[en] We are studying a method to decrease dose exposure in x-ray CT examination, for CT is one of the powerful tools in finding tumors. In this paper, an energy subtraction method is applied to CT imaging. The CT imaging of the energy subtraction method is compared with that of the current measurement method. It is found that the CT imaging of the energy subtraction method is more sensitive to the Iodine contrast media than that of the current measurement method. The results showed that the imaging by energy subtraction method had obvious advantages over that of the current measurement method. (author)