X-ray generating apparatus and X-ray CT apparatus using the same

1. An X-ray generating apparatus including

an X-ray tube for emitting X-ray,

tube voltage control means configured to control a tube voltage,

tube current control means configured to control tube current of the X-ray tube, and

X-ray control means configured to control high-energy X-ray and low-energy X-ray by the tube voltage control means, wherein

the X-ray tube includes

plural cathodes each of which has a filament,

one anode opposed to the plural cathodes,

grid electrodes each of which is individually provided to every cathode to control discharge of an electron beam emitted from the cathode,

grid voltage generating means configured to generate a voltage to be applied to each grid electrode, and

electron beam emission control means configured to alternately apply the grid voltage generated in the grid voltage generating means to each of the grid electrodes to control the emission of the electron beam, and wherein

the tube voltage control means includes

first tube voltage control means configured to control a high tube voltage corresponding to the high energy X-ray, and

second tube voltage control means configured to control a low tube voltage corresponding to the low energy X-ray, and wherein

the tube current control means includes

first tube current control means configured to control tube current corresponding to the high energy X-ray, and

second tube current control means configured to control tube current corresponding to the low energy X-ray.

2. The X-ray generating apparatus according to claim 1 , wherein the X-ray tube is an X-ray tube for emitting plural electron beams from the plural filaments and forming plural X-ray focal points on the anode so that the X-ray focal points are spaced from one another at a predetermined distance on the anode.

3. The X-ray generating apparatus according to claim 1 , wherein the X-ray tube further comprises electron beam deflecting means for deflecting the directions of the electron beams generated from the plural filaments.

4. The X-ray generating apparatus according to claim 3 , wherein the electron beam deflecting means has a deflection coil provided between the anode and the plural cathodes and deflection current supply means for supplying the deflection coil with current for deflecting the directions of the electron beams.

5. The X-ray generating apparatus according to claim 1 , wherein the tube current controlled by the second tube current control means is larger than the tube current controlled by the first tube current control means.

6. An X-ray CT apparatus that has a multi-energy imaging function, the X-ray CT apparatus comprising

an X-ray tube configured to irradiate X-ray to an examinee,

an X-ray detector configured to detect X-ray transmitted through the examinee,

scanner rotating means rotating around the examinee while the X-ray tube and the X-ray detector are mounted therein,

X-ray control means configured to irradiate X-rays having plural different energies emitted from the X-ray tube to the same slice position of the examinee while switching the X-rays every projection angle, and

image reconstructing means configured to reconstruct projection data detected by the X-ray detector to obtain a CT image, wherein

the X-ray tube comprises

plural cathodes each of which has a filament,

one anode opposed to the plural cathodes, and

grid electrodes each of which is individually provided every cathode to control emission of an electron beam emitted from the cathode, wherein

the X-ray control means comprises

tube current control means configured to heat the cathode filaments of the X-ray tube and control the tube current flowing between the anode and the cathodes,

tube voltage control means configured to control a tube voltage to be applied between the anode and the cathodes,

grid voltage generating means configured to generate a voltage to be applied to each grid electrode, and

electron beam emission control means configured to apply the grid voltages generated in the grid voltage generating means to the respective grid electrodes while alternately switching the grid voltages at every projection angle, thereby controlling emission of the electron beams, wherein

the tube voltage control means comprises

first tube voltage control means configured to control a high tube voltage corresponding to the high energy X-ray, and

second tube voltage control means configured to control a low tube voltage corresponding to the low energy X-ray, and wherein

the tube current control means comprises

first tube current control means configured to control tube current corresponding to the high energy X-ray, and

second tube current control means configured to control tube current corresponding to the low energy X-ray.

7. The X-ray CT apparatus according to claim 6 , wherein the X-ray tube is an X-ray tube for emitting plural electron beams from the plural filaments and forming plural X-ray focal points on the anode so that the X-ray focal points are spaced from one another at a predetermined distance on the anode.

8. The X-ray CT apparatus according to claim 6 , wherein the X-ray tube further comprises electron beam deflecting means for deflecting the directions of the electron beams generated from the plural filaments.

9. The X-ray CT apparatus according to claim 8 , wherein the electron beam deflecting means has a deflection coil provided between the anode and the plural cathodes and deflection current supply means for supplying the deflection coil with current for deflecting the directions of the electron beams.

10. The X-ray CT apparatus according to claim 6 , wherein the tube current controlled by the second tube current control means is larger than the tube current controlled by the first tube current control means.

11. The X-ray CT apparatus according to claim 6 , wherein the number of projection angles for detecting the projection data is larger than that under CT imaging using single X-ray energy.

12. The X-ray generating apparatus according to claim 1 , wherein the X-ray tube emits high energy X-ray and low energy X-ray alternately at each projection angle, under control of the X-ray control means, to perform dual energy imaging, by alternately apply the grid voltage to each of the grid electrodes at said each projection angle.

13. The X-ray generating apparatus according to claim 1 , wherein the tube voltage control means causes a high tube voltage to be applied between the anode and a first cathode of the plural cathodes, and causes a low tube voltage to be applied between the anode and a second cathode of the plural cathodes.

14. An X-ray generating apparatus comprising:

an X-ray tube configured to emit X-ray; and

an X-ray control part configured to control tube voltage and tube current of the X-ray tube, and to control the X-ray tube to emit high-energy X-ray and low-energy X-ray, wherein

the X-ray tube includes

plural cathodes each of which has a filament,

an anode opposed to the plural cathodes,

grid electrodes each of which is individually provided to every cathode to control discharge of an electron beam emitted from the cathode,

grid voltage generating part configured to generate a grid voltage to be applied to each grid electrode, and

electron beam emission control part configured to alternately apply the grid voltage to each of the grid electrodes to control the emission of the electron beam, and wherein

the X-ray control part comprises

first tube voltage control means configured to control a high tube voltage corresponding to the high energy X-ray,

second tube voltage control means configured to control a low tube voltage corresponding to the low energy X-ray,

first tube current control means configured to control tube current corresponding to the high energy X-ray, and

second tube current control means configured to control tube current corresponding to the low energy X-ray.