Development of an extremely soft x-ray generator

The development of an extremely soft x-ray generator with a tungsten-target tube and its applications including radiography are described. This generator consists of a high-voltage transformer, a filament power supply, and an x-ray tube. Negative high voltages are applied to the cathode electrode in the x-ray tube, and the tube voltage and current are regulated by the input voltage of the transformer and the filament voltage, respectively. The x-ray tube is a glass-enclosed double-focus diode with a tungsten target and a 0.2 mm-thick beryllium window. The maximum tube voltage and the electric power were 60 kV and 400 W, respectively. The focal-spot sizes were 4×4 (large) and 1×1 mm (small), respectively. Radiography was performed with a computed radiography system. In angiography using iodine-based microspheres, we observed fine blood vessels of about 50 μm or less with high contrasts. Using this generator, we designed an experimental setup for disinfection achieved with extremely soft x rays.