Apparatus and method for correcting object density in computed tomography data
First Claim
1. A method of processing computed tomography (CT) data representing an object in a region comprising:
- identifying a plurality of volume elements in the CT data associated with the object, each volume element having a density value;
identifying surface volume elements of the object, said surface volume elements of the object being located at a surface of the object;
computing a mean density of the object, said mean density being a mean of the density values of volume elements associated with the object; and
adjusting the density value of surface volume elements to an adjusted density value, said adjusted density value being based as a function of the mean density.
3 Assignments
0 Petitions
Accused Products
Abstract
Sheet explosives can be detected by analyzing voxels surrounding a test voxel. If the density is sufficiently different, it is concluded that the test voxel is associated with a sheet object. Sheet objects can also be detected by eroding the CT data then subtracting from the original data, leaving only thin sheet-shaped objects. 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 computed and compared to mass thresholds to classify the object as to whether it poses a threat. Multiple mass thresholds can be used. Bulk objects can be detected by a modified morphological connected components labeling (CCL) approach which performs a series of erosion and dilation steps to separate adjacent objects in the data such that they can be individually labeled and analyzed. A merging process can be used to reconnect related items, such as multiple sticks, that were separated during an erosion step. The merging process allows multiple objects that would individually pass as non-threat items to be combined into a single item that is correctly classified as a threat. The system can also identify objects that contain liquids, if desired.
138 Citations
33 Claims
-
1. A method of processing computed tomography (CT) data representing an object in a region comprising:
-
identifying a plurality of volume elements in the CT data associated with the object, each volume element having a density value; identifying surface volume elements of the object, said surface volume elements of the object being located at a surface of the object; computing a mean density of the object, said mean density being a mean of the density values of volume elements associated with the object; and adjusting the density value of surface volume elements to an adjusted density value, said adjusted density value being based as a function of the mean density. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. An apparatus for processing computed tomography (CT) data for an object in a region comprising:
-
means for identifying a plurality of volume elements in the CT data associated with the object, each volume element having a density value; means for identifying surface volume elements of the object, said surface volume elements of the object being located at a surface of the object; means for computing a mean density of the object, said mean density being a mean of the density values of volume elements associated with the object; and means for adjusting the density value of surface volume elements to an adjusted density value, said adjusted density value being a function of the mean density. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
-
-
23. A computed tomography (CT) system for processing CT data representing an object in a region comprising:
-
means for acquiring the CT data for the object; means for identifying a plurality of volume elements in the CT data associated with the object, each volume element having a density value; means for identifying surface volume elements of the object, said surface volume elements of the object being located at a surface of the object; means for computing a mean density of the object, said mean density being a mean of the density values of volume elements associated with the object; and means for adjusting the density value of surface volume elements to an adjusted density value, said adjusted density value being a function of the mean density. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
-
Specification