Exploring New Frontiers in X-ray Quantum Limited Portal Imaging Using Active Matrix Flat-panel Imagers (AMFPIs)

摘要

In recent years, indirect detection active matrix flat-panel imagers (AMFPIs) have become the gold standard in radiotherapy imaging. The excellent imaging performance of AMFPI-based electronic portal imaging devices (EPIDs) can be attributed to their ability to perform x-ray quantum limited imaging under radiotherapy conditions. However, all current commercial (AMFPI and non-AMFPI) EPIDs use only ～1% to 2% of the incident radiation. In this work, strategies to significantly improve the overall performance of indirect detection AMFPI-based EPIDs through novel designs, are presented. Specifically, the focus of this work is on thick, structured scintillators, which achieve high x-ray detection efficiency while simultaneously maintaining spatial resolution. Fundamental signal and noise measurements using prototype, small area, structured scintillators are reported. In addition, theoretical calculations were performed in order to estimate the signal and noise properties of various structured scintillator configurations. Results from theory and experiments were used to estimate the frequency-dependent detective quantum efficiency (DQE). Results suggest that these designs could yield DQE values that are significantly higher than those for current commercial EPID technologies.