Monte Carlo Modeling of An Experimental Benchtop L-shell X-ray Fluorescence Imaging/CT System Adopting Two Silicone Drift Detectors

Authors

Neerajan Nepal
Amrit Kaphle
Sandun Jayarathna
Sang Hyun Cho

Language

English

Publication Date

3-1-2025

Journal

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

DOI

10.1016/j.nima.2024.170197

PMID

40894265

PMCID

PMC12393803

PubMedCentral® Posted Date

12-31-2025

PubMedCentral® Full Text Version

Author MSS

Abstract

L-shell x-ray fluorescence (XRF) photons induced from gold nanoparticles (GNPs) after being irradiated by an x-ray beam allow for highly sensitive XRF imaging/computed tomography (XFCT) of biological samples containing GNPs at low concentrations on the order of parts-per-million (ppm). The primary goal of this Monte Carlo (MC) study was to investigate the feasibility of upgrading an existing experimental benchtop XRF/XFCT imaging setup adopting a single silicon drift detector (SDD), developed based on the aforementioned concept (often known as L-shell XFCT), by deploying another SDD within the same setup. Specifically, an MC model of the original single SDD L-shell XFCT setup, along with a filtered 62 kVp polychromatic x-ray beam, was developed using the Geant4 MC toolkit, and added with a second SDD at an equidistance of 11 cm from the isocenter on the opposite side. Besides the aforementioned feasibility study, this MC model was used to investigate other parameters that may affect the system performance but cannot be easily tested experimentally (e.g., use of monoenergetic photon beams). Upon completion of MC studies, a new commercial SDD was experimentally characterized for optimal performance and deployed to an existing single SDD L-shell XFCT setup. The MC results demonstrated the feasibility of highly sensitive detection of gold L-shell XRF photons and XRF/XFCT imaging of GNP-containing phantoms using the modeled dual SDD setup. According to the MC results, the GNP detection limit achievable from the dual SDD setup can be in the range of 5 to 10 ppm with a filtered 62 kVp beam and slightly improved (down to ~5 ppm) with the monoenergetic x-ray beams (15 and 20 keV). The experimental results showed the new SDD performed optimally under the current experimental conditions at the manufacturer suggested bias voltage (−135 V). The experimentally measured detection limit from both old and new SDDs was 10 ppm, consistent with the MC results. In addition to the results summarized above, some additional benefits/characteristics from a dual SDD setup (e.g., 2-fold reduction in the sample scan time at a given dose or 2-fold improvement in the image resolution at a given scan time) are immediately discernable.

Keywords

X-ray fluorescence, Benchtop x-ray fluorescence imaging, Silicon Drift Detector, Gold nanoparticles

Published Open-Access

yes

Recommended Citation

Nepal, Neerajan; Kaphle, Amrit; Jayarathna, Sandun; et al., "Monte Carlo Modeling of An Experimental Benchtop L-shell X-ray Fluorescence Imaging/CT System Adopting Two Silicone Drift Detectors" (2025). Faculty, Staff and Student Publications. 5478.
https://digitalcommons.library.tmc.edu/uthgsbs_docs/5478