PROCEDURE FOR GENERATING THE DATA FOR THE RECONSTRUCTION OF A VOLUME IN A FLAT OBJECT USING AN X-RAY SYSTEM

Abstract

The present invention relates to a procedure for generating the data for the reconstruction of a volume in a flat object 4 using an X-ray system, which has a tube 1, a detector 3 and an object 4 located between them. According to the invention, a laminography procedure is carried out, which is a combination of an object rotation and a translation, wherein the horizontal and the vertical direction are observed independently of each other, with the result that the resulting trajectory resembles the shape of a cross.

Claims

1. A procedure for generating the data for the reconstruction of a volume in a flat object (4) using an X-ray system, which has three imaging components, namely a tube (1), a detector (3) and an object (4) located between them, wherein the tube (1) has a focus (2), which, in a central position of the tube (1), forms the coordinate origin of a first Cartesian coordinate system, and emits a cone beam (10), the centre ray (14) of which forms the z axis of the first coordinate system and the x axis runs horizontally, wherein, in a central position of the detector (3), the centre ray (14) strikes the detector (3) perpendicularly and this point of impact forms the origin of a second Cartesian coordinate system, the z.sub.d axis of which, in the central position of the detector (3), is identical to the z axis in the central position of the tube (1) and the x.sub.d axis runs horizontally, wherein, in a neutral position (5) of the object (4), the object (4) has a third Cartesian coordinate system, the origin of which is the intersection between the centre ray (14) of the central position of the tube (1) and a vertically running axis of rotation of the object (4), the z.sub.o axis of which, in its neutral position (5), coincides with the centre ray (14) in the central position of the tube (1) and the x.sub.o axis of which, in its neutral position (5), runs parallel to the x axis in the central position of the tube (1), wherein at least two of the three imaging components are movable along their respective y axis, thus the tube (1) along they axis according to its central position, the detector (3) along the y.sub.d axis according to its central position, the object (4) along the y.sub.o axis according to its neutral position (5), wherein the object (4) is movable along the x.sub.o axis according to its neutral position (5) and rotatable about the y.sub.o axis according to its neutral position (5), passing through a vertical trajectory with the following steps: a1) moving at least two of the three imaging components into a configuration in which at least two of the three imaging components are located outside the basic position, the z, z.sub.o and z.sub.d axes run parallel to each other, the x, x.sub.o and x.sub.d axes run parallel to each other and there is a first swivel angle θ.sub.u between a central ray (11) and the z axis in the yz plane, wherein the detector (3) has a y.sub.d1 coordinate and the tube (1) has a y.sub.1 coordinate, wherein a central ray (11) strikes the detector (3) at the origin of the second Cartesian coordinate system; b1) then moving the object (4) along the y.sub.o axis from a first extreme point to a second extreme point, wherein X-ray images, which are stored in a storage medium, are made at predefinable distances along the movement, wherein the first extreme point has a y.sub.o1 coordinate and the second extreme point has a y.sub.o2 coordinate, wherein the object (4) has passed at least partially through the X-ray; c1) then moving at least two of the three imaging components into a configuration in which at least two of the three imaging components are located outside the basic position, the z, z.sub.o and z.sub.d axes run parallel to each other, the x, x.sub.o and x.sub.d axes run parallel to each other and there is a second swivel angle θ.sub.o between a central ray (11) and the z axis in the yz plane, wherein the detector (3) has a y.sub.d2 coordinate and the tube (1) has a y.sub.2 coordinate and the central ray (11) strikes the detector (3) at the origin of the second Cartesian coordinate system and wherein y.sub.2≠y.sub.1 and y.sub.d2≠y.sub.d1; d1) then moving the object (4) along the y.sub.o axis from a third extreme point to a fourth extreme point, wherein X-ray images, which are stored in a storage medium, are made at predefinable distances along the movement, wherein the third extreme point has a y.sub.o3 coordinate and the fourth extreme point has a y.sub.o4 coordinate, wherein the object (4) has passed at least partially through the X-ray; passing through a horizontal trajectory with the following steps: e1) moving the tube (1), the detector (3) and the object (4) into a configuration in which the tube (1) and the detector (3) are located in their respective central position and the object (4) is located in its neutral position (5); f1) then rotating the object (4) out of its neutral position (5) by a first angle of rotation β.sub.l about the y.sub.o axis and moving the object (4) parallel to the x axis of the tube (1) in its central position from a fifth extreme point to a sixth extreme point, wherein X-ray images, which are stored in a storage medium, are made at predefinable distances along the movement, wherein the fifth extreme point has an x.sub.o1 coordinate and the sixth extreme point has an x.sub.o2 coordinate, wherein the object (4) has passed at least partially through the X-ray; g1) then rotating the object (4) by a second angle of rotation β.sub.r, wherein β.sub.r≠β.sub.l, about the y.sub.o axis and moving the object (4) parallel to the x axis of the tube (1) in its central position from a seventh extreme point to an eighth extreme point, wherein X-ray images, which are stored in a storage medium, are made at predefinable distances along the movement, wherein the seventh extreme point has [about] an x.sub.o3 coordinate and the eighth extreme point has an x.sub.o4 coordinate, wherein the object (4) has passed at least partially through the X-ray.

