A carbon nanotube (CNT) emitter-based high-speed micro-computed tomography (CT) system is designed herein. CT scans result in prolonged exposure to radiation, thus, pulsed-field emission is performed to generate pulsed X-rays to reduce radiation dose. The radiation dose rates of continuous X-rays and X-rays generated by different pulses were compared. X-rays were stably generated 40 times per second through a pulsed-field emission current with MOSFET circuit. The CNT field emitter characteristic was maintained for more than 35 hours continuously, which means more than 5 million X-ray shots can be taken when sufficient current flows on pulse mode. X-ray images were also successfully acquired through such pulse driving.
A Carbon nanotube (CNT) cold cathode emitter-based compact X-ray tube for X-ray application is studied in this paper. In the electron gun, the conventional filament was replaced by CNT emitter; CNTs were grown on metal alloy substrate. Using this electron gun, electron emission can be controlled by applying voltage rather than heating. Up to 2 mA tube current can be generated by this CNT electron gun. Also, the pulsed tube current and pulsed radiation dose can be generated by using MOSFET circuit. We measured the radiation dose generated in 30 frames per second, and confirmed that the waveform was generated as a square wave. From that waveform, it was confirmed that unnecessary radiation exposure can be minimized. The body of the X-ray tube is made of ceramic, which has strong durability against impact and high temperature. The ceramic used for the tube has an insulation distance of 30 mm and shows stable insulation performance in an environment where a voltage of 70 kV is applied. Using this X-ray tube, we successfully obtained X-ray images of various objects with acceleration voltages between 45 kV and 70 kV.
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