Simulation Study of Plasma Display Panel-Based Flat Panel X-Ray Detector

Abstract

Screen-film-based radiography is being rapidly replaced by digital radiography (DR). Thin-film-transistors (TFT) with amorphous silicon (a-Si) or amorphous selenium (a-Se) are usually used in DR X-ray imaging systems. Another flat panel display, plasma display panel (PDP), has a structure that is similar to that of the conventional gas type radiation detectors, and can be manufactured with lower costs than the TFT-based detector panels. The motivation of this study was to develop a cost-effective DR detector using the PDP. In order to apply the PDP technologies in gaseous detectors for X-ray imaging, we modified the pixel's structure and optimized the materials inside the PDP panel. To maximize the signal's intensity, we re-designed the panel's structure based on the gas microstrip detector (GMD), and estimated the performance of the proposed detector using the Monte Carlo simulation method. Signal intensity of gaseous detector is determined by the amount of ionization as well as by the avalanche effect. The ionization and avalanche processes were simulated using the Geant4 and Garfield, respectively. Four types of gas mixtures and various values of electric fields have been explored. The results show that a higher proportion of Xe helps to generate more ionization electrons. The results also suggest that the electric field, which is applied between anode and cathode strips, is a dominant factor for the avalanche effect to occur. In this study, the GMD structure was adopted for the plasma-display-panel-based X-ray detector. A quantitative verification of the effectiveness of the proposed structure was performed as well.