2. The procedure according to claim 1, wherein the object (4) is movable along the z.sub.o axis and the detector (3) is movable along the z.sub.d axis.

3. The procedure according to claim 1, wherein the detector (3) is fully illuminated by the cone beam (10) during the taking of each X-ray image.

4. The procedure according to claim 1, wherein the tube (1) is rotatable about the y axis and/or the tube (1) is rotatable about the x axis and/or the detector (3) is rotatable about the y.sub.d axis and/or the detector (3) is rotatable about the x.sub.d axis.

5. The procedure according to claim 4, wherein the central ray (11) is always perpendicular to the surface of the detector (3).

6. The procedure according to claim 1, wherein the object (4) passes right through the cone beam (10) during each partial trajectory.

7. A procedure for generating the data for the reconstruction of a volume in a flat object (4) using an X-ray system, which has three imaging components, namely a tube (1), a detector (3) and an object (4) located between them, wherein the tube (1) has a focus (2), which, in a central position of the tube (1), forms the coordinate origin of a first Cartesian coordinate system, and emits a cone beam (10), the centre ray (14) of which forms the z axis of the first coordinate system and the x axis runs horizontally, wherein, in a central position of the detector (3), the centre ray (14) strikes the detector (3) perpendicularly and this point of impact forms the origin of a second Cartesian coordinate system, the z.sub.d axis of which, in the central position of the detector (3), is identical to the z axis in the central position of the tube (1) and the x.sub.d axis runs horizontally, wherein, in a neutral position (5) of the object (4), the object (4) has a third Cartesian coordinate system, the origin of which is the intersection between the centre ray (14) of the central position of the tube (1) and a vertically running axis of rotation of the object (4), the z.sub.o axis of which, in its neutral position (5), coincides with the centre ray (14) in the central position of the tube (1) and the x.sub.o axis of which, in its neutral position (5), runs parallel to the x axis in the central position of the tube (1), wherein at least two of the three imaging components are movable along their respective y axis and their respective x axis, thus the tube (1) along the y axis/x axis according to its central position, the detector (3) along the y.sub.d axis/x.sub.d axis according to its central position, the object (4) along the y.sub.o axis/x.sub.o axis according to its neutral position (5), with the following steps: passing through a vertical trajectory with the following steps: a2) moving at least two of the three imaging components into a configuration in which at least two of the three imaging components are located outside the basic position, the z, z.sub.o and z.sub.d axes run parallel to each other, the x, x.sub.o and x.sub.d axes run parallel to each other and there is a first swivel angle θ.sub.u between a central ray and the z axis in the yz plane, wherein the detector (3) has a y.sub.d1 coordinate and the tube (1) has a y.sub.1 coordinate, wherein a central ray (11) strikes the detector (3) at the origin of the second Cartesian coordinate system; b2) then moving the object (4) along the y.sub.o axis from a first extreme point to a second extreme point, wherein X-ray images, which are stored in a storage medium, are made at predefinable distances along the movement, wherein the first extreme point has a y.sub.o1 coordinate and the second extreme point has a y.sub.o2 coordinate, wherein the object (4) has passed at least partially through the X-ray; c2) then moving at least two of the three imaging components into a configuration in which at least two of the three imaging components are located outside the basic position, the z, z.sub.o and z.sub.d axes run parallel to each other, the x, x.sub.o and x.sub.d axes run parallel to each other and there is a second swivel angle θ.sub.o between a central ray and the z axis in the yz plane, wherein the detector (3) has a y.sub.d2 coordinate and the tube (1) has a y.sub.2 coordinate and the central ray (11) strikes the detector (3) at the origin of the second Cartesian coordinate system and wherein y.sub.2≠y.sub.1 and y.sub.d2≠y.sub.d1; d2) then moving the object (4) along the y.sub.o axis from a third extreme point to a fourth extreme point, wherein X-ray images, which are stored in a storage medium, are made at predefinable distances along the movement, wherein the third extreme point has a y.sub.o3 coordinate and the fourth extreme point has a y.sub.o4 coordinate, wherein the object (4) has passed at least partially through the X-ray; passing through a horizontal trajectory with the following steps: e2) moving at least two of the three imaging components into a configuration in which at least two of the three imaging components are located outside the basic position, the z, z.sub.o and z.sub.d axes run parallel to each other, the x, x.sub.o and x.sub.d axes run parallel to each other and there is a first angle of rotation β.sub.l between a central ray (11) and the z axis in the xz plane, wherein the detector (3) has an x.sub.d1 coordinate and the tube (1) has an x.sub.1 coordinate, wherein a central ray (11) strikes the detector (3) at the origin of the second Cartesian coordinate system; f2) then moving the object (4) along the x.sub.o axis from a fifth extreme point to a sixth extreme point, wherein X-ray images, which are stored in a storage medium, are made at predefinable distances along the movement, wherein the fifth extreme point has an x.sub.o1 coordinate and the sixth extreme point has an x.sub.o2 coordinate, wherein the object (4) has passed at least partially through the X-ray; g2) then moving at least two of the three imaging components into a configuration in which at least two of the three imaging components are located outside the basic position, the z, z.sub.o and z.sub.d axes run parallel to each other, the x, x.sub.o and x.sub.d axes run parallel to each other and there is a second angle of rotation β.sub.r between a central ray (11) and the z axis in the xz plane, wherein the detector (3) has an x.sub.d2 coordinate and the tube (1) has an x.sub.2 coordinate and the central ray (11) strikes the detector (3) at the origin of the second Cartesian coordinate system, wherein x.sub.2≠x.sub.1 and x.sub.d2≠x.sub.d1; h2) then moving the object (4) along the x.sub.o axis from a seventh extreme point to an eighth extreme point, wherein X-ray images, which are stored in a storage medium, are made at predefinable distances along the movement, wherein the seventh extreme point has an x.sub.o3 coordinate and the eighth extreme point has an x.sub.o4 coordinate, wherein the object (4) has passed at least partially through the X-ray.

