Photon-counting detectors (PCDs) are replacing energy integrating detectors in electromagnetic wave transmission
imaging to achieve high performance. The purpose of this study was to develop an indirect PCD system for
transmission imaging. The detector module is a combination of scintillator and SiPM, the SiPM is insensitive to
magnetic field and operating at low voltage. A 2D array of a GAGG coupled with SiPM, positioning logic circuit,
and preamplifier were enclosed in housing that sealed from light. A channel reduction circuit was used to
identify the channel from the positioning logic circuit, and then output an analog pulse signal corresponding to
the valid channel. The pulse signal measurements were performed using a oscilloscope. The profile analysis of
the flood map confirmed that each point was distinct in both the center and peripheral regions. Additionally,
the letters engraved on the phantom in the images were confirmed. Therefore, the indirect PCD system has
potential for transmission imaging. Our future work will design an indirect PCD for low-energy photon detection
and multi-energy imaging.