hazard associated with excessive voltages was eliminated with the advent of all-solid-state TVs, which have no tubes other than the CRT. Since 1969, the FDA has limited TV X-ray emission to 0.5 mR (milliroentgen) per hour. With the switch from CRTs to other screen technologies starting in the 1990s, there are no vacuum tubes capable of emitting X-rays at all. See also Electron beam tomography Coronary angiography Synchrotron radiation X-ray fluorescence X-ray generator glass-to-metal-seal Patents Coolidge, , "X-ray tube" Langmuir, , "Method of and apparatus for controlling X-ray tubes Coolidge, , "X-ray tube" Coolidge, , "X-ray tube" References External links X-ray Tube - A Radiograph of an X-ray Tube The Cathode Ray Tube site NY State Society of Radiologic Sciences Collection of X-ray tubes by Grzegorz Jezierski of Poland Excillum AB, a manufacturer of metal-jet-anode microfocus x-ray tubes example of how X-ray tubes work. English inventions Radiology Tube Particle accelerators