Three-dimensional (313) ultrasound has become a useful tool in cardiac imaging, OB/GYN and other clinical applications. It enables clinicians to visualize the acquired volume and/or planes that are not easily accessib...
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ISBN:
(纸本)9780819466310
Three-dimensional (313) ultrasound has become a useful tool in cardiac imaging, OB/GYN and other clinical applications. It enables clinicians to visualize the acquired volume and/or planes that are not easily accessible using 2D ultrasound, in addition to providing an intuitive understanding of the structural anatomy in three dimensions. One effective way to examine the acquired volumetric data is by clipping away parts of the volume using cross-sectional cuts to reveal the underlying anatomy masked by other structures. Ideally, such boundaries should reflect the orientation and location of the clip surfaces without altering the information content of the original data. Because of the artificial surface introduced by the clip boundary, shading employed to enhance the surfaces of the object gets modified, resulting in inconsistent shading and noticeable artifacts in the case of ultrasound data. Consistent shading of clip surfaces was previously studied for graphics hardware-based volume rendering, and an algorithm was developed and demonstrated in MRI, CT and non-medical datasets. However, that algorithm cannot be applied directly to fast software-based rendering approaches such as the shear-warp algorithm. Furthermore, ultrasound data require a different clipping approach due to their fuzzy nature, lower signal-to-noise ratios, and real-time requirements. In this paper, we present a software-based volume clipping technique that can effectively and efficiently overcome the difficulties associated with the shading of the clip boundaries in ultrasound data using shear-warp. Our technique improves the viewer's comprehension of the clip boundary without altering the original information content within the volume. The method has been implemented on programmable processors while maintaining the interactive speed in rendering.
The proceedings contain 126 papers. The topics discussed include: progress with type-II superlattice IR detector arrays;comparison of type-II superlattice and HgCdTe infrared detector technologies;performance of focal...
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ISBN:
(纸本)0819466646
The proceedings contain 126 papers. The topics discussed include: progress with type-II superlattice IR detector arrays;comparison of type-II superlattice and HgCdTe infrared detector technologies;performance of focal plane arrays for the photon counting arrays (PCAR) program;small pitch large format long-wave infrared QWIP plane arrays for polarimetric imagery;signalprocessing core for high performance thermal imaging;uncooled MEMS IR imagers with optical readout and imageprocessing;solid state optical thermal imagers;recent development of ultra small pixel uncooled focal plane arrays of DRS;advanced electromechanical micro-shutters for thermal infrared night vision imaging and targeting systems;passivation of W-structured type-II superlattice long-wave infrared photodiodes;scene-based nonuniformity correction using texture-based adaptive filtering;and nonuniformity correction algorithm based on a noise-cancellation system for infrared focal-plane arrays.
The proceedings contain 126 papers. The topics discussed include: progress with type-II superlattice IR detector arrays;comparison of type-II superlattice and HgCdTe infrared detector technologies;performance of focal...
详细信息
ISBN:
(纸本)0819466646
The proceedings contain 126 papers. The topics discussed include: progress with type-II superlattice IR detector arrays;comparison of type-II superlattice and HgCdTe infrared detector technologies;performance of focal plane arrays for the photon counting arrays (PCAR) program;small pitch large format long-wave infrared QWIP plane arrays for polarimetric imagery;signalprocessing core for high performance thermal imaging;uncooled MEMS IR imagers with optical readout and imageprocessing;solid state optical thermal imagers;recent development of ultra small pixel uncooled focal plane arrays of DRS;advanced electromechanical micro-shutters for thermal infrared night vision imaging and targeting systems;passivation of W-structured type-II superlattice long-wave infrared photodiodes;scene-based nonuniformity correction using texture-based adaptive filtering;and nonuniformity correction algorithm based on a noise-cancellation system for infrared focal-plane arrays.
Cardiac C-arm CT is a promising technique that enables 3D cardiac image acquisition and real-time fluoroscopy on the same system. Retrospective ECG gating techniques have already been adapted from clinical cardiac CT ...
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ISBN:
(纸本)3540710906
Cardiac C-arm CT is a promising technique that enables 3D cardiac image acquisition and real-time fluoroscopy on the same system. Retrospective ECG gating techniques have already been adapted from clinical cardiac CT that allow 3D reconstruction using retrospectively gated projection images of a multi-sweep C-arm CT scan according to the desired cardiac phase. However, it is known that retrospective gating of projection data does not provide an optimal signal-to-noise-ratio (SNR) since the measured projection data is only partially considered during the reconstruction. In this work we introduce a new reconstruction technique for cardiac C-arm CT that provides increased SNR by including additional corrected and resampled filtered back-projections (FBP) from temporal windows outside of the targeted reconstruction phase. We take advantage of several motion corrected FDK-like reconstructions of the subject to increase SNR. In the presented results, using in vivo data from an animal model, the SNR could be increased by approximately 30 percent.
Optical tracking systems pioneered the use of position sensors in surgical navigation. The requirement to maintain a clear line-of-sight between the emitters and detectors, however, renders them unsuitable for trackin...
