A deliverable four dimensional intensity modulated radiation therapy planning method is disclosed, for delivery using a linear accelerator with a dynamic multi-leaf collimator. A precursor is provided containing preselected constituents of a chromia- or alumina-forming Fe-, Fe, Ni, or Ni-based alloy, at least one of the constituents for forming a nanoscale precipitate MaXb where M is Cr, Nb, Ti, V, Zr, or Hf, individually and in combination, and X is C, N, O, B, individually and in combination, a=1 to 23 and b=1 to 6. When the engaging rib is inserted into the engaging slot and the engaging recess accepts the engaging projection, the socket body remains free from any adverse impact at its end portions and can thus be protected from damage. Optionally, a conductive layer may be deposited on a substrate in the multi-level waveguide.