Apparatus and method for combining related objects in computed tomography data
First Claim
1. A method of processing computed tomography (CT) data for objects in a region comprising:
- identifying a plurality of volume elements associated with a plurality of objects in the CT data, each volume element being associated with a density value;
computing (a) a distance between a first object and a second object, (b) a first density associated with the first object and a second density associated with a second object, (c) a difference between the first density and the second density; and
combining the first object and the second object into a single combined object if the difference between the first density and the second density is below a predetermined density difference threshold and the distance between the first object and the second object is below a predetermined distance threshold.
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Abstract
Sheet-shaped objects can be detected by analyzing a neighborhood of voxels surrounding a test voxel. If the density is sufficiently different, then the voxel is associated with a sheet object. Sheet objects can also be detected by eroding the CT data so as to eliminate voxels associated with thin objects. Remaining objects are then subtracted from the original data, leaving only thin sheet-shaped objects. If the number of voxels having densities below a predetermined threshold exceeds a predetermined number, then it is assumed that the test voxel is a surface voxel and is removed from the object. A connectivity process can be applied to voxels to combine them into objects after sheets are detected. A dilation function can then be performed to replace surface voxels. A corrected mass can be compared to mass thresholds. Bulk objects can be detected by a modified morphological connected components labeling (CCL) approach. A merging process can be used to reconnect related items. The system can also identify objects that contain liquids. The object detection rate and false alarm rate can be adjusted by adjusting individual object detection rates and/or false alarm rates.
174 Citations
42 Claims
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1. A method of processing computed tomography (CT) data for objects in a region comprising:
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identifying a plurality of volume elements associated with a plurality of objects in the CT data, each volume element being associated with a density value; computing (a) a distance between a first object and a second object, (b) a first density associated with the first object and a second density associated with a second object, (c) a difference between the first density and the second density; and combining the first object and the second object into a single combined object if the difference between the first density and the second density is below a predetermined density difference threshold and the distance between the first object and the second object is below a predetermined distance threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An apparatus for processing computed tomography (CT) data for objects in a region comprising:
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means for identifying a plurality of volume elements associated with a plurality of objects in the CT data, each volume element being associated with a density value; means for computing a distance between a first object and a second object; means for computing a first density associated with the first object and a second density associated with a second object; means for computing a difference between the first density and the second density; and means for combining the first object and the second object into a single object if the difference between the first density and the second density is below a predetermined density difference threshold and the distance between the first object and the second object is below a predetermined distance threshold. - 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 an object in a region comprising:
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means for acquiring CT data for the object; means for identifying a plurality of volume elements associated with a plurality of objects in the CT data, each volume element being associated with a density value; means for computing a distance between a first object and a second object; means for computing a first density associated with the first object and a second density associated with a second object; means for computing a difference between the first density and the second density; and means for combining the first object and the second object into a single object if the difference between the first density and the second density is below a predetermined density difference threshold and the distance between the first object and the second object is below a predetermined distance threshold. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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Specification