Background: Dose reference levels (DRLs) are used as indicators as well as guidance for dose optimization and to ensure justification of appropriate dose for a given clinical indication. The main aims of this study were to establish local DRLs for each CT imaging protocol as a reference point to evaluate the radiation dose indices and to compare our DRLs with those established in other countries and against the internationally reported guidelines. Materials and methods: 2000 CT dose reports of different adult imaging protocols from January 2021 until April 2022 were collected retrospectively at different hospitals in Jordan. Data were collected from CT scans that were performed using different types and models of CT scanners and included four adult non-enhanced, helical CT imaging protocols; Head, Chest, Abdomen-Pelvis, and Chest-Abdomen-Pelvis. Results: The average doses of CTDIvol, DLP, and effective dose were (65.11 mGy, 1232.71 mGy·cm, 2.83 mSv) for the head scan, (16.6 mGy, 586.6 mGy·cm, 8.21 mSv) for the chest scan, (17.91 mGy, 929.9 mGy·cm, 13.9 mSv) for the abdomen-pelvis scan, and (19.3 mGy, 1152 mGy·cm, 17.25 mSv) for the chest-abdomen-pelvis scan. In comparison with results from different international studies, DLP values measured in the present study were lower for the chest-abdomen-pelvis and abdomen-pelvis CT scans, and higher for the head CT and chest CT scans. Conclusions: It is very important that each country establishes its own DRLs and compares them with those reported by other countries, especially the developed ones. It is also important that these levels are regularly updated.
This paper presents the research results on the design of a three-dimensional head phantom for cone beam projection. The head model is based on a Shepp-Logan mathematical head model, which is used to simulate the operation of the CT scanner. The model is then compared with the reference data for structural similarity, reasoning, and shape. The geometric parameters of the obtained images are investigated. The reconstructed image is analyzed using the FDK method. The results show that the geometric parameters directly correlate with the number of projections. A mathematical framework of cone beam 3d reconstruction via the first derivative of the radon transform is presented.
PL
W artykule przedstawiono wyniki badań nad projektem trójwymiarowego fantomu głowy do projekcji wiązki stożkowej. Model głowy jest oparty na matematycznym modelu głowy Shepp-Logan, który jest używany do symulacji działania skanera CT. Model jest następnie porównywany z danymi referencyjnymi pod kątem podobieństwa strukturalnego, rozumowania i kształtu. Badane są parametry geometryczne uzyskanych obrazów. Zrekonstruowany obraz jest analizowany przy użyciu metody FDK. Wyniki pokazują, że parametry geometryczne mają bezpośredni związek z liczbą projekcji. Przedstawiono matematyczne ramy rekonstrukcji 3D wiązki stożkowej za pomocą pierwszej pochodnej transformaty radonowej.
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Chronic obstructive pulmonary disease (COPD) is a complex and multi-component respiratory disease. Computed tomography (CT) images can characterize lesions in COPD patients, but the image intensity and morphology of lung components have not been fully exploited. Two datasets (Dataset 1 and 2) comprising a total of 561 subjects were obtained from two centers. A multiple instance learning (MIL) method is proposed for COPD identification. First, randomly selected slices (instances) from CT scans and multi-view 2D snapshots of the 3D airway tree and lung field extracted from CT images are acquired. Then, three attention-guided MIL models (slice-CT, snapshot-airway, and snapshot-lung-field models) are trained. In these models, a deep convolution neural network (CNN) is utilized for feature extraction. Finally, the outputs of the above three MIL models are combined using logistic regression to produce the final prediction. For Dataset 1, the accuracy of the slice-CT MIL model with 20 instances was 88.1%. The backbone of VGG-16 outperformed Alexnet, Resnet18, Resnet26, and Mobilenet_v2 in feature extraction. The snapshotairway and snapshot-lung-field MIL models achieved accuracies of 89.4% and 90.0%, respectively. After the three models were combined, the accuracy reached 95.8%. The proposed model outperformed several state-of-the-art methods and afforded an accuracy of 83.1% for the external dataset (Dataset 2). The proposed weakly supervised MIL method is feasible for COPD identification. The effective CNN module and attention-guided MIL pooling module contribute to performance enhancement. The morphology information of the airway and lung field is beneficial for identifying COPD.
