Beam-off motion thresholds in radiation therapy based on breath-hold level determination
A computer-implemented method of performing a treatment fraction of radiation therapy comprises: determining a current position of a target volume of patient anatomy; based on the current position of the target volume, computing an accumulated dose for non-target tissue proximate the target volume; determining that the accumulated dose is less than a current value for a dose budget of the non-target tissue; and in response to the accumulated dose being less than the current value for the dose budget, applying a treatment beam to the target volume while the target volume is in the current position.
1. A computer-implemented method of performing a treatment fraction of radiation therapy, the method comprising:
determining a current position of a target volume of patient anatomy;
based on the current position of the target volume, computing an accumulated dose for non-target tissue proximate the target volume;
determining that the accumulated dose is less than a current value for a dose budget of the non-target tissue; and
in response to the accumulated dose being less than the current value for the dose budget, applying a treatment beam to the target volume while the target volume is in the current position.
2. The computer-implemented method of claim 1 , wherein the current position is at least partially outside a planned treatment location for the target volume.
3. The computer-implemented method of claim 1 , further comprising generating a new value for the dose budget by subtracting the accumulated dose from the current value for the dose budget.
4. The computer-implemented method of claim 3 , further comprising, based on the new value of the dose budget, modifying a beam-off threshold position for the target volume.
5. The computer-implemented method of claim 4 , wherein modifying the beam-off threshold position for the target volume comprises associating the beam-off threshold position with a first range of target positions and disassociating the beam-off threshold position from a second range of target positions, wherein the first range of target positions is closer to a planned treatment location for the target volume than the second range of target positions.
6. The computer-implemented method of claim 1 , further comprising, prior to applying the treatment beam to the target volume, determining that the current position is within a range of beam-off threshold positions for the target volume.
7. The computer-implemented method of claim 6 , further comprising, when a detected position of the target volume is outside the range of beam-off threshold positions, blocking application of the treatment beam for a portion of the treatment fraction.
8. The computer-implemented method of claim 1 , further comprising:
determining an equivalent breath-hold level based on the current position of the target volume; and
computing the accumulated dose based on the equivalent breath-hold level.
9. The computer-implemented method of claim 8 , wherein the equivalent breath-hold level is associated with a specific accumulated dose.
10. The computer-implemented method of claim 1 , further comprising:
determining a treatment beam intensity that is applied to the target volume while the target volume is in the current position; and
computing the accumulated dose based on the treatment beam intensity.
11. The computer-implemented method of claim 1 , wherein determining the current position of the target volume comprises measuring an external motion signal.
12. The computer-implemented method of claim 1 , wherein determining the current position of the target volume further comprises performing X-ray imaging of the target volume.
13. The computer-implemented method of claim 1 , wherein applying the treatment beam to the target volume while the target volume is in the current position comprises a portion of the treatment fraction.
14. The computer-implemented method of claim 1 , further comprising based on the current position of the target volume, computing an accumulated dose for target tissue proximate the target volume.
15. A system for performing a treatment fraction of radiation therapy, the system comprising:
an X-ray imaging device;
a treatment-delivering X-ray source configured to direct treatment X-rays to a target volume of patient anatomy;
an imaging X-ray source configured to direct imaging X-rays through the target volume and toward the X-ray imager; and
a processor configured to:
determine a current position of the target volume;
based on the current position of the target volume, compute an accumulated dose for non-target tissue proximate the target volume;
determine that the accumulated dose is less than a current value for a dose budget of the non-target tissue; and
in response to the accumulated dose being less than the current value for the dose budget, cause the treatment-delivering X-ray source to apply a treatment beam to the target volume while the target volume is in the current position.
16. The system of claim 15 , wherein the current position is at least partially outside a planned treatment location for the target volume.
17. The system of claim 15 , further comprising generating a new value for the dose budget by subtracting the accumulated dose from the current value for the dose budget.
18. The system of claim 17 , further comprising, based on the new value of the dose budget, modifying a beam-off threshold position for the target volume.
19. The system of claim 15 , wherein determining the current position of the target volume further comprises performing X-ray imaging of the target volume with the X-ray imaging device and the imaging X-ray source.
20. The system of claim 15 , wherein causing the treatment-delivering X-ray source to apply the treatment beam to the target volume while the target volume is in the current position comprises a portion of the treatment fraction.