X-ray generating tube, X-ray generating apparatus and X-ray imaging system using the same
Provided is an X-ray generating tube with improved withstand voltage property by a simple structure, the X-ray generating tube including a cathode connected to one opening of an insulating tube and an anode connected to the other opening, in which a resistive film having a lower sheet resistance value than that of the insulating tube is disposed on an outer periphery of the insulating tube, and the cathode and the anode are electrically connected to each other via the resistive film.
1. An X-ray generating tube comprising:
an insulating tube;
a cathode comprising an electron emitting source, the cathode covering one opening of the insulating tube so that a peripheral edge portion thereof is joined to an end surface of the one opening;
an anode comprising a target, the anode covering the other opening of the insulating tube so that a peripheral edge portion thereof is joined to an end surface of the other opening; and
a resistive film disposed on an outer periphery of the insulating tube, the resistive film having a smaller sheet resistance value than a sheet resistance value of the insulating tube,
wherein the cathode and the anode are electrically connected to each other via the resistive film.
2. The X-ray generating tube according to claim 1 , wherein a dark current at 100° C. when a voltage of 100 kV is applied between the cathode and the anode is 0.1 μA or more to 10 μA or less.
3. The X-ray generating tube according to claim 1 , wherein:
at least one of the cathode and the anode comprises an extending portion protruding from the peripheral edge portion in a longitudinal direction of the insulating tube; and
the resistive film is connected to the extending portion.
4. The X-ray generating tube according to claim 3 , wherein the resistive film is sandwiched between the extending portion and the insulating tube.
5. The X-ray generating tube according to claim 3 , wherein the extending portion is sandwiched between the resistive film and the insulating tube.
6. The X-ray generating tube according to claim 5 , wherein an end portion of the resistive film joined to the extending portion is covered with a conductive paste.
7. The X-ray generating tube according to claim 3 , wherein an electrical connection portion between the resistive film and the at least one of the cathode and the anode is positioned on an outer peripheral portion of the insulating tube.
8. The X-ray generating tube according to claim 1 , wherein an electrical connection portion between the resistive film and at least one of the cathode and the anode is positioned on an end surface of the insulating tube.
9. The X-ray generating tube according to claim 1 , wherein the insulating tube is made of ceramic, and the resistive film is made of a glass material.
10. The X-ray generating tube according to claim 9 , wherein the insulating tube is made of alumina, and the resistive film is made of glaze.
11. The X-ray generating tube according to claim 1 , wherein:
a specific resistance of the insulating tube at 100° C. is 1×10 Ωm or more to 1×10 14 Ωm or less; and
R s 2/R s 1 is 1×10 −5 or more to 1×10 −1 or less, where R s 1 represents a sheet resistance value of the insulating tube at 100° C., and R s 2 represents a sheet resistance value of the resistive film at 100° C.
12. The X-ray generating tube according to claim 1 , wherein the outer periphery of the insulating tube is an outer periphery of the X-ray generating tube.
13. The X-ray generating tube according to claim 1 , wherein the resistive film defines a space electric field between the cathode and the anode.
14. The X-ray generating tube according to claim 1 , wherein the anode comprises an end window including a transmissive target.
15. An X-ray generating apparatus comprising:
the X-ray generating tube according to claim 1 ; and
a container for storing the X-ray generating tube,
wherein the container comprises an emission window for emitting X-ray generated by the X-ray generating tube, and a rest space inside the container storing the X-ray generating tube is filled with insulating liquid.
16. The X-ray generating apparatus according to claim 15 , wherein the insulating liquid comprises at least any one of silicone oil, transformer oil, and fluorine-containing oil.
17. An X-ray imaging system comprising:
the X-ray generating apparatus according to claim 15 ;
an X-ray detecting device configured to detect X-ray emitted from the X-ray generating apparatus and passing through a subject to be investigated; and
a control device configured to control the X-ray generating apparatus and the X-ray detecting device in a coordinated manner.