Spectral optimization of iodine-enhanced CT: Quantifying the effect of tube voltage on image quality and radiation exposure determined at an anthropomorphic phantom

•An experimental basis for spectral optimization of iodine-enhanced CT is presented.•Mutually consistent measurements are performed at an anthropomorphic body phantom.•Data analysis does not use prior knowledge on noise characteristics.•Low voltage CT substantially reduces radiation exposure while maintaining contrast.•Characteristic curves are derived that help to optimize iodine-contrast CT.