Dual-energy X-ray tubes

1. A duel-energy x-ray tube comprising:

an evacuated enclosure;

an anode positioned within the evacuated enclosure;

an electron target inside the anode;

a first electron passageway and a second electron passageway extending through the anode, the first electron passageway defining a portion of a first electron path to the electron target and the second electron passageway defining a portion of a second electron path to the electron target;

a first cathode positioned within the evacuated enclosure and configured to emit electrons towards the electron target for passage through the first electron passageway extending through the anode, wherein the first cathode is electrically insulated from about ground; and

a second cathode positioned within the evacuated enclosure and configured to emit electrons towards the electron target for passage through the second electron passageway extending through the anode, wherein the second cathode is electrically coupled to about ground,

wherein the first cathode and the second cathode are configured to operate simultaneously at different voltages.

2. The dual-energy x-ray tube as recited in claim 1 , wherein:

the anode configured to operate at a positive high voltage;

the first cathode configured to operate at a negative high voltage; and

the second cathode configured to operate at about zero voltage.

3. The dual-energy x-ray tube as recited in claim 2 , wherein:

the anode is configured to operate between 50 kV and 320 kV; and

the first cathode is configured to operate between −50 kV and −320 kV.

4. The dual-energy x-ray tube as recited in claim 1 , wherein an operation state of the second cathode results in x-rays that are about half the energy of the x-rays that result from an operation state of the first cathode.

5. The dual-energy x-ray tube as recited in claim 1 , wherein an operation state of the second cathode results in x-rays that have an energy that is greater than or less than half the energy of the x-rays that result from an operation state of the first cathode.

6. The dual-energy x-ray tube as recited in claim 1 , wherein the first cathode includes a first cathode emitter and the second cathode includes a second cathode emitter, and the dual-energy x-ray tube further comprising one or more grids positioned within the evacuated enclosure between the first and second cathode emitters and the anode, wherein the one or more grids are configured to substantially allow electrons to reach the electron target of the anode from only the first cathode emitter or the second cathode emitter at any given time.

7. A dual-energy x-ray tube comprising:

an evacuated enclosure;

an anode positioned within the evacuated enclosure;

an electron target inside the anode, wherein the anode is structured to include a first opening defining a portion of a first electron path to the electron target and a second opening defining a portion of a second electron path to the electron target;

a first cathode positioned within the evacuated enclosure and configured to emit electrons towards the electron target for passage through the first opening of the anode, the first cathode configured to operate at a negative high voltage; and

a second cathode positioned within the evacuated enclosure and configured to emit electrons towards the electron target for passage through the second opening of the anode, the second cathode configured to operate at about zero voltage,

wherein the first cathode and the second cathode are configured to continuously operate simultaneously.

8. The dual-energy x-ray tube as recited in claim 7 , wherein:

the anode is configured to operate between 50 kV and 320 kV; and

the first cathode is configured to operate between −50 kV and −320 kV.

9. The dual-energy x-ray tube as recited in claim 8 , wherein an operation state of the second cathode results in x-rays that are about half the energy of the x-rays that result from an operation state of the first cathode.

10. The dual-energy x-ray tube as recited in claim 8 , wherein an operation state of the second cathode results in x-rays that have an energy that is greater than or less than half the energy of the x-rays that result from an operation state of the first cathode.

11. The dual-energy x-ray tube as recited in claim 7 , wherein:

the first cathode is electrically insulated from about ground; and

the second cathode is not electrically insulated from about ground.

12. The dual-energy x-ray tube as recited in claim 7 , wherein the first cathode and the second cathode are configured to generate x-rays at dual energies simultaneously.

13. The dual-energy x-ray tube as recited in claim 7 , wherein the first cathode includes a first cathode emitter and the second cathode includes a second cathode emitter, and the dual-energy x-ray tube further comprising one or more grids positioned within the evacuated enclosure between the first and second cathode emitters and the anode, wherein the one or more grids are configured to substantially allow electrons to reach the electron target of the anode from only the first cathode emitter or the second cathode emitter at any given time.

14. A dual-energy x-ray system comprising:

a high-voltage generator configured to continuously generate a single positive high voltage and a single negative high voltage;

an x-ray tube comprising:

an evacuated enclosure;

an anode positioned within the evacuated enclosure;

an electron target inside the anode;

a first electron passageway extending through the anode and defining a portion of a first electron path to the electron target and a second electron passageway extending through the anode and defining a portion of a second electron path to the electron target positioned inside the anode;

a first cathode positioned within the evacuated enclosure and configured to emit electrons towards the electron target for passage through the first electron passageway that extends through the anode, the first cathode configured to operate at the single negative high voltage; and

a second cathode positioned within the evacuated enclosure and configured to emit electrons towards the electron target for passage through the second electron passageway that extends through the anode, the second cathode configured to operate at about zero voltage,

wherein the first cathode and the second cathode are configured to continuously operate simultaneously.

15. The dual-energy x-ray system as recited in claim 14 , wherein the high-voltage generator is configured to continuously generate the single positive high voltage between 50 kV and 320 kV and the single negative high voltage between −50 kV and −320 kV.

16. The dual-energy x-ray system as recited in claim 14 , wherein the high-voltage generator is balanced such that the single positive high voltage is about opposite the single negative high voltage.

17. The dual-energy x-ray system as recited in claim 14 , wherein the high-voltage generator is unbalanced such that the single positive high voltage is not opposite the single negative high voltage.

18. The dual-energy x-ray system as recited in claim 14 , wherein the first cathode and the second cathode are configured to generate x-rays at dual energies simultaneously.

19. The dual-energy x-ray system as recited in claim 14 , wherein the first cathode includes a first cathode emitter and the second cathode includes a second cathode emitter, and the x-ray tube further comprising one or more grids positioned within the evacuated enclosure between the first and second cathode emitters and the anode, wherein the one or more grids are configured to substantially allow electrons to reach the electron target of the anode from only the first cathode emitter or the second cathode emitter at any given time.