8. The procedure according to claim 7, wherein the object (4) is movable along the z.sub.o axis and the detector (3) is movable along the z.sub.d axis.

9. The procedure according to claim 7, wherein the detector (3) is fully illuminated by the cone beam (10) during the taking of each X-ray image.

10. The procedure according to claim 7, wherein the tube (1) is rotatable about the y axis and/or the tube (1) is rotatable about the x axis and/or the detector (3) is rotatable about the y.sub.d axis and/or the detector (3) is rotatable about the x.sub.d axis.

11. The procedure according to claim 10, wherein the central ray (11) is always perpendicular to the surface of the detector (3).

12. The procedure according to claim 7, wherein the object (4) passes right through the cone beam (10) during each partial trajectory.

13. A procedure for generating the data for the reconstruction of a volume in a flat object (4) using an X-ray system, which has a tube (1), a detector (3) and an object (4) located between them, wherein the tube (1) has a focus (2), which, in a central position of the tube (1), forms the coordinate origin of a first Cartesian coordinate system, and emits a cone beam (10), the centre ray (14) of which forms the z axis of the first coordinate system and the x axis runs horizontally, wherein, in a central position of the detector (3), the centre ray (14) strikes the detector (3) perpendicularly and this point of impact forms the origin of a second Cartesian coordinate system, the z.sub.d axis of which, in the central position of the detector (3), is identical to the z axis in the central position of the tube (1) and the x.sub.d axis runs horizontally, wherein, in a neutral position (5) of the object (4), the object (4) has a third Cartesian coordinate system, the origin of which is the intersection between the centre ray (14) of the central position of the tube (1) and a vertically running axis of rotation of the object (4), the z.sub.o axis of which, in its neutral position (5), coincides with the centre ray (14) in the central position of the tube (1) and the x.sub.o axis of which, in its neutral position (5), runs parallel to the x axis in the central position of the tube (1), wherein the tube (1) is movable along they axis according to its central position, wherein at least two of the three imaging components are movable along their respective x axis, thus the tube (1) along the x axis according to its central position, the detector (3) along the x.sub.d axis according to its central position, the object (4) along the x.sub.o axis according to its neutral position (5), wherein the object (4) is movable about the y.sub.o axis according to its neutral position (5) and rotatable along the x.sub.o axis in each case according to its neutral position (5), with the following steps: passing through a vertical trajectory with the following steps: a3) moving the three imaging components into the basic position, in which the z, z.sub.o and z.sub.d axes coincide and the x, x.sub.o and x.sub.d axes run parallel to each other, and rotating the object (4) by a first swivel angle θ.sub.u about the x.sub.o axis; b3) then moving the object (4) along the y.sub.o axis from a first extreme point to a second extreme point, wherein X-ray images, which are stored in a storage medium, are made at predefinable distances along the movement, wherein the first extreme point has a y.sub.o1 coordinate and the second extreme point has a y.sub.o2 coordinate, wherein the object (4) has passed at least partially through the X-ray; c3) then rotating the object (4) by a second swivel angle θ.sub.o, which differs from the first swivel angle θ.sub.u, about the x.sub.o axis; d3) then moving the object (4) along the y.sub.o axis from a third extreme point to a fourth extreme point, wherein X-ray images, which are stored in a storage medium, are made at predefinable distances along the movement, wherein the third extreme point has a y.sub.o3 coordinate and the fourth extreme point has a y.sub.o4 coordinate, wherein the object (4) has passed at least partially through the X-ray; passing through a horizontal trajectory with the following steps: e3) moving at least two of the three imaging components into a configuration in which at least two of the three imaging components are located outside the basic position, the z, z.sub.o and z.sub.d axes run parallel to each other, the x, x.sub.o and x.sub.d axes run parallel to each other and there is a first angle of rotation β.sub.l between a central ray (11) and the z axis in the xz plane, wherein the detector (3) has an x.sub.d1 coordinate and the tube (1) has an x.sub.1 coordinate, wherein a central ray (11) strikes the detector (3) at the origin of the second Cartesian coordinate system; f3) then moving the object (4) along the x.sub.o axis from a fifth extreme point to a sixth extreme point, wherein X-ray images, which are stored in a storage medium, are made at predefinable distances along the movement, wherein the fifth extreme point has an x.sub.o1 coordinate and the sixth extreme point has an x.sub.o2 coordinate, wherein the object (4) has passed at least partially through the X-ray; g3) then moving at least two of the three imaging components into a configuration in which at least two of the three imaging components are located outside the basic position, the z, z.sub.o and z.sub.d axes run parallel to each other, the x, x.sub.o and x.sub.d axes run parallel to each other and there is a second angle of rotation β.sub.r between a central ray (11) and the z axis in the xz plane, wherein the detector (3) has an x.sub.d2 coordinate and the tube (1) has an x.sub.2 coordinate and the central ray (11) strikes the detector (3) at the origin of the second Cartesian coordinate system, wherein x.sub.2≠x.sub.1 and x.sub.d2≠x.sub.d1; h3) then moving the object (4) along the x.sub.o axis from a seventh extreme point to an eighth extreme point, wherein X-ray images, which are stored in a storage medium, are made at predefinable distances along the movement, wherein the seventh extreme point has an x.sub.o3 coordinate and the eighth extreme point has an x.sub.o4 coordinate, wherein the object (4) has passed at least partially through the X-ray.

14. The procedure according to claim 13, wherein the object (4) is movable along the z.sub.o axis and the detector (3) is movable along the z.sub.d axis.

15. The procedure according to claim 13, wherein the detector (3) is fully illuminated by the cone beam (10) during the taking of each X-ray image.

16. The procedure according to claim 13, wherein the tube (1) is rotatable about the y axis and/or the tube (1) is rotatable about the x axis and/or the detector (3) is rotatable about the y.sub.d axis and/or the detector (3) is rotatable about the x.sub.d axis.

17. The procedure according to claim 16, wherein the central ray (11) is always perpendicular to the surface of the detector (3).

18. The procedure according to claim 13, wherein the object (4) passes right through the cone beam (10) during each partial trajectory.

