Abstract:
An x-ray radiator has an x-ray tube disposed in a protective housing and a fastening means having a portion attached to the x-ray tube inside the housing, and a portion which extends through the housing to the exterior of the housing. The exterior portion serves as a fastener to attach the x-ray radiator to a mount. The x-ray tube, within the housing, thus becomes directly attached to the exterior mount, which improves the precision with which the specified position of the central ray of the x-ray beam emanating from the x-ray tube can be achieved.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is directed to an x-ray radiator of the type having an x-ray tube contained in a protective housing, and having an external fastening means for fastening the x-ray radiator to a mount. 
     2. Description of the Prior Art 
     X-ray radiators are usually constructed with the x-ray tube disposed in the protective housing mounted in a carrier which is, in turn, affixed to one of the interior walls of the housing. For mounting the x-ray radiator in an x-ray diagnostics apparatus, the housing is provided with an external fastener as described, for example, in Austrian Patent 144 813, U.S. Pat. No. 4,247,782, German GM 74 25 609 and U.S. Pat. No. 2,216,887. 
     A problem in such known structures is that the positional or attitudinal tolerances of the central ray of the x-ray beam which is generated by the x-ray tube within the x-ray radiator are not only dependent on the manufacturing tolerances of the external fastener and of the external mount, but are also dependent on the extent to which the position of the x-ray tube within the protective housing deviates from its specified position. Manufacturing tolerances as well as imprecisions in the assembly of the x-ray radiator can result in deviations of the position of the x-ray tube from its specified position. A significant outlay, with corresponding costs, is thus required in order to assure that the deviations in the position of the central ray from its specified position remain within permissible tolerances. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an x-ray radiator of the type having an x-ray tube contained in a protective housing wherein an improvement in maintaining the specified position of the central ray of x-ray beam emanating from the x-ray radiator are achieved in a simple manner and with little component outlay. 
     The above object is achieved in accordance with the principles of the present invention in an x-ray radiator having an x-ray tube and a protective housing in which the x-ray tube is contained, and a fastening means for fastening the x-ray radiator to an external mount, the fastening means having one end attached to the x-ray tube in the housing, and passing through a wall of the housing to the exterior of the housing for direct connection of the x-ray tube to the mount. The precision with which the central ray assumes its specified position relative to the fastening means is therefore dependent only on the precision with which the fastening means is attached to the x-ray tube. The precision with which the specified position of the central ray relative to the mount is achieved, when the x-ray radiator is attached to the mount, is dependent only on the precision with which the fastening means is attached to the x-ray tube, and on the manufacturing precision of the fastening means itself, because the x-ray tube is, in effect, directly attached to the mount by means of the fastening means. In the x-ray radiator constructed in accordance with the principles of the present invention, the position that the x-ray tube assumes within the protective housing is of no consequence with regard to the position of the central ray relative to the fastening means. In comparison to known x-ray radiators, it is much simpler in the x-ray radiator disclosed herein, and involves less outlay, to maintain the specified position of the central ray relative to the fastening means or relative to the mount, because there is no intervening carrier attaching the x-ray tube to the protective housing. 
     Since the fastening means will usually be formed of a metallic material, in one embodiment of the invention the x-ray tube includes an evacuated housing which is metallic at least in the region at which the fastening means is attached to the x-ray tube. This presents the possibility of joining the fastening means to the evacuated housing of the x-ray tube in a simple manner by soldering or welding. 
     In further embodiment of the invention, the protective housing is formed by multiple connected parts, with parts of the protective housing being respectively attached to the fastening means. A simple assembly of the x-ray radiator is thereby assured. Moreover, special measures for connecting the protective housing to the x-ray tube can be eliminated, since parts of the housing are attached to the fastening means, which is already present. 
     In order to provide the fastening means with a high degree of mechanical stability, it is preferable in a further embodiment of the invention to form the fastening means in the shape of a flange. It is also preferable in this embodiment that a part of the protective housing which is attached to the fastening means have a fastening flange, which preferably presses liquid-tight against the fastening means, since the protective housing is usually filled with a liquid coolant. 
