An anode assembly (50) includes a thermally conductive bearing encasement (52) covering a portion of a bearing (64). An anode (56) rotates on the bearing (64) and has a target (58) with an associated focal spot (60). The thermally conductive bearing encasement (52) is configured and expansion limited to prevent displacement of the focal spot (60) of greater than a predetermined displacement during operation of the anode (56).