Room: Karl Dean Ballroom C
Purpose: X-ray CT plays a pivotal role in diagnostic imaging, radiotherapy, and its indispensable contribution to preclinical small animal imaging research. It is possible to image recently developed molecular probes from high atomic number elements using X-rays-based novel emerging CT that uses energy-resolving-detectors. This study characterizes the distinctive energy spectrum of 3-mercaptobenzoic-acid (3MBA)-protected-144-atoms gold-nanoparticles (3MBA-Au-144-NPs) after X-ray excitation for the first time to the best of our knowledge.
Methods: We designed a four-chamber heart apex model using a 3D-printer. Each chamber was filled with different concentrations of 3MBA-Au-144-NPs. Thus, 0.1 mL of 3MBA-Au-144-NPs (17 mg/mL) was diluted with 0.0, 0.05, 0.1, and 0.2 mL of water. The X-ray system was equipped with a pencil beam collimator which was calibrated using a 1x1 inÂ² large radiochromic film. The tube was operated at 320 kVp with12.5 mA current and multiple filtration options were available for the X-ray excitation source. The resulting pencil beam had a 3.2â€‚mm diameter. Each sample chamber was irradiated for 2 minutes. The excited 3MBA-Au-144-NPs emitted fluorescent X-rays that were detected with CdTe and Silicon Drift (SD) detectors. The detectors and the probe sample chamber were shielded elaborately with lead to effectively suppress scatter background from the X-ray tube and provide a high sensitivity for the measurement.
Results: Two distinctive L-shell energy peaks were observed at 10KeV and 11.13KeV for 3MBA-Au-144-NPs in the energy spectrum of the SD detector. K-shell fluorescence events vanished in the Compton scatter and characteristic background of the tungsten source due to the lead shielding for the SD and CdTe detectors. The distinctive L-shell fluorescence energy peaks of 3MBA-Au-144-NPs are useful characteristic feature for molecular imaging. There is a space missing at 12.5KeV.
Conclusion: These distinct energy spectrum in the L-shell fluorescent energies render 3MBA-Au-144-NPs as a viable contrast agents for future XFCT imaging.