Clinical CT has reached a very high performance level by now. The introduction of spiral scanning and of multirow detectors have allowed to image even large body sections in very short time and with isotropic, high spatial resolution of better than 1 mm. For further improvements with respect to detector technology the use of flat-panel detectors (FPD), which have been developed for radiographic applications, is currently under investigation. In this article we discuss the general demands on CT detectors and specifically the suitability of FPDs with respect to CT imaging. FPDs offer excellent performance for the imaging of high-contrast structures with high spatial resolution.Low-contrast resolution and dose efficiency, however, do not yet reach the level of performance of dedicated CT detectors; temporal resolution is also limited. FPDs appear primarily suited for special applications in CT as for example 3D angiography or intraoperative imaging which also allows for improvements in workflow. For standard diagnostic CT they are not to be recommended at present, last but not least for dose reasons. The respective technical developments will have to be reassessed constantly in the future. The development of detector systems which are equally suited for radiography and CT constitutes an attractive goal.