Apparatus for electron beam treatment of three-dimensional parts that includes cavities in a shielded rotating drum that preferably includes additional rotation mechanism for rotating parts within cavities in said drum. Radiation associated with the electron beam emitter is substantially shielded by the combination of the drum and the additional radiation shielding. The rotating drum is preferably made of at least four sections axially stacked, and its shielding properties are enhanced by including lead filled holes drilled in the sections.