Abstract: An airbox plug, for temporarily covering an airbox having an airbox opening and an airbox rim at the airbox opening. The airbox rim having a mounting bracket strip extending across the airbox rim. The mounting bracket strip has a mounting hole and a mounting core centered on the bracket strip. The airbox plug has a gasket cover having a top, bottom, and periphery, and a gasket mounted to the gasket cover bottom and corresponding with the periphery. A central bolt extends through the gasket cover and is partially surrounded on the bottom by a pair of complementary arcs. The airbox plug is installed to cover the airbox opening by engaging the central bolt into the mounting hole, engaging the mounting core with the complementary arcs to prevent the gasket cover from spinning as the gasket is tightened onto the airbox rim.

Abstract: A method of radiotherapy includes irradiating a treatment volume containing a high atomic number contrast medium with a photon beam characterized by a peak energy of at least 1 MeV and a mean energy in excess of 250 keV. The irradiation may be provided by a beam from a linear accelerator operating without a flattening filter. The linear accelerator may have multiple modes including one or more modes for operating with a flattening filter and one or modes for operating without a flattening filter.