Target and X-ray generating tube including the same, X-ray generating apparatus, X-ray imaging system

1. A target comprising;

a target layer configured to be irradiated with an electron to generate an X-ray, and

a support substrate configured to support the target layer, wherein the support substrate is a polyhedron containing a polycrystalline diamond and including multiple structure planes each of which has a normal line from one another, and

wherein the target layer is supported by the support substrate at a structure plane with a smaller area density of a monocrystalline domain showing a {101} plane than each of an area density of a monocrystalline domain showing a {100} plane and an area density of a monocrystalline domain showing a {111} plane.

2. The target according to claim 1 , wherein the support substrate is a free-standing polycrystalline diamond formed by growing a crystal of polycrystalline diamond on a seed crystal substrate by chemical vapor deposition and then removing the seed crystal substrate, and the structure plane supporting the target layer is a plane on a side of the support substrate from which the seed crystal substrate has been removed.

3. The target according to claim 1 , wherein the target layer contains a target metal selected at least from tungsten, tantalum, and molybdenum.

4. The target according to claim 3 , wherein the target layer contains a carbide of the target metal.

5. The target according to claim 1 , wherein the target is a transmissive target in which an X-ray generated at the target layer is released from a structure plane of the support substrate that is on an opposite side from the structure plane supporting the target layer.

6. An anode comprising:

the target according to claim 1 ; and

an anode member electrically connected to the target layer.

7. The anode according to claim 6 , wherein the anode member includes an opening and is connected to a periphery of the support substrate in the opening.

8. An X-ray generating tube comprising:

the anode according to claim 6 ;

a cathode including an electron emission source configured to irradiate the target layer with an electron beam flux; and

an insulation tube connected to the anode and the cathode at opposite ends in a tube axis direction.

9. An X-ray generating apparatus comprising:

the X-ray generating tube according to claim 8 ; and

a tube voltage circuit configured to apply tube voltage across the anode and the cathode.

10. An X-ray imaging system comprising:

the X-ray generating apparatus according to claim 9 ; and

an X-ray detection unit configured to detect an X-ray emitted from the X-ray generating apparatus and having passed through a subject.

11. A target comprising a target layer configured to be irradiated with an electron to generate an X-ray and a support substrate configured to support the target layer, wherein the support substrate is a polyhedron containing a polycrystalline diamond and including multiple structure planes each of which has a normal line from one another,

wherein the target layer is supported by the support substrate at a structure plane with a smaller normalized area density of a monocrystalline domain showing a {101} plane than each of a normalized area density of a monocrystalline domain showing a {100} plane and a normalized area density of a monocrystalline domain showing a {111} plane,

wherein the area densities in the multiple structure planes are denoted by S 101 , S 100 , and S 111 corresponding to plane orientations {101}, {100}, and {111}, and each of the area densities of the multiple structure planes is a normalized area density obtained by normalizing by an area of the structure plane a total value of areas of monocrystalline domains showing a plane orientation with an angle of deviation of 10 degrees of smaller from a central axis of the plane orientation, and

wherein normalized area densities NS 101 , NS 100 , and NS 111 corresponding to the plane orientations {101}, {100}, and {111} are represented by general formulas 1 to 3:

NS 101 =S 101 /( S 101 +S 100 +S 111 )  (general formula 1);

NS 100 =S 100 /( S 101 +S 100 +S 111 )  (general formula 2); and

NS 111 =S 111 /( S 101 +S 100 +S 111 )  (general formula 3).

12. The target according to claim 11 , wherein the target layer is supported at the structure plane with the normalized area density NS 101 of the monocrystalline domain showing the {101} plane, of 33.3% or lower.

13. The target according to claim 12 , wherein the target layer is supported at the structure plane with the normalized area density NS 101 of the monocrystalline domain showing the {101} plane, of 20% or lower.

14. The target according to claim 11 , wherein the target is a transmissive target in which an X-ray generated at the target layer is released from a structure plane of the support substrate that is on an opposite side from the structure plane supporting the target layer.

15. An anode comprising:

the target according to claim 11 ; and

an anode member electrically connected to the target layer.

16. The anode according to claim 15 , wherein the anode member includes an opening and is connected to a periphery of the support substrate in the opening.

17. An X-ray generating tube comprising:

the anode according to claim 15 ;

a cathode including an electron emission source configured to irradiate the target layer with an electron beam flux; and

an insulation tube connected to the anode and the cathode at opposite ends in a tube axis direction.

18. An X-ray generating apparatus comprising:

the X-ray generating tube according to claim 17 ; and

a tube voltage circuit configured to apply tube voltage across the anode and the cathode.

19. An X-ray imaging system, comprising:

the X-ray generating apparatus according to claim 18 ; and

an X-ray detection unit configured to detect an X-ray emitted from the X-ray generating apparatus and having passed through a subject.