Apparatus for gauging and determining spatial coordinates for a source of radiation to be employed in obtaining a radiograph of a patient

A template-like gauge has a plate-like body which is at least in most part transparent and carries a reference point and a first plurality of parallel lines along with a read-out portion which in turn is made-up of second and third pluralities of lines to cooperatively define a plurality of gauge areas, each of the gauge areas represents a different set of coordinates for aiming an associated X-ray source; an additional plurality of radiating angularly spaced gauge lines are also provided; when the plate-like body is placed against a lateral cephalogram and the reference point is situated at the articulare and the palatal plane of the cephalogram is positioned at least parallel to one of the lines in the first plurality of parallel lines, the sella appears in one of the gauging areas and the coordinates corresponding thereto are employed for aiming the X-ray source.