Tungsten Target Optimization for Photon Fluence Maximization of a Transmission-Type Flat-Panel X-Ray Source by Monte Carlo Simulation and Experimental Measurement

• Published in: IEEE transactions on radiation and plasma medical sciences Vol. 2; no. 5; pp. 452 - 458
• Main Authors: Wang, Kun, Xu, Yuan, Chen, Daokun, Zhang, Guofu, Zhang, Zhipeng, She, Juncong, Deng, Shaozhi, Xu, Ningsheng, Chen, Jun
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01.09.2018; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Anodes; Cathode rays; Cold cathodes; Computer simulation; Current sources; Detectors; Electric potential; Figure of merit; Flat-panel X-ray source; Fluence; Glass; II-VI semiconductor materials; Image resolution; Monte Carlo (MC) simulation; Monte Carlo simulation; Nanotechnology; Nanowires; Optimization; Photonics; Photons; Target thickness; Thin films; transmission-type target; Tungsten; Voltage; X ray absorption; X ray sources; X-ray imaging; X-rays; Zinc oxide
• ISSN: 2469-7311; 2469-7303
• DOI: 10.1109/TRPMS.2018.2849099

The cold cathode flat-panel X-ray source is a new type of X-ray source with advantage of smaller footprint and lower-dose imaging than current sources. In this paper, we optimized the thickness of the anode target of a flat-panel X-ray source to maximize the photon fluence of X-rays generated from the device. Utilizing EGSnrc-based Monte Carlo code, X-ray fluence was calculate from the simulated photons deposited in the virtual detector. These results revealed an optimal target thickness at a specific anode voltage to maximize the output of X-ray intensity. For experimental validation, tungsten thin film anodes with different thicknesses were prepared, and a flat-panel X-ray source was fabricated using a ZnO nanowire cold cathode. A figure of merit was introduced to characterize the output efficiency of the X-rays. The experimental results agree well with the simulation results, showing an optimal tungsten-target thickness of 1200 nm at an anode voltage of 40 kV. Using a flat-panel X-ray source with the optimized anode thickness, we took X-ray absorption images of both biological and nonbiological subjects, and high-resolution images were demonstrated.