Cone-beam reconstruction apparatus and computed tomography apparatus
View Patent ↗A method for obtaining data from CT scans, including obtaining projection data from at least one detector row in a CT system; applying a weighting function including cone-angle dependent weight to projection data; filtering weighted data; and backprojecting weighted data while accounting for cone-angle. The method finds application to an X-ray CT apparatus, including a helical scanning device configured to collect projection data while at least one of a gantry and a couch moves along an axial direction, the helical scanning device including an X-ray source to generate X-rays, and a detector having detector elements arranged in rows along the axial direction to produce projection data; and a processor, which includes a weighting device to apply a weighting function including cone-angle dependent weight to projection data, thereby obtaining weighted data, a filtering device to filter weighted data, and a backprojecting device to backproject weighted data while accounting for cone-angle.
1. A method for obtaining data from a computed tomography (CT) scan, comprising:
obtaining projection data from at least one detector row in a CT system;
applying a weighting function including a cone-angle dependent weight corresponding to data validity to the projection data, thereby obtaining weighted data;
filtering the weighted data; and
backprojecting the weighted data taking cone-angle into account.
2. The method according to claim 1 , wherein the backprojecting step includes applying Feldkamp reconstruction.
3. The method according to claim 1 , wherein the weighting function includes an MHS function.
4. The method according to claim 1 , wherein the weighting function includes an OS function.
5. An X-ray CT apparatus, comprising:
a helical scanning device configured to collect projection data while at least one of a gantry and a couch moves along an axial direction of the couch, the helical scanning device including,
an X-ray source configured to generate X-rays, and
a detector having detector elements arranged in a plurality of rows along the axial direction and configured to produce the projection data; and
a processor comprising,
a weighting device configured to apply a weighting function including
a cone-angle dependent weight corresponding to data validity to the projection data, thereby obtaining weighted data,
a filtering device configured to filter the weighted data, and
a backprojecting device configured to backproject the weighted data taking cone-angle into account.
6. The apparatus according to claim 5 , wherein the backprojecting device is configured to perform Feldkamp reconstruction.
7. The apparatus according to claim 5 , wherein the weighting function includes an MHS function.
8. The apparatus according to claim 5 , wherein the weighting function includes an OS function.
9. An X-ray CT apparatus, comprising:
a helical scanning device configured to collect projection data while at least one of a gantry and a couch moves along an axial direction of the couch, the helical scanning device including,
an X-ray source configured to generate X-rays, and
a detector having detector elements arranged in a plurality of rows along the axial direction and configured to produce the projection data; and
a processor comprising,
means for weighting that applies a weighting function including a cone-angle dependent weight corresponding to data validity to the projection data, thereby obtaining weighted data,
a filtering device configured to filter the weighted data, and
a backprojecting device configured to backproject the weighted data taking cone-angle into account.
10. The apparatus according to claim 9 , wherein the means for backprojecting performs Feldkamp reconstruction.
11. The apparatus according to claim 9 , wherein the weighting function includes an MHS function.
12. The apparatus according to claim 9 , wherein the weighting function includes an OS function.
13. A method for processing data obtained from a CT scan, comprising:
defining at least one parameter;
calculating a first cone-angle for at least one detector row;
storing the first cone-angle for the at least one detector row;
calculating at least one OS weight for at least one direct ray and a plurality of complementary rays;
determining a value of the at least one OS weight;
calculating a second cone-angle for the plurality of complementary rays;
calculating at least one row dependent weight;
calculating a normalized weight based on the at least one row dependent weight, thereby obtaining the normalized weight for use in backprojection, wherein
the calculating a second cone-angle is performed with a limitation to avoid extraordinary cases.
14. The method of claim 13 , wherein the method further comprises obtaining a number of valid complementary rays before determining a value of the at least one OS weight.
15. The method of claim 14 , wherein a number of the plurality of complementary rays is two to four.
16. The method of claim 13 , wherein a number of the plurality of complementary rays is six or more.
17. A computer program product storing instructions for execution on a computer system, which when executed by the computer system, causes the computer system to perform the method recited in any one of claims 1 - 4 13 , and 14 - 16 .
18. A method for obtaining data from a computed tomography (CT) scan, comprising:
obtaining projection data from at least one detector row in a CT system;
applying a weighting function including a cone-angle dependent weight to the projection data, the weight on a region of measured data being larger than the weight on an outside region of measured data, thereby obtaining weighted data; and
reconstructing a tomography image based on the weighted data taking cone-angle into account.
19. An X-ray CT apparatus, comprising:
a helical scanning device configured to collect projection data while at least one of a gantry and a couch moves along an axial direction of the couch, the helical scanning device including,
an X-ray source configured to generate X-rays, and
a detector having detector elements arranged in a plurality of rows along the axial direction and configured to produce the projection data; and
a processor comprising,
means for weighting that applies a weighting function including a cone-angle dependent weight to the projection data, the weight on a region of measured data being larger than the weight on an outside region of measured data, thereby obtaining weighted data,
a filtering device configured to filter the weighted data, and
a backprojecting device configured to backproject the weighted data taking cone-angle into account.