The study aimed touse3D computed tomography (CT) to analyse a joint between two dissimilar materials produced by friction stir welding (FSW). As the materials joined, i.e., aluminum and copper, differ in properties (e.g., density and melting point), the weld is predicted to have an inhomogeneous microstructure. The investigations involved applying microfocus computed tomography (micro-CT) to visualize and analyze the volumetric structure of the joint. Volume rendering is extremely useful because, unlike computer modelling, which requires many simplifications, it helps create highly accurate representations of objects. Image segmentation into regions was performed through global gray-scale thresholding. The analysis also included elemental mapping of the weld cross-sections using scanning electron microscopy (SEM) and examination of its surface morphology by means of optical microscopy (OP). The joint finds its use in developing elements used in the chemical, energetics and aerospace industries, due to the excellent possibilities of combining many different properties, and above all, reducing the weight of the structure.
The aim of this study was to examine the behavior of the carbon fiber reinforced polymer (CFRP) composites depending on the fiber orientation and to understand the influence of microstructural discontinuities on mechanical properties. For the tests 210 gsm prepreg composite and 200 gsm carbon fabric with polymer matrix have been used. Samples were structured and later examined according to the ASTM-D3039 and ASTM-D3878 (equivalents are ISO 20975, ISO 527-4 and ISO 527-5). Accordingly, to the number of layers, three ways of the fibers arranging in relation to the applied force were used. Mechanical properties were determined in a static tensile test. The results of imaging studies, which included analyzes of Digital Image Correlation, Computed Tomography and Scanning Electron Microscopy, showed structural discontinuities, specific stress distribution and propagation of stresses depending on the production technology, which were correlated with the obtained strength results. The source of the gradual development of the degradation of the composite structure was observed in local microdamages and microcracks. As a result of a sub-critical crack growth within the resin matrix material, the defects are subject to a complex, multi-axial stress field on the micro-scale, even if the globally applied force is axial. Samples in which the load was applied along the axis of the fibers behave like an elastic material, while samples, where the force is applied at an angle to the axis of the fibers, tend to behave like an elastic-plastic material.
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The main aim of the researches was the three-dimensional morphological assessment of the mandible in children. Materials&Methods: The research group consisted of 34 infants from 21 to 417 days of age (0-13 months). Models of the mandibles were developed on the basis of tomographic images. Characteristic anatomical points were marked on the models, on the basis of which characteristic distances and angles were calculated, determining the length, width and height of the mandible as well as its proportion and symmetry. Based on the obtained database, models of mandibular growth in the first year of life in three directions were also developed. Conclusion: The analysis of the results revealed some significant objective information on the growth and development of the normal mandible.
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This paper has proposed a new perspective of studying internal structure-based tests, the results of which will improve the present experimental methods and enrich our understanding of rock structure-based modeling without any core preparations, with low cost in a short time. Pore volume compressibility (PVC) is an important feature of rock and is related to mechanical and structural behavior of porous rock sample. An accurate evaluation of pore volume compressibility depends on experimental test which is time-consuming and costly. This paper outlines new method for evaluation of PVC of rock cores using a computed tomography (CT) scan-based finite element method (FEM). The verification studies were performed on a series of porous rock cores which were extracted from deep oil reservoirs in Iran. In order to construct a finite element model, a relationship between spatial elastic properties of samples and CT-scanned data images was derived. The samples were scanned by a conic beam computed tomography (CBCT) machine, and the scanned data were converted into a model to simulate PVC tests. The pore volumetric strains were obtained from a linear elastic analysis for each stress and pore pressure step. To validate the finite element analysis (FEA) results, a series of experimental PVC tests were conducted on the pre-scanned samples and PVC curves were extracted. As a result, the predictions calculated from the CT scan-based numerical models have shown a good correlation with the results obtained from laboratory experiments. The results revealed that it is possible to simulate PVC tests using this numerical proposed evaluation method in such a way that the cost and time of the tests were lowered.
