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[ACM Press the 2nd International Conference - Sydney, NSW, Australia (2018.10.06-2018.10.08)] Proceedings of the 2nd International Conference on Graphics and Signal Processing - ICGSP'18 - A Comparative Analysis of Clustering Algorithms for Ultrasound Image Despeckling Applications
摘要： This paper proposes a novel framework for speckle noise suppression and edge preservation using clustering algorithms in ultrasound images. The algorithms considered are K-means clustering, fuzzy C-means clustering, possibilistic C-means, fuzzy possibilistic C-means, and possibilistic fuzzy C-means clustering. This work presents an exhaustive comparative analysis of the above clustering algorithms to consider their suitability for despeckling and identifies the best clustering algorithm. Two types of dataset are considered: medical ultrasound images of the thyroid, and synthetically modelled ultrasound images. The framework consists of several distinct phases - first the edges of the image are identified using the Canny edge operator, and then a clustering algorithm applied on high frequency coefficients extracted using wavelet transform. Finally, the preserved edges are added back to speckle suppressed image. Thus, the proposed clustering method effectively accomplishes both speckle suppression and edge preservation. This paper also presents a quantitative evaluation of results to demonstrate the effectiveness of the clustering approach.
关键词： speckle noise,Image quality metrics,Wavelet transform,Ultrasound image analysis,Canny edge detector,Clustering algorithms
更新于2025-09-04 15:30:14
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Ultrasound assisted ZnO coating in a microflow based photoreactor for selective oxidation of benzyl alcohol to benzaldehyde
摘要： Heterogeneous photocatalysis in a microflow system for generation of value added chemicals is a novel green chemistry approach requiring the understanding of photocatalysis, microfluidics and reactor design. Research on the development of a low energy and environmentally friendly based photo-microreactor system for photocatalysis is yet to be explored. Commercial ZnO nanoparticles were deposited in the inner wall of a fluoropolymer using a low energy ultrasound bath under mild conditions and later used for selective conversion of aromatic alcohols to aldehydes. The deposition of the nanoparticles on the fluoropolymer is mainly attributed to the physical changes taking place inside the microtubes under the effect of ultrasound.
关键词： Benzyl alcohol,Microflow photoreactor,Ultrasound,Benzaldehyde,ZnO coating,Selective oxidation,Green Chemistry
更新于2025-09-04 15:30:14
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Ultrasonic Studies of Solid Azobenzene-Decorated Polymer Thin Films
摘要： This work investigates the effect of ultrasound on switching of cis azobenzene isomers to their trans counterparts in solid films of methyl methacrylate and methacryloyloxyazobenzene copolymers [P(MMA/MOAB)]. Ultraviolet?visible and 1H nuclear magnetic resonance spectroscopies demonstrate that 46% of the cis isomer converts to the trans form purely by ultrasonic agitation and 46% converts to the trans isomer by localized ultrasound-induced heating effects. Comparative studies of isomerization by ultrasound wave, heat, and visible irradiation show that ultrasound exposure requires a longer time to switch the cis-to-trans conformation. The estimated activation energy for the cis-to-trans conversion in solid polymer films is shown to be comparable to previous values of azobenzene isomerization, indicating that incorporation of the chromophore in a polymeric system affects the kinetics of transition but not the barriers to conformational change.
关键词： azobenzene,nuclear magnetic resonance spectroscopy,polymer thin films,ultrasound,isomerization,ultraviolet?visible spectroscopy
更新于2025-09-04 15:30:14
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[IEEE 48th European Solid-State Device Research Conference (ESSDERC 2018) - Dresden (2018.9.3-2018.9.6)] 2018 48th European Solid-State Device Research Conference (ESSDERC) - HV Floating Switch Matrix with Parachute Safety Driving for 3D Echography Systems
摘要： The paper describes the design challenges and implemented solutions studied and in high voltage (HV) bidirectional and floating switch. The main characteristics are the isolation voltage up to positive and negative 200V, ultra-low power consumption for switch driving, fully floating at high slew rate up to 30V/ns. The final IC integrates a matrix of 512 (8x64) independent HV switch, the other important requirement is the minimal area.
