The invention is directed to an x-ray device and method for radiation treatment comprising an x-ray source 1, a collimator 4 incorporating conditional optics, such as a capillary lens 3 for directing and focusing the x-ray radiation, and implantable needles. One or more capillary semilenses 16, 17 are positioned along the optical axis of the x-ray beam allow to form a movable focus by changing the distance between the semilenses. The input end of the collimator 4 is optically and mechanically conjugated with the x-ray source 1. The output end of the collimator is optically and mechanically conjugated with an originating end of the needle 5. At its output end is a transparent window 6 on which can repose a layer 13 that substantially absorbs and re-emits radiation which passes through the window 6.