Waveguide for a linear accelerator and method of operating a linear accelerator

1. A waveguide for use in a linear accelerator, the waveguide comprising:

multiple cells arranged to receive a beam of charged particles therethrough along a particle path, the waveguide being configured to receive an electromagnetic field from a source of electromagnetic radiation, wherein a plurality of the multiple cells are individually switchable cells, and wherein each individually switchable cell includes a respective switch configured to adjust a supply of electromagnetic radiation to the individually switchable cell; and

a first supply channel and a second supply channel arranged substantially parallel to the particle path, wherein each individually switchable cell is arranged between the first supply channel and second supply channel, and wherein the first supply channel and the second supply channel are each configured to supply the electromagnetic radiation to each individually switchable cell.

2. The waveguide of claim 1 , the multiple cells further comprising:

an input cell for receiving a charged particle at an input end of the particle path; and

an output cell from which a charged particle can leave the waveguide at an output end of the particle path, wherein the individually switchable cell is positioned between the input cell and the output cell.

3. The waveguide of claim 1 , wherein each cell of the multiple cells is an individually switchable cell, and wherein each of the respective switches are configured such that the supply of electromagnetic radiation to a first individually switchable cell positioned closer to an input end of the particle path than an output end of the particle path can be reduced relative to the supply of electromagnetic radiation to a second individually switchable cell positioned between the first individually switchable cell and the output end of the particle path.

4. The waveguide of claim 1 , wherein each of the individually switchable cells are configured such that the supply of electromagnetic radiation to each of the individually switchable cells can be individually switched on and off.

5. The waveguide of any of claim 1 , wherein each, switch comprises a field aperture and a valve, wherein each valve is individually controllable to open and close the field aperture to the electromagnetic radiation.

6. The waveguide of claim 1 , wherein the electromagnetic radiation is radio frequency radiation.

7. A linear accelerator comprising:

a waveguide including:

multiple cells arranged to receive a beam of charged particles therethrough along a particle path, the waveguide being configured to receive an electromagnetic field from a source of electromagnetic radiation, wherein each cell of the multiple cells is an individually switchable cell, and wherein each individually switchable cell includes a respective switch configured to adjust a supply of electromagnetic radiation to the individually switchable cell, and

a first supply channel and a second supply channel arranged substantially parallel to the particle path, wherein each of the individually switchable cells are arranged between the first supply channel and second supply channel, and wherein the first supply channel and the second supply channel are each configured to supply the electromagnetic radiation to each of the individually switchable cells.

8. The linear accelerator of claim 7 , wherein the linear accelerator comprises the source of electromagnetic radiation configured to supply electromagnetic radiation to the waveguide.

9. The linear accelerator of claim 7 , wherein each respective individually switchable cell comprises a first switch and a second switch, the first switch configured to adjust the supply of electromagnetic radiation supplied to the individually switchable cell from the first supply channel, and the second switch configured to adjust the supply of electromagnetic radiation supplied to the individually switchable cell from the second supply channel.

10. The linear accelerator of claim 9 , wherein the first switch comprises:

a first field aperture through which the electromagnetic field enters a particular cell from the first supply channel and a first valve controllable to close the first field aperture to the electromagnetic field; and

a second field aperture through which the electromagnetic field enters a second particular cell from the second supply channel and a second valve controllable to close the second field aperture to the electromagnetic field.

11. The linear accelerator of claim 7 , further comprising:

a radiotherapy device.

12. A method of controlling a waveguide, the method comprising:

supplying electromagnetic radiation to a first number of cells and to a third number of cells, while restricting the supply of electromagnetic radiation to a second number of cells, wherein each of the second number of cells are individually switchable cells placed between the first number of cells and the third number of cells along a particle path, wherein a first supply channel and a second supply channel are each configured to supply the electromagnetic radiation to each of the individually switchable cells, wherein the first supply channel and the second supply channel are arranged substantially parallel to the particle path, and wherein each of the individually switchable cells are arranged between the first supply channel and the second supply channel.

13. The method of claim 12 , further comprising:

increasing or reducing an amount of the second number of cells by adjusting the supply of electromagnetic radiation to at least one of the individually switchable cells, in order to adjust the energy of the charged particles exiting the waveguide.

14. The method of claim 12 , the method comprising:

supplying electromagnetic radiation to the first number of cells to accelerate charged particles along the particle path;

effecting a reduction in, or stopping, the supply of electromagnetic radiation to the second number of cells, into which the accelerated charged particles travel; and

supplying electromagnetic radiation to the third number of cells to reform the charged particles exiting the second number of cells into bunches.

15. The method of claim 12 , further comprising:

supplying electromagnetic radiation to bunching cells placed before the first number of cells, to form charged particles travelling along the particle path into bunches before the charged particles enter the first number of cells.

16. A non-transitory computer readable medium comprising computer executable instructions which, when executed by a processor, cause the processor to:

supply electromagnetic radiation to a first number of cells of a waveguide and to a third number of cells of the waveguide, while restricting the supply of electromagnetic radiation to a second number of cells of the waveguide, wherein each of the second number of cells are individually switchable cells placed between the first number and the third number of cells along a particle path, wherein a first and a second supply channel are each configured to supply the electromagnetic radiation to each of the individually switchable cells, wherein the first supply channel and the second supply channel are arranged substantially parallel to the particle path, and wherein each of the individually switchable cells are arranged between the first supply channel and the second supply channel.

17. The non-transitory computer readable medium of claim 16 , wherein the instructions further cause the processor to:

increase or reduce an amount of the second number of cells by adjusting the supply of electromagnetic radiation to at least one of the individually switchable cells, in order to adjust the energy of the charged particles exiting the waveguide.

18. The non-transitory computer readable medium of claim 16 , wherein the instructions further cause the processor to:

supply electromagnetic radiation to the first number of cells to accelerate charged particles along the particle path;

reduce or stop, the supply of electromagnetic radiation to the second number of cells, into which the accelerated charged particles travel; and

supply electromagnetic radiation to the third number of cells to reform the charged particles exiting the second number of cells into bunches.