High-Spatial-Resolution Benchtop X-ray Fluorescence Imaging through Bragg-Diffraction-Based Focusing with Bent Mosaic...

Area of Science:

• Medical Imaging
• Nanotechnology
• Materials Science

Background:

• X-ray fluorescence imaging (XFI) enables high-resolution localization of nanoparticle (NP)-based probes for diagnostics and therapy.
• Current in vivo XFI systems are limited to lighter elements (Z≤45) for high spatial resolution.
• There is a need for XFI techniques capable of imaging mid-Z elements (42≤Z≤64) in vivo at high resolution.

Purpose of the Study:

• To investigate the feasibility of using mosaic graphite crystal ellipsoidal lenses to focus hard X-rays.
• To enable high-resolution in vivo XFI for mid-Z elements using conventional X-ray tubes.
• To assess the sensitivity and resolution of this focusing-optics concept for preclinical applications.

Main Methods:

• Monte Carlo simulations were employed to characterize the proposed focusing-optics concept.
• In silico tumor-bearing mice models were utilized, loaded with palladium (Pd) and barium (Ba) NPs.
• XFI sensitivity was quantitatively predicted under various dose exposure scenarios.

Main Results:

• The minimum detectable mass of PdNPs per scan position is predicted to be in the hundreds of nanograms under in vivo conditions.
• Detection of PdNP masses as low as 50-150 ng is feasible with a 600 μm resolution.
• Successful imaging of abdominal tumor lesions was simulated across low-dose (0.8 μGy) to high-dose (8 μGy) exposures.

Conclusions:

• The proposed hard X-ray focusing-optics concept using mosaic graphite crystals is a promising step towards high-resolution in vivo XFI.
• This approach could enable the use of conventional X-ray tubes for advanced XFI applications with novel NP formulations.
• The technology has the potential to improve diagnostic and theranostic capabilities using mid-Z elements.