The first dedicated dental Coolidge X-Ray tube, “The Right Angle Tube”, made by “Victor” introduced in 1919 by General Electric, running up to 50 kV and 10 mA, cooled by a multi-layer copper radiator, painted black, and mounted on the protruding anode shaft. Flat spiral filament cathode inside a focusing cup. Tungsten target embedded in the heavy copper anode. Note the directions of the anode and the cathode, at a right angle to one another.

               Note also the clear lead glass protective shield specially adapted to this tube. Previously, the tube was used almost naked with practically no protection to the operator or to the patient,  held in what used to be called “The Dental Gun”, equipped with a typical centering radio-lucent cone, but widely open on the sides.

               The advertisement, top right on this page,  probably the earliest known for this tube, appeared in the “Dental Cosmos”, in 1919.                  

                                                             (Ref:http://bium.univparis5.fr/sfhad/vol8/article10.htm)

After the advent of the line focus tube in 1922 (CHF Müller), late versions of  this Dental  Coolidge tube applied the line focus principle.  Note  on the  picture to the right, the change in the shape of the filament components, and the low angle of the anode-target combination, resulting in a better loadability of the tube.