Fast generation of multi-leaf collimator (MLC) openings using hierarchical multi-resolution matching

1. A device for optimizing a radiation therapy plan for delivering therapeutic radiation to a patient using a therapeutic radiation source while modulated by a multi-leaf collimator (MLC), the device comprising:

at least one electronic processor connected to a radiation therapy device; and

a non-transitory computer readable medium storing instructions readable and executable by the at least one electronic processor to perform a radiation therapy plan optimization method, the method comprising:

optimizing MLC settings of the MLC respective to an objective function wherein the MLC settings define MLC leaf tip positions for a plurality of rows of MLC leaf pairs at a plurality of control points (CPs),

wherein: the optimizing is performed in two or more iterations with a resolution of the MLC settings increasing in successive iterations; and the optimizing comprises reducing a travel range of the leaf tip positions and increasing a resolution of the leaf tip positions within the reduced travel range in the successive iterations.

2. The device of claim 1 , wherein the optimizing comprises:

in a first iteration, optimizing the MLC leaf tip positions over a coarse grid; and

in succeeding iterations, optimizing the MLC leaf tip positions over a finer grid than the last iteration until a mechanical resolution of the MLC leaf tips is reached.

3. The device of claim 1 , wherein the optimizing further comprises reducing a range constraint on the leaf tip positions in successive iterations.

4. The device of claim 1 , wherein the optimizing comprises increasing a number of rows of MLC leaf pairs in successive iterations.

5. The device of claim 4 , where the optimizing further comprises:

in a first iteration, reducing the number of rows of MLC leaf pairs compared with a physical number of rows of MLC leaf pairs in the MLC by grouping adjacent leaf rows such that the MLC settings are optimized over a coarse grid in a direction transverse to the rows; and

in succeeding iterations, grouping the leaf rows using a finer grid until the physical number of rows of the MLC leaf pairs in the MLC is reached.

6. The device of claim 4 , where the optimizing further comprises:

in a first iteration, reducing the number of rows of MLC leaf pairs compared with a physical number of rows of MLC leaf pairs in the MLC by selecting a sub-set of the leaf rows and interpolating unselected rows between the selected rows of the sub-set such that the MLC settings are optimized over a coarse grid in a direction transverse to the rows; and

in succeeding iterations, increasing the number of rows in the selected sub-set until the physical number of rows of the MLC leaf pairs in the MLC is selected.

7. The device of claim 1 , wherein the optimizing comprises controlling a number of angular positions of the CPs along a trajectory comprising an arc.

8. The device of claim 1 , wherein the radiation therapy plan optimization method further comprises:

optimizing a fluence map by optimizing beamlets at the CPs along a trajectory comprising an arc respective to clinical objectives of the radiation therapy plan; and

wherein the objective function is defined by the optimized fluence map.

9. The device of claim 1 , wherein the objective function comprises clinical objectives of the radiation therapy plan, the clinical objectives comprising a minimum number of leaf pairs in an opening, a minimum opening area, a smoothness of an opening, and or other characteristics of the shape of an opening.

10. The device of claim 1 , further comprising a radiation therapy device configured to deliver therapeutic radiation to the patient using the therapeutic radiation source of the radiation therapy device traversing a trajectory comprising arc while modulated by the MLC in accordance with a radiation therapy plan optimized by the radiation therapy plan optimization method;

wherein the traversing of the trajectory comprises moving the therapeutic radiation source along the arc.

11. A non-transitory computer readable medium storing instructions executable by at least one electronic processor to perform a radiation therapy plan optimization method, the method comprising:

optimizing multi-leaf collimator (MLC) settings of an MLC of a radiation therapy device respective to an objective function wherein the MLC settings define MLC leaf tip positions for a plurality of rows of MLC leaf pairs at a plurality of control points (CPs) along an arc,

wherein the optimizing is performed in two or more iterations with a resolution of the MLC settings increasing in successive iterations; and the optimizing comprises reducing a travel range of the leaf tip positions and increasing a resolution of the leaf tip positions within the reduced travel range in the successive iterations.

12. The non-transitory computer readable medium of claim 11 , wherein the optimizing comprises:

in a first iteration, optimizing the MLC leaf tip positions over a coarse grid; and

in succeeding iterations, optimizing the MLC leaf tip positions over a finer grid than the last iteration until a mechanical resolution of the MLC leaf tips is reached.

13. The non-transitory computer readable medium of claim 11 , wherein the optimizing further comprises reducing a range constraint on the leaf tip positions in successive iterations.

14. The non-transitory computer readable medium of claim 11 , wherein the optimizing further comprises increasing a number of rows of MLC leaf pairs in successive iterations.

15. The non-transitory computer readable medium of claim 14 , where the optimizing further comprises:

in a first iteration, reducing the number of rows of MLC leaf pairs compared with a physical number of rows of MLC leaf pairs in the MLC by grouping adjacent leaf rows such that the MLC settings are optimized over a coarse grid in a direction transverse to the rows; and

in succeeding iterations, grouping the leaf rows using a finer grid until the physical number of rows of the MLC leaf pairs in the MLC is reached.

16. The non-transitory computer readable medium of claim 11 , wherein the optimizing comprises optimizing angular positions of the CPs along the arc.

17. The non-transitory computer readable medium of claim 11 , wherein the radiation therapy plan optimization method further comprises:

optimizing a fluence map by optimizing beamlets at the CPs along the arc respective to clinical objectives of the radiation therapy plan;

wherein the objective function is defined by the optimized fluence map.

18. The non-transitory computer readable medium of claim 11 , wherein the objective function comprises clinical objectives of the radiation therapy plan.

19. A radiation therapy plan optimization method, comprising:

optimizing multi-leaf collimator (MLC) settings of an MLC of a radiation therapy device respective to an objective function wherein the MLC settings define MLC leaf tip positions for a plurality of rows of MLC leaf pairs at a plurality of control points (CPs) along the arc; and

delivering therapeutic radiation to the patient using a therapeutic radiation source of the radiation therapy device traversing the arc while modulated by the MLC in accordance with a radiation therapy plan;

wherein: the optimizing is performed in two or more iterations with a resolution of the MLC settings increasing in successive iterations; and the optimizing comprises reducing a travel range of the leaf tip positions and increasing a resolution of the leaf tip positions within the reduced travel range in the successive iterations.