关键词： multiplexer,floating,slew rate,DMOS,pulser,switches,high voltage,ultrasound,echography,linearity
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Penetration Depth Evaluation of Split Ring Resonator sensor using In-Vivo Microwave Reflectivity and Ultrasound Measurements
摘要： This article focuses on the application of split ring resonator based sensor for follow up recovery of lower extremity trauma patients. The proposed sensor mainly monitors the changes of dielectric properties of lower limb tissues such as skin, fat, muscle and bone. As part of the characterization of microwave sensor, it is crucial to assess the signal penetration in in-vivo tissues. This work presents a new approach for investigating the penetration depth of Split Ring Resonator sensor in in-vivo context of the femoral area. The method is based on the measurement of skin, fat, and muscle tissue thicknesses from ultrasound images. The microwave reflectivity, S11 measurements are done in conjunction with ultrasound measurements on four volunteers to deduce the effective permittivity of the in-vivo tissues. The tissue thickness information derived from ultrasound measurements were used to create 3D simulation model in CST studio 2017. The measured S11 values are used to optimize the effective permittivity of that model. The penetration depths are calculated from the simulation of electric field distribution in the optimized model. The analysis on measured data shows that the thigh region contributes highest penetration depth up to 17.5mm. This result has higher significance in demonstrating the in-vitro penetration depth measurements and other tests which are going to be performed in the future.
关键词： Microwave,Ultrasound,Sensor,Penetration depth,Split Ring Resonator
更新于2025-09-04 15:30:14
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Passive ultrasound aided acoustic resolution photoacoustic microscopy imaging for layered heterogeneous media
摘要： Photoacoustic imaging reconstructions usually assume a known speed-of-sound (SOS) distribution; however, in most cases, the SOS distribution is not revealed and is dif?cult to estimate from photoacoustic signals. In this paper, we propose passive ultrasound aided acoustic resolution photoacoustic microscopy which simultaneously reconstructs SOS distributions and photoacoustic images for layered heterogeneous media. The passive ultrasound is a kind of laser-induced acoustic wave generated by a transducer absorbing the backscattered light. It can be used to measure the layer thicknesses due to its sensitivity to structural information and broad bandwidth and further determine the SOS distributions. After estimating the SOS distributions, a phase shift plus interpo- lation is employed to reconstruct the photoacoustic image for heterogeneous media. Without intro- ducing additional hardware, this method can be conveniently incorporated into a conventional photoacoustic imaging system. A curved shell immersed in water is adopted as a layered heteroge- neous phantom, and the proposed method reconstructs the targets (carbon rods) under this shell. Under the test of a 5 MHz focused transducer (NA 0.25), the maximum reconstruction deviation of 1.2 mm carbon rods is only 0.15 mm.
关键词： passive ultrasound,speed-of-sound distribution,acoustic resolution photoacoustic microscopy,layered heterogeneous media,photoacoustic imaging
更新于2025-09-04 15:30:14
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Enhance contrast in PCA based beamformers using smoothing kernel
摘要： The contrast and resolution have trade-off in medical ultrasound imaging. Most of adaptive beamformer can enhance the imaging resolution significantly but not improve the contrast at the same time. The principal component analysis (PCA) based beamformers such as the eigenspace-based minimum variance (ESBMV) beamformer provide a good imaging resolution. Neighbors of the focal point include the common noise, interface and signal components. Echo signal of the neighbor points can be used to suppress the noise and extract the signal component of the focal point. Based on this idea, in order to improve the quality of PCA based beamformers both in the imaging contrast and resolution, a novel beamforming method is proposed. This proposed beamformer utilizes a kernel to select neighbor points. The number of eigenvectors is estimated by using any PCA method. Then the number of selected eigenvectors for each focal point is compared with the number of selected eigenvectors of its neighbor points and is changed to a new value. The selected eigenvectors of the covariance matrix is used to construct the signal subspace. The estimated signal subspace is projected onto the minimum variance (MV) weight vector to calculate the desire weight vector. Results of experiments show that the proposed beamformer can improve the imaging contrast significantly while keeping the resolution quality similar to ESBMV beamformer.
