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de Leeuw den Bouter, M.L. (author), van Gijzen, M.B. (author), Remis, R.F. (author)In this paper we present a magnetic resonance imaging (MRI) technique that is based on multiplicative regularization. Instead of adding a regularizing objective function to a data fidelity term, we multiply by such a regularizing function. By following this approach, no regularization parameter needs to be determined for each new data set...journal article 2021
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Koolstra, Kirsten (author), Remis, R.F. (author)Purpose: To learn a preconditioner that accelerates parallel imaging (PI) and compressed sensing (CS) reconstructions. Methods: A convolutional neural network (CNN) with residual connections was used to train a preconditioning operator. Training and validation data were simulated using 50% brain images and 50% white Gaussian noise images....journal article 2021
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de Leeuw den Bouter, M.L. (author), van den Berg, P.M. (author), Remis, R.F. (author)In this paper we discuss an imaging method when the object has known support and its spatial Fourier transform is only known on a certain k-space undersampled pattern. The simple conjugate gradient least squares algorithm applied to the corresponding truncated Fourier transform equation produces reconstructions that are basically of a similar...journal article 2021
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Ahishakiye, Emmanuel (author), van Gijzen, M.B. (author), Tumwiine, Julius (author), Wario, Ruth (author), Obungoloch, Johnes (author)Medical image reconstruction aims to acquire high-quality medical images for clinical usage at minimal cost and risk to the patients. Deep learning and its applications in medical imaging, especially in image reconstruction have received considerable attention in the literature in recent years. This study reviews records obtained...review 2021
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Ahishakiye, Emmanuel (author), van Gijzen, M.B. (author), Tumwiine, Julius (author), Obungoloch, Johnes (author)Objective: Image denoising has been considered as a separate procedure from image reconstruction which could otherwise be combined with acquisition and reconstruction. This paper discusses a joint image reconstruction and denoising algorithm in low-field MRI using a dictionary learning approach. Method: Our proposed algorithm uses a two-level...conference paper 2020
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López-Marín, Antonio (author), Springeling, Geert (author), Beurskens, Robert (author), Van Beusekom, Heleen (author), van der Steen, A.F.W. (author), Koch, Arjun D. (author), Bouma, Brett E. (author), Huber, Robert A. (author), Van Soest, Gijs (author), Wang, Tianshi (author)In this study, we demonstrate a 12x36 mm motorized capsule for OCT imaging of the esophagus. The capsule produces unobstructed images by using a distal reflector design, thus avoiding shadow caused by the motor wires. The motor synchronous control enables three working modes: circumferential imaging, angular sector imaging and accurate beam...conference paper 2020
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Ahishakiye, Emmanuel (author), van Gijzen, M.B. (author), Tumwiine, Julius (author), Obungoloch, Johnes (author)Background: Magnetic resonance imaging (MRI) is a safe non-invasive and nonionizing medical imaging modality that is used to visualize the structure of human anatomy. Conventional (high-field) MRI scanners are very expensive to purchase, operate and maintain, which limit their use in many developing countries. This study is part of a project...journal article 2020
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Zhao, Wenzhao (author), Wang, Hongjian (author), Gemmeke, Hartmut (author), van Dongen, K.W.A. (author), Hopp, Torsten (author), Hesser, Jürgen (author)Image reconstruction of ultrasound computed tomography based on the wave equation is able to show much more structural details than simpler ray-based image reconstruction methods. However, to invert the wave-based forward model is computationally demanding. To address this problem, we develop an efficient fully learned image reconstruction...journal article 2020
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Pezzotti, Nicola (author), Yousefi, Sahar (author), Elmahdy, Mohamed S. (author), van Gemert, Jeroen Hendrikus Fransiscus (author), Schuelke, Christophe (author), Doneva, Mariya (author), Nielsen, Tim (author), Lelieveldt, B.P.F. (author), Staring, M. (author)Adaptive intelligence aims at empowering machine learning techniques with the additional use of domain knowledge. In this work, we present the application of adaptive intelligence to accelerate MR acquisition. Starting from undersampled k-space data, an iterative learning-based reconstruction scheme inspired by compressed sensing theory is...journal article 2020
