Automated phase selection for ECG-gated cardiac axial CT scans
Provided are one or more systems and/or techniques for mitigating motion artifacts in a computed tomography image of an anatomical object. Extended scan data is received and includes projections and backprojections acquired for parallel rays emitted by a radiation source at different angular locations within a first range of source angles. The projections and the backprojections are compared to identify differences between the projections and the backprojections at the different angular locations. Movement of the anatomical object during acquisition of the extended scan data at the different angular locations is quantified, and short scan data is identified. The short set includes a subset of the extended scan data acquired at different locations within a second range of source angles where the quantified movement of the anatomical object is less than a movement threshold. The computed tomography image of the anatomical object is reconstructed from the short scan data.
1. A method of mitigating motion artifacts in a computed tomography image of an anatomical object, the method comprising:
receiving, at an image reconstructor, extended scan data comprising projections and backprojections acquired for parallel rays emitted by a radiation source at different angular locations within a first range of source angles, wherein the first range of source angles extends greater than 240° about an axis of rotation;
comparing the projections and the backprojections to identify differences between the projections and the backprojections at the different angular locations;
based on the identified differences between the projections and the backprojections, quantifying movement of the anatomical object during acquisition of the extended scan data at the different angular locations;
identifying short scan data comprising a subset of the extended scan data acquired at different locations within a second range of source angles where the quantified movement of the anatomical object is less than a movement threshold, wherein the second range of source angles is less than the first range of source angles about the axis of rotation; and
reconstructing the computed tomography image of the anatomical object from the short scan data.
2. The method of claim 1 , wherein comparing the projections and the backprojections comprises conducting a comparison of the projections and the backprojections in a sinogram domain, before the computed tomography image is reconstructed.
3. The method of claim 1 , wherein the computed tomography image of the anatomical object is reconstructed exclusive of a portion of the extended scan data that is not included in the short scan data.
4. The method of claim 1 , wherein the first range of source angles extends at least 270° about the axis of rotation.
5. The method of claim 4 , wherein the first range of source angles extends 360° about the axis of rotation.
6. The method of claim 5 , wherein the second range of source angles extends up to 240° about the axis of rotation.
7. The method of claim 1 comprising:
determining the movement threshold based on the quantified movement of the anatomical object during acquisition of the extended scan data at the different angular locations within the first range of source angles.
8. The method of claim 1 , wherein the extended scan data corresponds to a midplane sinogram captured by one or more centrally-located sensors in a detector array.
9. A computed tomography system, comprising:
a radiation source;
a detector array; and
an image reconstructor configured to:
receive extended scan data comprising projections and backprojections acquired for parallel rays emitted by the radiation source at different angular locations within a first range of source angles, wherein the first range of source angles extends greater than 240° about an axis of rotation of the radiation source;
compare the projections and the backprojections to identify differences between the projections and the backprojections at the different angular locations;
based on the identified differences between the projections and the backprojections, quantify movement of an anatomical object during acquisition of the extended scan data at the different angular locations;
identify short scan data comprising a subset of the extended scan data acquired at different locations within a second range of source angles where the quantified movement of the anatomical object is less than a movement threshold, wherein the second range of source angles is less than the first range of source angles about the axis of rotation; and
reconstruct a computed tomography image of the anatomical object from the short scan data.
10. The computed tomography system of claim 9 , wherein the image reconstructor is configured to compare the projections and the backprojections in a sinogram domain, before the computed tomography image is reconstructed.
11. The computed tomography system of claim 9 , wherein the image reconstructor is configured to reconstruct the computed tomography image of the anatomical object exclusive of a portion of the extended scan data that is not included in the short scan data.
12. The computed tomography system of claim 9 , wherein the first range of source angles extends at least 270° about the axis of rotation.
13. The computed tomography system of claim 12 , wherein the first range of source angles extends 360° about the axis of rotation.
14. The computed tomography system of claim 13 , wherein the second range of source angles extends up to 240° about the axis of rotation.
15. The computed tomography system of claim 9 comprising:
determining the movement threshold based on the quantified movement of the anatomical object during acquisition of the extended scan data at the different angular locations within the first range of source angles.
16. The computed tomography system of claim 9 , wherein the extended scan data corresponds to a midplane sinogram captured by one or more centrally-located sensors in a detector array.
17. A non-transitory computer readable medium comprising computer executable instructions that when executed via a processing unit cause performance of operations involving extended scan data comprising projections and backprojections acquired for parallel rays emitted by a radiation source at different angular locations within a first range of source angles, wherein the first range of source angles extends greater than 240° about an axis of rotation, the operations comprising:
comparing the projections and the backprojections to identify differences between the projections and the backprojections at the different angular locations;
based on the identified differences between the projections and the backprojections, quantifying movement of an anatomical object during acquisition of the extended scan data at the different angular locations;
identifying short scan data comprising a subset of the extended scan data acquired at different locations within a second range of source angles where the quantified movement of the anatomical object is less than a movement threshold, wherein the second range of source angles is less than the first range of source angles about the axis of rotation; and
reconstructing a computed tomography image of the anatomical object from the short scan data.
18. The non-transitory computer readable medium of claim 17 , wherein the projections and the backprojections are compared in a sinogram domain, before the computed tomography image is reconstructed.
19. The non-transitory computer readable medium of claim 17 , wherein the computed tomography image of the anatomical object is reconstructed exclusive of a portion of the extended scan data that is not included in the short scan data.
20. The non-transitory computer readable medium of claim 17 , wherein the operations comprise:
determining the movement threshold based on the quantified movement of the anatomical object during acquisition of the extended scan data at the different angular locations within the first range of source angles.