Quantitative evaluation of Flat Panel detector scintillator effect on interventional device visualisation in x-ray fluoroscopy

Abstract

In Flat Panel (FP) detectors, fluoroscopy image quality is greatly affected by a variety of design and fabrication parameters. Among those parameters, the thickness of scintillator layer is very important and can be readily changed in fabrication. A thick scintillator layer can improve x-ray photon conversion efficiency but also degrade modulation transfer function due to a larger spatial blurring. It is proposed to optimise the selection of scintillator layer thickness for a better visualisation of small interventional devices. We applied quantitative experimental techniques and simulated three detector models including a direct detector and two indirect detectors. Two interventional devices, stent and guidewire, were investigated. Human observer experiments and computational model studies were conducted. Both of them demonstrate that the detection depends on the detector scintillator thickness and the structure of interventional device. At low x-ray exposures, a thick scintillator outperforms a thin scintillator in detection performance. A simulated direct detector has the least blurring in the images and hence gives even better detection performance for the stent detection. The thick indirect detector gives contrast sensitivities equal to those from the direct detector in the studies of guidewire detection and stent deployment.