Methods and apparatus for x-ray imaging with focal spot deflection

1. An x-ray tube comprising:

a cathode configured to emit electrons; and

an anode having a target with an angled target surface defining a target angle, the emitted electrons deflected onto the angled target surface, and wherein the angled target surface is substantially aligned with a z-axis parallel to a gantry rotation axis.

2. An x-ray tube in accordance with claim 1 where the emitted electrons are deflected onto a plurality of locations on the target surface.

3. An x-ray tube in accordance with claim 2 wherein the plurality of locations are positioned substantially along the z-axis.

4. An x-ray tube in accordance with claim 2 wherein the plurality of locations are positioned substantially along a target track.

5. An x-ray tube in accordance with claim 2 wherein the plurality of locations are positioned substantially along both a target track and the z-axis.

6. An x-ray tube in accordance with claim 1 wherein the cathode extends along a longitudinal axis that is offset from the z-axis.

7. An x-ray tube in accordance with claim 1 wherein the target surface includes an outer angled portion that is aligned with the z-axis.

8. An x-ray tube in accordance with claim 1 further comprising a housing enclosing the cathode and anode, and wherein the housing is adjustable relative to the z-axis.

9. An x-ray tube in accordance with claim 8 wherein the housing is pivotally adjustable.

10. An x-ray tube in accordance with claim 8 wherein the housing is dynamically adjustable.

11. An x-ray tube in accordance with claim 1 wherein the target surface includes a plurality of grooves extending along the surface.

12. An x-ray tube in accordance with claim 11 wherein the plurality of grooves are spaced apart along the target surface at different focal spots.

13. An x-ray tube in accordance with claim 11 wherein each of the grooves includes at least one angled wall.

14. An x-ray tube in accordance with claim 13 wherein the at least one angled wall is configured to define a target angle relative to an x-ray plane that is less than about ten degrees.

15. An x-ray tube in accordance with claim 1 comprising at least one of an electromagnetic field source and an electrostatic field source configured to deflect the electrons emitted by the cathode.

16. An x-ray tube in accordance with claim 1 wherein the deflected electrons form a plurality of electron beams to produce a plurality of focal spots along the target.

17. An x-ray tube in accordance with claim 1 wherein the angled target surface is configured to increase a spacing between focal spots generated from the electrons emitted from the cathode.

18. An x-ray tube in accordance with claim 1 wherein the target comprises a planar surface offset from the z-axis.

19. An x-ray tube in accordance with claim 18 wherein the cathode is aligned axially with the anode and the target.

20. A computed tomography (CT) system comprising:

a gantry having a gantry opening therethrough defining a z-axis, the gantry configured to rotate about the z-axis; and

a radiation source coupled to the gantry, the radiation source utilizing focal spot deflection to project x-rays into the gantry opening and wherein the radiation source is offset from the z-axis.

21. A CT system in accordance with claim 20 wherein the radiation source is adjustably coupled to the gantry.

22. A CT system in accordance with claim 20 wherein the radiation source is dynamically adjustable.

23. A CT system in accordance with claim 20 wherein the radiation source is pivotally rotatable about an axis parallel to the z-axis.

24. A CT system in accordance with claim 20 wherein the radiation source comprises an x-ray tube having a target and wherein the x-ray tube is offset from the z-axis such that a surface of the target is aligned with the z-axis.

25. A CT system in accordance with claim 24 wherein the surface of the target includes a plurality of grooves.

26. A CT system in accordance with claim 20 wherein the gantry is configured to rotate the radiation source in a step-and-shoot mode.

27. A CT system in accordance with claim 20 further comprising a table configured to translate into the gantry opening and wherein the gantry and table remain stationary during data acquisition to generate an x-ray radiography image.

28. A CT system in accordance with claim 20 further comprising a table configured to translate into the gantry opening and wherein the gantry remains stationary and the table translates along the z-axis during data acquisition to generate a tomosynthesis image.

29. A CT system in accordance with claim 20 wherein the radiation source comprises an x-ray tube having a housing and wherein the housing is configured to be adjusted relative to the z-axis during a scan with the gantry remaining stationary.

30. A method for generating x-ray beams with an x-ray tube, the method comprising:

generating a plurality of deflected focal spots along a target of the x-ray tube; and

aligning an angled surface of the target with a z-axis along which x-ray beams generated by the deflected focal spots are projected.