A tomographic imaging apparatus includes an X-ray detector comprising a plurality of dual mode pixels and configured to detect radiation that has passed through an object, and at least one processor configured to obtain scan data from the X-ray detector, and control each pixel of the plurality of dual mode pixels to operate in one of a first mode and a second mode, wherein each pixel of the plurality of dual mode pixels includes a sensor configured to generate a scan signal by converting incident radiation into an electric signal, a first signal path circuit configured to transmit the scan signal in the first mode, a second signal path circuit configured to transmit the scan signal in the second mode, and a photon counter configured to count photons from the scan signal transmitted through one of the first and second signal path circuits.
