Apparatus and method for detecting sheet objects in computed tomography data
First Claim
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1. A method of detecting a sheet object represented in computed tomography (CT) data for a region comprising:
- identifying a plurality of volume elements in the CT data, each volume element being associated with a density value;
for each volume element, selecting a plurality of neighboring volume elements in proximity to the volume element;
computing a mean density of the density values associated with the plurality of neighboring volume elements;
computing a difference between the density value associated with the volume element and the mean density;
comparing the computed difference to a predetermined threshold difference; and
labeling the volume element as being associated with a sheet object if the computed difference exceeds the predetermined threshold difference.
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Abstract
A method and apparatus for detecting objects in computed tomography (CT) data, including sheet-shaped objects such as sheet explosives can be detected by analyzing a neighborhood of voxels surrounding a test voxel. If the density of the test voxel is sufficiently different from the mean density of the neighboring voxels, then it is concluded that the test voxel is associated with a sheet object. A connectivity process can be applied to voxels to combine them into objects after sheets are detected to prevent sheets from being inadvertently removed from the data by erosion.
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Citations
42 Claims
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1. A method of detecting a sheet object represented in computed tomography (CT) data for a region comprising:
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identifying a plurality of volume elements in the CT data, each volume element being associated with a density value; for each volume element, selecting a plurality of neighboring volume elements in proximity to the volume element; computing a mean density of the density values associated with the plurality of neighboring volume elements; computing a difference between the density value associated with the volume element and the mean density; comparing the computed difference to a predetermined threshold difference; and labeling the volume element as being associated with a sheet object if the computed difference exceeds the predetermined threshold difference. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An apparatus for detecting a sheet object represented in computed tomography (CT) data for a region comprising:
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means for identifying a plurality of volume elements in the CT data, each volume element being associated with a density value; means for selecting, for each volume element, a plurality of neighboring volume elements in proximity to the volume element; means for computing a mean density of the density values associated with the plurality of neighboring volume elements; means for computing a difference between the density value associated with the volume element and the mean density; means for comparing the computed difference to a predetermined threshold difference; and means for labeling the volume element as being associated with a sheet object if the computed difference exceeds the predetermined threshold difference. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A computed tomography (CT) scanning system for identifying objects in a region comprising:
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means for acquiring CT data for the region; means for identifying a plurality of volume elements in the CT data, each volume element being associated with a density value; means for selecting, for each volume element, a plurality of neighboring volume elements in proximity to the volume element; means for computing a mean density of the density values associated with the plurality of neighboring volume elements; means for computing a difference between the density value associated with the volume element and the mean density; means for comparing the computed difference to a predetermined threshold difference; and means for labeling the volume element as being associated with a sheet object if the computed difference exceeds the predetermined threshold difference. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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Specification