<P> Following Röntgen's work on X-rays in 1895, Clarence and his brother Charles worked on the development of the Edison X-ray focus tube, developing the fluoroscope using calcium tungstate . The Edison fluoroscope produced sharper images than the Röntgen fluoroscope, which used barium platinocyanide . At the time, the levels of X-rays produced were not believed to be dangerous . However, Edison noted how "the x-ray had affected poisonously my assistant, Mr. Dally ." </P> <P> By 1900, Clarence Dally was suffering radiation damage to his hands and face sufficient to require time off work . In 1902, one lesion on his left wrist was treated unsuccessfully with multiple skin grafts and eventually his left hand was amputated . An ulceration on his right hand necessitated the amputation of four fingers . </P> <P> These procedures failed to halt the progression of his carcinoma, and despite the amputation of his arms at the elbow and shoulder, he died from mediastinal cancer . Dally is thought to be the first American to die from the effects of experimentation with radiation . Following this, Thomas Edison abandoned his research on X-rays . In 1903, Edison said "Don't talk to me about X-rays, I am afraid of them ." </P>

Who is the researcher who lost his fingers hands and eventually his arms to radiation