Influence of Acquisition Parameters on Silver Sulfide Nanoparticle Contrast in Photon-Counting Digital Mammography: A Phantom Study

Photon-counting mammography is an emerging modality that allows for spectral imaging and provides a differentiation of material compositions. The development of photon-counting mammography-specific contrast agents has yet to be explored. In this study, the contrast, sensitivity, and organ dose between silver sulfide nanoparticles (Ag2S-NPs) and a clinically approved iodinated agent (iopamidol) were investigated using a contrast-embedded gradient ramp phantom and a prototype scanner. For a given agent, the signal intensity increased with concentration, tube voltage (kV), and high bin fraction, while remaining constant with the tube current exposure time product (mAs). Moreover, Ag2S-NPs produced significantly stronger contrast and improved sensitivity compared to iodine, especially when imaged at lower tube energies. Therefore, the use of photon-counting techniques and a silver-based contrast agent may markedly increase the contrast and contrast-to-noise ratios or reduce the radiation dose for contrast-enhanced mammography. Silver may be better suited than iodine for contrast agent development for spectral photon-counting mammography.