Metal Halide CsCu₂I₃ Flexible Scintillator with High Photodiode Spectral Compatibility for X-Ray Cone Beam Computed Tomography (CBCT) Imaging

Copper-based halides have emerged as promising scintillator materials for X-ray imaging due to their favorable photophysical characteristics, such as negligible self-absorption, high light output, and fast decay. Among these materials, Cs3Cu2I5, a blue emitter, currently delivers the highest scintillation light output under steady-state X-rays. However, there is a significant spectral mismatch between its emission band and the spectral responsivity of regular flat-panel photodiode arrays. In this study, a comprehensive analysis of the physical properties of the CsCu2I3 scintillator is conducted, and its perfect spectral compatibility is discovered, which results in a higher photodiode signal despite its relatively lower light output compared to typical Cs3Cu2I5 scintillators. Furthermore, CsCu2I3 exhibits faster light decay properties, making it especially suitable for Computed Tomography (CT) X-ray imaging. High-quality X-ray cone beam computed tomography (CBCT) imaging is successfully demonstrated using the fast-decaying CsCu2I3 scintillator screen. Additionally, the flexibility of the scintillator allows for non-planar imaging, showcasing advantages not available with traditional rigid scintillators. These results not only highlight the significant promise of the CsCu2I3 scintillator but also emphasize the necessity of considering spectral compatibility when designing novel scintillator materials.