【Device Papers】β−Ga₂O₃ a Potential Scintillator for Photon Counting X-Ray Detectors

      Researchers from the Delft University of Technology have published a dissertation titled "β−Ga₂O₃ a Potential Scintillator for Photon Counting X-Ray Detectors" in 2025 IEEE Nuclear Science Symposium (NSS), Medical Imaging Conference (MIC) and Room Temperature Semiconductor Detector Conference (RTSD).

Abstract

      Photon-counting computed tomography (PCCT) offers a compelling opportunity to significantly reduce patient radiation dose while simultaneously improving contrast-to-noise ratio [1]. With the growing interest in PCCT, the demand for cost-effective alternatives to current semiconductorbased direct-conversion detectors has become increasingly apparent. Although direct-conversion detectors enable X-ray photon counting, the production of high-quality cadmium-telluride or CZT layers remains costly and complex. Challenges such as charge sharing and material defects continue to limit both image quality and detector performance in direct conversion detectors. Recent studies have demonstrated that indirect-conversion detectors based on scintillators not only represent a feasible alternative, but may even offer distinct advantages, including improved spectral fidelity [2]–[4]. Nevertheless, the requirements for scintillators for photon-counting applications remain stringent. In this work, we investigate the use of beta gallium oxide (β−Ga₂O₃) as a potential scintillator for photon-counting CT detectors. Previous studies have shown that β-Ga₂O₃ exhibits an excellent primary decay time constant of 2 ns, an energy resolution of approximately 7 % at 662 keV, and a light yield of around 8 photons per keV. Here, we present an in-depth characterization of β-Ga₂O₃, including measurements of self-absorption, nonproportionality, decay time, and afterglow. To evaluate the performance of β−Ga₂O₃ under realistic operating conditions, we furthermore couple β−Ga₂O₃ crystals to SiPMs and assess the resulting pulse shape. Preliminary results are consistent with earlier findings, yet reveal two additional long decay components: one with a decay constant of 34.3 ns (accounting for ∼26% of total intensity) and another with 367 ns (with ∼7% intensity), which may affect counting and spectral performance.

DOI：

https://doi.org/10.1109/NSS/MIC/RTSD57106.2025.11287763