A Partial-Volume Correction for Quantitative Spectral X-Ray Radiography

The technique of spectral radiography has been shown to accurately discriminate a material's elemental composition by using known X-ray physics. In previous work, we presented a system for determining the total compositional mass of UO2 powder. This is achieved with a state-of-the-art pixelated spectrometer and a high-fidelity physical model. Similar to other radiographs, the system suffers from partial-volume attenuation where the sample projection onto a pixel is only a fraction of the pixel area, leaving the rest unattenuated. This study updates the physical model to account for fractional area which challenges the existing algorithm. We present how this update is made and explore approaches to stabilize the algorithm through parameter scaling, constrained optimization, and hyperparameter selection. We applied the updated algorithm to calculate the total uranium and oxygen mass of UO2 powder simulations. The average relative error on total uranium mass was reduced from 1.4% to 0.068% and on total oxygen mass from 122.2% to 4.2%.