Novel irradiation side sampling system flexible flat panel detectors with high image quality and light weight

Cassette type digital radiography detectors consisting of indirect conversion flat panel detectors (FPDs) find extensive applications in general radiography. Recently, these detectors are being employed not only for conventional hospital and clinical use but also in the field of home medical care. Therefore, image quality improvement, X-ray dose reduction, and weight reduction are essential for such detectors. To achieve these goals, we have developed novel FPDs with high image quality and light weight by combining the irradiation side sampling (ISS) system technology and flexible photodiode and thin film transistor (PD-TFT) technology. The ISS system enables effective detection of light emitted from a scintillator near the photodiode, resulting in higher sensitivity and resolution than those obtained with common penetration side sampling (PSS) systems. In addition, by employing a 40-μm flexible polyimide film as the PD-TFT array substrate instead of a conventional 0.5-mm rigid glass, the X-ray attenuation and scattering at the substrate are expected to be reduced, resulting in further improvements in sensitivity and resolution. We have developed two types of ISS system flexible FPDs with Gd2O2S:Tb (GOS) and CsI as scintillators. These FPDs realized higher sensitivities, modulation transfer functions, and detective quantum efficiencies than the conventional ISS system rigid FPDs for both the scintillators. In addition, we achieved approximately 35% weight reduction with the flexible FPDs compared to similarly sized conventional rigid FPDs.