Tehran University of Medical Sciences Frontiers in Biomedical Technologies 2345-5837 9 4 2022 03 05 291 296 Sara Khademi Mashhad University of Medical Sciences, Mashhad, Iran Hosein Azimian Mashhad University of Medical Sciences, Mashhad, Iran Hossein Ghadiri Department of Medical Physics and Biomedical Engineering, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran, Research Center for Molecular and Cellular Imaging, Tehran University of Medical Sciences, Tehran, Iran, Preclinical Core Facility, Tehran University of Medical Sciences, Tehran, Iran 2021 11 08 2021 12 12 Purpose: Gold Nanoparticles (GNPs) with high density and an atomic number have lately been proposed as an alternative contrast agent for Computed Tomography (CT). Materials and Methods: In the present study, the Contrast-to-Noise Ratio (CNR) of GNPs from various shapes, sizes, concentrations, and surface chemistry was compared with an iodine contrast agent using CT at different X-ray tube voltages and concentrations. Results: Our findings showed that GNPs in various concentrations, shapes, sizes, and X-ray tube energies from 80 to 140 kVp revealed greater image CNR than iodinated contrast media (Omnipaque). Smaller spherical GNPs (13 nm) had greater CNR than larger ones (60 nm) and Gold Nanorods )GNRs( with a larger Aspect Ratio (AR) represented excellent effect on CNR. In addition, Polyethylene Glycol (PEG) covering on GNRs decreased CNR. We observed image CNR was increased using increasing in kVp and concentration. Conclusion: Smaller spherical GNPs can be proposed as a potential candidate as a future contrast agent alternative to iodinated contrast media. https://fbt.tums.ac.ir/index.php/fbt/article/view/428 https://fbt.tums.ac.ir/index.php/fbt/article/download/428/249