Visualisation of Ultrasound Computer Tomography Breast Dataset

Medical visualisation plays a vital role in diagnosing and detecting early symptoms. In particular, visualising the anatomy of breast model allows doctors or practitioners to identify first signs of the breast cancer. However, despite the advancement in visualisation techniques, most standard visualisation approaches in the medical field still rely on analysing 2D images which lack spatial information. In this paper, we present an interactive web-based 3D visualisation tool for ultrasound computer tomography (USCT) breast dataset. We base our implementation on the Web-based Graphics Language (WebGL) technology that utilises the GPU parallel architecture. The tool serves as a common platform among research collaborators to analyse and share findings on their dataset. We render the data using state-of-the-art algorithms of interactive computer graphics and produce results with quality comparable to the desktop application. Aside from that, our tool enables researchers to perform arbitrary view slicing, modality thresholding and multiple rendering modes. In the evaluation, our tool maintains an interactive frame rate above 30 fps on a standard desktop

Image-Based Fracture Mechanics with Digital Image Correlation and Digital Volume Correlation

Analysis that requires human judgement can add bias which may, as a result, increase uncertainty. Accurate detection of a crack and segmentation of the crack geometry is beneficial to any fracture experiment. Studies of crack behaviour, such as the effect of closure, residual stress in fatigue or elastic-plastic fracture mechanics, require data on crack opening displacement. Furthermore, the crack path can give critical information of how the crack interacts with the microstructure and stress fields. Digital Image Correlation (DIC) and Digital Volume Correlation (DVC) have been widely accepted and routinely used to measure full-field displacements in many areas of solid mechanics, including fracture mechanics. However, current practise for the extraction of crack parameters from displacement fields usually requires manual methods and are quite onerous, particularly for large amounts of data. This thesis introduces the novel application of Phase Congruency-based Crack Detection (PC-CD) to automatically detect and characterise cracks from displacement fields. Phase congruency is a powerful mathematical tool that highlights a discontinuity more efficiently than gradient based methods. Phase congruency’s invariance to the magnitude of the discontinuity and its state-of-the-art de-noising method, make it ideal for the application to crack tip displacement fields. PC-CD’s accuracy is quantified and benchmarked using both theoretical and virtual displacement fields. The accuracy of PC-CD is evaluated and compared with conventional, manual computation methods such as Heaviside function fitting and gradient based methods. It is demonstrated how PC-CD can be coupled with a new method that is based on the conjoint use of displacement fields and finite element analysis to extract the strain energy release rate of cracks automatically. The PC-CD method is extended to volume displacement fields (VPC-CD) and semi-autonomously extracts crack surface, crack front and opening displacement through the thickness. As a proof of concept, PC-CD and VPC-CD are applied to a range of fracture experiments varying in material and fracture behaviour: two ductile and one quasi-brittle for surface displacement measurements; and two quasi-brittle and one ductile for volume measurements. Using the novel PC-CD and VPC-CD analyses, the crack geometry is obtained fully automatically and without any user judgement or intervention. The geometrical parameters extracted by PC-CD and VPC-CD are validated experimentally through other tools such as: optical microscope measurements, high resolution fractography and visual inspection

Proceedings of the International Workshop on Medical Ultrasound Tomography: 1.- 3. Nov. 2017, Speyer, Germany

Ultrasound Tomography is an emerging technology for medical imaging that is quickly approaching its clinical utility. Research groups around the globe are engaged in research spanning from theory to practical applications. The International Workshop on Medical Ultrasound Tomography (1.-3. November 2017, Speyer, Germany) brought together scientists to exchange their knowledge and discuss new ideas and results in order to boost the research in Ultrasound Tomography

Development of a simulation platform for the evaluation of PET neuroimaging protocols in epilepsy

Monte Carlo simulation of PET studies is a reference tool for the evaluation and standardization of PET protocols. However, current Monte Carlo software codes require a high degree of knowledge in physics, mathematics and programming languages, in addition to a high cost of time and computational resources. These drawbacks make their use difficult for a large part of the scientific community. In order to overcome these limitations, a free and an efficient web-based platform was designed, implemented and validated for the simulation of realistic brain PET studies, and specifically employed for the generation of a wellvalidated large database of brain FDG-PET studies of patients with refractory epilepsy

Design and Evaluation of a Novel Lens-Based SPECT System Based on Laue Lens Gamma Diffraction: GEANT4/GAMOS Monte Carlo Study