     The x-ray tube is preferably a rotating anode x-ray tube, having an electric motor for driving the rotating anode, with the stator of this electric motor being attached to the fastening means and being disposed outside of the evacuated housing of the x-ray tube. This results in a simple and reliable holding of the stator. The stator can be attached directly to the fastening means, or can be attached thereto by an intervening bracket. In a further embodiment of the invention, the fastening means is provided with centering means for cooperating with corresponding centering means on the mount so as to align the fastening means at a specified position on the mount. The term &#34;centering means&#34; as used herein is used in its broadest sense, for example, as encompassing any type of mating and/or engaging parts such as annular or otherwise shaped projections or openings which interact with corresponding depressions, pins, screws, etc. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a longitudinal sectional view of an x-ray radiator constructed in accordance with the principles of the present invention, with only those components thereof necessary for explaining the invention being shown. 
     FIG. 2 is an enlarged sectional view of a detail of further embodiment of an x-ray radiator constructed in accordance with the principles of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The x-ray radiator constructed in accordance with the principles of the present invention shown in FIG. 1 includes an x-ray tube 1 of known construction. The x-ray tube 1 has an evacuated housing 2 which is metallic, with the exception of the required insulators, and is contained in a protective housing 3 which is filled with an electrically insulating coolant. The x-ray tube 3 is shown broken away in the region of its beam exit window 4, and is a rotating anode x-ray tube having an electric motor for driving the rotating anode in a known manner. The stator 5 of the electric motor is located outside of the evacuated housing 2, and surrounds a region of the x-ray tube 1 having a diminished diameter, in which the rotor (not visible in the drawing) of the electric motor is situated. 
     The x-ray radiator includes a fastening means, generally referenced 7, for attaching the x-ray radiator to an x-ray radiator mount 6 in an x-ray diagnostics apparatus, which may be a computer tomography apparatus, the remainder of which is not shown in detail in the drawings. The fastening means is in the form of an annular component having an approximately L-shaped cross section, and which is dynamically balanced relative to the central axis M of the x-ray tube 1. The fastening means 7 includes a hollow-cylindrical tube section 7a and a circular segment-shaped flange section 7b. The middle portion of the evacuated housing 2 of the x-ray tube 1 is received in the tube section 7a, this being the portion of the x-ray tube having a larger diameter in which the anode dish (not visible) is located. The glow cathode (also not visible) is disposed in the projection extending from the larger end face of the evacuated housing 2. The tube section 7a of the fastening means 7 is connected to the evacuated housing 2 by welding or soldering. 
     The flange section 7b of the fastening means 7 presses against the x-ray radiator mount 6 to which it is secured by screws, with only the center lines of two screws being shown in FIG. 1. The surface of the x-ray radiator mount 6 against which the flange section 7b presses has a circular countersink 9, having an outer diameter selected so that the countersink 9 and the outer circumferential edge of the flange section 7b interact so as to center the flange section 7b relative to the mount 6. 
     The x-ray tube 1 contained in the x-ray radiator is thus directly attached to the x-ray radiator mount 6 via the fastening means 7, in the sense that an interposition of the housing 3 between the x-ray tube 1 and the x-ray radiator mount 6 is avoided. The flange section 7b of the fastening means 7 thus emerges from the interior to the exterior through the protective housing 3. In the embodiment shown in FIG. 1, the protective housing 3 consists of two housing parts 3a and 3b, which are both shell-like, deep-drawn parts. The housing parts 3a and 3b have respective fastening flanges 10a and 10b which press liquid-tight against the flange section 7b, to which they are connected by screws, with the center lines of two such screws being shown in FIG. 1. If necessary, a known sealant may be disposed between the fastening flanges 10a and 10b and the fastening means 7. 
     The housing part 3a has a beam exit window 11 which is disposed in registry with the beam exit window 4 of the x-ray tube 1, so that the x-ray beam emanating from the x-ray tube 1, of which only the central ray Z is shown in FIG. 1, can emerge from the x-ray radiator. 
