CMOS sensors excel at capturing visible light but require a "translator" for high-energy radiation. This deep dive explores how scintillators bridge that gap in X-ray imaging. We compare the high-resolution columnar structure of Caesium Iodide (CsI) against the rugged efficiency of Gadox (Gd2O2S), explaining how material choice, thickness, and MTF (Modulation Transfer Function) directly impact image clarity, patient safety, and industrial precision in 2026.