Experimental optimization of detector pixel size for stent visualization in X-ray fluoroscopy

To visualize small interventional device such as stent in angiographic x-ray fluoroscopy, detector pixels must be sufficiently small to limit contrast dilution for partial-area effects. However, X-ray photon number per pixel and pixel signal-to-noise ratio (SNR) are decreasing with the smaller pixels. There must be a size in between with improved visualization. Using quantitative experimental and modeling techniques, we determined the optimal pixel sizes for visualization of a stent 50 /spl mu/m in wire diameter for different detector types. With regard to detecting the presence of a stent, with an idealized direct detector, the 100 /spl mu/m pixel size resulted in maximum measured contrast sensitivity. For the idealized indirect detector, optimal pixel size reaches at 200 /spl mu/m pixel size. With regard to stent deployment, the target is smaller, and the result is more sensitive to pixel size, resulting in a steeper drop in performance with large pixels. We also applied a spatial-temporal channelized human observer model to predict and fit to the experiment results.