Method and apparatus of segmenting an object in a data set and of determination of the volume of segmented object
First Claim
Patent Images
1. A method of segmenting an object in a data set, said method comprising the following steps:
- a) initial segmenting of the object, in particular by using a region growing method, resulting in a first set (N0) of voxels, b) performing an erosion operation on the first set (N0) of voxels resulting in an eroded set (N−
) of voxels and c) performing a dilation operation on the eroded set (N−
) of voxels resulting in a dilated set (N+) of voxels, wherein the erosion operation depends on a variable erosion threshold (Θ
−
) and wherein the dilation operation depends on a variable dilation threshold (Θ
+).
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Abstract
The invention relates to a method of segmenting an object in a data set, wherein the object is initially segmented resulting in a first set (N0) of voxels. An erosion operation is performed on the first set (N0) of voxels resulting in an eroded set (N−) of voxels. A dilation operation is performed on the eroded set (N−) of voxels resulting in a dilated set (N+) of voxels. The erosion operation depends on a variable erosion threshold (Θ−), and the dilation operation depends on a variable dilation threshold (Θ+)
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Citations
40 Claims
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1. A method of segmenting an object in a data set, said method comprising the following steps:
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a) initial segmenting of the object, in particular by using a region growing method, resulting in a first set (N0) of voxels, b) performing an erosion operation on the first set (N0) of voxels resulting in an eroded set (N−
) of voxels andc) performing a dilation operation on the eroded set (N−
) of voxels resulting in a dilated set (N+) of voxels,wherein the erosion operation depends on a variable erosion threshold (Θ
−
) andwherein the dilation operation depends on a variable dilation threshold (Θ
+). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 33, 34, 35, 38, 39, 40)
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24. A method of segmenting an object in a data set, said method comprising the following steps:
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a) initial segmenting of the object, in particular by using a region growing method, resulting in a first set (N0) of voxels, b) modifying the first set (N0) of voxels by;
determining a complement of the first set (N0) of voxels, performing a connected component analysis on the complement of the first set (N0) of voxels resulting in the largest connected non-segmented area (P), subtracting the largest connected non-segmented area (P) from the data set (V) resulting in a modified first set (N1) of voxels. c) performing a first distance transformation to determine for each of at least some voxels of the data set (V) the first minimal distance (E(ν
)) resulting in a first distance map, wherein the first minimal distance of each of at least some voxels of the data set (V) is the distance of the respective voxel of the at least some voxels of the data set (V) to a voxel outside of the first set (N1) having the shortest distance to the respective voxel of the at least some voxels of the data set (V),d) determining a seed point (S′
) in the first set (N1) of voxels being the position of a maximum, in particular of a local maximum, in the first distance map,e) determining an erosion threshold (Θ
−
) by performing a variable threshold region growing on the first distance map starting from the determined seed point (S′
) wherein the erosion threshold (Θ
−
) is equal to or larger than the highest threshold sufficient to reach the boundaries of the data set (V).f) performing an erosion operation on the first set (N1) of voxels resulting in an eroded set (N−
) of voxels, wherein the erosion operation is performed such that the eroded set (N−
) of voxels comprises all voxels of the first set (N1) of voxels whose first minimal distance is smaller than or equal to the erosion threshold (Θ
−
),g) performing a second distance transformation to determine for each of at least some voxels of the data set (V) the second minimal distance (D(ν
)), wherein the second minimal distance (D(ν
)) of each of the at least some voxels of the data set (V) is the distance of each of the at least some voxels of the data set (V) to a voxel of the eroded set (N−
) of voxels having the shortest distance to the respective voxel of the at least some voxels of the data set (V),h) performing a dilation operation on the eroded set (N−
) of voxels resulting in a dilated set (N+) of voxels such that the dilated set (N+) of voxels includes all voxels whose second minimal distance (D(ν
)) to voxels of the eroded set (N−
) of voxels is smaller than the dilation threshold (Θ
+), wherein the dilation threshold (Θ
+) is defined such that the dilated set (N+) of voxels comprises the same or more voxels than the first set (N1) of voxels and/or that the dilation threshold (Θ
+) is equal to or larger than the erosion threshold (Θ
−
). - View Dependent Claims (25, 26)
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27. A method of segmenting an object in a data set, said method comprising the following steps:
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a) initial segmenting of the object, in particular by using a region growing method, resulting in a first set (N0) of voxels, b) modifying the first set (N0) of voxels by;
