Development of a portable digital radiographic system based on FOP-coupled CMOS image sensor and its performance evaluation

As a continuation of our digital X-ray imaging sensor R&D, we have developed a cost-effective, portable, digital radiographic system based on a CMOS image sensor coupled with a fiber optic plate (FOP) and selected conventional scintillators. The imaging system consists of a commercially available CMOS image sensor of 48 μm × 48 μm pixel size and 49.2 mm × 49.3 mm active area, a FOP bundled with several millions of glass fibers of about 6 μm in diameter and 3 mm in thickness, phosphor screens such as Min-R or Lanex series, a readout IC board, a GUI software, and a battery-operated X-ray generator (20-60 kV_p; up to 1 mA). Here the FOP was incorporated into the imaging system to reduce the performance degradation of the CMOS sensor module caused by irradiation and also to improve image quality. In this paper, we described each imaging component of the fully-integrated portable digital radiographic system in detail, and also presented its performance analysis with experimental measurements and acquired X-ray images in terms of system response with exposure, contrast-to-noise ratio (CNR), modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE).