X-radiation of an electron beam in a relativistic BWO

In relativistic e-beam microwave generators, the electrons that have passed through the slow wave structure tend to be dumped onto a collector, and a part of their energy is converted into X-rays. To protect the personnel from this ionizing radiation, the microwave sources driven by high current and high repetition rate electron beams are surrounded with a thick Pb shielding to attenuate the X-radiation. Relativistic microwave generators, however, envisage the use of special channels to extract the radiation, which may lead to an undesirable leakage of the X-radiation to outside. This fact should not be neglected when considering the personnel safety.