19. A procedure for generating the data for the reconstruction of a volume in a flat object (4) using an X-ray system, which has a tube (1), a detector (3) and an object (4) located between them, wherein the tube (1) has a focus (2), which, in a central position of the tube (1), forms the coordinate origin of a first Cartesian coordinate system, and emits a cone beam (10), the centre ray (14) of which forms the z axis of the first coordinate system and the x axis runs horizontally, wherein, in a central position of the detector (3), the centre ray (14) strikes the detector (3) perpendicularly and this point of impact forms the origin of a second Cartesian coordinate system, the z.sub.d axis of which, in the central position of the detector (3), is identical to the z axis in the central position of the tube (1) and the x.sub.d axis runs horizontally, wherein, in a neutral position (5) of the object (4), the object (4) has a third Cartesian coordinate system, the origin of which is the intersection between the centre ray of the central position of the tube (1) and a vertically running axis of rotation of the object (4), the z.sub.o axis of which, in its neutral position, coincides with the centre ray (14) in the central position of the tube (1) and the x.sub.o axis of which, in its neutral position (5), runs parallel to the x axis in the central position of the tube (1), wherein the object (4) is movable along the x.sub.o axis and the y.sub.o axis in each case according to its neutral position (5), rotatable about the x.sub.o axis and the y.sub.o axis in each case according to its neutral position (5), with the following steps: passing through a vertical trajectory with the following steps: a4) moving the three imaging components into the basic position, in which the z, z.sub.o and z.sub.d axes coincide and the x, x.sub.o and x.sub.d axes run parallel to each other, and rotating the object (4) by a first swivel angle θ.sub.u about the x.sub.o axis; b4) then moving the object (4) along the y.sub.o axis from a first extreme point to a second extreme point, wherein X-ray images, which are stored in a storage medium, are made at predefinable distances along the movement, wherein the first extreme point has a y.sub.o1 coordinate and the second extreme point has a y.sub.o2 coordinate, wherein the object (4) has passed at least partially through the X-ray; c4) then rotating the object (4) by a second swivel angle Go, which differs from the first swivel angle θ.sub.u, about the x.sub.o axis; d4) then moving the object (4) along the y.sub.o axis from a third extreme point to a fourth extreme point, wherein X-ray images, which are stored in a storage medium, are made at predefinable distances along the movement, wherein the third extreme point has a y.sub.o3 coordinate and the fourth extreme point has a y.sub.o4 coordinate, wherein the object (4) has passed at least partially through the X-ray; passing through a horizontal trajectory with the following steps: e4) moving the tube (1), the detector (3) and the object (4) into a configuration in which the tube (1) and the detector (3) are located in their respective central position and the object (4) is located in its neutral position (5); f4) then rotating the object (4) out of its neutral position (5) by a first angle of rotation β.sub.l about the y.sub.o axis and moving the object (4) parallel to the x axis of the tube (1) in its central position from a fifth extreme point to a sixth extreme point, wherein X-ray images, which are stored in a storage medium, are made at predefinable distances along the movement, wherein the fifth extreme point has an x.sub.o1 coordinate and the sixth extreme point has an x.sub.o2 coordinate, wherein the object (4) has passed at least partially through the X-ray; g4) then rotating the object (4) by a second angle of rotation β.sub.r, wherein β.sub.r≠β.sub.l, about the y.sub.o axis and moving the object (4) parallel to the x axis of the tube (1) in its central position from a seventh extreme point to an eighth extreme point, wherein X-ray images, which are stored in a storage medium, are made at predefinable distances along the movement, wherein the seventh extreme point has [about] an x.sub.o3 coordinate and the eighth extreme point has an x.sub.o4 coordinate, wherein the object (4) has passed at least partially through the X-ray.

