With development of medical diagnostic and imaging techniques the sparing surgeries are facilitated. Renal cancer is one of examples. In order to minimize the amount of healthy kidney removed during the treatment procedure, it is essential to design a system that provides three-dimensional visualization prior to the surgery. The information about location of crucial structures (e.g. kidney, renal ureter and arteries) and their mutual spatial arrangement should be delivered to the operator. The introduction of such a system meets both the requirements and expectations of oncological surgeons. In this paper, we present one of the most important steps towards building such a system: a new approach to kidney segmentation from Computed Tomography data. The segmentation is based on the Active Contour Method using the Level Set (LS) framework. During the segmentation process the energy functional describing an image is the subject to minimize. The functional proposed in this paper consists of four terms. In contrast to the original approach containing solely the region and boundary terms, the ellipsoidal shape constraint was also introduced. This additional limitation imposed on evolution of the function prevents from leakage to undesired regions. The proposed methodology was tested on 10 Computed Tomography scans from patients diagnosed with renal cancer. The database contained the results of studies performed in several medical centers and on different devices. The average effectiveness of the proposed solution regarding the Dice Coefficient and average Hausdorff distance was equal to 0.862 and 2.37 mm, respectively. Both the qualitative and quantitative evaluations confirm effectiveness of the proposed solution.
Despite great technological progress scientists still are not capable of ascertaining how many species are there on Earth. Systematic studies are not only time-consuming, but sometimes also significantly impeded by constraints of available equipment. One of the methods for morphology evaluation, which is gradually more often used for taxonomical research is microcomputed tomography. It’s great spatial resolution and ability to gather volumetric data during single acquisition without sectioning specimen are properties especially useful in evaluation of small invertebrates. Nondestructive nature of micro-CT gives possibility to combine it with other imaging techniques even for single specimen. Moreover, in case of rare organisms studies it allows to collect full structural data without fracturing their bodies. Application of proper staining, exposure parameters or specific sample preparation significantly improves quality of performed studies. The following article presents summary of current trends and possibilities of microtomography in morphology studies of small invertebrates.
Internal structure of metal foams is one of the most important factors that determine its mechanical properties. There exists a number of methods for studying the nature of the inner porous structure. Unfortunately most of these processes is destructive and therefore it is not possible to reuse the sample. From this point of view, as a suitable method seems to be the ability of using the so-called X-ray microtomography (also micro-CT). This is a non-destructive methodology used in a number of fields (industry, science, archaeology, medicine) for a description of the material distribution in the space (e.g. pores, fillers, defects, etc.). In principle, this technology works on different absorption of X-ray radiation by materials with changing proton number. The contribution was worked out in collaboration with experts from the Faculty of Electrical Engineering and Computer Science of the VŠB-Technical University of Ostrava and it is focused on the analysis of internal structure of the metal foam casting with irregular arrangement of internal pores by using micro-CT. The obtained data were evaluated in the commercial software VGStudio MAX 2.2 and in the FOTOMNG system. For the evaluation of these data a new specialized module was introduced in this system. Several methods of pre-processing the image was prepared for the measurement. This preliminary processing consists, for example, from a binary image thresholding for better diversity between the internal porosity and the material itself or functions for colour inversion.
Leguminous plant products have great nutritional and economic importance in the European Union, which is reflected by its protein policy. These harvested yields are risked by stored product pests, such as Acanthoscelides obtectus Say, which can cause up to 50–60% loss in stored bean items. The bean weevil causes both quantitative and qualitative damage to seeds. We aimed to map the qualitative damage of this devastating pest, which deteriorates the nutritional content of bean kernels. Furthermore, our purpose was to determine accurately the decrease in the volume and density alteration in beans caused by this important stored product pest using CT-assisted imaging analysis. Our results showed that the nutritional arrangement in damaged beans was caused by A. obtectus. The measured nutrient content increment in damaged samples can be explained by the presence of extraneous organic material which originates from perished specimens of the bruchin pest. This is a negative phenomenon in bean items used as forage, because of the loss of valuable proteins and rancidity in herbal oils. Weight loss triggered by developing larvae was 49.42% in examined bean items. The use of 3D technologies has greatly improved and facilitated the detailed investigation of injured seeds. The density (75,834 HU; 41.93%) and the volume (296.162 mm3; 26.21%) values measured by CT of the examined samples were significantly decreased. The decreasing of tissue density in damaged beans can be accounted for by the consumption of starch present at a high ratio and that of the dense reserve components in the cotyledons.
