Spherical Hooded Anode

Coolidge Tube

This “Victor” Coolidge tube dates probably to the mid-twenties, before “Victor” became wholly owned by General Electric in 1926. Its peculiar spherical anode structure enclosing the tungsten target acts as a massive heat sink, while limiting the efficient radiation to the patient side of the tube.

In spite of its advantages compared to earlier Coolidge tubes, this tube type with its concentric helical filament, was relatively short-lived : The patent applied for in December 1923, was granted only in May 1929, well after the introduction by “Müller-Philips” of the “Media” line-focus type tube, the principle of which was widely adopted thereafter in the tube industry.

Starting with a cold target, this tube-type was intended for a maximum of 100mA,88kVp, and 5 seconds*. But the present discolored tube has certainly suffered some abuse. Although the filament is still intact in its focusing cup, and in spite of the multi-layered metal radiator, the tungsten target is severely pitted as seen through the lower opening of the anode sphere.

* Ed.C.Jerman, “Modern X-Ray Technic”, 1928, Bruce Publishing Company, p. 95

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