Zuzanna Krawczyk

Parallel implementation of the Artificial Ant Colony Algorithm applied to medical images segmentation

Artificial Ant Colony algorithm (AAC) can be applied to segmentation of bone structures out of CT data series. AAC procedure produces promising results in regions of adjacent bones and joints which are hard to distinguished by common segmentation algorithms. The article presents parallel implementation of the AAC which allows for significant speed-up of the segmentation procedure. The results of the segmentation for various bone structures in the area of the human pelvis are presented. Streszczenie. Algorytm kolonii mrówkowej (AAC) pozwala na segmentację struktur kostnych z serii obrazów tomografii komputerowej. AAC daje obiecujące wyniki dla przylegających do siebie fragmentów kości i stawów, które trudno rozróżnić przy pomocy często używanych filtrów obrazu. Artykuł przedstawia równoległą implementację algorytmu pozwalającą znacznie przyspieszyć operację segmentacji. Zaprezentowano w nim wyniki algorytmu dla wybranych struktur kostnych w obrębie miednicy. (Równoległa implementacja algorytmu mrówkowego zastosowanego do segmentacji obrazów medycznych).

Morphing algorithm for building individualized 3D skeleton model from CT data

There are constant efforts to improve speed and automation of the segmentation process of CT data. We propose a semi-automatic, atlas-based method of building 3D individualized skeletons. The intervention of human operator is minimal and is limited to selection of one voxel for each bone to be segmented, measuring a few distances for a successful reconstruction and approving the final result of an alignment. As a proof of the concept, an example of creating a patient-specific model of a left femur bone is presented. The results are discussed in order to chart the route to an automatic solution. It is believed that the areas like orthopedic operation planning and patient positioning systems could benefit from our method.

The comparative analysis of selected overvoltage protection measures for medium voltage overhead lines with covered conductors

The aim of this article is to analyze the investment and operational costs (the costs discounted) of the medium-voltage overhead lines with covered conductors as a function of applied overvoltage protection. On the basis of a technical-economic comparative analysis of the most popular and prospective protection measures, two surge protection systems (whose use is economically justified) will be further analyzed, taking into account the design parameters of the lines with covered conductors.

Segmentation of bone structures out of CT data: Fusion of methods

The article presents segmentation procedure of bone structures of the pelvis area based on a fusion of algorithms. In order to obtain sufficient segmentation results, a custom region growing procedure was combined with multistep Otsu thresholding, edge-detection algorithm, thresholding performed in the CIELab color space and heuristic swarm algorithm. The procedure was tested on the clinical CT data series.

Generation of skeletal structures for the pelvis area with the use of 3-dimensional binary thinning algorithm

The article presents the use of 3-dimensional thinning algorithm in creation of skeletal structures describing the area of pelvis and its surrounding. The skeletal descriptors are created for the models of pelvis and femurs and further transformed from its voxel representation into the graph. The result of the skeletonization is compared with the Reeb graphs created for the same bone models. The usefulness of the skeletons for the morphing algorithm is discussed.

Conformance criteria for validation of target volume surface reconstructed from delineation

This paper presents two conformance indexes that can be used to measure a similarity between two delineated structures. The authors use the presented conformance indexes for rating the results of Poisson Surface Reconstruction algorithm on real patient datasets. The rating is based on three delineations: original contours created during a standard procedure, reconstructed contours and reference contours created with an extra care by another physician.The chosen conformance indexes compare the delineations in two different forms: as a voxel grid and as a surface mesh. In this paper each of the conformance indexes is calculated in three different modes: the standard mode where all differences between datasets are taken into account and two more measuring how much one dataset exceeds the other. The last two modes are not symmetrical.The proposed conformance indexes allowed us to compare efficiently two delineations. The presented results also allow to state that the use of mesh reconstruction algorithms can improve delineations prepared within a limited time frame.

Log-periodic antenna — The comparison of different simulation models

This paper describes and compares three numerical models of small log-periodic dipole antenna, able to operate in wide band of frequencies. The experiments were performed in ANSYS HFSS, FEKO and NEC-2 simulation packages. The most important results are briefly compared.

Open access system for radiotherapy planning

The recent trends in software development transform classical desktop-based programs into distributed systems offered over the Internet. The authors adapt this approach to the radiotherapy planning software. A general concept and necessary components of such a system are presented.