determining a complement of the first set (N0) of voxels, performing a connected component analysis on the complement of the first set (N0) of voxels resulting in the largest connected non-segmented area (P), subtracting the largest connected non-segmented area (P) from the data set (V) resulting in a modified first set (N1) of voxels, c) performing a convex hull operation on the largest connected non-segmented area (P) resulting in a convex set of voxels, d) modifying the first set of voxels by intersecting the first set of voxels with the convex set of voxels wherein the intersection is the modified first set (N2) of voxels, e) performing a first distance transformation to determine for each of at least some voxels of the data set (V) the first minimal distance (E(ν
)) resulting in a first distance map, wherein the first minimal distance (E(ν
)) of each of at least some voxels of the data set (V) is the distance of the respective voxel of the at least some voxels of the data set (V) to a voxel outside of the first set (N2) having the shortest distance to the respective voxel of the at least some voxels of the data set (V),f) determining a seed point (S′
) in the first set (N2) of voxels being the position of the maximum in the first distance map,g) determining an erosion threshold (Θ
−
) by performing a variable threshold region growing on the first distance map starting from the determined seed point (S′
) wherein the erosion threshold (Θ
−
) is equal to or larger than the highest threshold sufficient to reach the boundaries of the data set (V),h) performing an erosion operation on the first set (N2) of voxels resulting in an eroded set (N−
) of voxels, wherein the erosion operation is performed such that the eroded set (N−
) of voxels comprises all voxels of the first set (N2) of voxels whose first minimal distance is smaller than or equal to the erosion threshold (Θ
−
),i) performing a second distance transformation to determine for each of at least some voxels of the data set (V) the second minimal distance (D(ν
)) wherein the second minimal distance (D(ν
)) of each of the at least some voxels of the data set (V) is the distance of each of the at least some voxels of the data set (V) to a voxel of the eroded set (N−
) of voxels having the shortest distance to the respective voxel of the at least some voxels of the data set (V),j) performing an dilation operation on the eroded set (N−
) of voxels resulting in a dilated set (N+) of voxels such that the dilated set (N+) of voxels includes all voxels whose second minimal distance (D(ν
)) to voxels of the eroded set (N−
) of voxels is smaller than the dilation threshold (Θ
+), wherein the dilation threshold (Θ
+) is defined such that the dilated set (N+) of voxels comprises the same or more voxels than the first set (N2) of voxels and/or that the dilation threshold (Θ
+) is equal to or larger than the erosion threshold (Θ
−
). - View Dependent Claims (28, 29)
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30. A method of determination of the volume of a segmented object, in particular a lesion, in a data set, said method comprising the following steps:
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defining an inner set (NC) of voxels comprising voxels arranged inside the segmented object and having a distance from the boundary of the segmented object which is larger than a predetermined minimum distance, wherein, if such voxels do not exist, the inner set (NC) of voxels is a zero set of voxels, defining an outer set (PC) of voxels comprising voxels arranged outside the segmented object and having a distance from the boundary of the segmented object which is larger than the predetermined minimum distance, defining a middle set (PV) of voxels comprising voxels which are not included in the inner (NC) or outer set (PC) of voxels, assigning to each voxel of the inner set (NC) of voxels the same weighting factor, in particular one, if the inner set (NC) of voxels is not a zero set of voxels, assigning to each voxel of the middle set (PV) of voxels a weighting factor (w(ν
)) which depends on the position and/or the value of the respective voxel within the middle set (PV) of voxels and/or the values of the voxels in the inner (NC) and outer set (PC) of voxels,determining the volume of the segmented object, wherein the weighting factors (w(ν
)) assigned to the voxels of the middle set (PV) of voxels and, if the inner set (NC) of voxels is not a zero set of voxels, of the inner set (NC) of voxels are added. - View Dependent Claims (31, 32, 37)
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36. An apparatus of determination of the volume of a segmented object, in particular a lesion, in a data set, said apparatus comprising:
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defining means (9), for defining an inner set (NC) of voxels comprising voxels arranged inside the segmented object and having a distance from a boundary of the segmented object which is larger than a predetermined minimum distance, wherein, if such voxels do not exist, the inner set (NC) of voxels is a zero set of voxels, for defining an outer set (PC) of voxels comprising voxels arranged outside the segmented object and having a distance from the boundary of the segmented object which is larger than the predetermined minimum distance, for defining a middle set (PV) of voxels comprising voxels which are not included in the inner (NC) or outer set (PC) of voxels, assigning means (10) for assigning to each voxel of the inner set (NC) of voxels the same weighting factor (w(ν
)), in particular one,for assigning to each voxel of the middle set (PV) of voxels a weighting factor (w(ν
)) which depends on the position and/or the value of the respective voxel within the middle set (PV) of voxels and/or the values of the voxels in the inner voxel and outer set (PC) of voxels,determining means (11) for determining the volume of the segmented object, wherein the determining means (11) is adapted to add the weighting factors assigned to the voxels of the middle set (PV) of voxels and, if the inner set (NC) of voxel is not a zero set of voxels, of the inner set (NC) of voxels.
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Specification