Patent Number: 054935997
Section: claims

1. An x-ray tube comprising: a generally toroidal housing having an evacuated annular interior;  an annular anode mounted in the toroidal housing interior;  a rotating frame rotatably disposed within the toroidal housing interior;  at least one cathode assembly mounted to the frame for rotation therewith, the cathode assembly including an electron source forming an electron beam that strikes the anode to generate an x-ray beam;  a pre-collimator supported within the evacuated annular interior of the toroidal housing, the precollimator having an x-ray passing slot; and,  a collimator mounted outside of the evacuated annular interior of the toroidal housing for collimating the x-ray beam which passed through the precollimator slot.  a generally toroidal housing having an evacuated annular interior;  an annular anode mounted in the toroidal housing interior;  a rotating frame rotatably disposed within the toroidal housing interior;  at least one cathode assembly mounted to the frame for rotation therewith, the cathode assembly including an electron source forming an electron beam that strikes the anode to generate an x-ray beam;  a precollimator supported in the toroidal housing interior having an x-ray passing slot, the pre-collimator being mounted on the rotating frame in alignment with at least one cathode assembly; and,  a collimator for collimating the x-ray beam passing through the precollimator slot.  a generally toroidal housing having an evacuated annular interior;  an annular anode mounted in the toroidal housing interior;  a rotating frame rotatably disposed within the toroidal housing interior;  at least one cathode assembly mounted to the frame for rotation therewith, the cathode assembly including an electron source forming an electron beam that strikes the anode to generate an x-ray beam;  a pre-collimator supported by the anode in the toroidal housing interior and having an x-ray passing slot; and,  a collimator for collimating the x-ray beam passed through the precollimator slot.  a generally toroidal housing having an evacuated annular interior;  an annular anode mounted in the toroidal housing interior;  a rotating frame rotatably disposed within the toroidal housing interior;  at least one cathode assembly mounted to the frame for rotation therewith, the cathode assembly including an electron source forming an electron beam that strikes the anode to generate an x-ray beam;  a precollimator supported in the toroidal housing interior having an x-ray passing slot;  a shield ring attached around the anode on a side opposite the pre-collimator; and,  a collimator for collimating the x-ray beam passed through the precollimator slot.  a generally toroidal housing having an evacuated, annular interior;  an annular anode mounted in the toroidal housing interior;  a rotating frame rotatably disposed within the toroidal housing interior;  at least one cathode assembly mounted to the rotating frame for rotation therewith, the cathode assembly including an electron source forming an electron beam that strikes the anode to generate x-rays;  a ring collimator supported by toroidal housing for collimating the x-rays into a beam, the collimator including a first ring and a second ring between which the x-ray beam is defined, the first and second rings having a common central axis, at least one of the first and second rings being adjustably mounted such that a distance between the first and second rings is adjustable, the first ring having a first diameter and the second ring having a second diameter, the first diameter being greater than the second diameter.  a generally toroidal housing having an evacuated, annular interior;  an annular anode mounted in the toroidal housing interior;  a rotating frame rotatably disposed within the toroidal housing interior;  at least one cathode assembly mounted to the rotating frame for rotation therewith, the cathode assembly including an electron source forming an electron beam that strikes the anode to generate x-rays;  a pre-collimator supported in the evacuated, annular interior of the toroidal housing, the precollimator having an x-ray passing slot disposed between the annular anode and the central axis such that x-rays pass through the precollimator prior to exiting the toroidal housing;  a ring collimator supported by toroidal housing for collimating the x-rays which passed through the precollimator slot into a beam, the collimator including a first ring and a second ring between which the x-ray beam is defined, the first and second rings having a common central axis, at least one of the first and second rings being adjustably mounted such that a distance between the first and second rings is adjustable.  a generally toroidal housing having an evacuated, annular interior;  an annular anode mounted in the toroidal housing interior;  a rotating frame rotatably disposed within tho toroidal housing interior;  at least one cathode assembly mounted to the rotating frame for rotation therewith, the cathode assembly including an electron source forming an electron beam that strikes the anode to generate x-rays;  a ring collimator supported by toroidal housing for collimating the x-rays into a collimated x-ray beam centered on a central axis, the collimator including a first ring and a second ring between which the x-ray beam is defined, the first and second rings having a common central axis, at least one of the first and second rings being adjustably mounted such that a distance between the first and second rings is adjustable; and  a means for controlling the first and second rings to adjust a width of the collimated x-ray beam by a selectively adjustable width and to translate the central axis of the collimated x-ray beam one-half of the selected width.  a patient support for supporting a selected portion of a patient in an examination region;  an x-ray tube including:  a patient support for supporting a selected portion of a patient in an examination region;  an x-ray tube including:  a ring of x-ray detectors extending around the toroidal housing adjacent and axially offset from the annular x-ray window, the x-ray detectors defining a second plane that is parallel to and displaced from the first plane;  a precollimator supported within the toroidal housing evacuated interior between the annular anode and the annular window;  a ring collimator including a first ring and a second ring, the first and second rings being disposed on opposing sides of the annular window, the ring collimator and the precollimator interacting to define an x-ray beam that originates at the anode in the first plane, crosses the central axis, and intersects the detectors at the second plane.  an evacuated housing;  an anode assembly disposed in the evacuated housing, the anode assembly having an annular anode track therearound;  a cathode assembly mounted in the evacuated housing for forming a beam of electrons that strike the anode track to generate x-rays; and,  a ring of x-ray blocking material mounted to the anode and extending around the anode track. 2. The x-ray tube as set forth in claim 1 wherein the collimator includes a ring collimator supported by toroidal housing for collimating the x-rays into a beam, the collimator including a first ring and a second ring between which the x-ray beam is defined, the first and second rings having a common central axis, at least one of the first and second rings being adjustably mounted such that a distance between the first and second rings is adjustable. 3. An x-ray tube comprising: 4. The x-ray tube as set forth in claim 3 further including a second pre-collimator supported by the anode, the second pre-collimator having a second slot for passage of the x-ray beam. 5. The x-ray tube as set forth in claim 4 further including a support ring of material having a low atomic number disposed between the second pre-collimator and the anode. 6. An x-ray tube comprising: 7. The x-ray tube as set forth in claim 6 further including a support ring of a material having a low atomic number disposed between the pre-collimator and the anode. 8. An x-ray tube comprising: 9. An x-ray tube comprising: 10. The x-ray tube as set forth in claim 9 further including a linear motion drive mechanism for selectively moving the first and second rings relative to each other to adjust the distance therebetween. 11. The x-ray tube as set forth in claim 9 further including a rotary motion drive for selectively moving the first and second rings relative to each other. 12. The x-ray tube as set forth in claim 11 wherein the second ring includes a line pitch screw threadingly disposed on a periphery thereof. 13. An x-ray tube comprising: 14. The x-ray tube as set forth in claim 13 wherein the pre-collimator is mounted on the rotating frame for rotation therewith. 15. The x-ray tube as set forth in claim 13 wherein the pre-collimator is connected to the anode. 16. The x-ray tube as set forth in claim 13 further including an x-ray shield disposed on a side of the anode opposite the pre-collimator. 17. An x-ray tube comprising: 18. An CT scanner comprising: 19. A CT scanner comprising: 20. An x-ray tube comprising: 21. The x-ray tube as set forth in claim 20 wherein the ring of x-ray blocking material has a narrow, annular x-ray passing window therein such that a beam of x-rays pass therethrough.