关键词： eigenvalue,beamforming,Ultrasound imaging,minimum variance
更新于2025-09-04 15:30:14
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[IEEE 2018 25th IEEE International Conference on Image Processing (ICIP) - Athens, Greece (2018.10.7-2018.10.10)] 2018 25th IEEE International Conference on Image Processing (ICIP) - A Functional Framework for Ultrasound Imaging
摘要： Delay-And-Sum (DAS), the state-of-art in ultrasound imaging, is known to be sub-optimal, resulting in low resolution and contrast. Most proposed improvements involve ad-hoc re-weighting, or hit computational bottlenecks given real-time requirements. This paper takes a fresh perspective on the problem, leveraging a functional framework to obtain a regularized least-squares estimate of the tissue reflectivity function. An explicit solution is derived, which – for specific cases – can be efficiently implemented, making it suitable for real-time imaging. In our formulation, DAS appears as a back-projection without any optimal properties. We illustrate the framework through first a one-dimensional set-up, and then a two-dimensional extension with Synthetic Aperture Focusing Technique (SAFT). The one-dimensional simulations show a 77% resolution improvement with respect to DAS, which artificially limits the available bandwidth. On a standard performance-assessment phantom, simulations show that SAFT depth resolution can be improved by 71%.
关键词： Sampling Operator,Ultrasound,Array Signal Processing,Pulse Compression,Inverse Problem
更新于2025-09-04 15:30:14
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[IEEE 2018 25th IEEE International Conference on Image Processing (ICIP) - Athens, Greece (2018.10.7-2018.10.10)] 2018 25th IEEE International Conference on Image Processing (ICIP) - Automatic Segmentation of Lumen Intima Layer in Transverse Mode Ultrasound Images
摘要： We propose an elliptical active disc technique for the segmentation of common carotid artery lumen intimal layer from transverse mode ultrasound images. The segmentation and subsequent outlining problem is posed as one of optimization of a local energy function with respect to the five degrees-of-freedom that characterize the elliptical active disc. Gradient descent technique is used to find the minimum of the energy function with respect to the five parameters that describe the disc. In addition, we use Green's theorem to optimize the computation of the partial derivatives. For automatic initialization of the active disc, we use the normalized cross-correlation technique. We report results of experimental validation on SPLab, Brno university database, which contains 971 transverse mode ultrasound images of the carotid artery. We achieve accurate carotid artery lumen intima detection in 97.63% of cases. In addition, for lumen intima layer segmentation we achieve an average Dice index of 94.83%.
关键词： ultrasound images,stroke,segmentation,active disc,Common carotid artery,lumen intima layer
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE International Conference on Imaging Systems and Techniques (IST) - Krakow, Poland (2018.10.16-2018.10.18)] 2018 IEEE International Conference on Imaging Systems and Techniques (IST) - Development of an iTomography infrastructure for non-destructive documentation of cultural heritage objects
摘要： In this paper, an new setup for the non-destructive scanning for cultural heritage applications is proposed. First, a multi-degree of freedom mechanical implementation is designed, for multiple angle and distance scanning of artworks via different modalities. Moreover, a specialized acquisition and control software is developed consequently created for the uni?ed platform. Additionally, various, onboard, post-processing image registration algorithms are realized for the combination of images originating on various sensors. The ?nal setup is tested on a mock-up icon, verifying the merits of the developed prototype for cultural heritage science work and research.
关键词： mapping tomography,ultrasound,spectroscopy,image processing,heritage science,non destructive testing
更新于2025-09-04 15:30:14