This paper describes a Virtual Environment system designed to aid in training interventional radiologists in inferior vena cava filter placement. It is being developed as part of a VE simulator for a number of surgica...
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ISBN:
(纸本)9051993862
This paper describes a Virtual Environment system designed to aid in training interventional radiologists in inferior vena cava filter placement. It is being developed as part of a VE simulator for a number of surgical and interventional radiology procedures at the laboratory for Advanced computer Applications in Medicine at the George Washington University. In this procedure a filter is placed in the inferior vena cava to prevent blood clots from the lower portion of the body from reaching the lungs and causing a pulmonary embolus. The simulation is designed to provide both tutorial and testing modes for the filter placement procedure.
A 1.5V resistive fuse for image smoothing and segmentation using bulk-driven MOSFETs is presented. The circuit switches on only if the differential voltage applied across its input terminals is less than a set voltage...
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A 1.5V resistive fuse for image smoothing and segmentation using bulk-driven MOSFETs is presented. The circuit switches on only if the differential voltage applied across its input terminals is less than a set voltage;it switches off if the differential voltage is higher than the set value. The useful operation range of the circuit is 0.4V with a supply voltage of 1.5V and threshold voltages of V-Tn = 0.828V and V-Tp = -0.56V for n and g channel MOSFETs, respectively.
In this paper, we present a new system to segment and label CT/MRI Brain slices using feature extraction and unsupervised clustering. In this technique, each voxel is assigned a feature pattern consisting of a scaled ...
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ISBN:
(纸本)0780341236
In this paper, we present a new system to segment and label CT/MRI Brain slices using feature extraction and unsupervised clustering. In this technique, each voxel is assigned a feature pattern consisting of a scaled family of differential geometrical invariant features. The invariant feature pattern is then assigned to a specific region using a two-stage neural network system. The first stage is a self-organizing principal components analysis (SOPCA) network that is used to project the feature vector onto its leading principal axes found by using principal components analysis. This step provides an effective basis for feature extraction. The second stage consists of a self-organizing feature map (SOFM) which will automatically cluster the input vector into different regions. The optimum number of regions (clusters) is obtained by a model fitting approach. Finally, a 3D connected component labeling algorithm is applied to ensure region connectivity. Implementation and performance of this technique are presented. Compared to other approaches, the new system is more accurate in extracting 3D anatomical structures of the brain, and can be apdated to real-time imaging scenarios.
A novel approach is proposed to obtain a record of the patient's occlusion using computervision. Data acquisition is obtained using intra-oral video cameras. The technique utilizes shape from shading to extract 3...
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A novel approach is proposed to obtain a record of the patient's occlusion using computervision. Data acquisition is obtained using intra-oral video cameras. The technique utilizes shape from shading to extract 3D information from 2D views of the jaw, and a novel technique for 3D data registration using genetic algorithms. The resulting 3D model can be used for diagnosis, treatment planning, and implant purposes. The overall purpose of this research is to develop a model-based vision system for orthodontics to replace traditional approaches. This system will be flexible, accurate, and will reduce the cost of orthodontic treatments.
We present a system to segment and label CT/MRI brain slices using feature extraction and unsupervised clustering. In this technique, each voxel is assigned a feature pattern consisting of a scaled family of different...
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We present a system to segment and label CT/MRI brain slices using feature extraction and unsupervised clustering. In this technique, each voxel is assigned a feature pattern consisting of a scaled family of differential geometrical invariant features. The invariant feature pattern is then assigned to a specific region using a two-stage neural network system. The first stage is a self-organizing principal components analysis (SOPCA) network that is used to project the feature vector onto its leading principal axes found by using principal components analysis. This step provides an effective basis for feature extraction. The second stage consists of a self-organizing feature map (SOFM) which will automatically cluster the input vector into different regions. The optimum number of regions (clusters) is obtained by a model fitting approach. Finally, a 3D connected component labeling algorithm is applied to ensure region connectivity. Implementation and performance of this technique are presented. Compared to other approaches, the new system is more accurate in extracting 3D anatomical structures of the brain, and can be adapted to real-time imaging scenarios.
This paper considers the problem of vector tomography on an arbitrary bounded domain in three dimensions. Previous work has given the formulas for the reconstructed scalar and vector potential functions in relation to...
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This paper considers the problem of vector tomography on an arbitrary bounded domain in three dimensions. Previous work has given the formulas for the reconstructed scalar and vector potential functions in relation to the vector field values inside the domain and on the boundary of the domain. Using these formulas. It is shown that the curl-free component can be reconstructed using only one probe measurement, and the divergence-free component can be reconstructed using only two probe measurements. No boundary measurements are necessary.
We propose a class of Gibbs random fields which incorporate geometric information into stochastic image modeling by means of morphological constraints. This class is shown to be capable of modeling shapes with given m...
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We propose a class of Gibbs random fields which incorporate geometric information into stochastic image modeling by means of morphological constraints. This class is shown to be capable of modeling shapes with given morphological size density. Simulation examples illustrate some model properties.
Vector tomography is the reconstruction of vector fields from measurements of their projections, In previous work, it has been shown that reconstruction of a general three-dimensional (3-D) vector field is possible fr...
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Vector tomography is the reconstruction of vector fields from measurements of their projections, In previous work, it has been shown that reconstruction of a general three-dimensional (3-D) vector field is possible from the so-called inner product measurements, It has also been shown how reconstruction of either the irrotational or solenoidal component of a vector field can be accomplished with fewer measurements than that required for the full field, The present paper makes three contributions. First, in analogy to the two-dimensional (2-D) approach of Norton, several 3-D projection theorems are developed. These lead directly to new vector field reconstruction formulas that are convolution backprojection formulas, It is shown how the local reconstruction property of these 3-D reconstruction formulas permits reconstruction of point flow or of regional flow from a limited data set, Second, simulations demonstrating 3-D reconstructions, both local and nonlocal, are presented, Using the formulas derived herein and those derived in previous work, these results demonstrate reconstruction of the irrotational and solenoidal components, their potential functions, and the field itself from simulated inner product measurement data, Finally, it is shown how 3-D inner product measurements can be acquired using a magnetic resonance scanner.
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