Artefact elimination for a medical pelvic registration using a tracked pelvic support known to the system

1. A method for registering a patient's body part in a medical workspace of a medical navigation system, wherein said body part is supported by at least one support device, comprising:

obtaining at least two x-ray or fluoroscopic recordings of the body part, wherein the at least one support device is situated in a radiation path of an x-ray or fluoroscopic recording apparatus during recordation of the at least two x-ray or fluoroscopic recordings;

using the medical navigation system to ascertain a position of the at least one support device and of the x-ray or fluoroscopic apparatus during recordation of the at least two x-ray or fluoroscopic recordings;

using the ascertained position of the at least one support device and the x-ray or fluoroscopic apparatus to identify an image of the at least one support device in the at least two x-ray or fluoroscopic recordings;

using the at least two recordings to register the body part in the medical workspace, wherein image data corresponding to the image of the at least one support device are not used to register the body part.

2. The method according to claim 1 , wherein ascertaining a position of the at least one support device includes:

attaching a reference device to the at least one support device; and

using the navigation system to track a position of the reference device.

3. The method according to claim 1 , wherein ascertaining a position of the at least one support device includes using known geometric data of the at least one support device to ascertain said position.

4. The method according to claim 3 , wherein using known geometric data includes retrieving geometric data of the at least one support device from memory of the medical navigation system.

5. The method according to claim 1 , wherein using the at least two recordings to register the body part includes subtracting the image data of the of the at least one support device from the at least two recordings.

6. The method according to claim 1 , wherein image data corresponding to the image of the at least one support device includes image contours of the at least one support device.

7. The method according to claim 1 , wherein identifying the image of the at least one support device includes using known grey values generated in the at least two recordings as an aid for identifying the image of the at least one support device.

8. The method according to claim 1 , wherein identifying the image of the at least one support device includes using known distances between support elements of the at least one support device as an identification aid.

9. The method according to claim 1 , wherein identifying the image of the at least one support device includes using known distances between support elements of the at least one support device and markers attached to the support device as identification aids.

10. The method according to claim 1 , wherein identifying the image of the at least one support device includes using known distances between support elements of the at least one support device and connecting lines of specific markers in or on the support as identification aids.

11. A system for registering a patient's body part in a medical workspace of a medical navigation system, wherein said body part is supported by at least one support device, comprising:

a medical navigation system including a processor and memory;

a reference device coupled to said at least one support device;

a tracking device communicatively coupled to said medical navigation system and operative to determine a position of said reference device;

an x-ray or fluoroscopic apparatus for capturing x-ray or fluoroscopic images of the body part; and

logic stored in said memory and executable by said processor, said logic including logic that eliminates an effect of image artefacts on registration of the body part, wherein said artefacts are caused by said at least one support device.

12. The system according to claim 11 , wherein said logic that eliminates the effect of image artefacts includes:

logic that ascertains a position of the at least one support device and of the x-ray or fluoroscopic apparatus during image capture;

logic that uses the ascertained position of the at least one support device and of the x-ray or fluoroscopic apparatus to identify an image of the at least one support device in the captured image; and

logic that prior to registration removes the image data corresponding to the at least one support device from the captured image data.

13. The system according to claim 11 , wherein geometric data of the at least one support device are stored in said memory.

14. The system according to claim 11 , wherein the at least one support device consists of a material that is permeable to x-ray radiation.

15. The system according to claim 12 , further comprising at least one marker arranged on the at least one support device at known locations relative to support elements of the at least one support device, said at least one marker comprising a material that is substantially impermeable to x-ray radiation.

16. A computer program stored on a machine readable medium for registering a patient's pelvis in a medical workspace of a medical navigation system, wherein said pelvis is supported by at least one support device, comprising:

code that directs the acquisition of at least two x-ray or fluoroscopic recordings of the body part, wherein the at least one support device is situated in a radiation path of an x-ray or fluoroscopic recording apparatus during recordation of the at least two x-ray or fluoroscopic recordings;

code that ascertains a position of the at least one support device and of the x-ray or fluoroscopic apparatus during recordation of the at least two x-ray or fluoroscopic recordings;

code that uses the ascertained position of the at least one support device and the x-ray or fluoroscopic apparatus to identify an image of the at least one support device in the at least two x-ray or fluoroscopic recordings;

code that uses the at least two recordings to register the body part in the medical workspace, wherein image data corresponding to the image of the at least one support device are not used to register the body part.