Badania przeprowadzone w ramach przygotowywania monografi i ukierunkowane były na utworzenie systemu pomiarowo-interpretacyjnego, którego rezultatem jest otrzymanie wiarygodnych wyników profilowań geofizyki otworowej z dokładnością pomiarów laboratoryjnych. Ciągłe pomiary rdzeni wiertniczych pozwoliły na wygenerowanie profilowań pozbawionych wpływu otworu oraz ułatwiły dopasowanie głębokościowe rdzenia do pomiarów otworowych. W pracy wydzielono cztery główne rozdziały dotyczące: metodyki badawczej wraz z opisem stosowanych urządzeń, częściowych wyników pomiarów rdzeni wykonanych na różnych typach skał, propozycji systemu prowadzenia badań oraz kompleksowej interpretacji danych dla wybranych otworów. Część metodyczna dotyczyła opisu aparatury do ciągłych pomiarów rdzeni wiertniczych w zakresie naturalnej promieniotwórczości gamma (K, U, Th) wraz z aplikacją do pomiarów gęstości objętościowej metodą gamma-gamma, spektrometrów fluorescencji rentgenowskiej XRF do pomiarów składu chemicznego skał oraz tomografi i komputerowej CT do obrazowania struktury rdzeni, jak również wyznaczania gęstości radiologicznej w jednostkach Hounsfi elda (HU). Badania skał przeprowadzono na materiale reprezentującym utwory o zróżnicowanej litologii, takie jak: łupki, piaskowce, wapienie, dolomity, anhydryty, mułowce oraz heterolitowe kompleksy piaskowcowo-mułowcowo-iłowcowe. Wyniki pomiarów wykonanych z zastosowaniem poszczególnych metod zostały szczegółowo opisane oraz zestawione z punktowymi wynikami pomiarów laboratoryjnych i profilowaniami otworowymi. Pomiary testowe wraz z przetwarzaniem i interpretacją danych wykonano na rdzeniach pochodzących z pięciu otworów wiertniczych (T-1, O-4, Pt-1, L-7, P-5H), natomiast kompleksową interpretację wyników badań przeprowadzono dla trzech otworów wiertniczych (J-1, P-4, T-2). Nowa metodyka spektrometrycznych pomiarów gamma pozwoliła na uzyskanie dokładnych koncentracji potasu, uranu i toru, zarówno w skałach o wysokiej, jak i niskiej radioaktywności. Wyniki badań umożliwiły standaryzację archiwalnych profi lowań gamma, wykonanych sondami typu radzieckiego z imp/min do jednostek standardowych API oraz uzyskanie danych na temat zawartości K, U, Th w interwale rdzeni. Zastosowanie źródła Cs-137 w aparaturze do pomiarów gamma umożliwiło przeprowadzenie pomiarów gęstości objętościowej w jednostkach g/cm3. Interpretacja litologiczna wykonana na podstawie pomiarów XRF i modeli mineralogiczno-chemicznych pozwoliła uzyskać profi le o zwiększonej rozdzielczości oraz większej liczbie składników mineralnych w stosunku do interpretacji pomiarów otworowych. Ponadto wykazano, że metodyka pomiarowa XRF może być stosowana podczas kierowania trajektorią otworu wiertniczego. Wyniki badań rdzeni metodą tomografi i komputerowej CT przedstawiono w postaci połączonych obrazów oraz ciągłych krzywych zmian gęstości w jednostkach HU. Zdobyte doświadczenie i przedstawienie pełnego zakresu prac pomiarowych oraz interpretacyjnych pozwoliły na zaproponowanie procedury prowadzenia pełnego zakresu analiz, z uwzględnieniem różnego rodzaju materiału dostarczonego do badań. Procedura uwzględnia zarówno pełny zakres analiz, jak również pomiary wybranych parametrów, w zależności od zapotrzebowania zleceniodawcy.
