Computed tomogrophy scanning

• US 20040218719A1
• Filed: 01/20/2004
• Published: 11/04/2004
• Est. Priority Date: 01/21/2003
• Status: Abandoned Application

• Current Assignee: Elekta AB
• Original Assignee: Elekta AB
• Inventors: Brown, Kevin John, Jaffray, David, Siewerdsen, Jeffrey H., van Herk, Marcel, Sonke, Jan-Jakob
• Application Number:
  US10/760,627
• Publication Number:
  US 20040218719A1
• Time in Patent Office: Days
• US Class Current: 378/95
• CPC Class Codes: A61N 5/1064 for adjusting radiation treatment in response to monitoring
• CPC Class Codes: G06T 11/005 Specific pre-processing for tomographic reconstruction, e.g. calibration, source positioning, rebinning, scatter correction, retrospective gating
• CPC Class Codes: G06T 2207/10081 Computed x-ray tomography [CT]
• CPC Class Codes: G06T 2207/20068 Projection on vertical or horizontal image axis
• CPC Class Codes: G06T 2207/20192 Edge enhancement; Edge preservation
• CPC Class Codes: G06T 2207/30061 Lung
• CPC Class Codes: G06T 2207/30096 Tumor; Lesion
• CPC Class Codes: G06T 2211/412 Dynamic
• CPC Class Codes: G06T 5/003 Deblurring; Sharpening vibration or motion blur correction for cameras comprising an electronic image sensor H04N23/682
• CPC Class Codes: G06T 5/009 Global, i.e. based on properties of the image as a whole applied in cameras using an electronic image sensor H04N23/80, H04N23/70
• CPC Class Codes: G06T 5/73 Deblurring; Sharpening
• CPC Class Codes: G06T 5/92 based on global image properties
• CPC Class Codes: G06T 7/0016 involving temporal comparison
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51

Abstract

Artefacts in the reconstructed volume data of cone beam CT systems can be removed by the application of respiration correlation techniques to the acquired projection images. To achieve this, the phase of the patients breathing is monitored while acquiring projection images continuously. On completion of the acquisition, projection images that have comparable breathing phases can be selected from the complete set, and these are used to reconstruct the volume data using similar techniques to those of conventional CT. Any phase can be selected and therefore the effect of breathing can be studied. It is also possible to use a feature in the projection image(s) such as the patient'"'"'s diaphragm to determine the breathing phase. This feature in the projection images can be used to control delivery of therapeutic radiation dependent on the: patient'"'"'s breathing cycle, to ensure that the tumour is in the correct position when the radiation is delivered.

Claims

1. A method of cone beam CT scanning in which respiration correlation techniques are applied to the acquired two-dimensional projection images.

2. A method of cone beam CT scanning according to claim 1 in which the phase of the patient'"'"'s breathing is monitored continuously during acquisition of projection images.

3. A method of cone beam CT scanning according to claim 2 in which projection images that have comparable breathing phases are selected from the complete data set on completion of the acquisition and are used to reconstruct the volume data.

4. A method of cone beam CT scanning according to claim 2 in which a feature in the projection image(s) is used to determine the breathing phase.

5. A method of cone beam CT scanning according to claim 4 in which the feature is the position of the patient'"'"'s diaphragm.

6. A method of cone beam CT scanning according to claim 1 in which visual and/or audible prompts are provided for the patient'"'"'s breathing.

7. A method of cone beam CT scanning according to claim 1 in which therapeutic radiation is delivered during the scan at times correlated with the patient'"'"'s breathing cycle.

13. A cone beam CT scanner according to claim 7 including means to provide visual and/or audible prompts for the patient'"'"'s breathing.

8. A cone beam CT scanner including means for acquiring information as to the patient respiration cycle and means for selection of acquired two-dimensional projection images from the set of data acquired during a scan on the basis of the respiration cycle information.

9. A cone beam CT scanner according to claim 8 adapted to monitor the phase of the patient'"'"'s breathing continuously during acquisition of projection images.

10. A cone beam CT scanner according to claim 9 arranged to select projection images that have comparable breathing phases from the complete data set on completion of the acquisition and to use these to reconstruct the volume data.

11. A cone beam CT scanner according to claim 9 including means for detecting a respiration-cycle-correlated feature in the projection image(s) thereby to determine the breathing phase.

12. A cone beam CT scanner according to claim 11 in which the feature is the position of the patient'"'"'s diaphragm.

14. A radiotherapy device comprising a cone beam CT scanner and a source of therapeutic radiation, in which the CT scanner applies respiration correlation techniques to the acquired two-dimensional projection images and therapeutic radiation is delivered during the scan at times correlated with the patient'"'"'s breathing cycle.