Extremely soft x-ray generator and its applications

The development of an extremely soft x-ray generator with a tungsten-target tube and its applications to radiography and disinfection are described. This generator consists of a high-voltage power supply, 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 of a 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 electric power were 60 kV and 400 W, respectively. The focal-spot sizes were 4×4 (large) and 1×1 mm (small), respectively. Extremely soft radiography was performed with a computed radiography system, and we observed fine blood vessels of about 100 μm with high contrasts. Using this generator, we performed the disinfection achieved with extremely soft x rays.