EN
The research carried out in the monograph aimed to create a measurement and interpretation system which is to obtain reliable results of well logging with the accuracy of laboratory measurements. Continuous core measurements allow for the generation of logging results without the impact of the borehole and facilitate the depth matching of the core to well log data. Four main chapters can be distinguished in this work: research methodology with a description of the devices used; partial results of core measurements made on various types of rocks; a proposal for a research system, and comprehensive data interpretation for selected boreholes. The methodological part concerned the description of the equipment for continuous measurements of cores in the field of natural gamma radioactivity (K, U, Th) with the application for bulk density measurements using the gamma-gamma method, X-ray fl uorescence spectrometers (XRF) for measuring the chemical composition of rocks and computed tomography (CT) for imaging of the core structure as well as determination of radiological density in Hounsfi eld units (HU). Rock studies were carried out on material representing formations of diff erent lithologies, such as shales, sandstones, limestones, dolomites, anhydrite, siltstones and heterolithic sandstone-siltstone-claystone complexes. The results of measurements made using individual methods have been described in detail and compared with the results of laboratory measurements and well logging data. Test measurements with data processing and interpretation were made on the cores from five boreholes (T-1, O-4, Pt-1, L-7, P-5H), whereas a comprehensive interpretation of the results was carried out for three other boreholes (J-1, P-4, T-2). The new methodology of spectral gamma measurements made it possible to obtain precise concentrations of potassium, uranium and thorium in rocks with high and low radioactivity. The results made it possible to standardise the archival gamma-ray logs made with the Russian-type probes from imp/min to API standard units and to obtain data on the content of K, U, and Th in the core intervals. Using the Cs-137 source in the device for the gamma equipment made it possible to carry out measurements of the bulk density in g/cm3 units. The lithological interpretation based on XRF measurements and mineralogical-chemical models allowed to obtain logs with increased resolution and a more signifi cant number of minerals than was the case with the interpretation of the well logging. In addition, it has been shown that the XRF measurement methodology can be used during the geosteering procedure. The results of the core tests using the CT computed tomography method were presented in combined images and continuous curves of density in HU units. The experience and the presentation of the full scope of measurement and interpretation workflow allowed to propose a procedure for conducting a full range of analyses, considering various types of material provided for research. The procedure considers the full range of analyses as well as the measurements of selected parameters depending on the client’s needs.
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Purpose: The current study proposes a method for automatically measuring slice thickness using a non-rotational method on the middle stair object of the AAPM CT performance phantom image. Method: The AAPM CT performance phantom was scanned by a GE Healthcare 128-slice CT scanner with nominal slice thicknesses of 0.625, 1.25, 2.5, 3.75, 5, 7.5 and 10 mm. The automated slice thickness was measured as the full width at half maximum (FWHM) of the profile of the middle stair object using a non-rotational method. The non-rotational method avoided rotating the image of the phantom. Instead, the lines to make the profiles were automatically rotated to confirm the stair’s location and rotation. The results of this non-rotational method were compared with those from a previous rotational method. Results: The slice thicknesses from the non-rotational method were 1.55, 1.86, 3.27, 4.86, 6.58, 7.57, and 9.66 mm for nominal slice thicknesses of 0.625, 1.25, 2.4, 3.75, 5, 7.5, and 10 mm, respectively. By comparison, the slice thicknesses from the rotational method were 1.53, 1.87, 3.32, 4.98, 6.77, 7.75, and 9.80 mm, respectively. The results of the non- rotational method were slightly lower (i.e. 0.25%) than the results of the rotational method for each nominal slice thickness, except for the smallest slice thickness. Conclusions: An alternative algorithm using a non-rotational method to measure the slice thickness of the middle stair object in the AAPM CT performance phantom was successfully implemented. The slice thicknesses from the non- rotational method results were slightly lower than the rotational method results for each nominal slice thickness, except at the smallest nominal slice thickness (0.625 mm).