Minimally invasive procedures for the kidney tumour removal require a 3D visualization of topological relations between kidney, cancer, the pelvicalyceal system and the renal vascular tree. In this paper, a novel methodology of the pelvicalyceal system segmentation is presented. It consists of four following steps: ROI designation, automatic threshold calculation for binarization (approximation of the histogram image data with three exponential functions), automatic extraction of the pelvicalyceal system parts and segmentation by the Locally Adaptive Region Growing algorithm. The proposed method was applied successfully on the Computed Tomography database consisting of 48 kidneys both healthy and cancer affected. The quantitative evaluation (comparison to manual segmentation) and visual assessment proved its effectiveness. The Dice Coefficient of Similarity is equal to 0.871 ± 0.060 and the average Hausdorff distance 0.46 ± 0.36 mm. Additionally, to provide a reliable assessment of the proposed method, it was compared with three other methods. The proposed method is robust regardless of the image acquisition mode, spatial resolution and range of image values. The same framework may be applied to further medical applications beyond preoperative planning for partial nephrectomy enabling to visually assess and to measure the pelvicalyceal system by medical doctors.
The paper presents the possibilities of quantitative analysis of results obtained from CT examination of organs and anatomical structures of the upper respiratory tract. The presented results of the analysis were obtained using proprietary software developed in the MATLAB 2018b environment (Image Processing toolbox). The software enables to visualize the original results of CT scan and, after evaluating the visible structures, enables to select the area to be subjected to quantitative analysis. After the initial identification of an area of interest requiring detailed diagnostics, its volume and the surface areas of individual cross-sections are calculated in the area separated for examinations. A graphical presentation of the analysis results – the surface areas of selected cross-sections possible to visualize in two- and three-dimensional space – enables quick analysis of changes in the examined region.
The paper presents an analysis of the results of ultrasound transmission tomography (UTT) imaging of the internal structure of a breast elastography phantom used for biopsy training, and compares them with the results of CT, MRI and, conventional US imaging; the results of the phantom examination were the basis for the analysis of UTT method resolution. The obtained UTT, CT and MRI images of the CIRS Model 059 breast phantom structure show comparable (in the context of size and location) heterogeneities inside it. The UTT image of distribution of the ultrasound velocity clearly demonstrates continuous changes of density. The UTT image of derivative of attenuation coefficient in relation to frequency is better for visualising sharp edges, and the UTT image of the distribution of attenuation coefficient visualises continuous and stepped changes in an indirect way. The inclusions visualized by CT have sharply delineated edges but are hardly distinguishable from the phantom gel background even with increased image contrast. MRI images of the studied phantom relatively clearly show inclusions in the structure. Ultrasonography images do not show any diversification of the structure of the phantom. The obtained examination results indicate that, if the scanning process is accelerated, ultrasound transmission tomography method can be successfully used to detect and diagnose early breast malignant lesions. Ultrasonic transmission tomography imaging can be applied in medicine for diagnostic examination of women’s breasts and similarly for X-ray computed tomography, while eliminating the need to expose patients to the harmful ionising radiation.
The paper presents the development procedures for both virtual 3D-CAD and material models of fractured segments of human spine formulated with the use of computer tomography (CT) and rapid prototyping (RP) technique. The research is a part of the project within the framework of which a database is developed, comprising both 3D-CAD and material models of segments of thoracic-lumbar spine in which one vertebrae is subjected to compressive fracture for a selected type of clinical cases. The project is devoted to relocation and stabilisation procedures of fractured vertebrae made with the use of ligamentotaxis method. The paper presents models developed for five patients and, for comparison purposes, one for a normal spine. The RP material models have been built basing on the corresponding 3D-CAD ones with the use of fused deposition modelling (FDM) technology. 3D imaging of spine segments in terms of 3D-CAD and material models allows for the analysis of bone structures, classification of clinical cases and provides the surgeons with the data helpful in choosing the proper way of treatment. The application of the developed models to numerical and experimental simulations of relocation procedure of fractured vertebra is planned.
This paper provides an overview of the effects of timing jitter in audio sampling analog-to-digital converters (ADCs), i.e. PCM (conventional or Nyquist sampling) ADCs and sigma-delta (ΣΔ) ADCs. Jitter in a digital audio is often defined as short-term fluctuations of the sampling instants of a digital signal from their ideal positions in time. The influence of the jitter increases particularly with the improvements in both resolution and sampling rate of today's audio ADCs. At higher frequencies of the input signals the sampling jitter becomes a dominant factor in limiting the ADCs performance in terms of signal-to-noise ratio (SNR) and dynamic range (DR).