20. The procedure according to claim 19, wherein the object (4) is movable along the z.sub.o axis and the detector (3) is movable along the z.sub.d axis.

21. The procedure according to claim 19, wherein the detector (3) is fully illuminated by the cone beam (10) during the taking of each X-ray image.

22. The procedure according to claim 19, wherein the tube (1) is rotatable about the y axis and/or the tube (1) is rotatable about the x axis and/or the detector (3) is rotatable about the y.sub.d axis and/or the detector (3) is rotatable about the x.sub.d axis.

23. The procedure according to claim 22, wherein the central ray (11) is always perpendicular to the surface of the detector (3).

24. The procedure according to claim 19, wherein the object (4) passes right through the cone beam (10) during each partial trajectory.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Further details and advantages of the invention are now explained in more detail with reference to embodiment examples represented in the drawings. There are shown in:

[0025] FIG. 1 schematic representation of the system geometry of an X-ray system with a representation of the possible axes of translation and rotation;

[0026] FIG. 2A a schematic representation of a first alternative of a vertical trajectory;

[0027] FIG. 2B the representation of the two configurations divided in two parts which are still represented together in FIG. 2a;

[0028] FIG. 2C a representation of the courses of the marginal rays during the recordings in the object in the case of the vertical trajectory;

[0029] FIG. 3A a schematic representation of a first alternative of a horizontal trajectory;

[0030] FIG. 3B the representation of the two configurations divided in two parts which are still represented together in FIG. 3a;

[0031] FIG. 3C a representation of the courses of a marginal ray and a further ray during the recordings in the object in the case of the horizontal trajectory;

[0032] FIG. 4 transverse layer of a printed circuit board in the case of translation only, rotation only and in the case of a combination of translation and rotation;

[0033] FIG. 5 horizontal layer of the printed circuit board from FIG. 4 in the case of translation only, rotation only and in the case of a combination of translation and rotation.

DETAILED DESCRIPTION

[0034] The system geometry of an X-ray system, which has a tube 1, an object 4 and a detector 3, is represented schematically in FIG. 1, wherein the respective possible axes of translation and rotation thereof are represented. In the following, only the translational and rotational axes important for the invention are explained, the other axes, which are also represented in FIG. 1, are not described. The rotational axes have an index r and, in the case of the translational axes, no index is present as indication of the translation.

[0035] Starting from its focus 2, the tube 1 defines a first Cartesian coordinate system, wherein the centre ray 14 of the emitted cone beam 10 of the X-radiation forms the z axis. The vertical direction is the y axis and the remaining horizontal direction (in addition to the likewise horizontally running z axis) is the x axis. The y axis can be formed not only as a translational axis but also as an axis of rotation; then the cone beam 10 could be repositioned if there is a very slanted geometry in which the detector 3 would be outside the cone beam 10 in the case of a non-rotated tube 1. However, as rotation is not used for the described embodiment examples of the invention, a representation of this axis was omitted. With regard to the embodiment examples of the invention, the represented position of the tube 1 is referred to as central position.