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van Hoek, Bob (author)Background: For both hospitals and patients it would be beneficial if the scan time of MR images could be reduced. At the moment, Compressed Sensing (CS) is introduced to reduce the scan time, however, new methods are developed such as a deep learning method, called the Recurrent Inference Machine (RIM). In this study the effect of...master thesis 2019
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Saeedifar, M. (author), Mansvelder, Jasmijn (author), Mohammadi, R. (author), Zarouchas, D. (author)This study aims to use the passive and active acoustic-based health monitoring methods for impact damage assessment of composite structures. To this aim, a Carbon Fiber Reinforced Polymer (CFRP) composite plate was fabricated and subjected to a simulated low-velocity impact by performing repeated quasi-static indentation tests where a loading...journal article 2019
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Waling, Manon (author)De CT-scanner heeft een belangrijke rol in de medische wereld. Helaas gebruikt de CT-scanner voor het opstellen van een scan schadelijke straling. In dit onderzoek is nagegaan of er een betere beeldreconstructietechniek te vinden is voor het opstellen van een CT-afbeelding met gebruik van minder straling.<br/>De standaard voor het opstellen van...bachelor thesis 2019
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Sun, S. (author), Kooij, B.J. (author), Yarovoy, Alexander (author)In this paper, the generalized multiple measurement vectors (GMMV) linear inversion method is applied to the reconstruction of the 3-D Fresnel data, provided by the Institue Fresnel (Marseille, France). The results show that the GMMV-based method can obtain good resolution along the x- and y- axes, while poor resolution along the z-axis,...conference paper 2019
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Dwivedi, P. (author), Konijnenberg, A.P. (author), Pereira, S.F. (author), Meisner, J.A. (author), Urbach, Paul (author)Ptychography is a form of coherent diffractive imaging; it employs far-field intensity patterns of the object to reconstruct the object. In ptychography, an important limiting factor for the reconstructed image quality is the uncertainty in the probe positions. Here, we propose a new approach which uses the hybrid input-output algorithm and...journal article 2019
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de Leeuw den Bouter, M.L. (author), van Gijzen, M.B. (author), Remis, R.F. (author)We consider the MRI physics in a low-field MRI scanner, in which permanent magnets are used to generate a magnetic field in the millitesla range. A model describing the relationship between measured signal and image is derived, resulting in an ill-posed inverse problem. In order to solve it, a regularization penalty is added to the least...journal article 2019
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Guo, Y. (author), Rieger, B. (author)Regularization has been introduced to electron tomography for enhancing the reconstruction quality. Since over-regularization smears out sharp edges and under-regularization leaves the image too noisy, finding the optimal regularization strength is crucial. To this end, one can either manually tune regularization parameters by trial and error...conference paper 2019
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Lopes Cunha, Max (author)<br/>This study focuses on the question how the bandwidth utilization of a high-quality video-stream from the Exposure Rendering framework can be minimized. Exposure Render uses a Monte-Carlo based rendering system to render volumetric data. The earliest estimation of lighting show high degrees of noise, leading to grainy images before...bachelor thesis 2018
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Mansvelder, Jasmijn (author)The high specific strength and stiffness of composite materials have resulted in a widespread introduction of composite structures in the commercial aviation industry. Although composite materials offer the possibility to design lightweight structures, they also suffer from complex failure modes of which damage progression is badly understood....master thesis 2018
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Arto Sanchez, Guillermo (author)In optical imaging, image quality is not only determined by the system itself but also by the media in which light traverse. Differences in the refraction index of the media encountered by a light wavefront produces phase aberrations which distort the image received from the original object. Currently, there are two main approaches for solving...master thesis 2017
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van Apeldoorn, Naphur (author)Parts of the Southwest Palace of Sennacherib (700 BC), which were located in Nineveh (Iraq), are now destroyed by the ongoing conflict in Iraq and Syria. The palace rooms used to be decorated with numerous Assyrian reliefs. Luckily, digital pictures of the site are available thanks to an Italian expedition in 2002. The goal of this research is...master thesis 2017