Encrypted login | home

Program Information

Alternative Geometries for X-Ray Fluorescence Computed Tomography (XFCT) Imaging of Gold Nanoparticles

C Dunning

C Dunning1*, M Bazalova-Carter1 , (1) University of Victoria, Victoria, BC


TH-AB-708-2 (Thursday, August 3, 2017) 7:30 AM - 9:30 AM Room: 708

Purpose: To explore different imaging geometries for X-ray Fluorescence CT (XFCT) imaging of gold nanoparticle (AuNP) solutions and determine the minimum concentration of AuNP that can be detected.

Methods: A cylindrical water phantom 2cm in diameter containing 0.5mm-2mm diameter vials with AuNP concentrations of 0.05%-0.4% by weight was modelled by FLUKA, a Monte Carlo software package. Two opposing square detector planes were placed 1 cm away from the edge of the phantom perpedicular to the beam, which scored K-shell and L-shell fluorescent x-rays with an energy resolution of 0.5keV and 0.2keV respectively. The phantom was irradiated to 30 mGy separately by a 15keV and 81keV monoenergetic photon beam of width 0.4mm to yield L-shell and K-shell x-ray fluorescence respectively by the presence of AuNPs, with 360 1-degree rotations. A pencil beam geometry (PBG) consisting of 55 steps served as the ideal case to create raytraced and filtered back-projected (FBP) images, while 55x55 pixel images generated using lead collimators had a fan beam geometry (FBG). Three types of collimators were considered: converging, parallel, and pinhole. The CNR was evaluated to find the lowest AuNP concentration for each image based on the Rose Criterion.

Results: The ideal raytraced L-shell PBG images yielded the lowest possible AuNP concentration detectable at 0.002%, while among the three collimator types the L-shell converging collimator image yielded the lowest minimum AuNP concentration at 0.013%. The L-shell image quality was superior to K-shell across all imaging geometries, however image quality degradation was significant for the K-shell FBG images.

Conclusion: This work demonstrates the feasibility of L-shell XFCT imaging for small animal studies using converging lead collimators which can detect AuNP concentrations approaching the level of ideal PBG images. An attenuation correction algorithm will be applied to the FBG images to further improve the image quality.

Contact Email: