Analytic comparison between X-ray fluorescence CT and K-edge CT.

X-ray fluorescence computed tomography (XFCT) and K-edge computed tomography (CT) are two important modalities to quantify a distribution of gold nanoparticles (GNPs) in a small animal for preclinical studies. It is valuable to determine which modality is more efficient for a given application. In this paper, we report a theoretical analysis in terms of signal-to-noise ratio (SNR) for the two modalities, showing that there is a threshold of GNPs concentration such that XFCT has a better SNR than K-edge CT when GNPs concentration is less than this threshold, vice versa. Numerical tests are performed for XFCT and K-edge CT on two kinds of phantoms with multiple concentration levels and structural features. Experimental results illustrate that XFCT is superior to K-edge CT when contrast concentration is lower than 0.4% which coincides with the theoretical analysis.