Niniejsza praca została poświęcona kompleksowej interpretacji interwałów otworu wiertniczego B-7, w przypadku którego dysponowano rdzeniami zbudowanymi z takich skał jak anhydryty, dolomity, węglany oraz mułowce. Do przeprowadzenia badań wykorzystane zostały dane uzyskane na podstawie ciągłych pomiarów rdzeni wiertniczych z zastosowaniem metod tomografii komputerowej (CT), fluorescencji rentgenowskiej (XRF) oraz naturalnej promieniotwórczości gamma (GR) wraz z pomiarem gęstości objętościowej (gamma-gamma). Wymienione metody wchodzą w zakres pomiarów nieniszczących; z wykorzystaniem odpowiednich kalibracji mogą być prowadzone na połówkach rdzeni archiwalnych. Dla uzyskania szczegółowej interpretacji profilowań rdzeni wiertniczych wymagane jest wykonanie laboratoryjnych pomiarów referencyjnych. W przypadku rdzeni z otworu B-7 badania laboratoryjne przeprowadzono na próbkach pobranych z roboczej części rdzenia. Zakres badań stacjonarnych obejmował pomiary składu chemicznego (ICP-MS/OES), mineralnego (XRD), promieniotwórczości naturalnej gamma (K, U, Th), gęstości objętościowej oraz porowatości. Wyniki pomiarów laboratoryjnych posłużyły do sprawdzenia jakości danych oraz do kalibracji ciągłych pomiarów rdzeni w postaci połówek walca (część archiwalna). Na podstawie skalibrowanych danych XRF i badań XRD utworzono modele mineralogiczno-chemiczne dla skał anhydrytowych, węglanowych i mułowcowych, dzięki którym przeprowadzono interpretację litologiczną. Badania gęstości i porowatości posłużyły do kalibracji krzywych gęstości uzyskanych z metody gamma-gamma oraz CT. W ramach kompleksowej interpretacji danych geofizycznych wyniki z ciągłych pomiarów rdzeni zostały porównane z profilowaniami geofizyki wiertniczej oraz z wynikami badań laboratoryjnych. Łącznie przebadano około 28 metrów rdzeni wiertniczych. Ponadto wykonano zestawienie wyników interpretacji litologicznej z pomiarów otworowych, jak i pomiarów na rdzeniach. Końcowe zestawienia zaprezentowano w postaci krzywych wynikowych oraz słupków litologicznych w domenie głębokości. Wybrane interwały rdzeni pozwoliły na przetestowanie stosowanej aparatury oraz metod interpretacji w szerokim zakresie zmienności litologicznej.
EN
This paper deals with the comprehensive interpretation of the B-7 borehole core intervals, which were composed of rock such as anhydrites, dolomites, carbonates and mudstones. Data obtained on the basis of continuous measurements of cores with the use of computed tomography (CT), X-ray fluorescence (XRF) and natural gamma radioactivity (GR) method with the application of bulk density measurement (gamma-gamma) were used to carry out the study. These methods are included in the scope of non-destructive measurements, and with the use of appropriate calibrations, they can be carried out on the halves of archival cores. For a detailed interpretation of core profiles, laboratory measurements are required for reference values. In the case of cores from the B-7 borehole, laboratory tests were carried out on samples taken from the part of the core intendent for research. The scope of stationary tests included the measurements of chemical composition (ICP-MS/OES), mineral composition (XRD), natural gamma radioactivity (K, U, Th), bulk density and porosity. The results of the laboratory measurements were used to check the quality of the data and to calibrate the continuous measurements of the cores in the form of half cylinders (archival part). On the basis of calibrated XRF data and XRD tests, mineralogical and chemical models were created for anhydrite, carbonate and mudstone rocks, with the use of which lithological interpretation was performed. The density and porosity tests were used to calibrate the density profiles obtained from the gamma-gamma and CT methods of the core measurements. As part of the comprehensive interpretation of geophysical data, the results of continuous core measurements results were compared with the well logging and the laboratory tests. About 28 meters of drill cores were tested in total. Furthermore, the final summaries are presented in the form of the well and core logs as well as lithological interpretation which was made based on the well logs and the measurements of the cores was presented in the depth domain. The selected core intervals allowed for the testing of the equipment and interpretation methods used in a wide range of lithological variability.
The liver is a vital organ of the human body and hepatic cancer is one of the major causes of cancer deaths. Early and rapid diagnosis can reduce the mortality rate. It can be achieved through computerized cancer diagnosis and surgery planning systems. Segmentation plays a major role in these systems. This work evaluated the efficacy of the SegNet model in liver and particle swarm optimization-based clustering technique in liver lesion segmentation. Over 2400 CT images were used for training the deep learning network and ten CT datasets for validating the algorithm. The segmentation results were satisfactory. The values for Dice Coefficient and volumetric overlap error achieved were 0.940 ± 0.022 and 0.112 ± 0.038, respectively for liver and the results for lesion delineation were 0.4629 ± 0.287 and 0.6986 ± 0.203, respectively. The proposed method is effective for liver segmentation. However, lesion segmentation needs to be further improved for better accuracy.