[0036] The detector 3 is a flat panel detector; in FIG. 1 it is formed square, wherein this is not limitative. The centre ray 14 of the tube 1 strikes the detector 3 centrally, as a result of which the origin of a second Cartesian coordinate system is defined. The axes of this detector coordinate system have the index d. The z.sub.d axis runs perpendicularly on its surface in the horizontal direction, and identically to the z axis of the tube 1. The vertical direction, which extends in the detector 3, is also the y.sub.d axis here and the horizontal direction extending in the detector 3 is the x.sub.d axis. With regard to the embodiment examples of the invention, the represented position of the detector 3 is referred to as central position.

[0037] The object 4, the axes of which have the index o, is located between tube 1 and detector 3. With regard to the embodiment examples of the invention, the represented position of the object 4 is referred to as neutral position 5, in which no rotation (and also no translation) has taken place. A third Cartesian coordinate system is assigned to the object 4, the origin of which lies at a point which lies on the centre ray of the tube 1—thus the z axis. In the neutral position 5 of the object 4, the z.sub.o axis extends along the z axis in the horizontal direction. The y.sub.o axis runs in the vertical direction and, in the represented neutral position 5 of the object 4, the x.sub.o axis runs parallel to the y.sub.d axis of the detector 3 in the horizontal direction. In addition to the three translational axes, the object 4 also has two rotational axes. Both the x.sub.o axis and the y.sub.o axis are also axes of rotation, thus the x.sub.ro axis and the y.sub.ro axis—wherein these axes can also be replaced by an equivalent movement of the tube 1 and the detector 3.

[0038] In FIG. 1, the distances of the y.sub.o axis from the focus 2 (FOD) and of the detector 3 from the focus 2 along the centre ray 14 (FDD) are also represented, on the basis of which the magnification M of the represented geometry can be determined; as already indicated above, it equals FDD/FOD.

[0039] For a person skilled in the art, it goes without saying that the orientation of the axes in FIG. 1 is not limitative, but that the invention also comprises all other orientations, thus for example if the z axis runs vertically or the whole system is tilted by a (desired) angle about the x axis and/or one of the other two axes (y axis and z axis).

[0040] The X-ray system additionally has a storage device, in which the data of the individual X-ray images are stored, and a processing device, in which the reconstruction of the object 4 using the above-named data is effected, together with a representation device connected thereto, such as for example a monitor, on which the reconstruction can be viewed. The components tube 1, object 4 and detector 3 are arranged in a radiation protection cabin so that the X-radiation used does not result in any damage to the health of any people located in the vicinity. The above-named components and their design, their cooperation and their arrangement are well known to a person skilled in the art, with the result that further statements in relation to this can be omitted.

[0041] For the trajectories according to the invention described in FIGS. 2 and 3, an X-ray system is required in which the tube 1 can carry out a y translation (y axis), the detector 3 can carry out both a y translation (y.sub.d axis) and a z translation (z.sub.d axis), which is necessary for adjusting the magnification, and the object 4, in addition to a translation along each of its three axes (x.sub.o, y.sub.o and z.sub.o axis) can also carry out a rotation both about the x.sub.o axis (the name of which is thus x.sub.ro axis—wherein this axis can also be replaced by an equivalent translation of the tube 1/of the object 4 and of the detector 3) and about the y.sub.o axis (the name of which is thus y.sub.ro axis—wherein this axis can also be replaced by an equivalent translation of the tube 1/of the object 4 and of the detector 3).

[0042] FIGS. 2a and 2b are side views—thus effectively a view in the x direction—onto the schematically represented three components of the X-ray system, tube 1, object 4 and detector 3. The vertical trajectory is described with reference to these figs., wherein the difference between the two figs. is that the two relevant positions are represented still together in FIG. 2a and the two positions are represented separately from one another in FIG. 2b. The view corresponds in each case to the yz plane.

