Determination of the position of a radiographic or radioscopic unit

1. A method for determining the position of a device providing images by X rays with respect to a reference frame as an image of an object is taken, said method comprising the steps of:

determining the position of a target with respect to the device, said target mechanically connected to the object, based on an impression of the target on the image of the object;

determining the position of the target with respect to the reference frame; and

determining the position of the device with respect to the reference frame based on the position of the target with respect to the device, and the position of the target with respect to the reference frame.

2. The method of claim 1 , in which the position of the target with respect to the reference frame is determined from the determination, by a localization system, of the position with respect to the reference frame of a rigid localization body mechanically connected to the target.

3. The method of claim 2 , in which the target is fixed with respect to the rigid body.

4. The method of claim 1 , in which a configuration of the target is determined by a feeler connected to a rigid localization body, the position of the feeler with respect to the reference frame being determined by a localization system.

5. The method of claim 2 , in which the target is connected to the rigid body by an articulated arm.

6. The method of claim 1 , in which the target is removed from the object between an acquisition of a first image and an acquisition of a second image.

7. The method of claim 1 , in which the determination of the position of the target with respect to the device is performed from the determination on the image of the impression of the target, said impression comprising a plurality of characteristic impressions, each of said plurality of characteristic impressions corresponding to a projection on the image of a separate element of the target.

8. The method of any of claims 1 to 7 , wherein the target comprising:

a plurality of elements transparent to X rays;

a second plurality of elements opaque to X rays; and

wherein said first plurality of elements comprises at least three supports transparent to X rays, each support containing said second plurality of elements comprising a plurality of balls opaque to X rays substantially aligned along a determined direction, the determined directions being non coplanar.

9. The method of claim 8 , in which at least two balls of said plurality of balls are of different diameters.

10. The method of claim 8 , wherein said target further comprises a hold means capable of maintaining the at least three supports according to a configuration from among several determined configurations.

11. A system for determining the position of a device providing image by X rays with respect to a reference frame when a radiography of an object is acquired, said system comprising:

a target connected to the object and comprising a plurality of elements opaque to X rays, each of said plurality of opaque elements being capable of providing a characteristic impression on the radiography of the object;

a means for determining the position of the target with respect to the reference frame;

a means for determining the position of the target with respect to the device based on the characteristic impressions of the radiography,

wherein said system is adapted to determine the position of the device with respect to a reference frame based on the position of the target with respect to the reference frame on the position of the target with respect to the device.

12. A method for determining the position of a device providing images by X rays with respect to a reference frame as an image of an object is taken, said method comprising the steps of:

determining the position of a target with respect to said device based on an impression of said target on the image of said object, said target being mechanically connected to the object and including a plurality of elements opaque to X rays which define the impression of the target;

determining the position of said target with respect to the reference frame using a rigid body that is mechanically connected to said target; and

determining the position of the device with respect to the reference frame based on the position of said target with respect to said device, and the position of said target with respect to the reference frame.

13. The method of claim 12 , wherein the target includes a plurality of elements transparent to X rays that includes at least three supports transparent to X rays, each support containing the opaque elements comprising a plurality of balls opaque to X rays, the balls being substantially aligned along a determined direction, the determined directions being non coplanar.

14. The method of claim 13 , in which at least two balls of said plurality of balls are of different diameters.

15. The method of claim 13 , wherein said target further comprises a hold means capable of maintaining the at least three supports according to a configuration from among several determined configurations.