Apparatus and method for reconstruction of volumetric images in a divergent scanning computed tomography system
An apparatus and method for reconstructing image data for a region are described. A radiation source and multiple one-dimensional linear or two-dimensional planar area detector arrays located on opposed sides of a region angled generally along a circle centered at the radiation source are used to generate scan data for the region from a plurality of diverging radiation beams, i.e., a fan beam or cone beam. Individual pixels on the discreet detector arrays from the scan data for the region are reprojected onto a new single virtual detector array along a continuous equiangular arc or cylinder or equilinear line or plane prior to filtering and backprojecting to reconstruct the image data.
1. A method of imaging an object using radiation, comprising:
obtaining projection data from at least one real detector array, the at least one real detector array obtaining projection data at two or more positions on a gantry, and having a geometry that is neither equilinear nor equiangular;
reprojecting the projection data from at least one real detector array onto a virtual detector having virtual pixels that are spaced either equilinearly or equiangularly; and
reconstructing the reprojected data from the virtual detector array.
2. The method of claim 1 , wherein the at least one real detector array comprises two or more detectors configured to obtain projection data at two or more positions.
3. The method of claim 1 , wherein the at least one real detector array comprises at least one detector that is movable to obtain projection data at two or more positions.
4. The method of claim 1 , further comprising:
projecting radiation from a source onto the at least one real detector array.
5. The method of claim 4 , wherein the radiation comprises x-ray radiation.
6. The method of claim 1 , wherein the virtual detector array is equilinear.
7. The method of claim 1 , wherein the virtual detector array is equiangular.
8. The method of claim 1 , wherein reprojecting the projection data onto a virtual array comprises:
for each virtual pixel, determining a corresponding real detector pixel in a real detector array that is intersected by a line connecting the virtual pixel to the source of projected radiation; and
using a radiation amplitude value detected at the corresponding real detector pixel to determine a radiation amplitude value for the virtual pixel.
9. The method of claim 8 , wherein determining a radiation amplitude value for the virtual pixel comprises interpolating a value from the radiation amplitude values of the corresponding real detector pixel and neighboring real detector pixels.
10. The method of claim 1 , further comprising:
filtering data from the virtual detector array; and
backprojecting data from the virtual detector array.
11. The method of claim 1 , wherein the at least one real detector array comprises at least one one-dimensional line detector.
12. The method of claim 1 , wherein the at least one real detector array comprises at least one two-dimensional flat panel detector.
13. A system for imaging an object using radiation, comprising:
a source of radiation;
at least one real detector array that obtains projection data at two or more positions on a gantry, and has a geometry that is neither equilinear nor equiangular; and
a data process for reprojecting the projection data from the at least one real detector array onto a virtual detector array having virtual pixels that are spaced either equilinearly or equiangularly, and for reconstructing the reprojected data from the virtual detector array.
14. The system of claim 13 , wherein the source comprises an x-ray source.
15. The system of claim 13 , wherein the at least one real detector array comprises at least one one-dimensional line detector.
16. The system of claim 13 , wherein the at least one real detector array comprises at least one two-dimensional flat panel detector.
17. The system of claim 13 , wherein the virtual detector array is equilinear.
18. The system of claim 13 , wherein the virtual detector array is equiangular.
19. The system of claim 13 , wherein the at least one real detector array comprises at least two detectors configured to obtain projection data at two or more positions.
20. The system of claim 19 , wherein the at least two detectors are disposed end-to-end, and angled relative to one another to approximate an arc having a radius centered at a focal spot of the source.
21. The system of claim 13 , wherein the at least one real detector array comprises at least one detector movable to two or more positions to obtain projection data.
22. The system of claim 13 , wherein the data process reprojects data by assigning a radiation amplitude value to each virtual pixel based upon a measured radiation amplitude value of a corresponding real pixel that intersects a line between the virtual pixel and the radiation source.