Including fiducial markers in radiation therapy planning to facilitate real-time position monitoring during treatment delivery
View Patent ↗An inverse planning method that is capable of controlling the appearance of the implanted fiducial(s) in segmented IMRT fields for cine MV or combined MV/kV image-guided IMRT is provided. The method for radiation treatment includes computing a radiation treatment plan and delivering beams to a target in accordance with the radiation treatment plan, where computing the radiation treatment plan includes introducing a penalty in an inverse planning objective function optimization calculation to discourage or avoid blockage of one or more fiducials in optimized multi-leaf collimator (MLC) apertures.
1. A method for radiation treatment comprising computing a radiation treatment plan and delivering beams to a target in accordance with said radiation treatment plan, wherein computing said radiation treatment plan comprises introducing a penalty in an inverse planning objective function optimization calculation to discourage or avoid blockage of one or more fiducials in optimized multi-leaf collimator (MLC) apertures, wherein for a given gantry angle θ and phase p, a weight w θp is provided for a phase-segment, wherein said radiation treatment plan optimizes shapes and weights of all said MLC aperture shapes.
2. The method of claim 1 , wherein said penalty comprises a hard penalty or a soft penalty, wherein said hard penalty avoids blockage of said fiducial, wherein said soft penalty discourages blockage of said fiducial.
3. The method of claim 1 , wherein said fiducials are selected from the group consisting of an implanted fiducial, a skin marker, a tissue feature point, and a tissue region.
4. The method of claim 1 , wherein said MLC aperture comprises segment aperture shapes that conform to a projection of said target in a beam's eye view of said delivery beam, wherein said shapes are optimized according to a space and phase of a breathing cycle in a patient.
5. The method of claim 1 , wherein motion of said fiducials is discretized into phase-segments.
6. The method of claim 5 , wherein a radiation dose provided to a voxel comprises a superposition of said radiation doses and phase-segments from all said MLC segments, wherein said dose is determined by summing a contribution from each said MLC segment for each said beam.
7. The method of claim 1 , wherein said MLC aperture comprise MLC segments, wherein a calculated dose distribution is a function of said MLC aperture shapes and weights of all said MLC segments.
8. The method of claim 1 , wherein said penalty is dedicated to a voxel with a dose higher than a designated upper bound or dedicated to a voxel with a dose lower than a designated lower bound.
9. The method of claim 1 , wherein said inverse planning objective function is optimized using a simulated annealing (SA) technique, wherein in each iteration of said SA a trial change of said aperture and trial change of a weight of said penalty is introduced, wherein said trial change is accepted or rejected according to a probability determined by an SA probability and whether an MLC segment blocks said fiducial or not.
10. The method of claim 1 , wherein said inverse planning objective function is optimized using an optimization function.
11. The method of claim 1 , wherein said inverse planning objective function comprises a 4D inverse planning objective function.
12. The method of claim 1 , wherein said penalty has a value in a range of 0to 1.