Analysis of absorption signal and noise in thin phosphor detectorsfor high-energy transmission radiography

Abstract

We investigated the detective quantum efficiency (DQE) of thin gadoliniumoxysulfide phosphor-based flat-panel detectors (FPDs) using cascaded-systemsanalysis and Monte Carlo (MC) simulations for applications in megavoltage(MV) x-ray industrial imaging. We decomposed the DQE formula into(dose-independent) upper-limit DQE and (dose-dependent) DQE-reductionfactors. We obtained the absorbed energy distributions (AEDs) forvarious x-ray detector designs and photon energies using MC simulationsand applied the AED analysis to the DQE formula. The investigationsexamined include the x-ray-detector-only DQE and the effect of thecoupling efficiency between the x-ray detector and readout panel,including electronic noise, on the upper-limit DQE. This study confirmsthat the design of the metal build-up layer on the phosphor is effectivefor MV imaging and emphasizes the importance of designing the readoutpanel to maintain the upper-limit DQE. We expect the proposed DQEanalysis to be suitable for designing and evaluating FPDs for high-energynondestructive x-ray testing.