Determine first information regarding physical-movement limitations pertaining to at least one multi-leaf collimator and also determine second information regarding movement of the treatment target with respect to the given patient. Then, while optimizing a radiation-treatment leaf-sequence plan, constrain individually-planned leaf positions as a function, at least in part, of the first information, the second information, and planned positions of adjacent leaves. By one approach, the first information can comprise information regarding a speed (such as a maximum speed) at which individual leaves of the multi-leaf collimator are able to move during a treatment session. By one approach, the second information can comprise information regarding a distance (such as a maximum distance) that one or more parts of the treatment target may possibly move as compared to a presumed position used during the optimizing of the radiation-treatment leaf-sequence plan.