Methods for radiation delivery in emission-guided radiotherapy
This application relates to methods for delivering radiation to a positron-emitting target within a subject under continuous PET guidance. Instead of directing radiation at a collinear path along each detected positron line-of-response (LOR), the methods generally include detecting a pattern of LORs that intersect the target. In response to the pattern, radiation may be delivered along paths that are not necessarily collinear to any of the LORs. Methods for further modifying radiation delivery as well as the detected LOR population are also described.
1. A method for delivering radiation to a subject comprising:
detecting a population of positron emission paths;
detecting a pattern of positron emission paths within the population;
determining one or more response paths based at least in part on processing of the pattern, wherein the one or more response paths is not collinear to any positron emission path from the detected pattern; and
delivering radiation along the one or more response paths to a target volume within the subject.
2. The method of claim 1 , wherein the pattern comprises collinear positron emission paths.
3. The method of claim 1 , wherein the pattern comprises non-intersecting position emission paths.
4. The method of claim 1 , wherein the pattern comprises positron emission paths that intersect at a point within the target volume.
5. The method of claim 1 , wherein the pattern comprises positron emission paths that intersect within the target volume to define a target area within the target volume.
6. The method of claim 1 , wherein the pattern comprises an arbitrary set of positron emission paths that intersect the target volume.
7. The method of claim 1 , wherein at least two response paths are collinear with a positron emission path from the detected pattern.
8. The method of claim 1 , wherein processing of the pattern comprises calculating the one or more response paths based on one or more detected positron emission paths in the pattern.
9. The method of claim 1 , wherein processing of the pattern comprises assigning a weight to the one or more response paths, the weight correlating to a radiation dose delivered along the one or more response paths.
10. The method of claim 9 , wherein the assigned weight has a negative value.
11. The method of claim 1 , wherein processing of the pattern comprises calculating a weight of a set of response paths, the weight being proportional to the number of positron emission paths in the detected pattern.
12. The method of claim 1 , wherein processing of the pattern comprises calculating a set of weighted response paths via a reprojection procedure.
13. The method of claim 1 , wherein processing of the pattern comprises binning the population of positron emission paths into a sinogram matrix.
14. The method of claim 13 , further comprising filtering the sinogram matrix.
15. The method of claim 14 , wherein filtering comprises applying a finite impulse response (FIR) filter to the sinogram matrix.
16. The method of claim 14 , wherein filtering comprises applying a linear or non-linear filter to the sinogram matrix.
17. The method of claim 1 , further comprising recording a dose of radiation delivered along the one or more response paths.
18. The method of claim 1 , further comprising recording one or more undelivered response paths, the undelivered response paths having a negative weight, and adding the negative weight to a weight of subsequently determined response paths.
19. The method of claim 1 , further comprising filtering the population of positron emission paths.
20. The method of claim 1 , further comprising repeating radiation delivery until a predetermined dose of radiation is received by the target volume.
21. The method of claim 1 , further comprising tracking motion speed of the target volume.
22. The method of claim 21 , wherein tracking motion speed of the target volume comprises tracking the respiratory rate of the subject.
23. The method of claim 21 , wherein tracking motion speed of the target volume reduces the size of a planned tumor volume (PTV) or an effective, real-time planned tumor volume (ERT PTV).
24. The method of claim 1 , wherein the method is performed by a system comprising:
a circular gantry;
a radiation source mounted on the gantry;
a plurality of positron emission detectors mounted on the gantry, wherein the plurality of positron emission detectors detect the population of positron emission paths; and
a controller in communication with the radiation source and the positron emission detectors.
25. The method of claim 24 , wherein the controller is configured to process the pattern and determine the one or more response paths.
26. The method of claim 24 , wherein the controller is configured to position the radiation source with respect to the one or more response paths.
27. The method of claim 26 , wherein the radiation source is positioned by rotating the gantry.
28. The method of claim 25 , wherein delivering radiation along the one or more response paths to the target volume occurs from opposite sides of the gantry.
29. The method of claim 25 , wherein delivering radiation along the one or more response paths to the target volume occurs from various positions on the gantry.
30. The method of claim 25 , wherein the target volume is PET-avid.