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ISBN:
(纸本)9780819466273
Optical tracking systems pioneered the use of position sensors in surgical navigation. The requirement to maintain a clear line-of-sight between the emitters and detectors, however, renders them unsuitable for tracking flexible invasive instruments. On the other hand, advances in electromagnetic tracking systems permit a key-enabling role in image-guided procedures. First-generation magnetic systems present a significant challenge for tracker designers to improve both performance and acceptance. Troublesome magnetic problems include inaccuracies due to the presence of metallic distorters in the tracking volume and to dynamic motion of the tracked object. A new magnetic tracker (3D Guidance (TM)), recently developed at Ascension Technology, seeks to address these problems. Employing third-generation pulsed-DC magnetic tracking technology and new signalprocessing techniques, the new tracker overcomes the distorting effects of non-magnetic conductive metals (300-series stainless steel, titanium and aluminum) and composite tables experienced by AC trackers. Ascension has developed a break-through flat transmitter that negates ferrous metal distortion emanating from procedural tables. The tracker development has also significantly advanced the state of the art in sensor miniaturization. The 3D Guidance (TM) features the world's smallest electromagnetic tracking sensors, opening the door to new applications for minimally invasive procedures. Finally, dynamic accuracy has been significantly improved with the implementation of Kalman based algorithms. Test results are reported.
The major difficulty concerning echocardiograph imageprocessing is speckle noise. In this paper, we present wavelet based algorithm for denoising echocardiograph images and then determine an optimal wavelet filter th...
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The major difficulty concerning echocardiograph imageprocessing is speckle noise. In this paper, we present wavelet based algorithm for denoising echocardiograph images and then determine an optimal wavelet filter that yields good quality images. The log transformed input is represented in multiscale wavelet domain. Global hard thresholding of subband coefficients is performed to achieve lossy compression of image. The inverse wavelet transformed image is free from speckle noise. The image quality is assessed in terms of objective and statistical measures, namely, peak-signal-to-noise ratio (PSNR), compression ratio, variance, mean square error (MSE). The experiments are performed using different wavelets at various levels of decomposition. The results show that bior6.8 with 2- level decomposition yields better quality despeckled images.
The logarithmic imageprocessing (LIP) theory is a mathematical framework that provides a set of specific algebraic and functional operations and structures that are well adapted to the representation and processing o...
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The logarithmic imageprocessing (LIP) theory is a mathematical framework that provides a set of specific algebraic and functional operations and structures that are well adapted to the representation and processing of nonlinear images, and more generally of non-linear signals, valued in a bounded intensity range. This very well structured theory determined us to use the logarithmic image representation in our approach for defining a new set of mathematical morphology operators based upon structuring elements with a variable geometrical shape or adaptative structuring elements. The purpose of this paper is to define and to analyze the new multiplicative logarithmic morphological operators used in medical image enhancement. Finally, the experimental results reveal that this method has wide potential areas of impact which may include: Digital x-ray, Digital Mammography, Computer Tomography Scans, Nuclear Magnetic Resonance imagery and Telemedicine applications.
A spot-adaptive compound clustering-enhancement-segmentation (CES) scheme was developed for the quantification of gene expression levels in microarray images. The CES-scheme employed 1/griding, for locating spot-regio...
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ISBN:
(纸本)9783540744825
A spot-adaptive compound clustering-enhancement-segmentation (CES) scheme was developed for the quantification of gene expression levels in microarray images. The CES-scheme employed 1/griding, for locating spot-regions, 2/Fuzzy C-means clustering, for segmenting spots from background, 3/background noise estimation and spot's center localization, 4/emphasizing of spot's outline by the CLAHE image enhancement technique, 5/segmentation by the SRG algorithm, using information from step 3, and 6/microarray spot intensity extraction. Extracted intensities by the CES-Scheme were compared against those obtained by the MAGIC TOOL's SRG. Kullback-Liebler metric's values for the CES-Scheme were on average double than MAGIC TOOL's, with differences ranging from 1.45bits to 2.77bits in 7 cDNA images. Coefficient-of-Variation results showed significantly higher reproducibility (p<0.001) for the CES-Scheme in quantifying gene expression levels. processing times for 1024x1024 16-bit microarray images containing 6400 spots were 300 and 487 seconds for the CES-Scheme and MAGIC TOOL respectively.
Convolution is a basic signal and imageprocessing application. In imageprocessing, kernel coefficients of convolution commonly remain constant across the entire image. A less common situation is where the kernel coe...
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Convolution is a basic signal and imageprocessing application. In imageprocessing, kernel coefficients of convolution commonly remain constant across the entire image. A less common situation is where the kernel coefficients change in value for each pixel in the image. We call this variable kernel convolution. In this paper we present what we believe are the first three FPGA implementations of variable kernel convolution. The first uses sequential streaming, the second uses pipelining and the third solution uses what we call convolve and gather and its hardware implementation has the highest area time rating (6.7 x better than streaming and 3.4x better than the pipelining solution). Both pipelining and convolve and gather have the same throughput (which is 25 x that of streaming), but convolve and gather has 71% smaller area footprint than the pipeline.
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