The Effect of Anode, Hot and Cold Cathode Structures Used in Miniature X-Ray Tubes on X-Ray Output Using Monte Carlo Simulation

Abstract

This study aimed to investigate the use of carbon layers (cold cathode) as an alternative to tungsten metal (hot cathode) for electron production in miniature X-ray tubes in the field of electronic brachytherapy. The structural impact of these tubes on X-ray production was also analyzed. Using a Monte Carlo code, hemispherical-conical, hemispherical, and truncated-conical miniature X-ray tubes were simulated. Both cold and hot cathodes were utilized as electron sources to calculate the X-ray spectrum and dose in two directions. The results showed that the ratios of axial and transverse doses of spherical to cylindrical cold cathodes were respectively 5.4, 4.8, and 4.6, and 2.4, 2.2, and 1.9 in the hemispherical-conical, hemispherical, and truncated-conical miniature sources. In conclusion, the structure of the hemispherical-conical miniature X-ray tubes demonstrated better performance compared to the hemispherical and truncated-conical tubes. The different shapes of the cathode and anode in miniature X-ray tubes had a significant impact on the generation of output X-rays.