The creation of systems for automatic processing of computed tomography (CT) results is associated with the task of recognizing individual areas in the image and building their contours. The paper proposes a method for constructing an external non-self-intersecting contour of a simply-connected two-dimensional region on a cross section of a computer tomogram, and also considers the main problems arising during its implementation.
KEYWORDS: 3D modeling, Magnetic resonance imaging, Data modeling, Computed tomography, Solids, Software development, Arteries, RGB color model, SolidWorks, Process modeling
Biomechanical modeling is used for preoperative planning of surgical treatment and allows you to choose the most rational option from the mechanical point of view. At the same time, the basic data for building models of the biological objects under study are the data of computed tomography (CT) and magnetic resonance imaging (MRI). To optimize and partially automate the process of constructing models of biological objects in Delphi, a software was developed that allows determining the outlines of areas corresponding to the object under examination on CT and MRI slices, to build a flat closed curve corresponding to the contour of a specific vessel lumen, to save data about the constructed curve to a file whose format corresponds to the format storage of curves in the software package Solid Works. The method of recursive two-dimensional frontal growth allows cutting off (due to the choice of the starting point) all “extra” shear vessels, which along with the section of interest can fall on the processed section. If the boundary of the object is determined, the algorithm does not imply further checks of the remaining pixels to reduce the number of operations and optimize the use of computer resources. In this case, the sensitivity of the method (the numerical value for the similarity criterion of pixels) can be changed manually by the user. Within the framework of the study, the frontal growth method is programmatically implemented. The created application allows you to create three-dimensional solid-state models of sections of the vascular bed on the basis of data from medical diagnostic equipment in a semi-automatic mode. This approach can significantly reduce the execution time of numerical modeling of hemodynamics of blood vessels.
Models of L4 and L5 vertebrae, sacrum and iliac bones were constructed on the basis of a computer tomogram. The sacrum model was constructed with three types of fractures: outward from the facet joint passing through the facet joint and inward relative to the facet joint. In addition, two main splinters of the sacrum were modeled, as well as screws passing through the iliac bones and elements of transpedicular fixation. Two variants of typical loads were considered: compression load and bending moment, compression load and rotation moment. In the case where screws passing through the iliac bones were combined with transpedicular screws, the maximum displacement in the models (for all three types of fracture) significantly decreased. This allows us to conclude that the variant of fixation with the help of a transpedicular structure makes the model more stable, that is, increases the rigidity of the structure, preventing the fixed elements of the vertebral-pelvic complex from shifting relative to each other. Equivalent stresses in the screws passing through the iliac bones were also reduced when installing the transpedicular structure. In this case, the stresses in the bone tissues did not differ significantly with different types of implants and loading options. Thus, if we evaluate the field of equivalent stresses in the models, a more rational from the point of view of biomechanics is the option of installing a transpedicular system in addition to screws passing through the iliac bones. This will reduce the risk of damage to both the structure and bone tissue.
The paper performs multiscale modeling of interaction between hybrid patch and blood vessels as well as patch with heart tissue by finite element method. Patch represented 3-dimensional cellular engineering structure consisted of three layers: carbon nanotube carcass, lipids of albumin and collagen and the aminosugar of chitosan. It was found that maximum stresses were observed in the contact area between media and the advent layers. It was found that in diastole the maximal values of patch displacement as well as the greatest stresses were concentrated in the area of contact between heart and patch.
Modern dentistry can not exist without dental implantation. This work is devoted to study of the "bone-implant" system and to optimization of dental prostheses installation. Modern non-invasive methods such as MRI an 3D-scanning as well as numerical calculations and 3D-prototyping allow to optimize all of stages of dental prosthetics. An integrated approach to the planning of implant surgery can significantly reduce the risk of complications in the first few days after treatment, and throughout the period of operation of the prosthesis.
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