[0043] The tube 1 emits a cone beam, which has a half opening angle cp and illuminates the whole detector 3 along the y.sub.d axis. This whole illumination is present both when the detector 3 is at its upper extreme point and at its lower extreme point. The two extreme points of the detector 3 lie on the y.sub.d axis, removed by y.sub.d1 or y.sub.d2, respectively, wherein, in the represented embodiment example, they are opposing and equal, with the result that there is a symmetrical design about the z axis. At the same time, the tube 1 has been moved either to its lower extreme point or to its upper extreme point. In the case of the two extreme points of the detector 3, the coordinate origins of the first Cartesian coordinate system lie on the y axis, removed by a second distance y.sub.1 or by a sixth distance y.sub.2, respectively—relative to the y axis in the central position of the tube 1, wherein they are opposing and equal, with the result that there is a symmetrical design about the z axis. The distances y.sub.d1 and y.sub.1 or y.sub.d2 and y.sub.2, respectively are matched to each other depending on the magnification M (FDD/FOD). The axis of the central ray 11 of the cone beam 10 is inclined relative to the z axis by the angle of inclination θ or −θ, respectively. There are the following values in the embodiment example: FDD=1200 mm, FOD=500 mm, y.sub.d1=+547 mm, y.sub.d2=−547 mm, y.sub.1=−391 mm, y.sub.2=+391 mm, θ=38°, θ.sub.1=8°, θ′=46°.

[0044] FIG. 2b shows the translation of the object 4 well. The object 4 is moved once right through the cone beam 10 along the y.sub.o axis in the configuration in which the tube 1 is at its lower extreme point and the detector 3 is at its upper extreme point (left-hand part of FIG. 2b) and once in the mirror-inverted arrangement, thus when the tube 1 is at its upper extreme point and the detector 3 is at its lower extreme point. The extreme points, together with their distances, correspond to those according to FIG. 2a. Along the translation—in which it does not matter whether it is effected from top to bottom or from bottom to top—X-ray images are made at predefinable distances of ˜10 mm per movement of the object 4 through the cone beam 50 (thus 100 X-ray images for the whole vertical trajectory 100).

[0045] In FIG. 2c, the patterns for the two marginal rays 13 which are formed during the translation of the object 4 according to the situation shown on the left in FIG. 2b are represented. The angle between these patterns in the object 4 and the z.sub.o axis is θ′ and, for the upper marginal ray 13 according to the left-hand situation in FIG. 2b, is the sum of the above-indicated angle of inclination θ and the upper partial opening angle θ.sub.1 of the cone beam 10—this is represented in the left-hand part of FIG. 2c. The representation of the right-hand part of FIG. 2c is the corresponding pattern for the lower marginal ray 13 according to the left-hand configuration in FIG. 2b. Here, the resultant angle is the difference between 0 and the lower partial opening angle θ.sub.2. The two partial opening angles θ.sub.1 and θ.sub.2 depend on the geometry of the X-ray system, in particular on FOD, FDD and θ. For the situation according to the right-hand situation in FIG. 2b, the result is the mirror-inverted situation for the patterns as represented in FIG. 2c. Since—as stated above—θ′ is 8° bigger than θ, the laminographic angle for the vertical trajectory is 46°, which results in a higher depth resolution.

[0046] In addition to the design of the vertical trajectory, which was described with reference to FIG. 2, a horizontal trajectory is also provided according to the invention and is explained in the following with reference to FIG. 3.

[0047] FIGS. 3a and 3b are top views—thus effectively a view in the y direction—onto the schematically represented three components of the X-ray system, tube 1, object 4 and detector 3. The horizontal trajectory is described with reference to these figs., wherein the two situations for carrying out the translational movements still represented together in FIG. 3a are represented separately in FIG. 3b. The view corresponds to the xz plane.

[0048] While passing through the horizontal trajectory, there is always a beam geometry, as was described above for translational laminography and in FIG. 1, with a half opening angle φ, wherein the whole detector 3 is continuously illuminated along the x.sub.d axis.

[0049] The object 4 is rotated out of the neutral position by a first angle of rotation β.sub.l about the y.sub.o axis (left-hand side of FIG. 3b). On the right-hand side of FIG. 3b, the object 4 is rotated in the opposite direction by a second angle of rotation β.sub.r (starting from the neutral position of the object 4). In the represented case, these two angles of rotation are the same size in absolute terms (15°) but directed in opposite directions. As a result, a larger laminographic angle is obtained, which corresponds to the sum of the half opening angle φ and the first/second angle of rotation β.sub.l/β.sub.r. This makes a larger depth resolution possible.

[0050] The translation along the x.sub.o axis can be clearly seen in FIG. 3b. The object 4 is moved right through the cone beam 10 parallel to the x axis, once in the configuration in which the object 4 was rotated by the first angle of rotation β.sub.l out of the neutral position 5 of the object 4 (left-hand representation in FIG. 3b) and once in the mirror-inverted arrangement, thus when the object 4 was rotated by the second angle of rotation β.sub.r out of the neutral position 5 of the object 4 (right-hand representation in FIG. 3b). In the translations, 50 X-ray images are made at predefinable distances—which are the same in the embodiment example as in the case of the vertical trajectory—along the movement direction at a distance of ˜10 mm per movement of the object through the cone beam. The movement direction —whether in the positive or negative x direction—is irrelevant; the necessary X-ray images can thus be made for example in a movement back and forth.