The 2019 Coronavirus (COVID-19) virus has caused damage on people's respiratory systems over the world. Computed Tomography (CT) is a faster complement for RT-PCR during peak virus spread times. Nowadays, Deep Learning (DL) with CT provides more robust and reliable methods for classifying patterns in medical pictures. In this paper, we proposed a simple low training proposed customized Convolutional Neural Networks (CNN) customized model based on CNN architecture that layers which are optionals may be included such as the layer of batch normalization to reduce time taken for training and a layer with a dropout to deal with overfitting. We employed a huge dataset of chest CT slices images from diverse sources COVIDx-CT, which consists of a 16,146-image dataset with 810 patients of various nationalities. The proposed customized model's classification results compared to the VGG-16, Alex Net, and ResNet50 Deep Learning models. The proposed CNN model shows robustness by achieving an overall accuracy of 93% compared to 88%, 89%, and 95% for the VGG-16, Alex Net, and ResNet50 DL models for the classification of 3 classes. When this relates to binary classification, the classification accuracy of the proposed model and the VGG-16 models were identical (almost 100% accurate), with 0.17% of misclassification in the class of Non-Covid-19, the Alex Net model achieved almost 100% classification accuracy with 0.33% misclassification in the class of Non-Covid-19. Finally, ResNet50 achieved 95% classification accuracy with 5% misclassification in the Non-Covid-19 class.
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Detecting spatial tortuosity and atherosclerotic changes of the ilio-femoral arteries are crucial for planning endovascular access. The aim of this study was to find a reliable quantification procedure of arterial lumen and tortuosity to qualify patients for a suitable endovascular procedure. We conducted computed tomographic angiography in 76 patients. All ilio-femoral segments of the arterial tree were visualized using Osirix Dicom Viewer software to help qualify the patients to one of two groups: with possible or non-recommended vascular access. The same tomograms were then analyzed with image processing algorithms to perform ilio-femoral artery segmentation and quantification. We chose a set of arterial tortuosity and lumen measuring methods, such as the modified Gustafson-Kessel clustering algorithm and Support Vector Machine classifier, to automatically classify arterial-tree regions. The two 2D feature spaces were selected with the modified Gustafson-Kessel clusterization to create a combined model to assign around 2/3 cases to the access groups with high specificity (more than 88%) whereas the remaining patients were selected for re-evaluation. We concluded that the novel modification of the Gustafson-Kessel clustering algorithm is more suitable to the highly inseparable data than commonly used approaches. To identify ilio-femoral access limitations, we recommend more complex decision model. This study confirmed high usability of our chosen methodology in the quantitative examination of arteries for endovascular access planning.
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The management of intracerebral hemorrhage (ICH) requires prompt diagnostic assessment and recognition. Accurate localization and categorization of ICH-type is crucial. There are two main categories of ICH: 1) hemorrhagic stroke (HS), which occurs in the deeper or subcortical regions of the brain, where the arterial network tapers to fine end-arteries, and, 2) cerebral amyloid angiopathy hemorrhage (CAAH), which occurs at the superficial or cortical-subcortical region of the grey and white matter junction. Computed tomography (CT) and magnetic resonance imaging (MRI) are the most used imaging tools in diagnosing ICH. However, availability, time, and cost often prevent emergent MRI use. Therefore, CT remains the primary tool in the diagnosis of ICH. The assessment of imaging studies is time-dependent, and a radiologist should do a detailed diagnostic evaluation. Human error can occur in a pressured clinical setting, even for highly trained medical professionals. Assisted or automated computer-aided analysis of CT/MRI may help to reduce the assessment time, improve the diagnostic accuracy, better differentiate between types of ICH, and reduce the risk of human errors. This review evaluates CT and MRI’s role in distinguishing between the two varieties of ICH-HS and CAAH. It focuses on how CT could be utilized as the preferred diagnostic tool. In addition, we discuss the role of automation using machine learning (ML) and the role or advantages of ML in the automated assessment of CT for the detection and classification of HS and CAAH. We have included our observations for future research and the requirements for further evaluation.
Casting is the most economical way of producing parts for many industries ranging from automotive, aerospace to construction towards small appliances in many shares. One of the challenges is the achievement of defect-free cast parts. There are many ways to do this which starts with calculation and design of proper runner system with correct size and number of feeders. The first rule suggests starting with clean melt. Yet, rejected parts can still be found. Although depending on the requirement from the parts, some defects can be tolerated, but in critical applications, it is crucial that no defect should exist that would deteriorate the performance of the part. Several methods exist on the foundry floor to detect these defects. Functional safety criteria, for example, are a must for today's automotive industry. These are not compromised under any circumstances. In this study, based on the D-FMEA (Design Failure Mode and Effect Analysis) study of a functional safety criterion against fuel leakage, one 1.4308 cast steel function block, which brazed-on fuel rail port in fuel injection unit, was investigated. Porosity, buckling, inclusion and detection for leak were carried out by non-destructive test (NDT) methods. It was found that the best practice was the CT-Scan (Computed Tomography) for such applications.
