Possibilities of Deep X-Ray Therapy with the Coolidge Water-Cooled Tube and Heavier Transformers

Abstract

THE purpose of this paper is not to describe any new form of therapy, but to present the apparatus and technic of a more intense application of X-rays than has hitherto been employed in treatment. Treatment of deep-seated lesions with X-radiations has progressed markedly within the past few years. The American type of closed, oil-encased transformer superseded the German open-core type; the gas tube was replaced by the hot cathode tube; machines thus came into use which could function continuously over many hours at a potential of two hundred thousand volts and an intensity of four or five milliamperes. The rays emitted were of a longer wave length and far less penetration than the gamma rays of radium, but possessed a beneficial therapeutic action in the field of malignancy and allied conditions, a form of ray therapy being thus developed by which treatment could be rapidly administered over a wide area, including the growth and its lymphatic connections. The search continued for more powerful transformers and for a type of vacuum tube which could carry higher amperage and higher voltage. A year ago Coolidge reported a water-cooled tube which with adequate transformers generates a far more powerful X-ray beam than has as yet been achieved in X-ray manufacture.2 We have been operating a Wappler machine (Fig. 1) functioning at two hundred thousand volts and four milliamperes for a couple of years, with complete satisfaction and uniformly gratifying results. When Coolidge perfected his invention, however, we hastened to install one of his water-cooled tubes for the sake of the heavier output promised. None of the stock transformers on the market appeared to have sufficient capacity to deliver a stable output at this high amperage and voltage; so we appealed to Dr. Waite of the Waite and Bartlett Manufacturing Company of Long Island City, N. Y. Dr. Waite constructed special heavy transformers which have proven most reliable. Working with this system, we have a complete water circulation under forty to fifty pounds pressure; the X-ray tube is kept at an even low temperature during its excitation by the flow of water through a seamless coil of copper pipe behind the tungsten target. A large automobile radiator of copper mesh with an eighteen-inch fan serves to maintain the low temperature of the water system. The X-ray tube is eight inches in diameter. There is a projecting molybdenum pin in the filament spiral which produces a more uniform heat gradient by producing a large focal spot. We have been able to operate this machine at two hundred and fifty thousand volts and fifty milliamperes, but for practical purposes of treatment we use two hundred and forty thousand volts and forty milliamperes. Advantages of the Water-Cooled Tube Comparative electroscopic measurements of this new device and of our old two hundred thousand volt machine prove the former apparatus to possess twenty times the power generated by the old machine.