Abstract While improvements in SPECT imaging techniques constitute a significant advance in biomedical science and cancer diagnosis, their limited spatial resolution has hindered their application to small animal research and early tumour detection. Using recent breakthroughs established by the high-energy astrophysics community, focusing X-ray optics provides a method to overcome the paradigm of low resolution and presents the possibility of imaging small objects with sub-millimetre resolution. This thesis aims to tackle the constraints associated with the current SPECT imaging designs by exploiting the notion of focusing high energy photons through Laue lens diffraction and developing a means of performing gamma rays imaging that would not rely on parallel or pinhole collimators. The gradual development of the novel system is discussed, starting from the single, modular, and multi-Laue lens-based SPECT. A customized 3D reconstruction algorithm was developed to reconstruct an accurate 3D radioactivity distribution from focused projections. A plug-in implementing the Laue diffraction concept was developed and used to model gamma rays focusing in the GEANT4 toolkit. The plug-in will be incorporated into GEANT4 upon final approval from its developers. The single lens-based, modular lens-based and multi lens-based SPECT models detected one hit per 42 source photons (sensitivity of 790 ⁄), three hits per 42 source photons (sensitivity of 2,373 ⁄), and one hit per 20 source photons (sensitivity of 1,670 ⁄), respectively. Based on the generated 3D reconstructed images, the achievable spatial resolution was found to be 0.1 full width at half maximum (FWHM). The proposed design’s performance parameters were compared against the existing SIEMENS parallel LEHR and multi-pinhole (5-MWB-1.0) Inveon SPECT. The achievable spatial resolution is decoupled from the sensitivity of the system, which is in stark contrast with the existing collimators that suffer from the resolution-sensitivity trade-off and are limited to a resolution of 2 . The proposed system allows discrimination between adjacent volumes as small as 0.113 , which is substantially smaller than what can be imaged by any existing SPECT or PET system. The proposed design could lay the foundation for a new SPECT imaging technology akin to a combination of tomosynthesis and lightfield imaging

Proceedings of the 5th International Workshop on Reconfigurable Communication-centric Systems on Chip 2010 - ReCoSoC\u2710 - May 17-19, 2010 Karlsruhe, Germany. (KIT Scientific Reports ; 7551)

ReCoSoC is intended to be a periodic annual meeting to expose and discuss gathered expertise as well as state of the art research around SoC related topics through plenary invited papers and posters. The workshop aims to provide a prospective view of tomorrow\u27s challenges in the multibillion transistor era, taking into account the emerging techniques and architectures exploring the synergy between flexible on-chip communication and system reconfigurability

Selected Papers from the 5th International Electronic Conference on Sensors and Applications

This Special Issue comprises selected papers from the proceedings of the 5th International Electronic Conference on Sensors and Applications, held on 15–30 November 2018, on sciforum.net, an online platform for hosting scholarly e-conferences and discussion groups. In this 5th edition of the electronic conference, contributors were invited to provide papers and presentations from the field of sensors and applications at large, resulting in a wide variety of excellent submissions and topic areas. Papers which attracted the most interest on the web or that provided a particularly innovative contribution were selected for publication in this collection. These peer-reviewed papers are published with the aim of rapid and wide dissemination of research results, developments, and applications. We hope this conference series will grow rapidly in the future and become recognized as a new way and venue by which to (electronically) present new developments related to the field of sensors and their applications

Untersuchung der Abbildungseigenschaften eines 3D-Ultraschall-Computertomographen zur Berechnung der 3D-Abbildungsfunktion und Herleitung einer optimierten Sensorgeometrie

Am Forschungszentrum Karlsruhe wird ein neues bildgebendes Verfahren zur verbesserten Diagnose von Brustkrebs entwickelt: Die 3D-Ultraschall-Computertomographie. Die Untersuchung der Abbildungseigenschaften ermittelt die Möglichkeiten und Grenzen der Bildgebung. In dieser Arbeit werden die wesentlichen Systemparameter ermittelt, hinsichtlich ihres Einflusses auf die Abbildungseigenschaften bewertet und eine Optimierung des Gesamtsystems bezüglich der erreichbaren Bildqualität durchgeführt

A fundamental investigation and ultrasonic characterisation of coal effective stress behaviour