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In this paper, polyamide 12 (PA12) blends with three types of metallic fillers are tested, which differ in the type of material and its’ morphology. Low content mixtures are taken into consideration (0.5, 1.0, 2.0, 5.0 wt%), since a low impact on mechanical properties along with obtaining antibacterial properties are desired. The investigation focuses on filler distribution as well as the influence on microstructural homogeneity of the base material after processing with polymer Laser Sintering. Moreover, the influence of the filler content on the mechanical properties and fracture behaviour were examined. Processability PA12 with bioactive metal fillers was confirmed, and no significant changes in ductile behaviour of PA12 were observed. An in-depth analysis of the effect of the filler on microstructural homogeneity was conducted.
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Purpose: The aim of this work was to establish the relationships of patient size in terms of effective diameter (Deff) and water-equivalent diameter (Dw) with lateral (LAT) and anterior-posterior (AP) dimensions in order to predict the specific patient dose for thoracic, abdominal, and pelvic computed tomography (CT) examinations. Methods: A total of 47 thoracic images, 79 abdominal images, and 50 pelvic images were analyzed in this study. The patient’s images were retrospectively collected from Dr. Kariadi and Kensaras Hospitals, Semarang, Indonesia. The slices measured were taken from the middle of the scan range. The calculations of patient sizes (LAT, AP, Deff, and Dwf) were automatically performed by IndoseCT 20b software. Deff and Dw were plotted as functions of LAT, AP, and AP+LAT. In addition, Dw was plotted as a function of Deff. Results: Strong correlations of Deff and Dw with LAT, AP, and AP+LAT were found. Stronger correlations were found in the Deff curves (R2 > 0.9) than in the Dw curves (R2 > 0.8). It was found that the average Deff was higher than the average Dw in the thoracic region, the average values were similar in the abdominal and pelvic regions. Conclusion: The current study extended the study of the relationships between Deff and Dw and the basic geometric diameter LAT, AP, and AP+LAT beyond those previously reported by AAPM. We evaluated the relationships for three regions, i.e. thoracic, abdominal, and pelvic regions. Based on our findings, it was possible to estimate Deff and Dw from only the LAT or AP dimension.
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The purpose of this study was to develop an automatic method for validating the computed tomography gantry tilt. A head polymethyl methacrylate phantom with a diameter of 16 cm was used. Gantry tilt angles were measured both manually and automatically. Manual measurements were performed by measuring the length of the anteroposterior and lateral diameters from acquired images using electronic calipers. Automatic measurements consisted of a number of steps: phantom segmentation, determination of the center of the phantom, measurement of the anteroposterior and lateral diameters, and computation of the gantry tilt angle. The method was implemented on the gantry angles from 0° to 15°. The proposed method of measuring gantry angles produced accurate gantry tilt angles. The differences with the angles displayed on the gantry were less than 1°. The results of the automatic method were the same as those of the manual method (R2 > 0.98).