[0051] In FIG. 3c, the patterns of the upper marginal ray 13 in FIG. 3b and of the further ray 12, which is located inside the cone beam 10 and in this fig. is represented below the central ray 11, are represented. The angle between these patterns in the object 4 and the z axis is φ+β.sub.l for the upper marginal ray 13 according to the right-hand situation in FIG. 3b. This is represented in the left-hand part of FIG. 3c. The representation of the right-hand part of FIG. 3c is the corresponding pattern for the ray represented continuous and running slightly below the centre ray 13 in the left-hand part of FIG. 3b. The resultant angle for the left-hand part of FIG. 3c is 30°. A larger laminographic angle, which corresponds to the sum of φ and the first/second angle of rotation β.sub.1/β.sub.r, is thus obtained compared to translational laminography, in which the laminographic angle is determined by the half opening angle φ (here 15°). This makes a larger depth resolution possible.

[0052] Volume data are then generated from the projections with the aid of a suitable reconstruction procedure known to a person skilled in the art.

[0053] FIG. 4 shows an exemplary transverse layer (side view)—corresponding to the procedure according to FIG. 2—of a printed circuit board—which here is the object 4, which was recorded with three different laminography procedures. The structures shown (they are BGAs), should appear round from this direction. However, the reduced depth resolution of laminography procedures compared to CT scans results in blurring of the structures, which is more strongly pronounced in the case of small laminographic angles. The result of translational laminography (horizontal and vertical) is shown on the left-hand side. Here, the depth resolution is limited by the opening angle of the X-ray (˜20°). In the middle, the result of a combination of linear (vertical) and swing laminography (horizontal) can be seen, in which a better depth resolution is made possible due to the large possible angle ranges in this case (vertical: ˜20°, horizontal: ˜55°). The right-hand side shows the result in the case of a procedure according to the invention. In this case, the best depth resolution can be achieved due to the largest resultant laminographic angle ranges (vertical: ˜40°, horizontal: ˜75°). The above-mentioned actual circular shape of the structures is most closely achieved by the combination of translation and rotation.

[0054] FIG. 5 shows an exemplary reconstructed lateral layer—corresponding to the procedure according to FIG. 3—of the printed circuit board from FIG. 4 recorded with the same laminography procedures as shown in FIG. 4. Here too, the different depth resolutions of the different methods can be clearly seen, as only the ring-shaped structures in this layer should be able to be seen, while the blurred structures of the round BGAs lying in other layers become less visible the larger the laminographic angle becomes (from left to right). In addition, a possible disadvantage of linear laminography can be seen here, which can arise in the case of asymmetrical angles (in the case of corresponding angle ranges this should also be visible in the case of swing laminography). The smaller of the two angles (˜5° compared with ˜15° in the other direction) in combination with the opening angle of the X-ray results in the ring structures not being radiographed perpendicularly in all areas of the image, with the result that they cannot be correctly resolved. This can be seen in the upper area in the middle image. The translation of the object 4 in the other two methods prevents this artefact from arising.

[0055] In summary it can be said that, in the invention—in order to increase the angle range for the laminography—the two trajectories are combined in a suitable manner, with the result that the object 4 is translated in the rotated state through the field of view both in the horizontal and in the vertical direction (wherein, in the vertical direction, the object rotation can also be realized through a simultaneous displacement of tube 1 and detector 3—when the corresponding axes are present, this can also happen in the horizontal direction). A laminography procedure is carried out, which is a combination of an object rotation and a translation, wherein the horizontal and the vertical direction are observed independently of each other, with the result that the resulting trajectory resembles the shape of a cross.

[0056] In order to increase the angle range for the laminography, in the present invention the two trajectories (the vertical and the horizontal) are combined in a suitable manner, with the result that the object 4 is moved in the rotated state through the field of view both in the horizontal and in the vertical direction. In the process, in each case only the maximum possible angles in the four spatial directions (top, bottom, left, right) are approached, with the result that in the simplest case the object 4 is moved through the field of view twice, both in the vertical and in the horizontal direction. It is not absolutely necessary for the maximum possible angles in each case to be symmetrical in the horizontal and vertical directions, respectively. If the achievable angle range is larger than the opening angle of the cone beam 10, intermediate angles are also approached in addition to the maximum angles and the number of translations through the field of view is correspondingly increased.

LIST OF REFERENCE NUMBERS

[0057] 1 (X-ray) tube [0058] 2 focus [0059] 3 (X-ray) detector [0060] 4 object [0061] 5 neutral position [0062] 10 cone beam [0063] 11 central ray [0064] 12 further ray [0065] 13 marginal ray [0066] 14 centre ray