X-ray fluorescence tomography (XFCT) has potential for high-resolution 3D molecular x-ray bio-imaging. In this
technique the fluorescence signal from targeted nanoparticles (NPs) is measured, providing information about the spatial
distribution and concentration of the NPs inside the object. However, present laboratory XFCT systems typically have
limited spatial resolution (>1 mm) and suffer from long scan times and high radiation dose even at high NP
concentrations, mainly due to low efficiency and poor signal-to-noise ratio.
We have developed a laboratory XFCT system with high spatial resolution (sub-100 μm), low NP concentration and
vastly decreased scan times and dose, opening up the possibilities for in-vivo small-animal imaging research. The system
consists of a high-brightness liquid-metal-jet microfocus x-ray source, x-ray focusing optics and an energy-resolving
photon-counting detector. By using the source’s characteristic 24 keV line-emission together with carefully matched
molybdenum nanoparticles the Compton background is greatly reduced, increasing the SNR. Each measurement
provides information about the spatial distribution and concentration of the Mo nanoparticles. A filtered back-projection
method is used to produce the final XFCT image.