Breast tomosynthesis system with shifting face shield

1. An x-ray system for imaging a patient's breast, comprising:

an x-ray source selectively emitting an imaging x-ray beam, an x-ray imaging receptor receiving the imaging beam, and a breast platform between the source and the receptor, said breast platform having a front edge against which a patient's chest wall presses when the patient's breast is imaged with said imaging beam;

a patient shield and a shield support supporting the shield between the source and the breast platform at least for selective back-and-forth movement of the shield between selected back-and-forth positions comprising a protective position and an access position;

wherein the protective position is closer to the front edge of the breast platform than the access position.

2. A system as in claim 1 in which said shield support additionally supports the shield for side-to-side movement relative to the source and the breast platform between selected side-to-side positions.

3. A system as in claim 2 further including sensors sensing whether the shield is in at least one of said selected back-and-forth and side-to-side positions and providing sensor signals indicative thereof.

4. A system as in claim 3 further including a control computer coupled to the sensors and the source and configured to control said source according to said sensor signals.

5. A system as in claim 4 in which said control computer is configured to control the source to prevent emission of said imaging beam when the shield is between the source and receptor but not in at least one of the selected back-and-forth positions.

6. A system as in claim 4 in which said selected side-to-side positions include a left position, a right positions and a center position and said control computer is configured to control the source to prevent emission of said imaging beam when the shield is between the source and receptor but not in at least one of the left, right and center positions thereof.

7. A system as in claim 4 further including a display coupled to said control computer and displaying an indication of the selected position of said shield, and an operator interface coupled to the control computer to receive and convey to the control computer an operator's confirmation that the shield is in a position in which the source should emit the imaging beam.

8. A system as in claim 4 further including a shield drive motor coupled to the shield and to the control computer and selectively driving the shield between at least two of said selected positions thereof in response to commands from the control computer.

9. A system as in claim 2 further including locks releasably locking the shield in at least one of the selected positions, said locks being manually releasable to thereby unlock the shield for manually moving the shield between said at least two selected positions.

10. A system as in claim 1 further including sensors sensing whether the shield is in at least one of said selected back-and-forth positions and providing sensor signals indicative thereof.

11. A system as in claim 10 further including a control computer coupled to the sensors and the source and configured to control said source according to said sensor signals.

12. A system as in claim 11 in which said control computer is configured to control the source to prevent emission of said imaging beam when the shield is between the source and receptor but not in at least one of the selected back-and-forth positions.

13. A system as in claim 12 further including a display coupled to said control computer and displaying an indication of the selected position of said shield, and an operator interface coupled to the control computer to receive and convey to the control computer an operator's confirmation that the shield is in a position in which the source should emit the imaging beam.

14. A system as in claim 12 further including a shield drive motor coupled to the shield and to the control computer and selectively driving the shield between at least two of said selected positions thereof in response to commands from the control computer.

15. A system as in claim 1 further including locks releasably locking the shield in at least one of the selected positions, said locks being manually releasable to thereby unlock the shield for manually moving the shield between said at least two selected positions.

16. A system as in claim 1 in which said shield is generally U-shaped in a section transverse to the imaging beam and comprises a front portion and a pair of wings, said wings having upper edges closer to the source and lower edges closer to the receptor, and said shield flaring such that the upper edges are closer to each other than the lower edges.

17. A system as in claim 1 operative selectively in a mammography mode and in a tomosynthesis mode and including a first support supporting the source, a second support supporting the receptor, breast platform and the shield support, said first and second arms being mounted for rotation in a first mode in which they are locked to each other and rotate as a unit and in a second mode in which they are unlocked from each other so that at least one can rotate relative to the other.

18. A method of operating a breast imaging x-ray system, comprising:

positioning a patient's breast on a breast platform having a front edge against which the patient's chest wall presses;

operating a patient shield supported at least for back-and-forth movement relative to the breast platform between selected back-and-forth positions relative to the breast support, including a protective position and an access position, by moving the patient shield toward the front edge of the breast platform and into the protective position from the access position in which the shield is further from the breast platform's front edge; and

taking at least one x-ray imaging exposure of the breast with an imaging x-ray imaging beam emitted from an x-ray source on one side of the breast and the breast platform and received by an x-ray imaging receptor on the other side, while the patient shield is in its protective position and the beast remains compressed.

19. A method as in claim 18 wherein said patient shield is further supported for side-to-side movement relative to the breast platform between selected side-to-side positions, and further operating the patient shield, before taking said at least one imaging exposure, to move the patient shield side-to-side relative to the breast platform to a selected one of side-to-side positions.

20. A method as in claim 19 including providing sensors and using the sensors to sense whether the shield is in at least one of its selected positions and emit sensor signals indicative thereof.

21. A method as in claim 20 including providing a control computer coupled to the sensors and the source and using the control computer to control said source according to said sensor signals.

22. A method as in claim 21 including using the control computer to control the source to prevent emission of said imaging beam when the shield is between the source and receptor but not in at least one of the protective and access positions.

23. A method as in claim 21 including providing a display coupled to said control computer and displaying an indication of the position of said shield, providing an operator interface coupled to the control computer to receive and convey to the control computer an operator's confirmation that the shield is in a position in which the source should emit the imaging beam.

24. A method as in claim 21 including driving the shield with a drive motor coupled to the shield and to the control computer and selectively driving the shield between at least two of the selected positions thereof in response to commands from the control computer.

25. A method as in claim 19 including releasably locking the shield in at least one of its selected positions, and manually releasing the locks to manually move the shield from one to another of the selected positions thereof.

26. A method as in claim 19 including selectively operating in a mammography mode in which a first support supporting the source and a second support supporting the receptor, breast platform and the shield support are mounted for rotation as a unit and in a tomosynthesis mode in which the first and second support arms are unlocked from each other so that at least one rotates relative to the other.

27. A fused tomosynthesis/mammography system for imaging a patient's breast with x-rays, comprising:

an x-ray source selectively emitting an x-ray imaging beam, an x-ray imaging receptor receiving the imaging beam, and a breast immobilizer between the source and receptor, said breast immobilizer being in the path of the imaging beam and having a front edge against which the patient's chest wall presses when a patient's breast is being imaged with said imaging beam;

a first support arm supporting the source and mounted for rotation about a first axis spaced from the source;

a second support arm supporting the breast immobilizer and the receptor and mounted for rotation about a second axis;

a control computer selectively rotating the first and second support arms and the breast immobilizer as a unit in a mammography mode of operation of the system and, in a tomosynthesis mode of operation, rotating at least the first support arm relative to the breast immobilizer;

a patient shield mounted to said second arm at least for selective back-and-forth motion selected positions comprising a protective position in which the shield is closer to said front edge of the breast immobilizer and an access position in which the shield is further from said front edge.

28. A system as in claim 27 in which said receptor is mounted for rocking motion relative to said breast immobilizer in said second mode of operation.

29. A system as in claim 28 in which in said tomosynthesis mode of operation the source rotates through a first angle and the receptor rocks through a second angle that is different from said first angle.

30. A system as in claim 27 in which said shield is further mounted for selective side-to-side motion relative to said second support arm.