1919 Coolidge Dental Tube

Ref. D4

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 black-painted copper radiator mounted on the protruding anode shaft.

Flat, slightly convex helical filament cathode inside a hemispheric focusing cup. Tungsten target embedded in the heavy copper anode. Anode and cathode, at a right angle to one another.

The pictures below show the “Dental Gun” assembly 22” (55 cm) long, and weighing some 7.5 lbs (3.5 Kg). They show the tube in its lead glass protection, with a cone centering device, and the bakelite high tension protection around the radiator (anode side) connection.

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

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 in 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 sharper X-ray pictures and improving the loadability of the tube.