Experimental comparison of flat-panel detector performance for direct and indirect systems.

The purpose of this study was to compare direct and indirect detectors in terms of their presampled modulation transfer function (MTF), Wiener spectrum (WS), and noise-equivalent quanta (NEQ). Measurements were made on two flat-panel detectors, the GE Revolution XR/d (indirect) and Shimadzu Safire (direct) radiographic techniques. The presampled MTFs of the systems were measured using an edge method. The WS calculated the difference in uniform images that changed exposure to radiation using the two-dimensional Fourier method. The NEQ were assessed from the measured MTF, WS, and estimated signal-to-noise ratios (SNR). The system linearity was excellent in the direct Safire system. Presampled MTF was notably higher for the direct Safire system. For the direct Safire system, the WS was relatively uniform across all frequencies. In comparison, the indirect Revolution XR/d system exhibited a drop in the WS at high frequencies. At lower frequencies, the NEQ for the indirect Revolution XR/d system was noticeably higher than the direct Safire system. For the direct Safire system, the NEQ at mid to high spatial frequencies were higher linearity.