X-ray machine comprising an x-ray detector mounted with a relative mobility on a support, wherein the detector and the support are enclosed in a first and a second respective cover elements, the second cover element of the detector being mobile with relation to the first cover element of the support, the detector and the support being connected together by means for connecting that traverse apertures of the cover elements, the means for connecting being surrounded by a cover element having opposite ends, a first end being fixed directly to the aperture of the first cover element and a second end being fixed to a positioning flange whose shape is adapted to the shape of the aperture of the second cover element and means for joining cooperating with complementary means for provided on the detector for the flange to position the second end of the cover element, in all relative positions of the detector with relation to its support, in such a way that the position of the second end corresponds to the position of the aperture of the second cover element after installation of the latter on the detector.