Retrofitting of a Novel X-Ray Fluorescence Imaging Setup Adopting Two Silicone Drift Detectors into a Commercial Cabinet Preclinical Irradiator
Abstract
Purpose
This work aimed to retrofit a novel x-ray fluorescence (XRF) imaging setup adopting two silicon drift detectors (SDD) into a commercial cabinet preclinical irradiator for highly sensitive quantitative imaging of metal nanoparticles (MNPs) such as gold nanoparticles (GNPs) present in biological samples (e.g., tumor tissues) from preclinical studies.
Methods
A novel portable XRF imaging setup from this work included two SDDs placed perpendicular to the beam direction, facing each other at opposite sides of the imaging object at an 8-cm isocenter-to-detector distance. Each detector was coupled with a 5-cm long stainless-steel collimator with a 2-mm diameter aperture. The imaging object was positioned on top of two motorized translation stages at a 26.5-cm source-to-isocenter distance and irradiated by a 62-kVp beam (filtered by 0.08-mm copper and 0.4-mm aluminum at 30 mA). Eppendorf tubes containing varying concentrations of GNPs were irradiated first for 60 s per tube to establish the calibration curve. Subsequently, a slab phantom (15×15×3.5 mm3) containing three 12-mm long square-shaped holes (2mm×2mm) were scanned (60 s per scan position) through horizontal and vertical translations with a 1.3-mm step size, to evaluate the imaging performance of the system. Custom software was developed to enable synchronized XRF data acquisition and automated stage motion. The acquired gold L-shell XRF signals, after background removal, were corrected for attenuation of both incident and XRF photons using the Compton scatter-based algorithm.
Results
The corrected XRF signals were linearly proportional to GNP concentrations. A GNP detection limit of ~25 parts-per-million/ppm was achieved. The slab phantom imaging clearly differentiated regions containing 1000, 0, 500 ppm GNPs, demonstrating quantitative imaging capability of the system.
Conclusion
A novel XRF imaging setup was successfully developed and integrated into a commercial cabinet irradiator. This work demonstrated the feasibility/effectiveness of the retrofitting-based approach for routine/widespread uses of XRF imaging with MNPs/GNPs.