System and method for optimized dynamic collimator rotation in volumetric modulated arc therapy

1. A method for treating a subject using a dynamic collimator volumetric modulated arc therapy (“VMAT”) plan, the method comprising:

receiving a representation of the subject comprising information related to target and non-target volumes of interest;

generating an objective function based on the representation of the subject, wherein the objective function accounts for dynamic collimator rotation;

performing an iterative optimization process using the objective function to generate the dynamic collimator VMAT plan;

identifying an aperture shape for a plurality of apertures by minimizing the objective function in the iterative optimization process; and

irradiating the subject in accordance with the dynamic collimator VMAT plan.

2. The method of claim 1 , wherein the representation comprises at least one image of the subject acquired using at least one of computed tomography (“CT”), magnetic resonance imaging (“MRI”), or positron emission tomography (“PET”).

3. The method of claim 1 , wherein the objective function comprises a first collimator term and a second collimator term.

4. The method of claim 3 , wherein the first collimator term calculates a cost of collimator rotation.

5. The method of claim 3 , wherein the second collimator term directs smooth collimator rotation between gantry angles.

6. The method of claim 3 , wherein the objective function further comprises a dose fidelity term that penalizes deviation from a prescription dose.

7. The method of claim 6 , wherein the dose fidelity term is an L2-norm term.

8. The method of claim 3 , wherein the objective function further comprises a first fluence term and a second fluence term, wherein the first fluence term directs smooth fluence mapping between successive apertures of the plurality of apertures and the second fluence term directs fluence mapping with an average fluence intensity.

9. The method of claim 1 , wherein the method further comprises minimizing the objective function in the iterative optimization process to identify the plurality of apertures, each defined by a fluence, the aperture shape and a collimator rotation.

10. The method of claim 9 , wherein the method further comprises applying a Primal Dual Hybrid Gradient (“PDHG”) algorithm to minimize the objective function.

11. The method of claim 1 , wherein the method further comprises delivering the dynamic collimator VMAT plan using a VMAT system.

12. The method of claim 1 , wherein the dynamic collimator rotation includes a rotation of a collimator about a first axis that is different than an axis of rotation of a rotatable gantry that includes a radiation source.

13. A volumetric modulated arc therapy (“VMAT”) system comprising:

a radiation source configured to generate and direct radiation to a subject;

a gantry housing the radiation source and configured to rotate about an axis of rotation;

a control mechanism configured to control the rotation of the gantry and a delivery of radiation from the radiation source to a target volume in the subject; and

a computer in communication with the control mechanism, wherein the computer is configured to:

receive a representation of the subject comprising information related to target and non-target volumes of interest;

generate an objective function based on the representation of the subject, wherein the objective function accounts for dynamic collimator rotation;

perform an iterative optimization process using the objective function to generate a dynamic collimator VMAT plan;

identify an aperture shape for a plurality of apertures by minimizing the objective function in the iterative optimization process; and

generate and provide control signals to the control mechanism, in accordance with the dynamic collimator VMAT plan, to irradiate the subject.

14. The system of claim 13 , wherein the objective function comprises a first collimator term and a second collimator term.

15. The system of claim 14 , wherein the first collimator term calculates a cost of collimator rotation.

16. The system of claim 14 , wherein the second collimator term directs smooth collimator rotation between gantry angles.

17. The system of claim 14 , wherein the objective function further comprises a dose fidelity term that penalizes deviation from a prescription dose.

18. The system of claim 17 , wherein the dose fidelity term is an L2-norm term.

19. The system of claim 14 , wherein the objective function further comprises a first fluence term and a second fluence term, wherein the first fluence term directs smooth fluence mapping between successive apertures of the plurality of apertures and the second fluence term directs fluence mapping with an average fluence intensity.

20. The system of claim of claim 13 , wherein the dynamic collimator rotation includes a rotation of a collimator about a first axis that is different than the axis of rotation of the gantry housing.