Filtering of a source of pulsed radiation

1. A system comprising:

a source of pulsed radiation; and

a positionable filter coupled to the source of pulsed radiation, the positionable filter comprising an element that produces an indication of a position of the filter, wherein the source is configured to receive the indication of the position of the filter, and to regulate emission of a pulse of radiation based on the indication.

2. The system of claim 1 , wherein the filter comprises a portion, the portion comprising a material that causes alteration of one or more of a flux, energy spectrum, position, or collimation of a beam of radiation that interacts with the material.

3. The system of claim 2 , wherein the portion comprises a plurality of sections, at least one of which comprises the material.

4. The system of claim 3 , wherein at least one of the plurality of sections is a blank section without the material such that a beam of radiation is unaltered as a result of interacting with the blank section.

5. The system of claim 3 , wherein at least one section comprises a second material different from the material.

6. The system of claim 1 , wherein the source of pulsed radiation regulates emission of the pulse of radiation by determining a particular time to emit the pulse of radiation.

7. The system of claim 4 , wherein the positionable filter rotates about an axis of rotation such that a pulse emitted from the source strikes one of the plurality of sections at a particular time.

8. The system of claim 7 , wherein the source of pulsed radiation regulates emission of the pulse of radiation by delaying emission of the pulse of radiation such that the emitted pulse strikes a selected one of the plurality of sections.

9. The system of claim 1 , wherein the source of pulsed radiation is a linear accelerator.

10. A device comprising:

an area comprising a material that alters a parameter of a beam of radiation that interacts with the material, the device being configured to move relative to a source of pulsed radiation; and

an element that provides a signal to the source of pulsed radiation indicating a position of the area relative to the source, the signal causing the source to trigger emission of a pulse at a time such that the emitted pulse is incident upon a portion of the area.

11. The device of claim 10 , wherein the device is configured to rotate about an axis of rotation, and the indication of a position of the device comprises an indication of an angular position of the device relative to the axis of rotation.

12. The device of claim 11 , wherein the device comprises a cylindrically shaped element defining a longitudinal axis parallel to the axis of rotation, the cylindrically shaped element comprises a first end and a second end, and the portion comprising the material is oriented between the first and second ends and along the longitudinal axis.

13. The device of claim 10 , wherein the portion comprising a material comprises a plurality of sections at least one of which is a blank section that does not include a material such that an emitted pulse is unaltered by interaction with the blank section.

14. The device of claim 13 , wherein the signal causes the source to delay the emission of the pulse such that the pulse is emitted when a selected one of the plurality of sections is in a path of the emitted pulse.

15. The device of claim 10 , wherein the signal is sufficient to cause the source to alter a timing of the emission of the pulse from the source.

16. A method of filtering a pulse of radiation, the method comprising:

accessing a position of a movable filter that comprises a plurality of sections, each section associated with a filtering characteristic; and

selecting, from among the plurality of sections, a particular section for filtering by triggering, based on the position of the movable filter, a radiation source to generate a pulse that strikes the particular section of the movable filter.

17. The method of claim 16 , wherein selecting from among the plurality of sections comprises selecting a section associated with a filtering characteristic that does not alter a parameter of the pulse.

18. The method of claim 16 , wherein accessing a position of the movable filter comprises receiving an indication of the position of the movable filter generated by the movable filter.

19. The method of claim 18 , wherein the movable filter rotates about an axis of rotation, and wherein accessing a position of the movable filter comprises receiving an angular position of the filter.

20. The method of claim 16 , wherein the particular section is selected independently of an energy output of from source.

21. A machine readable medium coupled to an electronic processor, the medium comprising instructions that, when executed, cause the processor to perform operations comprising:

accessing a position of a moving filter that comprises a plurality of sections, each section associated with a filtering characteristic;

determining, based on the position, a time at which a particular one of the plurality of sections is in the path of a pulsed radiation source; and

generating a signal sufficient to cause the source to emit a pulse such that the pulse strikes the particular one of the plurality of sections.

22. The medium of claim 21 , further comprising instructions to cause the processor to provide the signal to the source.

23. The medium of claim 21 , wherein the filter rotates about a longitudinal axis defined by the filter, and accessing a position of the filter comprises receiving an indication of an angular position of the filter relative to the longitudinal axis.