These various embodiments are employed in conjunction with the use of both a multi-leaf collimator and jaws that are interposed between a source of radiation and a treatment target while sourcing radiation from the source of radiation towards the treatment target. Generally speaking, during some portion of the aforementioned treatment, these teachings provide for manipulating the jaws to more tightly constrain, in at least one dimension, a beam-shaping aperture as is formed by the multi-leaf collimator. In many cases, as when the leaves of the multi-leaf collimator move back and forth horizontally, the foregoing can comprise manipulating the jaws in a vertical dimension