Room: Davidson Ballroom B
Purpose: To investigate the performance of a transmission computed tomography (CT) component implemented within the same platform of an experimental benchtop x-ray fluorescence CT (XFCT) for multimodal XFCT+CT imaging applications.
Methods: The transmission CT component within the current experimental benchtop XFCT system consisted of an industrial high-power (~ 3 kW) x-ray source, a CMOS-based panel x-ray detector, and a rotational stage. Cone-beam CT scans were performed with a cylindrically-shaped 3-D printed PMMA phantom (3cm in diameter/7 cm in height) containing six spirally-placed inserts (2 mm in diameter) loaded with various concentrations (0.05-1 wt. %) of gold nanoparticles (GNPs). A commercial CT QA phantom containing 3D line pair (LP) targets was also scanned. Two different tube voltages, 40 and 62 kVp, in combination with three current settings (2.5, 5, and 10 mA), were used. A filter made of 0.4 mm Al and 0.08 mm Cu was used for all CT scans. Other parameters for CT scans were 17 ms of the exposure time per projection, 150 mm of the source-to-object (phantom center) distance, and 115 mm of the object (phantom center)-to-detector distance. Order-subset simultaneous algebraic reconstruction technique, in conjunction with an improved distance-driven model and Total Variation-minimization methods, were used to reconstruct the images. Sparse projection and short-scan were considered to reduce x-ray dose. Contrast-to-Noise Ratio (CNR) and Modulation Transform Function (MTF) were calculated.
Results: The detectable concentration of GNPs (based on CNR>4) was 0.2 wt. % based on the images reconstructed using 80 (0.76 cGy) and 360 (11.74 cGy) projections for 40 and 62 kVp beams (at 10 mA), respectively. The MTF (50 %) was between 10LP/CM and 11LP/CM.
Conclusion: The transmission CT component within the current experimental benchtop XFCT system produces the images deemed acceptable for multimodal imaging purposes, while requiring no more than 1 cGy of x-ray dose.
Funding Support, Disclosures, and Conflict of Interest: Supported by NIH/NIBIB R01EB020658