Method and apparatus for emission guided radiation therapy

1. A method of treating a patient, the method comprising:

detecting an individual positron annihilation emission path originating from tissue at a first location using at least one positron emission detector;

positioning, in response to the detection of the individual positron annihilation emission path, a radiation source with respect to the individual positron annihilation emission path; and

applying radiation to the tissue without using a positron emission tomography (PET) image that is based on the detected individual positron annihilation emission path.

2. The method of claim 1 , further comprising generating a PET image based on the detected individual positron annihilation emission path after applying radiation to the tissue.

3. The method of claim 1 , wherein positioning the radiation source comprises aligning the radiation source along the detected individual positron annihilation emission path.

4. The method of claim 1 , wherein the radiation source is mounted on a rotatable gantry, and wherein positioning the radiation source comprises rotating the gantry.

5. The method of claim 4 , wherein rotating the gantry positions the radiation source at an angle with respect to the detected individual positron annihilation emission path.

6. The method of claim 4 , wherein detecting the individual positron annihilation emission path, positioning the radiation source and applying radiation to the tissue take place during a single treatment session.

7. The method of claim 6 , wherein applying radiation to the tissue comprises applying radiation to the tissue within a predetermined time during the session.

8. The method of claim 1 , further comprising:

detecting additional positron annihilation emission paths originating from the tissue;

positioning, in response to the detection of the additional positron annihilation emission paths, the radiation source with respect to the additional positron annihilation emission paths; and

applying radiation to the tissue without using a PET image based on the additional positron annihilation emission paths.

9. The method of claim 8 , further comprising:

recording dosages of the radiation applied by the radiation source to the tissue; and

accumulating a total radiation dosage for the radiation until the accumulated total radiation dosage satisfies a prescribed dose.

10. The method of claim 1 , further comprising:

detecting an additional positron annihilation emission path, wherein the additional positron annihilation emission path originates from tissue at a second location that is different from the first location;

positioning, in response to the detection of the additional positron annihilation emission path, the radiation source with respect to the additional positron annihilation emission path; and

applying radiation to the tissue at the second location without using a PET image based on the additional detected positron annihilation emission path.

11. The method of claim 1 , further comprising identifying a region of interest prior to detecting the individual positron annihilation emission path, wherein identifying the region of interest comprises detecting a plurality of positron annihilation emission paths and generating a map of the plurality of positron annihilation emission paths, and

applying radiation to the tissue if the first location is within the identified region of interest.

12. The method of claim 1 , further comprising administering a radiotracer to the patient prior to detecting the individual positron annihilation emission path, wherein the radiotracer comprises a positron-emitting radionuclide.

13. The method of claim 12 , wherein the positron-emitting radionuclide is selected from a list consisting of: fluourine-18, carbon-11, oxygen-15 and nitrogen-13.

14. The method of claim 1 , wherein a time interval between detecting the individual positron annihilation emission path and applying radiation to the tissue is less than the duration of a breathing cycle of the patient.

15. An apparatus comprising:

a rotatable gantry;

a radiation source mounted on the gantry;

one or more positron emission detectors mounted on the gantry, wherein the one or more positron emission detectors are configured to detect an individual positron annihilation emission path originating from tissue;

a controller in communication with the radiation source and the one or more positron emission detectors, the controller configured to rotate the gantry to position the radiation source in response to the detection of the individual positron annihilation emission path, wherein the radiation source is positioned with respect to the detected individual positron annihilation emission path, and

wherein the controller is configured to activate the radiation source to apply radiation to the tissue, wherein the radiation is applied without using a PET image based on the detected individual positron annihilation emission path.

16. The apparatus of claim 15 , wherein the controller is configured to generate a PET image based on the detected individual positron annihilation emission path after applying radiation to the tissue.

17. The apparatus of claim 15 , wherein the controller is configured to rotate the gantry such that the radiation source is aligned along the detected individual positron annihilation emission path.

18. The apparatus of claim 15 , wherein the controller is configured to rotate the gantry such that the radiation source is aligned at an angle with respect to the detected individual positron annihilation emission path.

19. The apparatus of claim 15 , wherein the controller is configured to position and apply radiation to the tissue within a time interval after detection of the individual positron annihilation emission path, wherein the time interval is less than the duration of a breathing cycle of a patient.

20. The apparatus of claim 15 , wherein the radiation source is selected from a list consisting of: a high energy photon source, a high energy electron source, a proton beam source, a neutron beam source, a heavy ion beam source, and a radioactive isotope source.