Celem niniejszej pracy było sprawdzenie możliwości wykorzystania rentgenowskiej tomografii komputerowej (CT) do obserwacji spękań w badanej próbce węgla przed i po teście geomechanicznym, przeprowadzonym w stanie trójosiowych naprężeń (TRX). W pracy przedstawiono zastosowanie dwóch specjalistycznych technik laboratoryjnych: rentgenowskiej tomografii komputerowej i geomechanicznego trójosiowego testu ściskania. Testy geomechaniczne przeprowadzono za pomocą zestawu pomiarowego TRX-070, GCTS (USA), rejestrując pełną charakterystykę naprężeniowo-odkształceniową. Podczas trójosiowych testów ściskania wykonano też innowacyjne równoczesne pomiary prędkości fal P i S. Próbkę analizowano w dwóch etapach, zdefiniowanych ze względu na stan próbki w obrazie CT: pomiar CT wykonany na nienaruszonej próbce węgla (etap 1) oraz otrzymany po teście zniszczeniowym (etap 2). W pierwszym etapie próbka została zeskanowana w celu odzwierciedlenia początkowego stanu struktury porowej wraz z układem mikropęknięć. Drugi etap reprezentuje próbkę po badaniu geomechanicznym. Dla każdego z etapów przeprowadzono szczegółową analizę struktury porowej. W wyniku proponowanego połączenia wymienionych metod w każdym etapie uzyskano obrazy struktury porów. Próbkę analizowano pod kątem liczby i kierunków propagacji pęknięć i zmian w strukturze porów. Interpretacja jakościowa i ilościowa opierała się na rejestracji zmiany liczby pustek, średnic pęknięć, kątów zapadania i porównaniu struktury porowej pomiędzy stanem początkowym próbki oraz po badaniu geomechanicznym. W 1 etapie (przed testem) największy obiekt (zidentyfikowany jako mikroszczelina) przyjmował objętość powyżej 16 mm3 , po wystawieniu próbki na działanie naprężeń (po zniszczeniu próbki) największy zidentyfikowany obiekt charakteryzował się objętością około 15 razy większą (240 mm3 ). Zidentyfikowane w etapie 2 (po teście wytrzymałościowym) pory są wydłużone (wysokie wartości parametru Elongation), a także nie wykazują znaczącego spłaszczenia (Flatness). Według uzyskanych wyników próbka węgla była podatna na pękanie w określonych kierunkach. Kompleksowe badania wykazały zasadność zastosowania proponowanej metodologii do oceny zmian w strukturze próbki podczas testu wytrzymałościowego.
EN
The study aimed to check the possibility of using computed tomography to observe fractures in coal samples before and after a triaxial compression test (TRX). The paper presents an innovative use of two specialized laboratory techniques: computed tomography and geomechanical triaxial compression test. Geomechanical tests were performed on a TRX-070, GCTS (USA) measuring triaxial system. A full stress-strain characteristic was recorded. Also, during the triaxial compression tests, the P and S wave velocities were measured and dynamic elastic moduli were determined. The results were compared. The sample was analyzed in two stages: CT measurement performed on raw coal sample (stage 1) and after the TRX test which destroyed the sample structure (stage 2). First, the sample was scanned reflecting the initial pores and microcracks system. The final stage represents the sample after the geomechanical test. A detailed pore structure analysis was performed for each of the stages. As a result of the proposed above-mentioned method, images of the pore structure were obtained after each step. The sample was analyzed for crack propagation and changes in the pore structure. The qualitative and quantitative interpretation was based on the determination of the number of voids, crack diameters, collapse angles, and comparison of the pore structure between the initial state of the sample and after the triaxial test. In the first stage (before the test), the largest object (identified as a microcrack) had a volume of approximately 16 mm3 , after the sample was stress-tested (after the sample was destroyed), the largest identified object was about 15 times larger (240 mm3 ). It appeared that the coal sample was prone to fracturing in defined directions. Comprehensive research has demonstrated the legitimacy of using the proposed methodology to evaluate changes in the sample structure during the triaxial test.
This paper presents a new image reconstruction method for spiral cone- beam tomography scanners in which an X-ray tube with a flying focal spot is used. The method is based on principles related to the statistical model-based iterative reconstruction (MBIR) methodology. The proposed approach is a continuous-to-continuous data model approach, and the forward model is formulated as a shift-invariant system. This allows for avoiding a nutating reconstruction-based approach, e.g. the advanced single slice rebinning methodology (ASSR) that is usually applied in computed tomography (CT) scanners with X-ray tubes with a flying focal spot. In turn, the proposed approach allows for significantly accelerating the reconstruction processing and, generally, for greatly simplifying the entire reconstruction procedure. Additionally, it improves the quality of the reconstructed images in comparison to the traditional algorithms, as confirmed by extensive simulations. It is worth noting that the main purpose of introducing statistical reconstruction methods to medical CT scanners is the reduction of the impact of measurement noise on the quality of tomography images and, consequently, the dose reduction of X-ray radiation absorbed by a patient. A series of computer simulations followed by doctor’s assessments have been performed, which indicate how great a reduction of the absorbed dose can be achieved using the reconstruction approach presented here.
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