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TH‐AB‐204‐09: High‐Sensitivity L‐Shell X‐Ray Fluorescence CT Imaging of Gold
Author(s) -
BazalovaCarter M,
Ahmad M,
Xing L,
Fahrig R
Publication year - 2015
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4926176
Subject(s) - imaging phantom , optics , detector , materials science , physics
Purpose: To experimentally demonstrate the feasibility of L‐shell x‐ray fluorescence CT (XFCT) imaging of gold contrast. Methods: We have built an experimental L‐shell XFCT imaging system consisting of two photon‐counting detectors, a silicon drift detector (SDD) and a CdTe detector, a miniature x‐ray tube, and a programmable translation/rotation stage. A 2.8‐mm diameter water phantom containing 4‐mm vials with gold solutions of 0.06%, 0.08%, and 0.1% Au located at 4mm depth was constructed. The phantom was imaged with the L‐shell XFCT system in 1st generation CT geometry with a 1‐mm 50‐kV x‐ray beam. XFCT data was acquired with both detectors placed at ±120° with respect to the excitation beam at 30 translation and 36 rotation steps. L‐shell XFCT images were reconstructed with maximum‐likelihood expectation‐maximization using gold Lα and Lβ fluorescence x‐rays for both detectors. Results: SDD L‐ shell x‐ray fluorescence (XRF) signal was approximately 13 times higher than CdTe XRF signal due to the higher measured SDD energy resolution of 220eV @ 14keV compared to the CdTe energy resolution of 660eV. While all 0.06–0.1% Au vials were detectable in the SDD L‐shell XFCT image, none of the vials were visible in the CdTe L‐shell XFCT image. The contrast‐to‐noise ratio of the 0.1% Au vial was 87.1 and 3.2 in the SDD and CdTe L‐shell XFCT images, respectively. SDD L‐shell XFCT signal was linear with Au concentration (R2>0.99). The detectability limits of the presented L‐shell XFCT imaging setup were 0.007% and 0.126% Au for L‐shell XFCT imaging performed with the SDD and CdTe detector, respectively. Conclusion: We have demonstrated the feasibility of L‐ shell XFCT imaging of gold located at shallow depths inside a small animal sized phantom. The very high sensitivity of L‐shell XFCT, permitting detection of Au concentrations as low as 0.06%, has not previously been achieved experimentally using conventional K‐shell XFCT.