X-ray tube with reverse position focal spot

Claim 1

AN X-RAY TUBE COMPRISING AN ELONGATE ENVELOPE, A CATHODE MOUNTED IN ONE END OF SAID ENVELOPE AND A ROTARY ANODE IN THE OPPOSITE END, SAID ANODE COMPRISING A ROTOR AND A STEM PROTRUDING COAXIALLY FROM SAID ROTOR TOWARD SAID CATHODE, A CIRCULAR, DISC LIKE TARGET MEMBER HAVING A FRONT AND A REAR FACE AND HAVING A CENTRAL APERTURE RECEIVING THE DISTAL END OF SAID STEM, SAID STEM HAVING A SHOULDER THEREON SPACED FROM SAID DISTAL END ENGAGING SAID TARGET MEMBER REAR FACE, SAID DISTAL STEM END BEING THREADED, A FASTENER ELEMENT SECURED ON SAID STEM AND ENGAGING SAID TARGET MEMBER FRONT FACE TO CLAMP THE TARGET MEMBER AGAINST SAID SHOULDER, SAID TARGET MEMBER HAVING ON ITS FRONT FACE AN ANNULAR TARGET AREA THE SURFACE OF WHICH IS PLANE AND PERPENDICULAR TO THE AXIS OF SAID STEM, MEANS IN SAID CATHODE FOR GENERATING AND FOCUSING UPON SAID TARGET AREA A BEAM OF ELECTRONS RECTANGULAR IN CROSS SECTION AND HAVING ITS LONGER AXIS EXTENDING RADIALLY WITH RESPECT TO SAID STEM AXIS, THE CENTRAL PORTION OF SAID TARGET MEMBER BEING INDENTED WITH RESPECT TO SAID SURFACE, SAID FASTENER ELEMENT HAVING A HEIGHT LESS THAN THE AMOUNT OF SAID INDENTATION SO THAT NO PORTION OF SAID ELEMENT PROJECTS BEYOND THE PLANE OF SAID TARGET AREA, WHEREUPON SAID FASTENER ELEMENT DOES NOT PROJECT INTO THE USEFUL BEAM OF X-RAYS EMITTED FROM THE FOCAL SPOT OF SAID ELECTRON BEAM AS VIEWED FROM A POSITION DIAMETRICALLY OPPOSITE SAID FOCAL SPOT WITH RESPECT TO SAID STEM AXIS.