Coal seam gas is an important energy resource worldwide. The methane extraction from coal seam is often accompanied by CO2 injection to enhance the gas recovery and reduce the greenhouse gas emission footprint. Amongst all processes active in coal seam gas extraction, understanding and characterizing the coal effective stress and its evolution with time need special attention. The reservoir characteristics of coal seam that control its effective stress evolution, however, differ from that of other hydrocarbon resources in granular sediments. In conventional reservoirs, it is the pore volume determining the gas storage, but in coal seams, it is the pore surface area that defines the capacity through adsorption. As naturally fractured reservoirs, coal seams often contain an extensive fracture network called cleats thus, the coupled relationship between the mechanical behaviour and sorption effect can significantly influence the effective stress and in turn permeability. The main aim of this dissertation is thus to investigate and model the interaction of effective stress evolution and adsorption/desorption processes using advanced and innovative laboratory experiments and numerical simulations. This dissertation includes four parts consisting of the modelling and fundamental studies employing novel experimental and numerical techniques. The first part of the dissertation seeks to understand the characteristics of sorption-hydromechanical behaviour through the microscale and non-destructive investigation using micro-computed tomography (μCT), ultrasonic and their combined measurements. These fundamental investigations shed light on the coupled physical processes in different coal samples extracted from the Sydney Basin Australia through tracking 3D internal geometry. Using an X-ray transparent triaxial system, a range of stress-pore pressure boundary conditions are applied on different coals to obtain the 3D internal structure. The different coal components and their fracture patterns are analysed with respect to the bulk, matrix, and fracture compressibilities. In a further step, the coupled stress and swelling strain responses of coal when exposed to carbon dioxide (CO2) and helium (He) are studied by imbedding ultrasonic sensors in the X-ray transparent triaxial system. With the real-time visualisation of fracture porosity due to different adsorption levels, the effects of CO2 adsorption and involved processes on ultrasonic responses are investigated. The combined physical and numerical methods determine the main factor influencing wave propagation in coal to i) assist developing the representative constitutive model and ii) be used in the acoustic-driven parameterisation in the final part of the dissertation. The micro-scale investigation highlights the importance of internal structure affecting the mechanical properties in coal and the acoustic wave velocity allows evaluating the changes in facture characteristics during CO2 adsorption. Using detailed understanding of the physical processes involved in coal multiphysics, a constitutive model based on the continuum mechanics and non-equilibrium thermodynamics is developed in the second part of the dissertation. The model considers changes in gas content in the tight coal matrix through sorption and diffusion processes along with gas leakage from the matrix into fractures where Darcy type flow takes place. Also, the time dependency of coupling processes is accounted for especially the volumetric strains induced by gas sorption and their overall effects on changes in the fracture aperture, hence in the bulk flow conductivity. The novelty of the proposed model specially lies in the derivation of the thermodynamically consistent formulation of time-dependent effective stress law. The next part of the dissertation seeks to validate the developed effective stress law experimentally and to investigate i) the performance of commonly used theoretical models for swelling stress estimation, ii) the validity of thermodynamics coupling coefficient defining the swelling stress and iii) the effect of external stress on coal volumetric strain response. Especially designed experiments on two coal samples are conducted, including time-dependent diffusion and volumetric strain experiments under various stress and CO2 pressure conditions. A new experimental method is proposed to characterize the key input of the model which is the swelling coupling coefficient. Results of these series of experiments also show that the stress induced compression has minor effect on gas desorption. Since the wave velocity and porosity are interrelated, in the last part of the dissertation, some key parameters involved in the set of developed hydromechanical relationships are measured/modelled using acoustic measurement and finite element simulation. First, the effective stress coefficient is predicted using the percolation theory and hydromechanical and ultrasonic laboratory measurements on coal samples. The swelling coefficient representing adsorption induced volumetric strain development is next studied using acoustic simulation. As a newly proposed coupling coefficient in the model development, the relationship between the coefficient and wave velocity are correlated in three pore pressure conditions and its response to each condition is collected and analysed. Finally, the fracture permeability in coal seams is estimated using a novel physics-informed neural network (PINN) technique. In the training of PINN model, a synthetic dataset is built from several ultrasonic measurements and numerical simulations, with input variables of wave velocity and density. This model is successfully applied in a field case study where downhole geophysical logging data is available. In general, the acoustic-driven technique provides a strong and useful pathway to predict model parameters using geophysical logging data in a field setting, where sonic logs are available