TY - JOUR
AU1 - Cassen, Benedict
AB - Some Recent Contributions of Physics and Engineering Research to Radiology 1 Benedict Cassen , Ph.D. Westinghouse Research Laboratories, E. Pittsburgh, Penna. ↵ 1 Read before the Radiological Society of North America, at the Twenty-sixth Annual Meeting, Cleveland, Ohio, May 2–6, 1940. Excerpt The Following selected topics are illustrative of the recent contributions made by physics and engineering research to the science of Radiology. They are by no means intended to represent with any degree of completeness the constant procession of advance and improvement of radiological equipment. Also, other, competitive ways of accomplishing similar results can frequently b employed. Unfortunately, perhaps, the topics selected bear more upon radiography than therapy. Before discussing these topics, I should like to include a few words to help increase the appreciation by radiologists of the attainments of development engineers. Many projected advances look quite simple and straightforward when first assigned to an engineer to be made into an accomplished fact. In the vast majority of cases, however, unforeseen difficulties arise which, even though they may seem of a trivial nature, must be overcome in order to get results. Translating laboratory accomplishment into apparatus of high reliability for use by the non-engineer has almost always this troublesome characteristic. Ignitron Timing To begin with I shall describe the development of ignitron timing in high-speed, high-power radiography. In many modern radiographic installations using rotating anode tubes the power-supply line and voltage generating equipment must handle as much as 75 kilowatts for a small fraction of a second. This power, if not accurately timed and controlled, can do much damage. At 250 volts it represents a current of 300 amperes. Theoretically, a synchronous mechanical timer designed to open and close the circuit when the alternating current through it is at its zero value would be suitable. Due, however, to power factor changes in the load with voltage and milliamperages at variations, the time of zero current varies relatively to the voltage. This introduces more or less arcing at the contacts, with all its attendant troubles. A similar problem exists in electric spot welding where, also, an accurately controlled high power is necessary for a very short time. This latter problem has been neatly solved by the use of ignitron tubes. It would seem at first that the same method could be used directly in x-ray timing, but it soon became apparent that much more engineering development was necessary. Figure 1 shows diagrammatically a circuit that has been found satisfactory. Copyrighted 1941 by the Radiological Society of North America, Inc.
TI - Some Recent Contributions of Physics and Engineering Research to Radiology
JF - Radiology
DO - 10.1148/37.3.338
DA - 1941-09-01
UR - https://www.deepdyve.com/lp/radiological-society-of-north-america-inc/some-recent-contributions-of-physics-and-engineering-research-to-dGin8o1jW0
SP - 338
VL - 37
IS - 3
DP - DeepDyve
ER -