Methods and apparatus for the planning and delivery of radiation treatments
Methods and apparatus are provided for planning and delivering radiation treatments by modalities which involve moving a radiation source along a trajectory relative to a subject while delivering radiation to the subject. In some embodiments the radiation source is moved continuously along the trajectory while in some embodiments the radiation source is moved intermittently. Some embodiments involve the optimization of the radiation delivery plan to meet various optimization goals while meeting a number of constraints. For each of a number of control points along a trajectory, a radiation delivery plan may comprise: a set of motion axes parameters, a set of beam shape parameters and a beam intensity.
1. A method for planning delivery of radiation dose to a target area within a subject, the method comprising:
defining a set of one or more optimization goals for delivery of radiation via a radiation delivery apparatus, the set of one or more optimization goals comprising a desired dose distribution in the subject;
specifying an initial plurality of control points along an initial trajectory, the initial trajectory involving movement of the radiation deliver apparatus and corresponding relative movement between a radiation source and the subject in a source trajectory direction; and
iteratively optimizing a simulated dose distribution relative to the set of one or more optimization goals to determine one or more radiation delivery parameters associated with each of the initial plurality of control points;
wherein, for each of the initial plurality of control points, the one or more radiation delivery parameters comprise positions of a plurality of leaves of a multi-leaf collimator (MLC) of the radiation delivery apparatus, the plurality of leaves moveable in a leaf-translation direction;
effecting movement of the radiation delivery apparatus and corresponding relative movement between the radiation source and the subject along the initial trajectory in the source trajectory direction;
while effecting movement of the radiation delivery apparatus and corresponding relative movement between the radiation source and the subject, moving the plurality of leaves of the multi-leaf collimator in the leaf-translation direction so that the positions of the leaves at each of the initial plurality of control points meet the one or more radiation delivery parameters determined in the iterative optimization; and
wherein during relative movement between the radiation source and the subject along the initial trajectory, the leaf-translation direction is oriented at a MLC orientation angle φ with respect to the source trajectory direction and wherein an absolute value of the MLC orientation angle φ satisfies 0°<|φ|<90°;
wherein the initial trajectory comprises first and second locations wherein a first beam directed from the radiation source toward the subject from the first location and a second beam directed from the radiation source toward the subject from the second location are substantially parallel but opposing one another.
2. A planning method according to claim 1 wherein the absolute value of the MLC orientation angle co satisfies 15°<=|φ|<=75°.
3. A planning method according to claim 1 wherein the absolute value of the MLC orientation angle go satisfies 30°<=|φ|<=60°.
4. A planning method according to claim 3 wherein the MLC orientation angle φ is constant throughout the initial trajectory.
5. A planning method according to claim 3 wherein the initial trajectory comprises a plurality of arcs, each arc involving relative movement between the radiation source and the subject within a corresponding plane.
6. A planning method according to claim 5 wherein, between a first one and a successive one of the plurality of arcs, the initial trajectory comprises inter-arc relative movement between the radiation source and the subject, the inter-arc relative movement comprising movement such that the corresponding planes associated with each arc intersect one another.
7. A planning method according to claim 5 wherein, between a first one and a successive one of the plurality of arcs, the initial trajectory comprises inter-arc relative movement between the radiation source and the subject, the inter-arc relative movement comprising movement such that the corresponding planes associated with each arc are parallel with one another.
8. A planning method according to claim 3 comprising, upon reaching one or more initial termination conditions:
adding one or more additional control points to obtain an increased plurality of control points;
iteratively optimizing the simulated dose distribution relative to the set of one or more optimization goals to determine one or more radiation delivery parameters associated with each of the increased plurality of control points.
9. A planning method according to claim 1 wherein the MLC orientation angle φ is constant throughout the initial trajectory.
10. A planning method according to claim 1 wherein the initial trajectory comprises a plurality of arcs, each arc involving relative movement between the radiation source and the subject within a corresponding plane.
11. A planning method according to claim 10 wherein, between a first one and a successive one of the plurality of arcs, the initial trajectory comprises inter-arc relative movement between the radiation source and the subject, the inter-arc relative movement comprising movement such that the corresponding planes associated with each arc intersect one another.
12. A planning method according to claim 10 wherein, between a first one and a successive one of the plurality of arcs, the initial trajectory comprises inter-arc relative movement between the radiation source and the subject, the inter-arc relative movement comprising movement such that the corresponding planes associated with each arc are parallel with one another.
13. A planning method according to claim 1 comprising, upon reaching one or more initial termination conditions:
adding one or more additional control points to obtain an increased plurality of control points;
iteratively optimizing the simulated dose distribution relative to the set of one or more optimization goals to determine one or more radiation delivery parameters associated with each of the increased plurality of control points.
14. A planning method according to claim 1 wherein the initial trajectory is confined to one or more planes defined by the radiation delivery apparatus.
15. A planning method according to claim 14 wherein the one or more planes are defined by motion axes of the radiation delivery apparatus.
16. A planning method according to claim 15 wherein the one or more planes are defined by rotation of the radiation delivery apparatus about a rotation axis of the radiation delivery apparatus.
17. A planning method according to claim 1 wherein the subject is a living subject.