Abstract: A mechanism for moving an X-ray source around the patient's head so that the image of an object, having shape of the dental arch, can be obtained on the film, the mechanism including a stationary frame, a rotatably movable support arm with an X-ray source and a film holder attached to its opposite ends on different sides of the object to be radiographed, and means for moving the center of rotation of the support arm rectilinearly during the radiographing, throughout the procedure in the same direction, perpendicular to the axis of symmetry of the dental arch, in such a manner that the position of the center of rotation in its rectilinear movement is dependent on the angular position of the support arm at any given moment, with the purpose of directing the X-ray beam from the X-ray source so that at any given moment it is substantially perpendicular to that part of the object which has the shape of the dental arch.

Abstract: A mechanism for moving an X-ray source around the patient's head so that the image of an object, having shape of the dental arch, can be obtained on the film, the mechanism including a stationary frame, a rotatably movable support arm with an X-ray source and a film holder attached to its opposite ends on different sides of the object to be radiographed, and means for moving the center of rotation of the support arm rectilinearly during the radio-graphing, throughout the procedure in the same direction, perpendicular to the axis of symmetry of the dental arch, in such a manner that the position of the center of rotation in its rectilinear movement is dependent on the angular position of the support arm at any given moment, with the purpose of directing the X-ray beam from the X-ray source so that at any given moment it is substantially perpendicular to that part of the object which has the shape of the dental arch.