[Evaluation of low-contrast resolution for liver image in digital phantom and clinical image]

The high performance of multi detector-row computed tomography (MDCT), enables a flow dynamic study of the liver that can be carried out within 10 seconds per one phase. In addition, it has been possible to obtain a stable image quality by utilizing the auto exposure control system. However, no clear standard of minimal CT value differences and minimal tumor sizes for detecting liver tumors has ever been shown. In order to help in their standardization, we developed novel software to make an arbitrary digital phantom. The limit of space occupied lesion (SOL) detection in each image quality could be determined by a detection study using digital phantoms superimposed on liver CT images. As a result, the detection rate of simulated tumors was significantly different, in comparisons of different image qualities for the late arterial phase and in comparison between the late arterial and equilibrium phases for the same image quality. Our method could help standardize the scan conditions for performing a liver CT.