X-ray CT scanning and dual-source CT system
A method is disclosed for x-ray CT scanning with a dual-source system, in which two radiation bundles are each delimited by diaphragms such that these radiation bundles are free of mutual points of intersection at least in the examination object. An embodiment of the invention also relates to a dual source CT system, including a controller configured to control radiation-delimiting diaphragms, which delimit and align the radiation bundles such that these run free of mutual points of intersection at least in the examination object.
1. A method of X-ray CT scanning of an examination object using two emitter-detector systems arranged at different angles on a shared gantry of a CT system, each of the two emitters including a focal point and each of the two detectors being embodied as a multi-row detector with a scattered radiation grid operating in a two-dimensional manner, the method comprising:
selecting an offset corresponding to a shift of the two emitter-detector systems relative to one another and moving at least one emitter-detector system by the offset along a system axis,
generating, during the scanning process between each of the respective focal points and an opposing one of the two detectors of each of the two emitter-detector systems, a radiation bundle diverging in two dimensions and acquiring an image for each of the two detectors, wherein the focal points are set with respect to their z-coordinates within the irradiated part of the detectors of the associated emitter-detector system, wherein the offset of the two emitter-detector systems in the z-direction is selected based on a relative fraction of the detector coverage in the isocenter.
2. The method of X-ray CT scanning of claim 1 , wherein the acquisition is performed in a sequence mode.
3. The method of X-ray CT scanning of claim 1 , wherein the acquisition is performed in a helical mode.
4. The method of X-ray CT scanning of claim 1 , wherein the two focal points run onto an identical peripheral line.
5. The method of X-ray CT scanning of claim 1 , wherein the two focal points run onto two separate peripheral lines.
6. The method of X-ray CT scanning of claim 1 , wherein the two radiation bundles each respectively irradiate their respective detectors entirely with respect to the peripheral direction.
7. A dual-source CT system for scanning an examination object, comprising:
two emitter-detector systems, arranged at different angles on a gantry, each including
at least one x-ray tube which forms a respective focal point during operation and which is configured to rotate on a peripheral line about a system axis running in the z-direction, and
a multi-row detector, configured to rotate about the system axis, detector rows of the multi-row detector being configured to run in the peripheral direction, the multi-row detector including a scattered radiation grid configured to operate in a two-dimensional manner, wherein, a displacement apparatus is provided for at least one emitter-detector system, which is configured to displace at least one emitter-detector system in the z-direction, wherein each respective focal point is set with respect to its z-coordinate within the irradiated part of the detectors of the associated emitter-detector system; and
a controller configured to select an offset of the two emitter-detector systems in the z-direction based on a relative fraction of the detector coverage in the isocenter.
8. The dual-source CT system of claim 7 , wherein at least one displacement apparatus is provided for at least one emitter-detector system, which is configured to displace the at least one emitter-detector system in the z-direction.
9. The dual-source CT system of claim 7 , further comprising a control unit for controlling the displacement apparatus.
10. The method of X-ray CT scanning of claim 1 , wherein the offset is adapted to the pitch.
11. The method of X-ray CT scanning of claim 1 , wherein the offset equals to a relative fraction of the detector coverage in the isocenter of 0.25 during operation.
12. The method of X-ray CT scanning of claim 1 , wherein the offset equals to a relative fraction of the detector coverage in the isocenter of 0.75 during operation.
13. The method of X-ray CT scanning of claim 1 , wherein the offset equals to a relative fraction of the detector coverage in the isocenter of −0.75 during operation.
14. The method of X-ray CT scanning of claim 1 , wherein the offset equals to a relative fraction of the detector coverage in the isocenter of 1 during operation.