Accelerated X-Ray Fluorescence Computed Tomography via Multi-Pencil-Beam Excitation

TL;DR

This paper introduces a multi-pencil-beam excitation method for X-ray fluorescence computed tomography, significantly reducing imaging time while maintaining image quality, enabling more practical routine imaging of metal nanoparticles.

Contribution

The study develops a workflow combining Monte Carlo simulations and 3D printing to design multi-pencil-beam collimators, demonstrating up to 4x acceleration in XFCT imaging.

Findings

2x acceleration with 2-MPB collimator on physical phantom and small animals

Confirmed feasibility of at least 4x acceleration with 4-MPB in simulations

Potential to reduce imaging time from hours to minutes

Abstract

X-ray fluorescence computed tomography (XFCT), a form of X-ray molecular imaging, offers detailed quantitative imaging capabilities for high-Z metal nanoparticles (MNPs), which are widely studied for their applications in multifunctional theranostics. Due to its affordability and accessibility, the benchtop XFCT prototype typically employs a single-pixel detector (SPD) with single-pencil-beam (SPB) X-ray excitation. While this design (resembling the first-generation CT geometry) achieves reliable detection sensitivity, it is hindered by long imaging times. The use of simultaneous multiple-pencil-beam (MPB) excitation presents a promising solution to significantly reduce imaging times. In this study, we developed a repeatable workflow that combines Monte Carlo (MC) simulations and 3D printing to design Nbeam-MPB collimator, where Nbeam is the number of beams generated by the collimator. As an initial test, we fabricated a 2-MPB collimator and evaluated the performance of 2-MPB-based XFCT imaging on a physical phantom and small animals surgically implanted with agarose pellets containing gold chloride (H[AuCl4]). The results demonstrated a 2x acceleration in image acquisition without compromising the contrast-to-noise ratio (CNR). We further investigated the concept of Nbeam-MPB acceleration on the MC computational XFCT system, which confirmed the feasibility of achieving at least 4x acceleration with 4-MPB excitation. Combined with additional system optimization, such as X-ray beam flux optimization, XFCT imaging could be further accelerated, reducing acquisition time from hours to minutes and meeting the requirements for routine MNP imaging.