Dual-source CT device and method for spiral scanning

1. Dual-source CT device, comprising:

two focus-detector systems, arranged on a gantry offset at an angle n, at least one detector in one of the two focus-detector systems having a different z-width in a system axis direction than at least one detector in the other of the two focus-detector systems; and

a computer system, including a program memory including at least one computer program, to, during operation the dual-source CT device, control a spiral scanning of a patient and reconstruct CT-image data from absorption data obtained from the two unequally wide detectors.

2. The dual-source CT device as claimed in claim 1 , wherein the at least one detector of the two focus-detector systems includes a different number of detector lines and wherein the at least one computer program, for control of the dual-source CT device, is embodied such that during operation it controls a spiral with a couch feed rate per rotation which is greater than a maximum couch feed rate possible with the at least one relatively narrower detector.

3. The dual-source CT device as claimed in the preceding claim 1 , the at least one detector of the two focus-detector systems includes a different number of detector lines and wherein the at least one computer program for control of the dual-source CT device is embodied such that during operation, it controls a spiral with a pitch of

p

max

=

2

⁢

π

⁡

(

1

+

(

N

q

1

+

N

q

2

2

-

1

)

⁢

cos

⁢

⁢

β

max

)

N

q

1

⁡

(

2

⁢

β

max

+

π

2

)

,

wherein:

N q 1 corresponds to the number of detector lines of the at least one relatively narrower detector,

N 9 2 corresponds to the number of detector lines of the at least one relatively wider detector, and

β max is the maximum fan angle of the at least one relatively narrower detector and if applicable, relatively longer detector.

4. The dual-source CT device as claimed in claim 1 , wherein means are provided, by which the data recording is triggered by a physiological signal of the patient.

5. The dual-source CT device as claimed in claim 4 , wherein the physiological signal of the patient is an EKG.

6. The dual-source CT device as claimed in claim 1 , wherein the at least one relatively narrow detector is twice the length in the peripheral direction than the at least one detector which is relatively wider in the system axis direction.

7. The dual-source CT device as claimed in claim 1 , wherein each of the two focus-detector systems include at least one of

a same number of detector elements, and

a same effective detector area.

8. The dual-source CT device as claimed in claim 1 , wherein the relatively wider at least one detector is twice as wide as the relatively narrow at least one detector.

9. The dual-source CT device as claimed in claim 1 , wherein the at least one relatively wider detector is arranged ahead of the at least one relatively narrower detector in a direction of rotation.

10. A method for spiral scanning and reconstruction of the tomographic image data of a patient with a dual-source CT device with two focus-detector systems arranged on a gantry offset at an angle n, one of the two focus-detector systems including at least one detector of a different width in the system axis direction than at least one detector of the other of the two focus-detector systems, wherein a cone of rays forms respectively between a focus and the at least one detector of each of the two focus-detector systems, the method comprising:

executing the spiral scanning, wherein a pitch is set in which, in relation to virtual detectors respectively formed by each of the two focus-detector systems in a center of rotation, a corner of a relatively wider of the virtual detectors, formed from a rear row of detector elements in a direction of rotation and a front line of detector elements in a z-direction, overlaps a rear detector line of the relatively narrow of the virtual detectors in a direction of feed;

reconstructing tomographic image data from attenuation data stemming from both of the two focus-detector systems, wherein data for reconstruction is selected, in each case, from both of the virtual detectors and wherein a volume of data from the relatively wide detector outweighs data from the relatively narrow detector; and

outputting at least one tomographic image data set of reconstructed tomographic image data from mixed data from the relatively narrow and relatively wide virtual detectors.

11. The method as claimed in claim 10 , wherein execution of at least one of the spiral scanning and detector data selection is EKG-triggered.

12. The method as claimed in claim 11 , wherein a ratio of the detector data selected and used for reconstruction is matched to a ratio of detector lines of both virtual detectors.

13. The method as claimed in claim 11 , wherein twice as many detector lines are used for the relatively wide detector relative to the relatively narrow detector.

14. The method as claimed in claim 11 , wherein the relatively narrow detector follows the relatively wide detector during scanning.

15. The method as claimed in claim 10 , wherein a ratio of the detector data selected and used for reconstruction is matched to a ratio of detector lines of both virtual detectors.

16. The method as claimed in claim 10 , wherein twice as many detector lines are used for the relatively wide detector relative to the relatively narrow detector.

17. The method as claimed in claim 10 , wherein the relatively narrow detector follows the relatively wide detector during scanning.

18. 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 10 .