Method for scanning a heart with a dual-source CT device and embodiment of a dual-source CT device
A method is disclosed for CT scanning a heart with a dual-source CT device including detectors of different widths in a system axis direction and for reconstruction of tomographic image data. In at least one embodiment, at least two circular scans are performed at different z positions and the spacing in the z direction is chosen such that at least two first scan zones are produced which are scanned by way of a circular scan with two detectors and at least one second scan zone is produced which is scanned twice by one detector in two successive circular scans, wherein a dual-source reconstruction is performed in the first scan zones and a two-segment reconstruction is performed in the at least one second scan zone and finally a common tomographic image data set is produced. Further, at least one embodiment is directed to a dual-source CT device in which the detectors have different widths in the system axis direction.
1. A method for CT scanning a heart with a dual-source CT device including two focus-detector systems with detectors of different widths in a system axis direction, and for reconstruction of tomographic image data, the method comprising:
performing at least two circular scans at different z positions, the spacing in the z direction being chosen such that at least two first scan zones are produced which are scanned by way of a circular scan with two detectors and at least one second scan zone being produced which is scanned twice by one detector in two successive circular scans;
reconstructing first tomographic image data in the at least two first scan zones using absorption data of a relatively narrower one of the two detectors and of a relatively wider one of the two detectors;
reconstructing second image data in the at least one second scan zone from absorption data of the relatively wider detector from two successive circular scans at different z positions; and
assembling a common tomographic image data set from at least the reconstructed first and second image data.
2. The method as claimed in claim 1 , wherein the CT scan is performed with ECG triggering.
3. The method as claimed in claim 1 , wherein only detector data from a resting phase of the heart is used for the reconstruction.
4. The method as claimed in claim 1 , wherein, as a function of an anticipated heart rate, a rotational speed is chosen which is time-resolution-optimized with respect to the reconstruction of second image data in the at least one second scan zone from absorption data of the relatively wider detector from two successive circular scans at different z positions.
5. The method as claimed in claim 1 , wherein the relatively narrower detector is half as wide as the relatively wider detector.
6. The method as claimed in claim 1 , wherein,
referring to the system axis direction, one or two marginal scan areas are present in which adequate scanning is performed with just one focus-detector system without changing the z position,
a reconstruction of an image data set is performed using detector data from a single sequence scan, and
said reconstructed image data is also added to the common tomographic image data set.
7. The method as claimed in claim 1 , wherein the detectors are displaced relative to each other in the system axis direction between two successive circular scans.
8. A dual-source CT device comprising:
two focus-detector systems arranged on a gantry so as to be angularly offset, detectors of the two focus-detector systems including different widths in a system axis direction; and
a computer system including a program memory with program data being provided by which the dual-source CT device is controlled and CT image data is reconstructed during operation of the two focus-detector systems.
9. The dual-source CT device as claimed in claim 8 , wherein the detectors of the two focus-detector systems are arranged on the gantry such that a relatively wider one of the detectors projects beyond a projection of a relatively narrower one of the detectors in the system axis direction to a same extent on either side of the projection of relatively narrower one of the detectors.
10. The dual-source CT device as claimed in claim 8 , wherein the detectors are constructed so as to be displaceable relative to each other in the system axis direction.
11. A dual-source CT device comprising:
two focus-detector systems arranged on a gantry so as to be angularly offset, detectors of the two focus-detector systems including different widths in a system axis direction; and
a computer system including a program memory with program data being provided by which the dual-source CT device is controlled and CT image data is reconstructed during operation of the two focus-detector systems, and wherein, a program code is stored in the program memory of the computer to perform the method as claimed in claim 1 when executed.
12. A tangible computer readable medium including program segments for, when executed on a computer device, causing the computer device to implement the method of claim 1 .
13. The method as claimed in claim 2 , wherein only detector data from a resting phase of the heart is used for the reconstruction.
14. The method as claimed in claim 3 , wherein, as a function of an anticipated heart rate, a rotational speed is chosen which is time-resolution-optimized with respect to the reconstruction of second image data in the at least one second scan zone from absorption data of the relatively wider detector from two successive circular scans at different z positions.