TREATING A TREATMENT VOLUME WITH THERAPEUTIC RADIATION USING A MULTI-LEAF COLLIMATION SYSTEM
A control circuit optimizes a radiation treatment plan for a patient treatment volume using an automatically iterating optimization process that optimizes as a function, at least in part, of predetermined cost functions, wherein at least one of the cost functions favors apertures for the multi-leaf collimation system having local curvature that deviates only minimally from a reference curvature. By one approach the control circuit determines the reference curvature as a function, at least in part, of at least one of setting the reference curvature to a static minimal local curvature, a shape of a projective mapping of the treatment volume onto an isocenter plane, and/or a fluence map associated with an amount of radiation to be administered to the treatment volume from a particular direction. By one approach the control circuit dynamically determines when to employ one or more such cost functions.
1 . An apparatus to facilitate treating a patient's treatment volume with therapeutic radiation using a multi-leaf collimation system, the apparatus comprising:
a control circuit configured to:
determine a reference curvature as a function, at least in part, of relative differences of a plurality of laterally adjacent leaf-widths of the multi-leaf collimation system; and
optimize a radiation treatment plan for the patient's treatment volume using an automatically iterating optimization process that optimizes as a function, at least in part, of predetermined cost functions, wherein at least one of the cost functions favors apertures for the multi-leaf collimation system having local curvature that deviates only minimally from the reference curvature by increasing a cost associated with increasing deviations of the local curvature with respect to the reference curvature; and
a radiation treatment platform operably configured to administer the therapeutic radiation to the patient in accordance with the radiation treatment plan as optimized by the control circuit.
2 . The apparatus of claim 1 wherein the control circuit is further configured to determine the reference curvature as a function, at least in part, of at least one of:
a shape of a projective mapping of the treatment volume onto an isocenter plane; and
a fluence map associated with an amount of radiation to be administered to the treatment volume from a particular direction.
3 . The apparatus of claim 1 wherein the control circuit is further configured to determine when to selectively employ the at least one of the cost functions that favors apertures for the multi-leaf collimation system having local curvature that deviates only minimally from the reference curvature.
4 . The apparatus of claim 3 wherein the control circuit is further configured to determine when to selectively employ the at least one of the cost functions that favors apertures for the multi-leaf collimation system having local curvature that deviates only minimally from the reference curvature as a function, at least in part, of at least one of:
anatomy for the patient; and
remaining fluence to be administered per the radiation treatment plan.
5 . The apparatus of claim 3 wherein the control circuit is further configured to determine when to selectively employ the at least one of the cost functions that favors apertures for the multi-leaf collimation system having local curvature that deviates only minimally from the reference curvature by selecting when to switch amongst a plurality of different reference curvatures.
6 . The apparatus of claim 1 wherein at least another of the cost functions favors larger apertures for the multi-leaf collimation system.
7 . The apparatus of claim 6 wherein the control circuit is further configured to determine when to selectively employ the at least one of the cost functions that favors larger apertures for the multi-leaf collimation system.
8 . The apparatus of claim 7 wherein the control circuit is configured to determine whether to selectively employ the at least one of the cost functions that favors larger apertures for the multi-leaf collimation system for one or more pairs of laterally adjacent leaves in the multi-leaf collimation system.
9 . The apparatus of claim 1 wherein the multi-leaf collimation system comprises a multi-layer multi-leaf collimator.
10 . An apparatus to facilitate treating a patient's treatment volume with therapeutic radiation using a multi-leaf collimation system, the apparatus comprising:
a control circuit configured to:
determine a reference curvature as a function, at least in part, of relative differences of a plurality of laterally adjacent leaf-widths of the multi-leaf collimation system; and
optimize a radiation treatment plan for the patient's treatment volume using an automatically iterating optimization process that optimizes as a function, at least in part, of predetermined cost functions, wherein at least a first one of the cost functions favors apertures for the multi-leaf collimation system having local curvature that deviates only minimally from the reference curvature, by increasing a cost associated with increasing deviations of the local curvature with respect to the reference curvature, and a second one of the cost functions favors larger apertures for the multi-leaf collimation system; and
a radiation treatment platform operably configured to administer the therapeutic radiation to the patient in accordance with the radiation treatment plan as optimized by the control circuit.
11 . The apparatus of claim 10 wherein the control circuit is further configured to determine when to selectively employ the first one of the cost functions and the second one of the cost functions.