     Since the fastening means 7 in the x-ray radiator constructed in accordance with the principles of the present invention is directly attached to the x-ray tube 1, the precision with which the central ray Z assumes its specified position relative to the fastening means 7 is essentially dependent only on the precision with which the fastening means 7 is attached to the x-ray tube 1. The precision with which the central ray Z assumes its specified position with respect to the x-ray radiator mount 6, given an x-ray radiator attached thereto, is dependent only on the manufacturing precision of the fastening means 7 and of the x-ray radiator mount 6, and on the precision with which the fastening means 7 is attached to the x-ray tube 1. 
     The stator 5 is held by means of a fastening ring 12, which is screwed to the flange section 7b of the fastening means 7. The center lines of two screws are shown in FIG. 1. In order to enable circulation of the coolant contained in the protective housing 3, the fastening ring 12 is provided with a plurality of openings 13, one of which is visible in FIG. 1. Openings 14, only one of which is visible in FIG. 1, are provided in the tubular section 7a of the fastening means 7 for the same purpose. 
     A further embodiment of the invention is shown in FIG. 2, wherein parts coinciding with those described in connection with FIG. 1 have the same reference numerals. 
     In the embodiment of FIG. 2, the fastening means 7 is formed of two separate parts, and comprises an annular flange 7c in addition to the ring having the L-shaped cross section with the tube section 7a and the flange section 7b. The annular ring flange 7c is disposed at the region of the fastening means 7 which emerges toward the exterior through the protective housing 3, and is attached to the x-ray radiator mount 6. The connection of the annular flange 7c to the flange section 7b is undertaken by shear pins 16 which are pressed into corresponding bores 15, the shear pins 16 having shanks which extend through corresponding bores 17 in the flange section 7b. The shanks terminate in threaded ends, onto which nuts 18 are screwed. The fastening ring 12 of the stator 5 is received between the flange section 7b and the annular flange 7c. One housing part 3b of the protective housing 3 is welded liquid-tight to the annular flange 7c of the fastening means 7. The fastening flange 10b, which was present in the embodiment shown in FIG. 1, can thus be eliminated. The fastening flange 10a is joined to the housing part 3a by welding. The fastening flange 10a is pressed against the annular flange 7c with an O-ring seal 19 interposed therebetween. The housing part 3a is fastened to the annular flange 7c by one or more bolts 20, each provided with a nut 21. 
     As in the embodiment of FIG. 1, the tube section 7a is attached to a metallized region of the evacuated housing 2 of the x-ray tube 1 by welding. As also in the case of the embodiment of FIG. 1, the x-ray radiator mount 6 has a countersink 9. The countersink 9 cooperates with the outer circumferential edge of the annular flange 7c of the fastening means 7 for centering. 
     As is clear from the embodiment of FIG. 2, the fastening means 7 need not necessarily consist of a single part, however, the important common feature of the embodiments of FIGS. 1 and 2 is that a direct connection of the x-ray tube 1 to the x-ray radiator mount 6 is produced via the fastening means 7, such that the position which the x-ray tube 1 assumes within the protective housing 3 does not influence the position of the central ray relative to the fastening means 7, or relative to the x-ray radiator mount 6. 
     In the above embodiments, the fastening means 7 has been constructed so as to be dynamically balanced, or substantially dynamically balanced. This need not necessarily be the case, and the fastening means could be formed, for example, by a plurality of clips or brackets attached to the x-ray tube 1 which extend to the exterior through the protective housing 3, with which the x-ray radiator is attached to the x-ray radiator mount 6. 
     Moreover, the embodiments of FIGS. 1 and 2 have been designed to cooperate with existing radiator mounts 6 of known design, since such mounts 6 are already present in existing x-ray diagnostics installations, and thus the x-ray radiator with the fastening means disclosed herein can be used in such existing installations without modifying the installation itself. The x-ray radiator with the fastening means disclosed herein, however, can be effectively utilized with other types of mounts and different mount structures. Moreover, attachment of the fastening means to the x-ray tube 1 need not necessarily ensue by welding; other suitable forms of attachment are possible. 
     Lastly, the mounting of the stator 5 need not necessarily be undertaken as shown in the exemplary embodiments, although given the structure of the x-ray tube 1 shown in those embodiments, the manner of mounting the stator 5 is particularly advantageous. 
     Although modifications and changes may be suggested by those skilled in the art, it is the intention of the inventors to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of their contribution to the art.