X-Ray Exposure in Manufacture and Operation of Certain Electronic Tubes

Abstract

The dangers of X-ray or radium-emanation exposure are well recognized and in most cases controlled in industry when it is known that they exist. When X-ray or radium is utilized for the examination, of industrial products or in radium-dial painting, proper controls are used, or at least there is a recognition of the potential dangers. Recently interest has been aroused in a possible similar hazard in the manufacture and operation of high-vacuum electronic tubes (1). We were confronted with a problem of this type and found on investigation that during the manufacture, testing, and operation of such tubes, measurable amounts of potentially harmful X-rays were produced. These tubes were tested or operated at voltages above 25 kilovolts. The presence of X-rays was detected with fluoroscopic screens and measured by means of the Victoreen minometer and dental X-ray films. A report by Daily (1) concluded that no harmful clinical effects resulted from exposure to a similar type of tube under normal operation. It is understood that since that report was written the voltages at which high-vacuum electronic tubes are operated have been increased, and it is believed that potential hazard now possibly exists, even under normal operating conditions. Although these tubes are not designed for production of X-rays, they are so constructed that they have the various elements necessary for X-ray emission. Commercial X-ray tubes are so constructed and shielded that the radiation is confined to a narrow beam. This is not true of the tubes in question and they may emit X-rays in many different directions.