Development of quality control system for flat-panel detectors

The characteristics of flat-panel detectors (FPD) are degraded by exposure to radiation. Degradation in a FPD progresses locally and has a nonlinear relationship to the radiation dose. In order to manage FPD systems properly, one must perform quality control (QC) such as evaluation of image degradation. However, no evaluation method for degradation has been established. In this paper, we first review the structure and degradation mechanism of FPDs, and then we propose a daily QC system for FPDs. To evaluate the degradation of FPDs, we investigated the number of defective pixels and lines, as well as the offset level of the pixel output. Furthermore, we developed daily QC software for FPD that can evaluate the image quality and is operationally simple. In the experiments, an indirect-conversion type FPD was evaluated by our proposed system. The offset level of FPD increased exponentially with X-ray exposure; no trends were seen for the number of defective pixels and defective lines. The required time for the evaluation of an FPD was about 1 min, and no special skills were needed for the analysis. These results indicate that our system may be useful for daily QC of FPDs.