Means for preventing excessive heating of an X-ray tube window

摘要

An x-ray tube includes an envelope (13) defining an evacuated chamber and having a window (30) transmissive to x-rays. An anode assembly and a cathode assembly operate within the envelope to produce x-rays which travel through the window transmissive to x-rays towards a patient or subject under examination. A shield transmissive (32) to x-rays is coupled to the envelope and positioned such that x-rays travelling through the window transmissive to x-rays must first travel through the shield. The shield prevents substantially all secondary electrons created during the production of x-rays from coming into contact with the window transmissive to x-rays thereby preventing excessive heating of the window transmissive to x-rays. An electrode (50) defined by the envelope in a region proximate the window transmissive to x-rays may additionally or alternatively be used to prevent secondary electrons from reaching the window transmissive to x-rays. <IMAGE>