Thomas Alva Edison

Thomas Alva Edison's reputation was well established by the time X rays were discovered in November, 1895. He had received patents for hundreds of inventions, including those for the motion picture camera and the first practical incandescent light. Upon learning of Röntgen's discovery, Edison set about assembling the necessary equipment to investigate this new phenomenon. Because X-ray tubes were difficult to obtain, Edison manufactured his own, something he was well equipped to do owing to his work with incandescent lights. In fact, some of his original X-ray tubes were little more than modified electric light bulbs. Edison's investigations into X rays were wide ranging but most of his initial research was devoted to improving upon the barium platinocyanide fluorescent screens used to view X ray images (Röntgen had discovered X rays by the fluorescence they created from a screen of barium platinocyanide.) After investigating several thousand materials, Edison concluded that calcium tungstate was far more effective than barium platinocyanide. By March of 1896, Edison had incorporated this material into a device he called the Vitascope (later called a fluoroscope), that consisted of a tapered box with a calcium tungstate screen and a viewing port. Similar devices already had been developed, but Edison's version quickly became the standard tool by which physicians viewed X-ray images. During the course of these investigations, Clarence Dally, one of Edison's most dependable assistants, developed a degenerative skin disorder which progressed into a carcinoma. In 1904, Dally succumbed to his injuries - the first radiation related death in the United States. Immediately, Edison halted all his X-ray research noting "the X rays had affected poisonously my assistant, Mr. Dally..."

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