Optimizing contrast and spatial resolution in hard x-ray tomography of medically relevant tissues

Abstract

Hard x-ray tomography with Paganin's widespread single-distance phase retrieval filter improves the contrast-to-noise ratio (CNR) while reducing spatial resolution (SR). We demonstrate that a Gaussian filter provided larger CNR at high SR with interpretable density measurements for two medically relevant soft tissue samples. Paganin's filter produced larger CNR at low SR, though a priori assumptions were generally false and image quality gains diminish for CNR > 1. Therefore, simple absorption measurements of low-Z specimens combined with Gaussian filtering can provide improved image quality and model-independent density measurements compared to single-distance phase retrieval.