LAUSR

The exacerbation of inherent light scattering with increasing scintillator thickness poses a major challenge for balancing the thickness‐dependent spatial resolution and scintillation brightness in X‐ray imaging scintillators. Herein, a thick pixelated needle‐like array scintillator capable of micrometer resolution is fabricated via waveguide structure engineering. Specifically, this involves integrating a straightforward low‐temperature melting process of manganese halide with an aluminum‐clad capillary template. In this waveguide structure, the oriented scintillation photons propagate along the well‐aligned scintillator and are confined within individual pixels by the aluminum reflective cladding, as substantiated from the comprehensive analysis including laser diffraction experiments. Consequently, thanks to isolated light‐crosstalk channels and robust light output due to increased thickness, ultrahigh spatial resolutions of 60.8 and 51.7 lp mm−1 at a modulation transfer function (MTF) of 0.2 are achieved on 0.5 mm and even 1 mm thick scintillators, respectively, which both exceed the pore diameter of the capillary arrays’ template (Φ = 10 µm). As far as it is known, these micrometer resolutions are among the highest reported metal halide scintillators and are never demonstrated on such thick scintillators. Here an avenue is presented to the demand for thick scintillators in high‐resolution X‐ray imaging across diverse scientific and practical fields.