite element analysis software. The results obtained are compared between different curvatures including a straight bone. We examined how the bone curvature affects the bending predictability and load carrying capacity of bones. Results were post processed to yield probability density functions (PDFs) for circumferential location of maximum equivalent stress for various bone curvatures to assess the bending predictability of bones. To validate our findings on the geometrically simplified ANSYS Workbench femur models, a digitally reconstructed femur model from a CT scan of a real human femur was employed. For this model we performed finite element analysis in the FEA tool, Strand7, executing multiple simulations for different load cases. The results from the CT scanned femur model and those from the CAD femur model were then compared. We found general agreement in trends but some quantitative differences most likely due to the geometric differences between the digitally reconstructed femur model and the simplified CAD models. As postulated by others, our results support the hypothesis that the bone curvature is a trade-off between the bone strength and its bending predictability. Bone curvature increases bending predictability at the expense of load carrying capacity.

Download or read book Additional Finite Element Method for Analysis of Reinforced Concrete Structures at Limit States written by Ermakova A.V. and published by Издательство АСВ. This book was released on 2012 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work presents the theoretical basis of Additional Finite Element Method (AFEM), which is a variant of the Finite Element Method (FEM) for analysis of reinforced concrete structures at limit state. AFEM adds to the traditional sequence of problem by FEM the units of the two well-known methods of the structural design: method of additional loads and limit state method. The problem is solved by introduction of ideal failure models and additional design diagrams formed from additional finite elements, where each AFE describes the limit state reached by the main element. The main relations defining the properties of AFEs as well as the examples of the use of Additional Finite Element Method for analysis of reinforced concrete structures at limit state are given in the work too.

Download or read book Convergence Behavior of High resolution Finite Element Models of Trabecular Bone written by Andy Chuan-chih Hsia and published by . This book was released on 1997 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: