Reduced acquisition time for L-shell x-ray fluorescence computed tomography using polycapillary x-ray optics.

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Physics

Background:

• X-ray fluorescence computed tomography (XFCT) is an advanced molecular imaging technique.
• It offers high atomic number contrast and deep tissue penetration, surpassing other modalities.
• Current limitations include lengthy acquisition times, hindering clinical translation.

Purpose of the Study:

• To demonstrate reduced acquisition times for L-shell XFCT imaging.
• To utilize x-ray focusing polycapillary optics for enhanced performance.
• To improve XFCT's feasibility for preclinical and clinical applications.

Main Methods:

• A prototype XFCT system with a custom polycapillary focusing optic was developed.
• The optic increased X-ray fluence rate by tenfold compared to standard collimation.
• Phantoms with varying gold concentrations were imaged using a silicon drift detector (SDD).

Main Results:

• XFCT acquisition time was reduced from 17 hours to under 1 hour.
• The polycapillary optic improved sensitivity by increasing fluence rate and reducing scatter.
• Gold concentrations as low as 60 μg/mL were visualized, with 300 μg/mL detected in a mouse phantom within 66 minutes.

Conclusions:

• High fluence rate from polycapillary x-ray sources significantly reduces signal integration time.
• L-shell XFCT can detect subtle contrast agent amounts within biologically relevant timeframes.
• Polycapillary x-ray source technology is suitable for preclinical L-shell XFCT; integrating more SDDs can further enhance sensitivity and reduce dose.