Characterization of detector scintillator effect on interventional device visualization in X-ray fluoroscopy

Hat panel detectors have a large number of parameters that affect fluoroscopy image quality. Scintillator thickness is very important and can be changed in fabrication. In general, with increasing thickness, there is a degradation of MTF with spatial blurring but improved conversion efficiency. This design trade-off should be optimized for visualization. Using quantitative experimental and techniques, we simulated three detector models, including a direct detector and two indirect detectors with different scintillator thickness (160 and 210 mg/cm(2)) and displayed each "acquired" pixel directly on the screen without further processing in a sequence of fluoroscopy images. To measure image quality, we investigated detection of two interventional devices: stents and guide wires. Human observers and a channelized human observer model both demonstrated that detection depended on detector scintillator thickness and the type of interventional device. Detection performance was improved with the thicker scintillator, especially at low exposure. A simulated direct detector gave less blurring and even better detection performance for stent detection. The thick indirect detector gave contrast sensitivities equal to those for the direct detector for the case of guide wire detection. An ideal observer model gave trends similar to those for human observers, even though it does not account for many features of human viewing of image sequences and gives extraordinarily high detection SNR values because it uses all images in a sequence.