| 摘要 |
In an X-ray tube with metal casing (10), the cathode (22) of which is earthed and the anode (34) connected to a very-high positive electrical voltage source (78), a metal dish (46) is fitted for protecting the anode (34) against return of the electrons which have rebounded on it. This dish (46) is fixed to the wall (12) of the casing (10) using an insulating support (54). The anode (34) is arranged at the bottom of the dish (46) and is electrically connected to it. An opening (60) and an X-ray transparent window (58) are made in the walls of the dish (46) and of the casing (10) respectively. In this way, the extra-focal X-rays produced by the secondary electrons do not contribute to the working beam (61) of the X-rays produced. The invention is applicable to medical, especially mammary, radiography. <IMAGE>
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