X-ray apparatus

• US 7,796,728 B2
• Filed: 07/25/2005
• Issued: 09/14/2010
• Est. Priority Date: 08/05/2004
• Status: Active Grant

• Current Assignee: Elekta AB
• Original Assignee: Elekta AB
• Inventors: Bergfjord, Per Harald
• Primary Examiner(s): Kiknadze; Irakli
• Application Number:
  US11/659,243
• Publication Number:
  US 20090213990A1
• Time in Patent Office: 1,877 Days
• Field of Search: 378/4, 378/15, 378/19, 378/65, 378/62, 378/64, 378/150
• US Class Current: 378/65
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/4021 involving movement of the focal spot
• CPC Class Codes: A61B 6/4035 the source being combined with a filter or grating
• CPC Class Codes: A61B 6/5241 combining overlapping images of the same imaging modality, e.g. by stitching
• CPC Class Codes: A61B 6/587 Alignment of source unit to detector unit
• CPC Class Codes: A61N 2005/1061 using an x-ray imaging system having a separate imaging source
• CPC Class Codes: G21K 1/02 using diaphragms, collimators
• CPC Class Codes: G21K 1/10 Scattering devices; Absorbing devices; Ionising radiation filters

Abstract

An investigative X-ray apparatus comprises a source of X-rays emitting a cone beam centred on a beam axis, a collimator to limit the extent of the beam, and a two-dimensional detector, the apparatus being mounted on a support which is rotatable about a rotation axis, the collimator having a first state in which the collimated beam is directed towards the rotation axis and the second state in which the collimated beam is offset from the rotation axis, the two-dimensional detector being movable accordingly, the beam axis being offset from the rotation axis by a lesser amount than the collimated beam in the second state. The X-ray source is no longer directed towards the isocentre as would normally be the case; the X-ray source is not orthogonal to the collimators. This is advantageous in that the entire field of the X-ray tube can be utilised. As a result, a lesser field is required of the X-ray tube and the choice of tube designs and capacities can be widened so as to optimise the performance of the X-ray tube in other aspects.

Claims

1. The investigative X-ray apparatus, comprising a source of X-rays emitting a cone beam centred on a beam axis, a collimator to limit the extent of the beam, and a two-dimensional detector, the apparatus being mounted on a support which is rotatable about a rotation axis, the collimator having a first state in which the collimated beam is directed towards the rotation axis and the second state in which the collimated beam is offset from the rotation axis, the two-dimensional detector being movable accordingly, the beam axis being offset from the rotation axis by a lesser amount than the collimated beam in the second state.

2. The investigative X-ray apparatus according to claim 1 in which the X-ray source is offset such that its natural axis is halfway between the two extremes called for by the collimator.

3. The investigative X-ray apparatus according to claim 2 in which the X-ray source is fixedly located in its offset position.

4. The investigative X-ray apparatus according to claim 3 of the preceding claims, having an isocentre, in which the X-ray source is not directed towards the isocentre.

5. The radiotherapeutic apparatus comprising:

a therapeutic source of high energy radiation; and

an investigative X-ray apparatus according to claim 3.

6. The investigative X-ray apparatus according to claim 2 in which the offset is between 3 and 4°

.

7. The investigative X-ray apparatus according to claim 6 of the preceding claims, having an isocentre, in which the X-ray source is not directed towards the isocentre.

8. The radiotherapeutic apparatus comprising:

a therapeutic source of high energy radiation; and

an investigative X-ray apparatus according to claim 6.

9. The investigative X-ray apparatus according to claim 2 of the preceding claims, having an isocentre, in which the X-ray source is not directed towards the isocentre.

10. The radiotherapeutic apparatus comprising:

a therapeutic source of high energy radiation; and

an investigative X-ray apparatus according to claim 2.

11. The investigative X-ray apparatus according to claim 1 having an isocentre, in which the X-ray source is not directed towards the isocentre.

12. The radiotherapeutic apparatus comprising:

a therapeutic source of high energy radiation; and

an investigative X-ray apparatus according to claim 11.

13. The radiotherapeutic apparatus comprising:

a therapeutic source of high energy radiation; and

an investigative X-ray apparatus according to claim 1.