TY - JOUR
AU - Corrigan, K. E.
AB - Further Development in Supervoltage Therapy Apparatus 1 T. Leucutia , M.D. and K. E. Corrigan , Ph.D. From the Department of Radiology, Harper Hospital Detroit ↵ 1 Presented before the Radiological Society of North America, at the Twenty-first Annual Meeting, at Detroit, Dec. 2–6, 1935. Excerpt THIS paper is the continuation, and, to some extent, an enlargement, of a similar one presented elsewhere (7) on the same subject about two years ago. It deals in the first instance with the latest development of supervoltage roentgen therapy apparatus, but also considers briefly certain other medical possibilities of extremely high voltages. Whereas it may be said that the general principles of engineering design in the high voltage field have been laid down in a most satisfactory way from the beginning, during the past two years numerous technical detail developments have been added which make a review of the entire question of construction worth while. (1) Sealed Vacuum Tubes —The development of sealed vacuum tubes for increasingly higher voltages has long formed a most intriguing problem of engineering research. From the point of view of therapeutic application, such a tube in appearance represents great simplicity of operation and hence is a most desirable instrument to the practical roentgenologist. However, the three following fundamental difficulties continue to place an upper limit to the engineering skill and ingenuity: the control of the cold cathode discharges, the screening off of the back diffusion electrons, and the assurance of a high vacuum. Through solution, in part or entirely, of some of these difficulties, the upper range of the sealed vacuum tube has been raised during the last year to 400 kv. constant (20 ma.), and Gross (6) a few months ago made public the characteristics of such a tube in a very comprehensive manner. An ever-increasing number of installations is now making good use of this tube (Fig. 1). Tubes Operating with a Continuous Pump —The above difficulties incited research also in another direction. It was thought that, by connecting the roentgen tube to a continuously evacuating pump, a sufficiently high vacuum could be obtained to insure satisfactory operation at increasingly higher voltages. In the beginning, mercury diffusion pumps were used but it was soon found that a liquid air trap had to be placed in the vacuum line between the last stage of the pump and the roentgen tube to remove the condensable mercury vapors collecting at normal temperature. This, then, although the pumping system was quite fast and efficient from the point of view of vacuum production, especially at higher voltages, had the drawback that a large amount of liquid air was consumed, entailing a great expense and considerable care to operate. In 1929, Burch (4) discovered that the method of evaporative distillation can be applied to some derivatives of petroleum, and that from these certain oils can be produced which have exceedingly low vapor pressure at atmospheric temperature. Copyrighted by The Radiological Society of North America, Inc.
TI - Further Development in Supervoltage Therapy Apparatus
JF - Radiology
DO - 10.1148/27.2.208
DA - 1936-08-01
UR - https://www.deepdyve.com/lp/radiological-society-of-north-america-inc/further-development-in-supervoltage-therapy-apparatus-I9YYdlQMds
SP - 208
VL - 27
IS - 2
DP - DeepDyve
ER -