An X-ray grid orthometer including a support having a generally horizontal surface over which is disposed a frame swingable from side-to-side relative to a fixed indicator which permits alignment of the frame with an X-ray tube of an associated X-ray machine. The frame can be in the form of a slide bearing,...http://www.google.es/patents/US4202355?utm_source=gb-gplus-sharePatente US4202355 - X-ray grid orthometer
